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Carefully, define a species

A species is defined using the Biological Species Concept:
A group of organisms that can interbreed in nature and produce fertile, viable offspring.
Members of the same species share a gene pool and are reproductively isolated from such other groups.

Why is it so hard to define a species

Some species reproduce differently
Asexually, so interbreeding doesn’t apply
Extinct, so no reproduction testing
Hybridization

Differentiate between species and speciation

Species are the outcome of distinct groups
Speciation is the process by which species splits into two or more new species

Explain how species can evolve

Through allopatric and sympatric speciation
Allopatric is when a geographical barrier separates populations. Ex: river, mountain, distance.
Sympatric occurs without a physical barrier, due to ecological differences, polyploidy in plants, or behavioral shifts.

Allopatric speciation define and give examples

Define: speciation that occurs due to geographic separation
Ex: Grand Canyon squirrels on opposite rims that no longer interbreed

Hybridization define and give examples

Define: Occurs when two species interbreed and create hybrids
Hybrids form new stable species, especially in plants, in animals they are most likely infertile or die in womb.
Ex: Hybrid sunflowers that thrive i unique habitats

Prezygotic Isolation define and give examples

Define: prevents fertilization
Ex: Temporal, Behavioral, and Mechanical/Gametic Isolation

Temporal define and give examples

Species breed at different times
Two frog species mating in different seasons

Behavioral define and give examples

Differences in courtship rituals
Bird species with unique mating dances

Mechanical/Gametic define and give examples

Incompatible reproductive structures or gametes
Snails with shells spiraling in opposite directions cant mate successfully

Post-zygotic isolation define and give examples

Define: occurs after fertilization
Ex: Reduced hybrid viability, reinforcement

Reduced hybrid viability define and give examples

Hybrids fail to develop properly or die early
Ex: zonkey that doesn’t make it out of womb

Reinforcement define and give examples

Natural selection strengthens reproductive barriers to prevent hybridization over time

Sympatric speciation define and give examples

Define: Occurs within same geographic space, speciation occurs due to behavioral change, etc
Ex: fly changes trees for eating