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evolutionary concepts notes

evolutionary concepts notes - f copulatory...

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Evolutionary Concepts: What is a species? Biological species concept: “A species is a naturally occurring breeding population that is reproductively isolated , either actually or potentially from other such groups.”-Ernst Mayr Recognition species concept: defines species based on unique traits or behaviors that allow members of one species to identify each other for mating Hybrids- an offspring of two separate species -does not occur in nature because of reproductive isolation -seen in lions and tigers at zoos -reasons for not cross-breeding in nature: Differ ecologically-preference to habitat Geographic isolation-separated geographically Reproductive Isolating Mechanisms: -Pre-mating a. geographic-don’t live in the same place b. seasonal-breeding seasonality c. temporal-nocturnal vs. diurnal d. habitat-forest levels, ground vs. tree-dwellers e. courtship-body language
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Unformatted text preview: f. copulatory failure-anatomical, mechanical -Post-mating a. failure to fertilize b. zygote death (zygote=fertilized egg) c. fetal death d. death of offspring e. offspring healthy but sterile (mules) Patterns of Speciation: • Allopatric-involves geographic separation-geographic separation between two populations of the same species triggers the emergence of a new species (pg. 95) • Parapatric-when two populations occur adjacent to one another, with continuous gene flow back and forth between them, speciation of one from the other is nevertheless possible, especially if one of both species occur over a very large geographic area • Sympatric-occurs in same population -species arise in the same place but are genetically different -outwardly look the same Cline: variation in a trait over a wide geographic area...
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