BIOL 123 Lecture Notes - Lecture 2: Egg Cell, Allopatric Speciation, Natural Selection
Document Summary
Later on, won"t be able to mate with each other. Hard to see in animals, but often in plants. Meiosis malfunction for plants, but won"t work for. Biological species concept: a way of defining when speciation occurred. Reproductive isolation: refers a failure of organisms to reproduce successfully in circumstances which they would normally mate. Animals might not mate due to different preferred habitats. Specific time of matings can isolate 2 species. Due to visual appearance, behavior, scent, etc. repelling the other sex. There might be a lack of fit in genital structures, preventing reproduction. Sperm comes into contact with eggs, but there is cellular mechanisms preventing foreign sperm from penetrating the ova. Postzygotic isolating mechanisms: act after fertilization occurs for reproductively isolated organisms. Hybrids are formed from 2 opposite species that can mate. Most are sterile, inviable, or have greatly reduced fertility.
