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Biology 30
Module 4
Organic Variation
Lesson 15
Genetic Variation and Biotechnology
Copyright: Ministry of Education, Saskatchewan
May be reproduced for educational purposes
Biology 30
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Lesson 15
Biology 30
50
Lesson 15
Lesson 15 Genetic Variation and
Biotechnology
Directions for completing the lesson:
Text References for suggested reading:


Read BSCS: An Ecological Approach
Pages 199-220, 323, 552-558
OR
Nelson Biology
Pages 502, 658-665, 673-675
Study the instructional portion of the lesson.

Review the vocabulary list.


Do the practice problems.
Do Assignment 15.
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Lesson 15
Vocabulary
adaptive radiation
anthropoids
biotechnology
chemical nature of cells
coevolution
convergent evolution
divergent evolution
functional changes
gene pool
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genetic equilibrium
genetic drift
Hardy-Weinberg Law
population genetics
speciation
species
structural changes
transgenic
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Lesson 15
Lesson 15 – Genetic Variation and
Biotechnology
Introduction
Organic variations or the evolving of life forms have been examined from several
perspectives now. Evidences of changes, peoples’ attitudes and thoughts about
them, and the “how” and the “why” of such changes, have been presented on the
basis of the most current information. One should keep in mind the rapidity with
which new information is being uncovered. This means that today’s theories or
conclusions about origins and changes in life in the past and present, could be
modified or changed very shortly.
In the early history of primate development, the human role in the changes occurring
to the physical and biotic aspects of environments was minimal – almost as a passive
participant. Gradually, expansion of culture and knowledge allowed humans to exert
increasing dominance over other living forms, as well as to modify and control
physical conditions. By doing so, a passive participant in many aspects of evolution
began to assume a more active role. Through hunting, domestications of plants and
animals and then modifications of habitats for agriculture, humans began to control
the direction of change of many species around them. More rapid gains in knowledge
have led to the developments of more complex tools, machines and processes. The
uses of these have placed humans into a present position of easily being able to
sustain or to extinguish the lives of many other organisms. Technology has also
reached the stage where there are more attempts, with varying degrees of success, to
“design” or to change species by altering their genetic components. This means that
humans could exert increasing control in the ways some species, including humans
themselves, could evolve or change.
This lesson will examine some technologies and the human use of these, especially in
relation to changing species or “creating” new ones. In doing so, it will probably
bring out issues and questions that are even now being discussed and debated in
public. Many of these relate to how far humans should go in manipulating genetic
identities of organisms, the procedures that should be followed, the reasons for doing
so, and how the outcomes should be utilized. The opinions, viewpoints and
convictions of individuals and groups will no doubt be as varied and as strongly
voiced as those for origins of life and evolution.
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Lesson 15
After completing this lesson you should be able to:
•
define “gene pools” and explain the Hardy-Weinberg Law with
respect to gene pools.
•
define genetic drift and discuss some of the conditions which could
promote it.
•
discuss speciation, especially with respect to the manner in which
it may occur.
•
describe some of the roles humans may play in speciation.
•
explain what coevolution is and why it occurs.
•
discuss primate evolution, with a particular emphasis on the
human line.
•
explain the meaning of biotechnology.
•
discuss the general impact that artificial selection has on gene
pools and species changes.
•
describe the relationships between habitat modifications, species
numbers and genetic pool diversities.
•
explain the meaning of cultural evolution and identify some
examples.
•
describe some of the effects of agriculture, primarily of the western
methods utilizing extensive cultivation and monoculture, on
evolution.
•
recognize some of the effects of social-economic conditions of
human populations on natural resources and species.
•
summarize some of the abilities scientists now have in the area of
genetic engineering and the implications these have for species
changes.
•
discuss some effects that transgenic plant or animal varieties could
have on prairie agriculture.
•
recognize and consider some of the questions and issues that will
be receiving more attention, as the human ability to manipulate
genetic changes grows.
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Lesson 15
Population Genetics and Applications to Evolution
Much of what has been described and discussed thus far has included beliefs,
generalizations and theories. These have been based on what has passed down
through generations or various physical and geological evidences from the past.
Scientific explanations and theories have been subject to changes or modifications,
as new methods of gathering information and new knowledge or evidences have
appeared. The areas of genetics and population studies have played prominent roles
in the last one hundred years. These areas have been able to supply new information
to help answer one of the questions which has been bothering evolutionists for so
long – that is, how evolution possibly proceeded in species. This section will look at
some of these areas of information.
Genetic Variation and Natural Selection
For a species or population to change, variations must first appear in the body or
cell characteristics of some individuals. In other lessons it was pointed out that the
main sources of variation are:

genetic recombinations, during meiosis and fertilization in the process of sexual
reproduction.

Another major source of variations is mutation. Again, mutagens and mutations
were examined in earlier lessons. Chromosomal and gene changes can have
varying effects in cells and organisms, depending on which genes are involved and
how many of them are included in a change.
An important consideration from a species standpoint is whether or not these
variations can be passed on from an individual to its offspring. There would be little
effect on a species if a mutation should occur in a body cell rather than a germ cell or
gamete, for that new characteristic would not be passed on.
Variations also have little or no benefit to a species if individuals are sterile or are
incapable of passing on their genes to a large number of offspring. The latter
situation is often evident in animal groups where males and/or females assume
orders of dominance and only certain individuals engage in reproduction.
The ability of some individuals to leave more offspring than others is usually related
to natural selection. Any particular environment has selective forces (or limiting
factors) favouring the survival of organisms having certain traits. Abiotic or biotic
selective forces could include such factors as climatic conditions, landscape features,
food supplies, predators and others. Organisms which have characteristics enabling
them to better deal with a particular environment at a particular time, are considered
to be well-adapted. Such individuals are more likely to survive and are also usually
the best reproducers. In a way, the process of natural selection “directs” changes in
populations through the reproductive abilities of individuals.
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Lesson 15
Genetic variation and natural selection can lead to diversities of many kinds. These
can range from:




Hardly noticeable structural changes in cells to visible changes in body organs or
parts.
Structural changes are often accompanied by various degrees of functional
changes. A species in which webs may have developed between the toes of feet
may then use its feet more for swimming than land use.
