Evoltuion 3 Flashcards
natural selection in a nut shell
too many offspring
compeition for limited resources
individuals show variation
survival: have better variations, better compete, can survive
people with bneficial variation need to reproduce for next generation
stabilizing
form of natural selection, intermediate phenotype favored, extreme eliminated
example of stabilizing
human birth weight, clutch size (number of eggs) in birds
disruptive
form of natrual selection, opposite of stabilizing, intermediate eliminated, extreme favored
example of disruptive
size of bird beaks (smal and large, small = soft seeds, large = harder seeds)
sexual selection
form of natural selection, mates chose mates for specific reasons
example of sexual selection
change gravel, evolve into background, dominant selection pressure
MATE CALL
directional
one phenotype over time replaced by another phenotyep
example of directional
peppered, guppy experiment, european black bear (during period of galciation european black bear become bigger
selection pressure
something in habitat that favor one variation over another
example of selection pressure
gravel, predator, female
specieis
individual of same type that are inner breeding and produce fertible offspring
speciation
evolution of a new species, two main types
allopatric
requires geographic isolation barrier
example of allopatric
darwins finches: each island has specific beaks for specific food on island, evolved from blue grass glass finch
allopatric devlopment
gene flow because can cross river, then over time stream became geopgrahic barrier = NO GENE FLOW, geographic isolation, differenect selection pressures occur on both sides, different variations accumulating, natrual selection, become repdouctively isolated (can’t and will not mate)= considered two different species
Type of gene drift
Bottle neck and founder
