prior to formation of zygote discourage attempts to mate Habitat isolation

Prior to formation of zygote discourage attempts to

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: prior to formation of zygote; discourage attempts to mateHabitat isolation - species live in same area but occupy different habitat -> less likely to meet and reproduceTemporal isolation - species with different breeding seasonsBehavioral isolation - species with different courtship/mating ritualsMechanical isolation - incompatibility of sex organs -> sperm can’t get to eggGamete isolation - sperm in vicinity of egg but doesn’t have enzymes to dissolve egg coating; sperm needs right characteristics to survive reproductive tractPostzygotic: prevent hybrid offspring (combination of 2 different genetic makeup) from developing/breedingHybrid inviability (zygote mortality) - spontaneously abort; can’t successful developHybrid sterility - organism born but can’t pass traits onto other offspring (sterile)Hybrid breakdown - reduced fitness; don’t live longModes of speciationAllopatric: 2 geographically isolated population of 1 species -> different species over time - gene flow interruptedCan be due to differing selection pressures in differing environmentsEg: squirrels at Grand Canyon; Panama grunt fishPeripheral isolation: few population members subject to different natural selection pressure -> new speciesAdaptive radiation: members of species invade new geographically separate environment (niche) -> population adapt to different environment -> new species evolve from 1 ancestral species (eg: Hawaiian honeycreeper)Sympatric: one population develops into 2 or more reproductively isolated groups; no prior geographic isolation (no physical barrier to interbreeding)Autoploidy- 2n plant -> 2n gametes (+n) = triploid (sterile, seedless)Alloploidy- plant tetraploid hybridization -> self-fertile species, reproductively isolated from both parent speciesPace of EvolutionPhyletic gradualism: speciation occurs gradually; stasis apparent but not real; transitional links found; ancestral species transform into new speciesPunctuated equilibrium: speciation occurs rapidly; species experiences stasis over long time; transitional links not found; subpopulation becomes new species; often living fossilClassification of Living ThingsSystematics: study of biological diversity and evolutionary history of life on earthGoals - discover all species; reconstruct phylogeny of a group, classify accordinglyTaxonomy: branch of biology concerned with naming (only one scientist gets to “name” species), identifying (anyone canwith a key) and classifying (group a species with closest relatives) organismsBegin with ancient Greeks/Romans - Aristotle classify organisms into groups (eg: horse, bird, oak) - Scala naturaeJohn Ray - believe each organism should have set nameCarolus Linnaeus- binomial system of nomenclature (Genusspecies) - written in LatinFirst word is genusname - used alone to refer to group of related speciesSecond word is specific epithet- refer to one species within genusThird word is subspecies (on way to becoming separate species but not there yet)
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