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Bio 1 General Biology – Exam 4 Outline
Evolution (Chapter 16 - 20)
Why are organisms different from each other? Why & how do organisms change over time?
Two main ways that these questions are answered: science based and faith-based. We will be discussing the sciencebased way of answering these questions.
I. What is Evolution?
A. Before Charles Darwin
1. It was believed Earth was a few thousand years old, species remained the
same and did not change over time, number of species stayed the same,
adaptations were pre-meditated or preplanned, and variations were just
B. Charles Darwin and Evolution
1. In 1831 became the naturalist aboard the HMS Beagle, a British naval
ship that was to sail around the world. Darwin’s mission was to find
natural resources in foreign lands. The voyage took 5 years all the while
Darwin made observations and collections of a variety of organisms
from around the world (Fig. 16.4). He began to
think that living forms descended from extinct
forms known only from fossils and that species were
not fixed but change over time. He also came up
with a reason why living things change over time.
2. Principles of Evolution
a. Descent with Modification – living forms have
descended from extinct forms.
Groups (species) of living things can undergo
modification in successive generations and
sometimes results in the formation of separate
b. Natural Selection – process in which the fit of an
organism with its environment selects those traits
that will be passed on with greater frequency from one
generation to the next.
According to these principles 1) living things are descended from other
varieties of living things and 2) living things are not fixed entities, but are
constantly undergoing change.
II. Evidence for Evolution
A. Fossil Evidence
The Fossil Record – the history of life
recorded by remains from the past
1. What pattern in life form complexity
does the fossil record show? (Fig. 19.3)
2. Fossils serve as transitional links between groups. How so?
a. Ex. Archaeopteryx is link between what two animal groups?
b. Ex. Evolution of Whales video
1. List the evidence that led scientists to believe that
whales evolved from other animals.
2. What type of animal did toothed whales evolve from?
c. Ex. Evolution of Land Animals (Tetrapods) video or read p. 353-354 “Vertebrates Move onto Land” and
answer the following:
1. List the evidence that led scientists to believe that land tetrapods evolved from other animals?
2. What type of animal did land tetrapods evolve from?
B. Biogeographical Evidence
1. Biogeography – the study of the distribution of organisms in different places of the world.
a. Darwin noted that Galapagos animals resembled species on the S. American mainland more than they
resembled similar animals from distant lands. Why would this be?
b. Why do so many species of finches live on the Galapagos Islands when they are not on the mainland?
c. Why is Australia home to so many kinds of pouched mammals (marsupials) and few placental mammals
(those in which embryonic development is completed in the uterus)?
C. Evidence from Comparing Anatomy of Different Species
1. Are these limbs made up of similar structures? (Fig
2. Are these limbs used for the same function? Why?
3. What does this suggest?
4. Homologous Structures:
D. Evidence from Comparing Embryos of Different Species
1. Are these embryos similar? (Fig. 16.10) How so?
2. What does this suggest?
E. Evidence from Molecular Biology
a. What large biological molecule makes up the instructions for
living organisms?
b. What else do living organisms share? (Fig. 16.13)
c. What does this suggest?
F. Evidence from Quickly Evolving Organisms
1. The process of evolution usually takes a very long time but
in certain cases we can observe changes occurring in our
life time. What are some examples of this? And explain
how and why they can evolve so quickly.
III. How Does Evolution Work?
A. What actually evolves?
1. Population:
B. Microevolution – evolutionary changes within a population
Microevolution occurs when a change of allele frequency occurs in a
population over a relatively short period of time (starting point of
evolution; smaller scale evolution).
1. Genes are the raw material of evolution in a population (genotype
largely determines phenotype)
a. Alleles – two forms of gene (one from mother one from father); though both may code for color one may
result in lighter or darker color.
b. In a population, genes usually come in many forms not just two.
c. Gene pool – all alleles that exist in a population; evolution works by using gene pool
Ex. If evolution were a card game, the gene pool would be a deck of cards, alleles would be individual
cards which are endlessly shuffled and dealt into different hands which are the genotypes that individuals
inherit. Depending on the game being played (condition of environment), different hands (genotypes) will
have different strengths.
