BIOL 1108 Lecture Notes - Lecture 7: Allopatric Speciation, Sympatric Speciation, Reproductive Isolation
Document Summary
Core concept 2: reproductive isolation is caused by barriers to reproduction before or after egg fertilization. Speciation in action: reproductive isolation: two categories: Physical (failure of sperm to be accepted by egg, size) Temporal (time) (breeding season, sperm and egg need to meet) Genetic incompatibility usually leading to failure of the zygote to develop: sheep and goat. Sterile offspring (genetic dead end: lyger, mule: parents can cross but produce sterile offspring. Core concept 3: speciation underlies the diversity of life on earth. Most speciation is thought to happen allopatrically. A single interbreeding population is split into two populations. Intermittently, we take individuals from each population and test them to see whether they can still interbreed. The two populations diverge genetically because different mutations occur and become fixed in each population over time. Speciation occurs when the two populations are unable to produce viable, fertile offspring: allopatric: away from origins.