Besides structural and functional changes, alterations could also appear in the
chemical nature (biochemistry) of cells or organisms and even in the general
behaviours of some organisms.
At certain times of the year, a species may experience significant behavioural
changes from those at other times of the year. Reproductive behaviours often
change the appearances or behaviours of individuals in many species. Mutations
affecting such appearances or behaviours could have significant effects on the
reproductive successes of individuals involved. Separation or fragmentation of
groups within species and such conditions as isolation from each other and
different selective forces (environments) could lead to the development of entirely
different species.
Population Genetics and the Hardy-Weinberg Law
Population genetics is concerned with the relative frequencies of dominant and
recessive alleles in a population of interbreeding organisms.
Geneticists doing population studies use the term gene pool to refer to all the
possible genes within a population at a given time. If a species or population was
to change or evolve over time, it means that a change must take place in its gene
pool. A change in a gene pool could involve the appearance of new genes from either
mutations or an inflow from other populations. Certain genes could disappear,
especially if they are dominant and new selective forces begin to act against them, or
if a population is small and some individuals leave. The usual change in gene pools
involves the frequency of individual alleles or genes. Rather then appearing or
disappearing, the numbers of particular ones will either rise or fall.
A population is in genetic equilibrium when the gene pool remains constant from
one generation to the next. Conditions must be “ideal” for genetic equilibrium to
occur. The ideal conditions would be as follows:
1. The population must be very large.
2. The mating must be random.
3. The population is isolated. There are no net movements of genes in or out of the
pool.
4. No mutations occur.
5. There can be no selection advantages. (No natural selection occurs). There must
be equal viability, fertility, and mating ability of genotypes. This means that all
genotypes have equal reproductive success.
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Lesson 15
In 1908, an American and a German researcher independently published their
conclusions about frequencies of genes in gene pools. These became part of the
Hardy-Weinberg Law.
The Hardy-Weinberg Law states that the frequencies of the
alleles for a given trait in a population remain the same
(are stable) from generation to generation, under
conditions of genetic equilibrium. (As stated in 1-5 on the
previous page.)
In addition, the Hardy-Weinberg Law established equations
that could be used to predict allele and genotype frequencies
in populations that were relatively stable at particular times.
If populations are changing, applying one of two equations will confirm a change
more readily (if the figures don’t fit into the equation). If populations are stable for a
time, application of the equations will usually produce a fairly accurate prediction of
frequencies of particular alleles and genotypes.
1. The first equation derived from the Hardy-Weinberg Law is used in determining
the frequency of two alleles for one trait. This equation is:
p+q=1
Let:
p stand for the frequency of the dominant allele.
q stand for the frequency of the recessive allele.
For example, the two alleles could be B (brown eyes) and b (blue eyes) of the trait
eye colour. If these are the only two alleles for that trait in the population, the
sums of their frequencies add up to l00%, or 1, in the equation.
From previous work involving dominant-recessive interactions between alleles,
information can be pointed out in the preceding example of eye colour:
 Two phenotypes are possible. The phenotypes are brown eyes and blue eyes.
 The number of genotypes possible is three: BB, Bb and bb. The genotypes of
recessive phenotypes are easy to identify, since they can only appear in
homozygous conditions (bb). The dominant phenotype, on the other hand, can
be either homozygous or heterozygous (BB, Bb).
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2. In trying to determine the frequencies of the alleles (B and b) and the three
genotypes (BB, Bb. Bb), a second equation can be used. This binomial expression
is obtained by squaring (p + q), to arrive at:
p2 + 2pq + q2 = 1
where:
q2 stands for the frequency of the individuals in
the population showing the recessive trait (bb).
2
p
stands for the frequency of homozygous
dominant individuals (BB).
2pq then includes all the heterozygotes (Bb).
Example:
Suppose a geneticist was trying to determine the frequency of
alleles for brown eyes and blue eyes in a sample population. The
researcher noted that 84% of all individuals were brown-eyed.
Solution:
Determine the frequency of both alleles:
1. Work with a figure that is definitely known. That is the
frequency of blue-eyed individuals (the recessive trait bb), which
is 16% (100 - 84). 16% can be converted to a decimal form
(16/100), which is 0.16. (This is the frequency of the
individuals showing the recessive trait, q2.)
2. If q2 = 0.16, take the square root of q2
 q  to find q. (Use a
2
calculator that has the
function.) q= 0.4 or 40% of the
alleles in the population are those for blue eyes. (Remember q =
frequency of the recessive allele (b).)
3. Use the first equation from the Hardy Weinberg Law, where
p + q = 1. The calculation for q was done in number 2.
Substitute for q and solve for p.
p + 0.4 = 1
p = 1 – 0.4
p = 0.6
The frequency of the dominant allele, brown (B), must therefore
be 0.6 or 60% of all the alleles.
4. If the geneticist wished to know how many of the brown-eyed
individuals were homozygous (p2) and how many were
heterozygous (2pq), the second equation could be utilized.
p2 + 2pq + q2 = 1
Knowing that:
then
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p = 0.6
q = 0.4
p2 = (0.6)2 = 0.36
2pq = 2(0.6)(0.4) = 0.48.
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Lesson 15
5. Check to see if you are correct:
p2 + 2pq +
q2 = 1
0.36 + 0.48 + 0.16 = 1
1 = 1
This means that:
36% of the population is homozygous brown-eyed (BB).
48% is heterozygous brown-eyed (Bb).
16% of the population is homozygous brown-eyed (bb).
The other observation made by both Hardy and Weinberg was
that even if one allele had a very high frequency and the other
was very low, those frequencies would not change in a stable
population.
Note: The Hardy-Weinberg equation applies to populations that are not changing (are
non-evolving). If the gene pool of a population changes, then the frequencies in the
population will NOT fit those predicted by the equation.
Genetic Drift
Selective forces of particular environments, or natural selections, are often cited as
the major reasons for changes in gene pools and populations. However, natural
selection does not always account for the manners in which certain changes occur.
Certain chance events could cause a gene pool to change in a direction not entirely
determined by environment. This is more common in smaller populations or in
populations that are experiencing sudden increases or decreases.
