Speciation & Macroevolution (E1) Flashcards
Allopatric speciation
Geographic isolation due to change in gene frequency
Species
A group of organisms that can interbreed and produce offspring
Liger/tigon
Hybrid species that can’t produce offspring
(F tiger & M lion)/(M tiger & F lion)
Reproductive isolation
Two populations of the same species can no longer mate together successfully
Ex.can mate but offspring aren’t fertile or viable
Reinforcement
Separates a species into two because of their mate recognition
(Process that solidifies the difference between a species)
Post-zygotic isolation
Parents can form zygote together but after that it’s all over for their lineage
(Miscarriages, no development of embryo, big fetuses that kill mother at birth)
Pre-zygotic isolation
Isolation happened between groups of the same species before an egg gets fertilized
(Behavioral changes(different mating songs), change to nocturnal, geographic)
Sympatric speciation
One species can diverge into two without being geographically separated but reproductively isolated in another way
Ex.Galapagos finches
Species concepts
Biological Species Concept=same species if they can interbreed and produce fertile offspring
morphology(physical characteristics)
Reproductive compatibility
Mate recognition
Ecological niche
Shared derived characters(most recent common ancestors)
Ring species
An incomplete circular chain of species that reproduce until the beginning and ending meet
Vicariance
Geological separation of a population, typically physical barrier, resulting in pair of closely related species
(Mountain formation,river change course)
Tempo speciation
Rate of which new species are formed
Ex.stasis, gradualism,punctuated equilibrium
Stasis speciation
Equilibrium in a stable environment
(If it ain’t broke don’t fix it)
Neutral evolution
Gradual speciation
Under modest: selection, genetic variation, hemoglobin changes
Ex. Bar-headed geese (higher oxygen affinity bc highest flying bird flying near Mt.Everest)
Punctuated equilibrium speciation
A stasis and rapid change occurs when: generation time is short(HIV), selection is “hard”(tuskless elephant), regulatory genes change(deletion of pitx1 in stickleback)
