Unit 4- Evolution & Classification Flashcards
(34 cards)
directional selection
a change in the allele frequency of a population when an organism favors an extreme phenotype
disruptive selection
a change in the allele frequency of a population when an organism is not favored for the most common phenotype
stabilizing selection
favors the average individuals in a population
geographical isolation
occurs when a physical barrier separates a population; ex. two populations are separated by a body of water or a mountain
behavioral isolation
two populations have different courtship rituals;
temporal isolation
occurs when two or more species reproduce at different times
habitat isolation
two species live in the same area but live in different habitats within that area; ex. a species snake lives on land and another species of snake lives in water
gametic isolation
sperm and egg cannot fuse because the surface proteins have changed
mechanical isolation
sex organs of closely related species are incompatible (meaning they do not fit together)
founder effect
allele frequencies change due to a migration; when a few individuals colonize a new habitat, the small founding population makes up the new gene pool; type of genetic drift
evolution
a long slow process of change over time; a change in the gene pool over time
bottleneck effect
drastic reduction in population size and by chance some individuals survive to make up the new gene pool; ex. natural disaster, fire, flood; type of genetic drift
genetic drift
an accidental change in gene frequency that affects small populations only as a result of chance
genetic equilibrium
a state of constant allele frequency in a population throughout generations
vestigial structure
an anatomical organ in organisms that is no longer used or has a function; ex. appendix in humans, eyes in sightless species
homologous structure
an anatomical structure that is found in different species, it has similar structure/make-up but different functions; ex arms, wings, and flippers
analogous structure
a structure that is found in different species that has a dissimilar structure but similar function; ex a bird wing, bat wing & butterfly wing
gene pool
the combined genetic material of all the members of a given population
paleontologist
a scientist that studies fossils
speciation
evolution of 1 or more new species from a single ancestor
natural selection
Darwin’s idea that individuals best adapted to the environment will survive and reproduce; nature provides variation and nature chooses which traits are best adapted
artificial selection
AKA selective breeding; nature provides variation and humans choose whcih traits are best adapted
niche
the role of an organism in the environment
adaptation
the long neck of a giraffe makes it better suited to survive