Evolution at its root is just a change in how common certain alleles are in a population. This depends on what
alleles get passed on to next generation.
2. Five Agents of Microevolution - forces that can bring about change in allele frequencies in a population
a. Mutation:
Can mutations be passed on to future generations?
Can mutations be beneficial?
This is the only way new genetic info comes about by which new proteins are produces that can modify
the form or capabilities of organisms.
b. Gene Flow (Gene Migration): (Fig. 17.4)
Ex. Hawaiian silverswords are derived from tarweeds in California.
Ex. Migration of people throughout the world is transferring alleles between
populations that were once isolated. Magazine cover shows changing gene
pools and culture with a computer generated image blending facial features
from several races.
c. Genetic Drift: (Fig. 17.5)
What population size is greatly affected by genetic drift?
Genetic drift can have large effects on small populations through two common scenarios: Populations
can be greatly reduced through disease or catastrophe, or a small subset can migrate elsewhere to start
a new population. The first is called the bottleneck effect; the second is called the founder effect.
1. Bottleneck effect – a change in allele frequencies in a population due to chance following a sharp
reduction in population size. Prevents the majority of genotypes from participating in the
production of the next generation. (Fig. 17.6)
What is the outcome of this effect?
Ex. Homo sapiens “When the Sea Saved Humanity” article on course website.
Ex. Northern elephant seals were hunted to about 50 individuals in the 1890’s. They since have
rebounded but now have low genetic diversity.
2. Founder effect – when rare alleles (genes) occur at a higher frequency in a subpopulation that has
migrated from the general population to start a new population and remains isolated.
Ex. A member of the founding population of Amish in Pennsylvania had a recessive allele for a
rare kind of dwarfism linked with polydactylism. The percentage of the Amish population
carrying this allele is much higher compared to that of the general population.
Ex. A rare eye condition consisting of a misshapen cornea is known to affect 113 people in world
and 78 of these are in Finland. Four hundred years ago a small population arrived in this isolated
area with at least one member carrying the recessive allele.
Ex. The Founder Effect in Human Evolution (Fig. 20.8 & 20.9)
What has happened to human genetic diversity in populations that have moved farther and
farther away from Africa?
a. The Importance of Genetic Diversity
Read p. 308-309 “Essay: The Price of Inbreeding” and answer the following:
1. Define inbreeding.
2. In terms of allele types, what does inbreeding tend to bring together and random breeding
tend to keep apart?
3. According to this article, what type of familiar animal has been highly inbred by humans?
d. Sexual Selection:
If an individual mates more than others, their alleles will increase in the next generation.
Ex. Male peacock
Mutation, gene flow, genetic drift, & sexual selection can cause microevolution but do they necessarily lead
to adaptation (more capable of surviving in environment)?
e. Natural Selection:
Some individuals will be more successful in surviving &
will reproduce because of traits that give them an
The alleles of those who reproduce more will increase in
frequency in a population.
This is how a population can become more suited to its
environment = adaptation!
Ex. Peppered moth
Watch “The Making of the Fittest: Natural Selection
and Adaptation” video on the rock pocket mouse
Ex. Sickle cell disease: Watch “The Making of the
Fittest: Natural Selection in Humans” video on
sickle cell anemia.
Read p. 294-295 “Essay: An Evolving Ability to Drink Milk” and watch “The Making of the Fittest:
Got Lactase? video and answer the following questions:
1. For tens of thousands of years, adult humans did not have the ability to digest milk. What event in
human history occurred around the same time as the ability for adult humans to digest milk?
2. What is the name of milk sugar and what type of biological molecule is it (carbohydrate, protein, lipid,
or nucleic acid)? What is the name of the molecule that humans use to break down milk sugar and what
type of biological molecule is it?