For instance:
1. In a small group of individuals (like a pack of wolves), there may only be one
dominant pair that engages in breeding. This means that only part of that pack’s
gene pool is utilized and future generations could show a change in frequencies of
particular genes. This could be even more noticeable if a mutation appears and it
just happens to be in one of the individuals engaged in reproduction. The mutant
gene or genes will increase fairly rapidly in the pool.
2. Sudden changes or actions in a certain environment could also have unique
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Lesson 15
effects on certain population groups. A fatal disease could wipe out many
members of one group, changing the frequencies of genes in the remaining gene
pool.
3. A small group may separate from a larger one and establish another breeding
group elsewhere. The few individuals that initially break away may carry gene
frequencies that are not the norm for the larger group. Again, it is a matter of
chance just which individuals are involved or affected.
Speciation
Hardy and Weinberg formulated the principle that, normally, gene frequencies in
populations tend to remain the same. However, exceptions to most conditions or
situations can generally be found and this is true for many populations. As a result
of the exceptions, genetic differences can appear and accumulate to the point where
significant changes in species can develop over time. If the changes are great
enough, new species may arise from previous ones.
A species is any natural population whose members can interbreed to produce fertile
offspring. Organisms which cannot, or do not, ordinarily interbreed to produce fertile
offspring are commonly regarded as belonging to separate species. From the
standpoint of gene pools, one could say that a species is group of individuals whose
members share a common gene pool. This gene pool would be unique and isolated
from the gene pools of other species. DNA sequences would be shared by species
that are close. They would share similar proteins. The more similar the nucleotide
sequences the closer the relationship between the organisms.
The section will briefly look at some mechanisms in speciation
or the development of new species from pre-existing ones. It
could show how adaptive radiation and speciation could result
in divergent evolution among various groups.
A relatively free exchange of genes among all members of a species tends to maintain
uniformity of characteristics within that species. Maintaining this similarity in the
chromosomes and genes keeps species groups intact. Any conditions that somehow
split up members of one species and keep the sub-groups separate from each other
would encourage the opposite effect. Genetic differences could begin to appear
between the sub-groups and, if subjected to different environmental selective forces,
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Lesson 15
differences between them could keep on increasing. Eventually, a point could be
reached at which the sub-groups are so different that, even if reunited, successful
interbreeding will not be accomplished. Such groups are then regarded as belonging
to separate species.
Migration is a frequent cause of splits developing in a species. Separations can
happen as an entire population is moving or if some members have an urge to move
before others do.
Once a split develops, isolation is usually the next important step in the
development of a new species. Preventing a gene flow between separated groups
allows gene pools to change in their own unique ways.
Isolation can be maintained in a number of possible ways:
1. After an initial separation, geographic isolation is probably the most common.
Groups may eventually come to be separated by considerable distances.
2. Physical barriers such as mountains, canyons, rivers, forests and even
human-made barriers such as highways and pipelines may serve to keep groups
apart.
3. Additional kinds of isolation could come into play once genetic differences begin to
appear.
Genetic variations and natural selection come into effect once groups are split and
isolated from each other. Different genetic variations between groups could be the
result of different kinds of recombinations (during sexual reproduction), different
(random) mutations and genetic drift. Genetic drift is common to smaller groups and
could result in either good or bad changes in relation to the environment. Selective
forces could then play a part in deciding whether a population decreases or
increases.
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Genetic variations and changes between isolated groups can stop short of changing
them into separate species. Reuniting them can result in successful interbreedings.
However, genetic differences could have resulted in some distinctive appearances
between the groups. This gives rise to the different breeds, varieties or races, of
organisms.
Speciation occurs after a geographical barrier (geographic isolation) prevents gene
flow between populations that originally belonged to a single species. In the diagram
below, a single population of flies was divided into two –with each being feed
different foods and being geographically isolated from each other. After several
generations had passed and the groups were mixed, no interbreeding would occur.
The appearance of certain genetic variations between groups can lead to additional
kinds of reproductive isolations, where certain individuals will not interbreed with
each other. Slight changes in the genetic nature can affect such things as physical
characteristics, reproductive patterns and behaviour patterns. Differences in
physical sizes, features and possibly (colour) markings could make members of
separate groups avoid each other reproductively. Behaviour patterns can do the
same thing. For instance, individuals of some species must follow very ritualized
types of courtship if successful mating or spawning is to take place. If a partner in a
courtship initiated by another partner does not attempt, or does not follow, the
correct sequence, reproductive behaviour usually stops. Reproductive isolation can
also come about through groups breeding at different times or in different seasons or
possibly in different places. In some instances, members of different species may
actually carry out successful fertilization or spawning. However, genetic differences
may have reached the point where embryos fail to develop or, if hybrids result, such
individuals are sterile.
The development of different species is often associated with adaptive radiation. In
this process, groups that have split and spread apart are subjected to different
selective forces. In time, members of sub-groups that are successful in surviving will
have experienced evolutionary adaptations making them better suited to their new
environmental conditions. An evolutionary adaptation can be regarded as any
genetic characteristic that somehow increases an organism’s fitness or chance of
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Lesson 15
surviving. From an evolutionary viewpoint, adaptive radiation can be looked upon as
an instance of divergent evolution. Groups spread out from a common ancestral
form to give rise to distinctly different individuals. The camel family is a good
illustration, with members ranging from South America (llama, alpaca...) to Asia and
to the Middle East (Bactrian camels and dromedaries). In an opposite type of
development, convergent evolution is also evident. Groups of entirely different
origin, subjected to similar selective forces, could come to look very similar –
although still remaining as separate species. Previous examples of some Australian
marsupials having placental “look-alikes” on other parts of this planet bear this out.
The Human Role in Speciation
If speciation does occur under natural conditions, it generally takes a long time for
most organisms. Becoming more and more apparent are human-influenced
speciations or evolutions taking place in shorter time intervals. This has been most
noticeable in domestic plants and animals. Humans have removed or separated
organisms from others subjected them to isolation and (artificial) selection and in so
doing, have brought about transformations in gene pools. Such transformations are
evident in different breeds, varieties and even new species of plants and animals.
Many other forms of human-influenced evolutions have not been directly planned.
