PHYSICS 1A03 Lecture Notes - Lecture 9: Hybrid Speciation, Sea Urchin, Ecological Niche

• School: McMaster University
• Department: Physics
• Course: PHYSICS 1A03
• Professor: Waldemar Okon

Document Summary

What is speciation, and why do we care? speciation is the splitting of one evolving group of organisms into two separately evolving groups this splitting, followed by continuing evolution, is why we have a tree of life. Individuals of different species evolve independently (fig 26. 1) Difficult to make this conceptual definition into a practical definition finches, again the biological species concept uses reproductive isolation to define species. Biological species concept: different biological species either: Produce inviable offspring (not viable = don"t develop to adulthood) Produce sterile offspring offspring aren"t fertile = can"t reproduce) Pre- vs. post-zygotic mechanisms offspring of their own. zygote = a cell formed by the fusion of a sperm and an egg: why don"t individuals from different species produce viable, fertile offspring, mechanisms of isolation are divided into two classes: Prezygotic isolation: any mechanism that prevents successful mating. The offspring of horses and donkeys grow up to be healthy, infertile adults.