Download convergent evolution- different populations or species evolving in

convergent evolution- different populations or species evolving in similar environments, process by which unrelated
organisms independently evolve similarities, evolution of similar traits in distantly related organisms, leads to production of
analogous structures, ex. wings of butterflies and birds, insect mimicry, streamlined shape of fish and whales
gene pool- combined genetic material for all members of a population, (all of the genes in a population)
genetic drift- random changes in the allele frequencies of a population due to chance happenings (events), generally
occurs in small populations (large populations tend to be able to withstand these events without significant effect on their
allele frequencies), unlike natural selection, an individual’s fitness generally does not have great influence on whether or not
it is removed from the gene pool during genetic drift (it is a non-selective event), small population is not representative of the
larger “parent population”, (certain alleles may be lost, over-represented, or under-represented), tends to be less genetic
diversity
bottleneck effect- example of genetic drift, occurs when catastrophic events (volcanic eruption, earthquake, fire, flood,
over-hunting) decimate a population so that only a small percentage of the population survives and are left to repopulate the
community (or the world, in severe instances), ex. cheetahs and the ice age, northern elephant seals and over-hunting
founder effect- small number of individuals from a large population migrate and colonize a new habitat, ex. “mutiny on the
bounty”, Pitcairn island, Darwin’s finches and the Galapagos islands
Hardy-Weinberg principle- describes the specific conditions required for genetic equilibrium to remain unchanged in a
population (conditions necessary for no evolution), conditions are: no natural selection, no migration, no mutations, mating
must be random (no preferential selection of mates), and it must be a large population
p = frequency of dominant allele (A)
q = frequency of recessive allele (a)
p + q = 1 (100%)
this principle can also be used to predict probability of genotypes:
p2 = frequency of homozygous dominant genotype (AA)
2pg = frequency of heterozygous genotype (Aa)
q2 = frequency of homozygous recessive genotype (aa)
p2 + 2pq + q2 = 1
example of calculating the allele frequencies and genotype frequencies-
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coevolution- process in which two species evolve in response to changes in each other, a change in one species acts as a
selective force on another species, ex. flowers (shape, scent, or color), and their pollinators (feedings structures of insects,
birds, bats), predators and prey
cladistics- approach that classifies organisms according to the order in time that branches arose in the evolutionary history,
ex.
isolating mechanisms- individuals of the same population interbreed and share a common gene pool, when two
populations of the same species become reproductively isolated from each other, they cannot interbreed, these populations
start to have separate gene pools and respond to natural selection as separate units, reproductive isolation can develop in a
variety of ways
behavioral isolation- occurs when two populations are capable of interbreeding, but have differences in behavior, such as
courtship rituals, ex. eastern and western meadowlarks use different mating songs
geographic isolation- allopatric speciation, occurs when two populations are separated by geographic barriers such as
mountains, oceans, or rivers, ex. subspecies Abert squirrel and Kaibab squirrel (separated by Colorado river about 10,000
years ago
temporal isolation- occurs when two or more species reproduce at different times, ex. three similar species of orchids all
live in the same rainforest, each species only releases pollen on a single day because each species releases pollen on a
different day, and they cannot pollinate one another
seed- mature fertilized ovule (a seed contains plant embryo and food reserve in protective coat)
fruit- a mature, fertilized ovary
flower- structure specialized for sexual reproduction in angiosperms
sepal- outermost part o flower that protects the unopened flower bud
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petal- layer of modified leaves just inside sepal (often colorful to attract insects)
stamen- male reproductive structures of flowers (produces pollen which contain sperm), anther: part of stamen where
pollen is produced, filament: long think stalk attached to anther
pistil- female reproductive structures of flowers (contains ovules which contain eggs), stigma: upper part of pistil where
pollen grams are received, style: stalklike structure between stigma and ovary, ovary: an egg producing structure found at
base of pistil
pollination- transfer of pollen grain from an anther to a stigma, ex. wind pollinated, insect pollinated
insect vs. wind pollinationinsect
wind
large, colorful petals
petals small or absent
produce nectar
do not produce nectar
flowers scented
flowers not scented
produce smaller amounts of pollen
produce large amounts of pollen
seed dormancy- “sleeping”, period of reduced metabolism and growth, in seeds plant embryo is inactive (a survival
adaptation assured by lowering water content
seed dispersal- adaptations that help seed travel to locations away from a parent plant, ex. seeds may disperse via wind,
water, animals, or propulsion
double fertilization- process in which a pollen grain produces two sperm, they travel down a pollen tube to reach the ovule
and enter through an opening in the ovule, one sperm fertilizes the egg inside the ovule to form an embryo, and the other
sperm combines with two polar nuclei that develop into a nutritive endosperm (3N) inside the seed, evolution of this
adaptation helps prevent the plant from wasting energy and nutrients on ovules that do not get fertilized
angiosperms- produce flowers for sexual reproduction (pollen and ovules produced in flowers, not cones), vascular plants
whose seeds develop in a protective ovary, “vessel seeds”, ovaries mature into fruit when fertilized, most successful and
diverse group of plants (approx. 250,000 species), many flowers arranged in whorls around central axis (sepals, petals,
stamen, pistil), angiosperms are divided into two classes  monocots and dicots based upon differences in their seeds,
stems, leaves, flowers, and roots
life cycle of an angiosperm-
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