The uses of antibiotics and chemicals (pesticides) have resulted in the appearances of
new strains of viruses, bacteria, insects and other organisms. These organisms have
evolved and are still evolving, with increasing resistance to present methods of
control.
Coevolution
Discussions on changing life forms will sometimes bring up the term coevolution.
Whenever there is some close symbiotic relationship between two organisms, a
change in one could have a significant effect on the other. Such symbiotic
relationships could include mutualism, commensalism, parasitism and mimicry. If
there is dependence between two organisms, whether it is one way or both ways, a
change in the physical structure or behaviour of one could remove the benefit for the
other. Unless the “partner” is able to change also, it could mean its extinction or the
extinction of both.
A very good example of coevolution can centre on particular plants and their
pollinators. Certain flower structures may require specific types of pollinators,
whether they are insects, birds or other agents. A particular plant species may have
evolved to the point where its flower structure may be pollinated by only one species
of bird, which uses that one plant as its primary food source.
Changes to one could mean that the other would have to change. Lamarck may have
said that an “inner need” to change would bring about that modification. However,
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Lesson 15
mutations or recombinations are random. A species change in coevolution would
only occur if there happen to be some variations in the population able to take
advantage of the partner’s change. If there were such variations, those individuals
would have the best chance of survival and reproducing more of their particular kind.
Other examples of coevolution include plant-herbivore relationships. Certain
herbivores’ eating habits have evolved with changes in particular plant species.
Some herbivores can only survive now on one species of plant, and perhaps on just a
certain part of that plant.
Examples of Coevolution:
Yucca moths and yucca plants
Yucca flowers are a certain shape so only that tiny moth can pollinate them.
The moths lay their eggs in the yucca flowers and the larvae (caterpillars) live
in the developing ovary and eat yucca seeds.
Photo by
Stan Shebs
Lichens
Lichens are composed of a mixture of fungi and algae. In each “species” of
lichen, the alga and fungus are so closely intertwined that whole lichens are
classified as species, rather than the component fungus/alga. The type of
fungus and alga are species-specific. The alga does photosynthesis and
produces sugars for fuel for both. The fungus attaches the whole lichen to its
substrate (tree, rock) and holds in water needed by the alga.
Photo by
Ross Agnus
Snapdragon
Coevolution is often seen in a number of species of flowering
plants that coevolved with specific pollinators (insects, bats, etc).
The pollinator gets a reward such as nectar for pollinating the
plant. Moth-pollinated plants often have spurs or tubes the exact
length of a certain moth’s “tongue.” For example, Charles Darwin
predicted the existance of a moth in Madagascar based on the
size and shape of a flower he saw there. The moth was actually
discovered about 40 years later. The common snapdragons that
many people plant in their gardens are designed for a bumblebee
of just the right weight to trip the opening mechanism.
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Lesson 15
Primate Evolution
An area of evolution that has probably experienced the most critical attention, has
been that of the primate line. This includes human-like and human life forms. Many
of the difficulties in attempting to establish phylogenetic trees or pathways that
include humans have been due to lack of fossil evidence. Often, only fragments of
skulls, jaws or other skeletal parts have been found. Recreating entire bodies from
fragments has been difficult, leaving doubts as to their accuracy. Such doubts have
extended into the task of trying to determine whether or not certain fossils belong to
the same or different groups; also, as to the times when certain groups may have
diverged from each other and in what orders. As time goes on, new study and
reconstruction techniques should add many more items of information. Experts can
now reconstruct remarkably accurate facial features from skulls or skull fragments
alone. Continuing finds are also being made of primate fossils and these should
assist in filling in gaps in the fossil records.
Ancestors of the earliest primates may have resembled tree shrews or a type of
squirrel. Some of the primate traits related to tree life may have developed from these
initially tree-dwelling and insect-eating ancestors. These include features such as:
mobile digits (fingers, toes) and sometimes opposable thumb; free arms and flexible
hands; binocular vision (for depth perception); complex central nervous system,
including a larger brain (for sensory interpretations); and, a sometimes complex, but
flexible, social system.
The primate line has so far been traced back about 65 to 66 million years. Shortly
after it appeared, it seems to have split in two directions. One of these is referred to
as prosimians, or “lower” primates. Lemurs, Lorises, and Tarsiers are
representatives of these today. The other direction was that of the anthropoids or
the human-like line. One of the branches of the anthropoid line included the
hominids, of which apes and humans are part.
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Lesson 15
Scientists estimate that the human or hominid line diverged from the rest of the
hominoid line between 4 and 9 million years ago. Increasing finds of human-like
fossils dating between 2.5 and 3 million years are being made. To try and separate
humans from the rest of the hominoids, researchers focused on what they considered
to be uniquely human characteristics. These included: being bipedal, which is often
determined by the manner in which bones come together at the knee and also the
shape of the pelvis; having the foramen magnum (where the spinal cord enters the
skull) at the bottom of the skull; having a fairly large brain cavity (at least over 400
cc); and, the shape of the jaw.
One of the older hominid fossil remains is that of an individual (called “Lucy”) dated
at between 3 and 3.5 million years. She was given the classification of
Australopithecus afarensis. After Lucy, there may have been a divergence into two or
three lines. Between 2 and 3 million years ago, it is believed that there may have
been clusters of hominids, some perhaps living side by side. The major ones were the
Australopithecus and the Homo lines. The more primitive Australopithecus line
became an “evolutionary dead end”, while the Homo line led to the present humans.
Separation between various groups in all lines is frequently based on brain size, as
this generally shows the greatest evolutionary advancement through this vertebrate
line. The following indicates relative sizes of various human groups, along with
chimpanzees as a comparison:
Chimpanzees
–
280 – 400 cc
Australopithecines
–
400 – 550 cc
Homo erectus
–
775 – 1100 cc
Homo sapiens
–
1300 – 1400 cc
The brain size, and especially the front part or cerebrum, gives an indication of the
ability to receive and interpret sensations, to coordinate responses and to carry out
thinking or reasoning skills. These abilities have an effect on the evolutionary
success of particular organisms.
The Homo line may have originated about 2.4 million years ago, as indicated by a
recent find classified as Homo rudolfensis. The next find to fill the chronological
order was that of Homo habilis (2 million years), which appears to have been the first
tool-user. Homo erectus made its appearance about 1.5 million years ago.
