Speciation Notes

Species

a population of organisms that are able to interbreed with each other but not with other populations

Speciation

Process in which a group of organisms becomes a new species

Speciation occurs when 2 populations of the same species become isolated from each other and cannot interbreed.

Reproductive Isolation

• There are three different ways for species to become _____ isolated

Geographical Isolation

• Species do not interbreed due to geographical separation (river, mountain range, ocean, etc.)

• Ex: Spotted owls 

-Separated by desert and mountains, do not interbreed

Behaviorial Isolation

• Species do not interbreed because they have different mating behaviors

• Ex: Different mating calls in different species of birds

-Each bird species only responds to their particular mating call

Temporal Isolation

• Species do not interbreed due to different timing of reproduction

• Can be time of day, time of year, or any other timing issue

• Ex #1: different species of frogs mate at different times of the year

• Ex #2: Closely related species of fireflies mate at different times of the night 

Convergent Evolution

• Though not related, species evolve similar solutions to similar environmental pressures

  • Will have analogous structures

    • Similar in function but not structure

  • Ex. mimicry

Divergent evolution

• Species with a common ancestor evolve differences over time

  • Will have homologous structures

    • Similar in structure but not function

Coevolution

• A species evolves in response to the evolution of another

  • Predator-prey relationship, parasite-host relationships, and flowers & pollinators