Evolution and It's Processes Flashcards
Bottleneck Effect
the magnification of genetic drift as a result of natural events or catastrophes
Founder Effect
a magnification of genetic drift in a small population that migrates away from a large parent population carrying with it an unrepresentative set of alleles
What are two effects of genetic drift?
Bottleneck and Founder Effect
Gene Flow
the flow of alleles in and out of a population due to the migration of individuals or gametes
Vestigial Structure
a physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor (ex: penguins with wings)
Embryonic Structures
Structures that are absent in some groups often appear in their embryonic forms and disappear by the time the adult or juvenile form is reached. For example, all vertebrate embryos, including humans, exhibit gill slits at some point in their early development.
Evidence of Evolution
Embryonic structures, Biogeography (distributed groups on separated mainlands), convergence of form (white arctic foxes and birds), vestigial structures, universality of DNA.
Speciation
the formation of two species from one original species. Is impossible for two species to interbreed.
Allopatric Speciation
a speciation that occurs via a geographic separation
Sympatric Speciation
a speciation that occurs in the same geographic space
What is the process of speciation through geographic separation?
Natural selection through different environments will cause divergent adaptions. Genetic drift will cause divergence through smaller populations. Mating between both populations becomes less likely.
What are the two parts of reproductive isolation?
prezygotic mechanisms (those that operate before fertilization) postzygotic mechanisms (those that operate after fertilization).
Prezygotic Mechanisms
Traits that allow the individuals to find each other, such as the timing of mating, sensitivity to pheromones, or choice of mating sites. Prevents courtship rituals.
Postzygotic Mechanisms
Include genetic incompatibilities that prevent proper development of the offspring, or if the offspring live, they may be unable to produce viable gametes themselves.
What are the two allopatric processes?
Dispersal and Vicariance
Dispersal
An allopatric speciation that occurs when a few members of a species move to a new geographical area.
Vicariance
An allopatric speciation that occurs when something in the environment separates organisms of the same species into separate groups.
Adaptive Radiation
A speciation when one species radiates out to form several other species. Ex. Galapagos Finches and beak shapes.
What are the sympatric processes?
Polyploidy, genetic flexibility that separates population from parent population (Ex. fish and new food), mutation or behavior changes (Ex. Apple Maggot fly)
Polyploidy
Polyploidy is a condition in which a cell, or organism, has an extra set, or sets, of chromosomes. results from an error in meiosis in which all of the chromosomes move into one cell instead of separating.
What are the two types of polyploidy
Autoploidy and Allopolyploid
Autoploidy
a polyploid individual will have two or more complete sets of chromosomes from its own species
Allopolyploid
Allopolyploid occurs when gametes from two different species combine.