Approximately 500 000 years ago, the first lines of our own species appeared, with
Homo sapiens neanderthalensis (which became another evolutionary dead end) and
then Homo sapiens (Cro-Magnons). It is felt that a small number of individuals from
this group gave rise to all of the present human race.
Fossil evidence suggests that humans have not changed much anatomically in the past
200 000 years.
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Lesson 15
The second half of this lesson will examine some technologies and the human use of these,
especially in relation to changing species or “creating” new ones. It will bring out issues and
questions that are discussed and debated in the public forum. Many of these relate to how far
humans should go in manipulating genetic identities of organisms, the procedures that should
be followed, the reasons for doing so, and how the outcomes should be utilized. The opinions,
viewpoints and convictions of individuals and groups will no doubt be as varied and as
strongly voiced as those for origins of life and evolution.
Biotechnology
The term “technology” can have slightly different meanings. In general, it can be
looked on as the body of knowledge associated with a particular science, along with
the tools, skills or processes arising from it. Frequently, the idea of some practical
use or achieving some benefit is tied in with the meaning. Biotechnology refers more
specifically to the relationships humans have with technology: how they use it, the
effects they cause with it, or how they are themselves affected by it.
Some of the direct benefits to ourselves may be seen in what we sometimes do to our
bodies, internally or externally. Individuals may have eyeglasses, artificial knee
joints or hips, artificial heart valves or hearts and assortments of other devices or
“gadgets”. Even the clothes that we wear, the foods that we eat or the vehicles that
we ride in or on, are part of biotechnology, since these were also produced or
achieved with the aid of technology. By extension, we can expand this to include the
effects that our technologies have on environments, which would include both the
non-living and the living.
The level of technological development in a culture and its degree of use can have
many effects. On the human population itself, it generally determines the well-being
or “comfort levels” of the majority of its individual members. On surrounding
environments the effects are far-ranging and numerous. Technology drives and
frequently transforms the ways in which all natural resource industries are utilized –
from farming to wildlife management. Many of the effects these utilizations have are
related to species and gene pool changes.
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Lesson 15
Natural Selection-Artificial Selection
Part of Darwin’s theory on evolution had to do with natural selection. That is, certain
selection pressures in particular environments could have significant effects on
organisms’ chances of survival. The selection pressures, or natural selection, would
be directing the ways particular populations change. What really led Darwin to his
observations and conclusions about natural selection came from his initial
observations as to what was happening in agriculture. He noted that plant and
animal breeders were directing developments or changes of their varieties or breeds.
They were doing this by selecting the individuals that were to serve as breeding stock.
In effect, the livestock or plant managers were themselves serving as selection
pressures, by breeding only those individuals with “desirable” traits.
Artificial selection is usually part of a process of genetic screening, which involves
an analysis of organisms’ genotypes or genetic components (genomes). Originally,
organisms’ genotypes were decided upon (not always accurately) by their phenotypes,
or external appearances and behaviours. Plants or animals having traits or qualities
liked by their owners would be selected for breeding. Such a practice meant that
many genes in gene pools would not be utilized and their frequencies over
generations would fall. A gene pool would keep getting smaller, unless special
breeding programs concentrated on crosses between different varieties. Artificial
selection or controlled breeding would “evolve” plants and animals that are
genetically similar and uniform. Organisms could also be selected and developed for
some prominent or distinctive traits.
Early forms of artificial selection often took considerable periods of time and involved
many generations of individuals. With plants, periods of dormancy for particular
varieties added more time to the programs of trying to develop certain kinds of
individuals. While periods of dormancy extend the time period, there are some
techniques for speeding up the breeding programs.
Artificial insemination and embryo transplants allow for rapid increases in animal
numbers from parents that are considered to be genetically superior. For plant
breeding, research stations scattered in widely separated locations in the northern
and southern hemispheres have allowed some plants to be grown without
interruptions due to dormancies. Chemicals and hormones have also been used to
break dormancies and to speed up germination times. Culturing and cloning are
increasing in use as means of producing large numbers of genetically uniform
individuals, in shorter periods of time.
As genetic pools shrink, plants and animals become more and more similar to other
members of their species. There is a decrease in genetic diversity within pools, which
results in fewer variations. Particular varieties or breeds of organisms could become
very specialized for specific environmental conditions or environments. Anytime a
high degree of specialization occurs or a gene pool shrinks, it makes a species
susceptible to extinction.
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Lesson 15
Factors, such as a major disease or some type of climatic
incident out of the ordinary for the species or the
influences of humans invading more natural habitats,
could wipe it out. Such consequences are possible
whether species are artificially selected or are selected
naturally, since there are many wild populations with
limited numbers or small genetic pools (such as whooping
cranes, cheetahs...).
Various individuals and groups are campaigning to
maintain sample populations of some older breeds or
varieties of animals and plants. By doing so, they
maintain, there will be genetic pools to draw from should
some misfortunes occur to “newer” varieties. Another
possibility for these old gene pools is that they could
provide a source of genes which could still prove useful in
present populations.
A Whooping Crane
Habitat Modifications and Their Effects
Individuals find it difficult to locate larger expanses of land that do not show some
signs of humans or human activities. Effects of acid rain, increased levels of
radioactive fallout or other substances released by human activities could influence
even uninhabited and supposedly undisturbed areas. Oceans have not escaped
either, even though the effects are usually not as obvious. Demands for particular
kinds of natural resources by humans have generally been accelerating, as
population numbers have gone up or as new consumer demands have been made.
These demands, in turn, have accelerated the rates at which natural environments or
habitats have been modified or changed. Clearing of forests, cultivation of natural
grasslands and the flooding of certain lands (for hydroelectric or irrigation projects)
are just some of the activities associated with resource use.
Altering habitats also alters evolution or the ways in which evolution could occur. In
certain instances, habitat modification may simply change the rate of evolution. It
could either delay or increase the speed at which species change. For instance, if an
area had been becoming more desert-like and irrigation was introduced to some parts
of it, that action could delay the development or introduction of species more suited
to desert conditions. Introduction of industrial pollution to the English countryside
accelerated the change in a species of peppered moth from a light to a dark colour.