3. What was the default position for the human lactase gene and why was this the default position?
4. What mechanisms brought about the ability for adults to digest milk in three different regions?
5. Did lactase persistence arise recently and over a relatively short period of time or early on and over a
long period time in human existence?
How does a single species transform into different species?
C. Macroevolution – evolution that results in the formation of new species (result of evolution; larger scale)
Species – a group of organisms who can successfully interbreed with one another in nature but who don’t
successfully interbreed with members of other such groups
How can speciation occur?
1. How populations can stop interbreeding (Table 18.1)
Read pp. 321-323: “How Do New Species Arise?” and Table 18.1, and define the following 7
reproductive isolating mechanisms:
a. Geographic Isolation:
b. Ecological Isolation:
c. Temporal (Time) Isolation:
d. Behavioral Isolation:
e. Mechanical Isolation:
f. Gametic Isolation:
g. Hybrid Inviability/Infertility:
2. When is Speciation Likely to Occur?
Read pp. 325-328: “Adaptive Radiation and the Pace of Speciation” answer the following questions:
a. Define what a “niche” in an environment is.
b. What type of environment is ripe with possibilities for change (speciation) and describe why?
c. Define “adaptive radiation”. And, state what is necessary for an adaptive radiation to take place.
IV. Now what does evolution mean?
1. Any genetically based phenotypic change in a population of organisms over successive generations.
2. Process by which species of living things can undergo modification over successive generations, with such
modification sometimes resulting in the formation of a new species.
V. The Evolution of Human Beings
Read p. 362-375 “Arriving Late, Traveling Far: The Evolution of Human Beings” and answer the following:
1. What is the name of the taxon of human-like primates and how many species are candidates for membership in
this category? Also, what is the name of our own species?
2. On what continent have all of the oldest hominin fossils and oldest known remains of modern humans been
3. What are the two most important defining features of a hominin?
4. Comment on the brain size of Australopithecus afarensis and Homo ergaster.
5. What was Homo erectus the first to do? Comment on how long H. erectus existed and describe a possible
reason why their increased intelligence arrived with such seeming speed.
6. Homo neanderthalensis was a more modern hominin species than those previously described but still differed
from our species. Describe those differences.
7. Explain why 1 – 4 % of the DNA of today’s Europeans and Asians is of Neanderthal origin.
8. Describe what has happened to genetic variation in human populations from sub-Saharan Africa and in
populations from increasing distances from Africa. Also, explain why this trend in human genetic variation has
Ecology (Chapter 34-36)
A. Hierarchy of Biological Organization
1. Organism (species): a group of similar organisms whose members successfully interbreed
2. Population: members of the same species that live together in the same area
3. Community: all the populations of different species that live and interact together within an area
4. Ecosystem: a community together with its physical environment
II. Population Ecology
A. How Populations Grow (Fig. 34.4)
1. Exponential growth (J curve):
2. Logistic growth (S curve):
a. Carrying capacity (K):
B. Human Population (Fig. 34.10)
C. Life History Patterns of Populations (Fig. 34.7)
1. r-selected (Opportunistic) populations:
2. K-selected (Equilibrium) populations:
III. Community Ecology
A. How Species Interact Within a Community
1. Ecological Niche: the role a species plays in its community, its habitat, and its interactions with other
2. Competition
a. When does competition occur?
b. Outcomes of direct competition: (Fig. 35.4)
Competitive exclusion:
Resource partitioning:
3. Predator/Prey Interactions
a. Why are predator/prey interactions important to have in a community?
1. How do these interactions affect abundances? (Fig. 35.8)
2. How do these interactions affect fitness (evolution)?
3. How do these interactions affect species diversity?
Example of predator and their cascading effects in a(n):
Intertidal (tide pool) community:
Kelp forest community:
4. Symbiotic Relationships
READ pp. 676, 678 & 680 define each of the following relationships and provide examples:
a. Parasitism:
b. Mutualism:
c. Commensalism:
C. How Communities Change Over Time
1. Ecological Succession: (Figs. 35.16 & 35.17)
2. Is disturbance a bad thing in a community?
a. The Importance of Fire in Fire Adapted Communities
b. Fire adapted communities depend on fires to burn every 2 to 3 years. Why?
c. Low Intensity Fires vs. High Intensity Fires
Low intensity fires: move slowly, no root damage,
recycles nutrients, quick regrowth occurs,
High intensity fires: destroy large areas, kill trees,
damages soil, regrowth takes many years
What area has more small fires?
