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level: 10.3 Speciation

Questions and Answers List

level questions: 10.3 Speciation

QuestionAnswer
What are the 3 different types of reproductive isolation?temporal behavioral geographic
Why does speciation occur?bec of divergence of isolated populations it can be gradual or happen abruptly
What are different types of selection? examples?directional stabilising disruptive
What are population bottlenecks? (4)when an event greatly reduces the population size can be natural (fires) or human induced (overhunting) the remaining population will be smaller = less genetic variability eg: overhunting northern elephant seals
What is the founder effect?when a new population is made by a small subset of the larger population = less genetic variation + greater genetic drift
What are the 3 main types of selection? effect?stabilizing: intermediate phenotype is favored over the extremes directional: one phenotypic extreme is chosen disruptive: both extremes are selected over the intermediate phenotype
What is reproductive isolation? what are the 2 types?reproductive barriers emerge to keep 2 population from interbreeding = gene pools become separated pre-zygotic: before fertilisation happens (no offspring) post-zygotic: after fertilisation happens (infertile offspring)
what are the 3 pre-zygotic reproductive isolation types? examples?temporal = diff period of activity and for reproduction EG: leopard and wood frogs breed at diff times behavioral = different courtship behaviors EG: some birds only respond to specific mating calls geographic = populations are in diff habitats within a region EG: lions and tigers usually live in different habitats
what are the 3 post-zygotic reproductive isolation types? examples?Hybrid unviability = fail to develop reproductive maturity EG: some tadpoles die before maturity Hybrid Infertility = the hybrids don't produce functional gametes eg: mules are sterile Hybrid breakdown = the 2nd generation of hybrids fail to develop properly EG: offspring of hybrid copepods have lower survival potential
What is speciation? (5)causes the formation of new species happens when isolation barriers prevent gene flow bw 2 populations = diverge due to genetic drift and natural selection there are 2 types: allopatric = divergence due to geographical isolation sympatric = divergence in the same location
What is allopatric speciation?geographical separation of population with a physical barrier = exposed to different environmental conditions and diverge eventually cant interbreed - speciation eg: darwin's finches
What is sympatric speciation?divergence of species in the same location bec of difference in reproductive or behavioral isolation eg: polyploidy in Allium
What is polyploidy? (4)additional set of chromosomes if sex cells fail to undergo cytokinesis = abnormal zygotes more common in plants bec they can self fertilise reproduce asexually
What are the 2 models of speciation?phyletic gradualism: from continuous change at a constant pace gradual accumulation of genetic mutations over time Punctuated equilibrium: from abrupt bursts bw periods of stability bec of rapid environmental changes
What is phyletic gradualism? evidence to support?continuous divergence at a constant pace = speciation supported by intermediate forms in the fossil record
What is punctuated equilibrium? evidence?short evolutionary bursts bw stable periods supported by gaps found in fossil records
What is the determination of speciation limited by?certain organisms not reproducing sexually (bacteria) breeding capacity is impossible to determine w fossils physically impossible for certain members in a species to mate