BIOL 121 Lecture Notes - Lecture 30: Hadean, Hydrogen Cyanide, Lightning
Document Summary
*cannot be interbreed anymore because they were isolated from each other reproductive isolated. Antelope squirrels grand canyon: birds & other organisms that easily disperse across canyon have not diverged into different species on opposite side of the canyon. Allopatric speciation can occur via a founder event: establishment of a new population by a small number of individuals. How did ancestor get to the galapagos islands: galapagos islands < 10 million yrs. ago, ancestor unlikely to be small, gigantism better for long distance rafting, split between ancestors of two lineages of tortoises on south. Why speciation in finches, not in tortoises: ancestors arrived at different times, different rates of evolutionary change, tortoises longer to reach sexual maturity (20-25 yrs. ) Fewe generations: finches able to exploit a greater no. of niches (diet) Diversity of life: 1. 5 million known species but an estimated 10. 9 million spp, about 4. 6 billion years ago the planet formed.
