Biology 1001A Lecture Notes - Lecture 10: Species, Reproductive Isolation, Zygote

• School: Western University
• Department: Biology
• Course: Biology 1001A
• Professor: Tom Haffie

Document Summary

Before: criteria used by the morphological, biological and phylogenetic species concepts to define species. Morphological focuses on similarities (appearance) between two organisms. Biological focuses on reproductive abilities between two organisms (fertile offspring and decent fitness). Phylogenetic focuses on common ancestor and one branch of organisms: weaknesses/limitations of these different species concepts. Morphological, some look similar but are different, some look different but are same. Phylogenetic, not enough information yet: distinguish between pre-zygotic and post-zygotic isolating mechanisms and recognize examples of each. Pre-zygotic isolating mechanisms are those that take effect before a hybrid zygote is conceived, includes: ecological, temporal, behavioral, mechanical, gametic. Post-zygotic takes effect after the offspring is conceived, includes: hybrid inviability, hybrid sterility, hybrid breakdown. Before: competing theories about where modern humans (homo sapiens) evolved, and which is best supported by available evidence. First one is the african emergence theory and states that humans arose in africa.