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Lesson 15
In many situations, habitat modification by humans is unfortunately too rapid for
species to experience variations which could increase survival chances. Species
caught in these situations can either try to migrate or they will become extinct.
Besides changing rates of evolution among species of plants and animals, habitat
modifications have major effects in reducing population sizes and genetic diversities.
Some scientists estimate tropical rainforests to contain about 50 000 species of trees.
In addition, there could be up to 500 insect species associated with each variety of
tree, not to mention birds and other organisms. Reduction of tropical rainforests can
therefore have a great impact on reducing total numbers of species and gene pool
diversities. Changing habitats can also establish barriers to movements of
organisms. Clearcutting in different areas of one forest region could mean that
movements of organisms can be limited, which reduces gene sharing. Constructing
canals, pipelines or highways can do the same thing.
Another form of habitat modification comes with growing human populations. This is
the trend towards increasing urbanization. Urban and suburban developments are
taking increasing amounts of land out of natural states or out of agricultural
production. Creation of these artificial, paved-over ecosystems forces out or destroys
many previously established species.
A phenomenon sometimes associated with urbanization is cultural evolution that
some animals go through. Cultural evolution is frequently a change in a behaviour
or in a manner of living, which is often passed on to future generations. Some
species, or some members of certain species, will not necessarily leave due to urban
developments. Members of the human public may be surprised at the amount of
wildlife that does exist within town or city limits. Rabbits, foxes, coyotes, skunks and
raccoons are just some of the mammals which sometimes make urban developments
their homes or parts of their territories. Many of these species go through forms of
cultural evolution where they change their lifestyles. Raccoons learn to use attics or
unused parts of buildings as shelters. Coyotes establish regular routes where they
scavenge for garbage, feed from household pets’ dishes or prey on small pets.
Peregrine falcons have learned to substitute ledges of buildings for rocky cliffsides as
nesting areas.
Occasionally, a cultural evolution could involve a physiological change due to a
change in the manner of living. One example of this includes humans. Agriculture
and the increasing use of dairy products or a milk diet has resulted in an increasing
development of lactose tolerance. Certain cultures of people and many people in
general don’t have a good digestive capacity for the milk of other species. However,
with increasing consumption of cows’ milk as part of their diets, new generations of
people have higher numbers of those who are able to properly digest cow’s milk.
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Lesson 15
Effects of Agriculture
Agriculture could have been included in the last section. However, because it is the
single human activity that has the greatest effect on habitats, it is deserving of its
own section. The effects of agriculture on landscapes are probably best visible from
an aerial view. Looking down on the prairies from a height, one would usually see an
uninterrupted patchwork pattern of fields. Bodies of water or waterways often have
control structures or some connections to surrounding lands.
Before agriculture, humans were often just members of biotic communities. With the
domestication of plants and livestock, environments began to be changed to better
suit the needs of plant and animal management. In most instances, communities
were “simplified”; native plants and native animals were removed to reduce
competition for the domesticated varieties. Thus, the familiar pattern of a decrease in
total numbers of species and reductions in gene pools is evident with this activity.
A common aspect of western agriculture is that of monoculture. Entire fields or
areas often support just one particular variety of plant or animal. As with natural
populations, reduction in the numbers of species or in the gene pools sets up
situations where entire populations could be at risk. A disease or an unusual
weather pattern could destroy all the living organisms of one species in one area.
Associated with a monoculture type of land use, are some of the related activities that
go with it. Rapid and extensive cultivation techniques, along with heavy use of
chemicals (herbicides and pesticides), also limit the number of different species and
even the natural (biotic) controls common to areas.
These techniques and products are generally harsh on the land as well, contributing
to the problems of loss of organic matter in the soils, buildup of salinities and
susceptibility to erosion. All of these can create different selection pressures on the
plants and animals that have to deal with them. Some plant and animal “pests”
subjected to certain chemicals or cultivation methods have begun to evolve in ways to
make them more resistant. It is now common to have certain insects, plants and
animals resistant to previously successful control methods used by humans.
Continuous plant and animal breeding and selections for particular traits have also
increased the dependence of domesticated varieties on humans. Certain varieties of
plants or breeds of animals can only be raised now in very controlled conditions and
under the care and supervision of humans. Most wheat varieties and other cereal
grains could not survive without humans. The original wild wheat had heads which
“shattered” when ripe. This allowed the light seeds to be scattered or blown away.
When the first domestic variety was created without the shattering ability and heavier
seeds, the plants could no longer scatter their seeds. This, and their requirement for
loose soils, would put present cereals at a disadvantage and on a road to extinction, if
left on their own. The same would apply if many breeds of birds or animals were left
to fend for themselves on the prairies under natural conditions.
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Lesson 15
Economic-Social Issues and Their Implications
Many human relationships with their environments are part of economic and social
conditions. Almost everyone desires to be well off financially and have many of the
comforts common to a society. Unfortunately, financial profits are often made at the
expense of environments. These could involve extracting certain resources (forestry,
mining...) or making use of certain resources (as farming does with soil and water...)
in ways that put pressures on other species and humans themselves. Certain logging
practices, forms of strip mining and other activities have the effects of changing
landscapes or environments relatively quickly. Many previously established species
have decreased in numbers, have been forced to move, or have simply disappeared.
Profit-making often employs methods of resource extraction, usage or processing that
contributes to pollution. Acid rain, oil spills, toxic wastes and contamination of soils
and waters frequently result from the refusal of individuals and groups to invest more
time or more money into their activities. For certain industries, the added costs of
“cleaner” methods of production, or those that are more environmentally friendly,
could mean the difference between profit and loss. Some industries, in some years,
even lobby governments for reduced standards in emission or in production.
Potential losses to governments of millions of tax dollars and all the spinoff effects of
jobs make many of these lobbies successful. Depressed economies and job shortages
even change the attitudes of many in the general public. Most people would sooner
prefer to have jobs even if it means that some workplaces are kept going because of
lower production standards. Political parties and various interest groups commonly
set goals of eliminating poverty or food shortages within certain time intervals.
