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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- 1 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 2 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- 3