What area has fewer fires altogether?
What area has more large fires?
What area seems like it has more high intensity fires?
Why do you suppose this area has more high intensity fires?
IV. Ecosystem Ecology
A. How energy flows in ecosystems
1. Producers – use simple inorganic molecules to make
complex organic molecules (ex. photosynthesize)
Consumers – eat producers and others to gain energy,
cannot gain energy just from simple inorganics
Decomposers – break down dead material to make
2. What type of energy is given off at each level?
Is it available to the next level?
B. Primary Productivity:
Whatever the ecosystem, primary productivity sets the spending limit for the energy budget of the entire ecosystem
because consumers must acquire food from producers.
D. How the energy is divided among trophic levels in an ecosystem
1. How much energy will be transferred to the next trophic
2. Ecological (Energy) Pyramid: (Fig. 36.14) displays amount
of energy available at each trophic level
a. Why is there a stepwise decline of
energy as you go up the levels?
b. Why more lower level consumers (ex. zebras)
than higher level consumers (ex. lions)?
c. What type of consumer is more “expensive” for an ecosystem to support? Why?
d. Why can certain animals at lower levels be much larger in size than top carnivores?
e. Vegetarians (herbivores) vs. Meat Eaters (carnivores)
What type of consumer is more “expensive” for an ecosystem to support?
Biodiversity & Extinction
Biodiversity (Fig. 35.3)
A. The Importance of Biodiversity: Why Do We Need
1. Ecosystem Services
II. Extinction
A. Extinction
1. Background extinction
2. Mass extinction (Fig. 19.3)
3. Ecologically extinct
III. What causes species loss?
Scientists estimate that for every 2000 species that have ever lived, 1999 of
them are extinct today.
Scientists estimate that species are presently becoming extinct at a rate
of at least 50-100 times the natural rate of background extinctions.
A. Habitat Loss
1. Agricultural lands currently occupy 35 % of the earth’s land.
Agriculture also has huge impact on aquatic ecosystems due to
water diversions.
2. Every year, humans destroy an area of tropical rain forest equal to the size of West Virginia.
3. Habitat Fragmentation
B. Exotic Species: foreign species in an ecosystem in which it did not evolve in
1. How are exotic species introduced into new areas?
2. Examples:
- Northern snakehead: in May 2002 a fisherman in Maryland caught this fish in a pond. Found hundreds of
juveniles in the pond. Native to eastern asia where it is a prized delicacy. Local man bought 2 snakeheads
in NY raised them as pets and then released them after they outgrew his aquarium
Zebra mussel: entered St. Lawrence Seaway in mid 1980s ballast water released by cargo ship that had
traveled from the mussel’s native Caspian Sea.
Lake Victoria, East Africa: 200 of the 300 species of native fishes, found nowhere else but in this lake,
have become extinct since Europeans introduced a non-native predator, the Nile perch in the 1960s.
Caulerpa taxifolia – marine green alga from Mediterranean, was bred in aquarium and then accidentally
released into the Mediterranean where it took over and spread over seafloor. Caulerpa was been banned in
the U.S. in 1975 but is still commonly brought in. It is now in southern California; San Diego and
Huntington Harbor.
U.S. has at least 50,000 introduced species. Purposefully introduced invasive species have cost the U.S.
economy $130 billion.
3. Why are exotic species so harmful?
C. Overexploitation – purposefully taking species out of the system (for food, to eradicate ‘nuisance’ species,
over-hunting, poaching); commercial harvest or sport hunting, by-catch