Despite the good intentions, such goals are not often realized. At the same time,
many fail to realize that attempts to raise income levels or food supplies require
increased use of natural resources, increased food production and creation of more
jobs. Each one of these activities uses up more natural resources and eliminates
more natural habitats. Although this type of outlook may seem discouraging, one
should realize that promises or certain programs don’t necessarily come without
costs. Situations and conditions should be looked at from wider views, with greater
awareness of all the implications.
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Lesson 15
Genetic Engineering: “Artificial” Evolution
While habitat modification has been, and still is, a major human influence on other
species, something else has been assuming prominence. Simple forms of artificial
selection, such as choosing just which individuals breed or cross-pollinate, are now
giving way to more advanced forms of genetic engineering. Rapid accumulations of
new genetic information have been the basis for the increasing ability of humans to
actually manipulate genetic components of individual organisms. Advanced
techniques in genetic screening now allow scientists and researchers to “read” base
sequences in DNA, or to actually identify individual genes. Processes or procedures
are also being worked on to replace segments of chromosomes and even individual
genes. Such techniques give humans even greater abilities to direct changes in plant
and animal species.
The ability to insert “made-to-order” DNA molecules, or “designer” genes, has been
increasingly successful in producing transgenic individuals. These are plant or
animal individuals which have genes from other species inserted into them.



Dairy cattle, in one instance, have had the insertion of a human gene. The aim of
this is to try and have the animals produce milk which is more easily digested by
humans.
Another research facility has worked with the insertion of human genes into pigs.
By doing so, it hopes to develop animals which would produce or carry hormones
or organs more compatible to humans. Should injections or transplants of these
into humans be required, there would be less chance of rejection.
Attempts are also being made to insert particular genes into wheat. By doing so,
researchers are trying to develop varieties showing such traits as greater
resistance to frost damage, greater resistance to certain herbicides or more salttolerance. Creating such “designer” grains or other species is another argument
for trying to preserve “wild” gene pools. Genes of native or wild populations
sometimes carry traits which could be useful in commercial varieties. Developing
specifically designed plants or animals which are suitable for certain conditions,
could have significant effects on certain economies.
o In Saskatchewan, there could be possibilities of growing transgenic cereal
grains, oilseeds or fruits, in areas where current species are unable to grow.
Such possibilities may not only mean new species for particular areas, but
could also result in differences in farming methods, storage and transportation
techniques, environmental effects and many other changes.
Genetic engineering and just how far it can be developed will be a focus of attention
when changes or evolutions of species are considered. That humans now have the
abilities to modify or change species is not in doubt. What will likely be increasingly
asked is just what sorts of future changes will be seen in plants, animals and even in
humans. What will be the long term effects of such “manipulated” changes on
species? What will be the long term effects on ecosystems or on environments?
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Lesson 15
Summary
Our own (human) role in evolution can be regarded in different ways. The Divine
Concept has human creation as being the last to occur, on the sixth day. It also
presents the idea of other forms of life as revolving around, and even being controlled
by, humans. Another viewpoint is that human life could be compared to a particular
period in the history of our planet, where a certain group of organisms was dominant.
As with the age of reptiles, human existence and influence may eventually end up as
just a tiny slice in one of the Earth’s geologic layers or strata.
Once humans advanced to the point of using tools and especially after they began to
domesticate plants and animals, modifications of habitats increased quickly. The
general effect of most habitat modifications on life forms is to cause a decrease in
the number of species and also a decrease in the diversity of gene pools.
Regulating reproduction of various species of plants and animals, through artificial
selection, brings about the same general effects. Such activities not only affect the
ways in which particular organisms may evolve or change, but also place some at the
risk of extinction.
Since the l950s, science and the public have seen dramatic increases in information
and technology levels. In biology, the amount of genetic information and the skills
developed in working with genetic material has been opening up possibilities that
would have been hard to imagine a short time ago. Scientists are now capable,
through genetic screening and genetic engineering, of actually directing the way(s)
species change. In other words, they can “design” life forms in particular manners.
Although still having difficulties in certain attempts, future knowledge and
innovations will likely keep expanding human control in the genetic area and in the
evolving of species.
With the increasing effectiveness of humans in controlling species changes, one may
well wonder what the long term effects on changes will be. In many areas, such as
agriculture, designed species may be very beneficial to environments, producers and
consumers. At the same time, questions also arise as to the fate of many “natural”
species and their gene pools. Related to this is another consideration related to the
human species itself: that is, how much control will there be on human evolution
itself?
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Lesson 15
Note:
You will NOT have a calculation question on gene frequencies on
the final examination. An example question is given in the
following pages if you are interested in knowing more yourself.
Practice Questions (for Hardy-Weinberg Law):
Review
In 1908, an American and a German researcher independently published their
conclusions about frequencies of genes in gene pools. These became part of the
Hardy-Weinberg Law.
The Hardy-Weinberg Law states that the frequencies of the
alleles for a given trait in a population remain the same
(are stable) from generation to generation, under
conditions of genetic equilibrium. (See numbers 1-5 below.)
In addition, the Hardy-Weinberg Law established equations
that could be used to predict allele and genotype frequencies in
populations that were relatively stable at particular times.
A population is in genetic equilibrium when the gene pool remains constant from
one generation to the next. Conditions must be “ideal” for genetic equilibrium to
occur. The ideal conditions would be as follows:
1. The population must be very large.
2. The mating must be random.
3. The population is isolated. There are no net movements of genes in or out of the
pool.
4. No mutations occur.
5. There can be no selection advantages. (No natural selection occurs). There must
be equal viability, fertility, and mating ability of genotypes. This means that all
genotypes have equal reproductive success.
NOTE: The following exercise is intended as a means of applying the
equations in determining gene and genotype frequencies. Do the questions
then check the answers that are given to see how you have done.
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Lesson 15
Question:
Tobacco seedlings can germinate to produce leaves which are green (due to the
presence of chlorophyll) or are albino (or yellowish or white in the absence of
chlorophyll). G stands for the gene for green chlorophyll and g represents the albino
gene. Tobacco plants with GG or Gg genotypes are green, while those with gg are
albino.
The following represent the genotypes of 200 young tobacco plants:
GG
GG
Gg
Gg
GG
Gg
GG
Gg
GG
Gg
GG
GG
Gg
GG
Gg
GG
GG
Gg
GG
GG
1.
GG
GG
GG
gg
GG
Gg
GG
GG
gg
GG
Gg
Gg
GG
Gg
Gg
Gg
Gg
Gg
Gg
GG
gg
gg
GG
GG
Gg
GG
Gg
GG
GG
Gg
GG
GG
gg
GG
GG
Gg
GG
GG
GG
GG
Gg
GG
GG
GG
GG
gg
GG
Gg
Gg
gg
GG
GG
Gg
Gg
Gg
GG
Gg
Gg
Gg
gg
GG
GG
Gg
Gg
Gg
Gg
GG
gg
GG
GG
Gg
GG
GG
Gg
GG
Gg
GG
GG
Gg
GG
gg
gg
GG
GG
GG
Gg
Gg
GG
GG
Gg
GG
gg
Gg
Gg
Gg
GG
Gg
gg
GG
gg
GG
GG
Gg
Gg
Gg
GG
GG
GG
Gg
GG
Gg
GG
GG
Gg
GG
Gg
Gg
Gg
Gg
Gg
Gg
GG
GG
GG
GG
Gg
Gg
GG
GG
Gg
GG
Gg
Gg
GG
Gg
gg
Gg
GG
Gg
Gg
GG
Gg
GG
GG
Gg
GG
GG
Gg
GG
GG
GG
Gg
GG
Gg
GG
GG
GG
Gg
GG
gg
Gg
GG
Gg
Gg
Gg
GG
GG
Gg
Gg
Gg
Gg
Gg
Gg
gg
Gg
Gg
GG
GG
GG
gg
Determine the frequency of the genes in the population. Individually, count
the numbers of G’s and g’s.
a.
Number of G’s:
_______________
b.
Number of g’s:
_______________
c.
Frequency of G.
number of G’ s
total number of genes (G’ s and g’ s )
(Leave your answer in decimal form.)
Use the formula G 
Frequency of G:
Biology 30
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Lesson 15
d.
Frequency of g.
g
number of g’ s
total number of genes
Frequency of g:
_______________
Correct calculations of frequencies of G and g will result in a sum of 1.0 (or 100 percent)
when you add the two frequencies.
The first Hardy-Weinberg equation is:
p + q = 1.0 (or 100 percent)
p = frequency of dominant gene (G)
q = frequency of recessive gene (g)
Do a check. Your value of p + your value of q = ________ + ________ = ________. This
should equal 1. If not, go back and check your work, or call your teacher.
2.
Now examine the frequencies of the various phenotypes.
a.
Frequency of albino plants 
albinos
total number of plants
(Leave your answer in decimal form.)
Frequency of albino plants:
3.
____
b.
Is this frequency greater or smaller than the frequency of the g gene? ____
c.
Is the frequency of albino plants equal to 2q or q2 ?
____
Knowing that p + q = 1, and that q2 = the frequency of a recessive
phenotype, you can determine gene frequencies in a population even if you
don’t know all the genotypes, as were presented to you with the tobacco plants.
Suppose there are 100 squirrels in a particular spruce grove area of Duck
Mountain Provincial Park. Of these, 64 have a dominant phenotype of a longer
tail. 36 have a recessive shorter tail. If L stands for the dominant long tail
gene and l for the recessive short tail gene, then the genotypes for long tail
could be LL or Ll, and short tail is ll.
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Lesson 15
Show all work for questions (a)-(f) below.
a.
What is q2, or the frequency of the recessive trait ll?
b.
What is the frequency of the dominant phenotype?
c.
What does q equal?
d.
What does p equal? (Recall that p + q = 1.)
e.
If q2 is the frequency of the recessive trait ll, then p2 is the frequency of
the homozygous LL trait.
What is the value of p2 ?
(This is the frequency of the dominant LL trait.)
f.
Having calculated the frequencies of ll (q2) and LL (p2), the only
remaining frequency to be calculated is that of the heterozygotes Ll. The
second Hardy-Weinberg equation is:
p2 + 2pq + q2 = 1
Therefore, the heterozygotes Ll are 2pq.
Using this equation, what is the frequency of the heterozygotes?
Summary Statement
According to the Hardy-Weinberg law, the frequency for genes for a particular trait
should remain fairly constant in a stable population (where there are no
exceptionally prominent selective pressures or forces). This means that a gene,
whether it is dominant or recessive can have a low frequency in a population and still
remain present in that population over generations. It also emphasizes that recessive
genes, in particular, will not disappear over time.
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Lesson 15
Practice Question Answer Sheet
1.
This question is dealing with individual genes (so you can calculate the
frequency of G and g in the population).
a.
Count the number of individual G’s = 280
b.
Count the number of individual g’s = 120
c.
G
280
 0.7
400
d.
g
120
 0.3
400
Check:
p+q=1
p = frequency of dominant gene
q = frequency of recessive gene
From (c) p = 0.7
From (d) q = 0.3
So
2.
0.7 + 0.3
1.0
= 1.0
= 1.0
Now you are dealing with the phenotypes. (To have a phenotype you are
dealing with 2 alleles.)
a.
albinos
18

 0.09
total number of plants 200
b.
Compare answer from 2a to 1d.
0.09 is smaller
c.
2q
2(0.3)
0.6
or
q2
(0.3)2
0.09
The answer is q2.
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Lesson 15
3.
Remember q2 = the frequency of a recessive phenotype.
a.
There are 36 squirrels out of 100 that show the recessive (ll) shorter tail.
q2 
b.
36
 0.36
100
There are 64 squirrels out of 100 that show the dominant trait. Their
genotypes are both LL and L1.
64
 0.64
100
c.
g  q 2  0.36  0.6
d.
p + q =1
Substitute 0.6 for q.
p + 0.6 = 1
p = 1 – 0.6
p = 0.4
e.
p2 = (0.4)2
f.
2pq
2(0.4)(0.6)
= 0.16 or 16% of the 100 squirrels have LL genotype.
= 0.48 or 48% of the 100 squirrels have L1 genotype or
are heterozygous.
Check:
p2
+ 2pq +
q2 = 1
0.16 + 0.48 + 0.36 = 1
1
= 1
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Lesson 15