Evolutionary mechanisms, evidence, and biodiversity

Notes

EVOLUTION STUDY GUIDE (COMPLETE REVIEW) This guide covers everything in your syllabus and is organized the way teachers usually ask it in exams. ⸻ 1. EVOLUTION Definition Evolution is the change in the genetic characteristics (allele frequencies) of a population over generations. Key idea: * Individuals do not evolve. * Populations evolve. ⸻ Evidence for Evolution 1. Fossil Record Fossils show how organisms have changed through time. Example: * Ancient horse fossils show gradual increases in size. 2. Comparative Anatomy Homologous Structures Same evolutionary origin, different functions. Example: * Human arm * Whale flipper * Bat wing These indicate common ancestry. Analogous Structures Different evolutionary origin, same function. Example: * Bird wing * Insect wing These indicate convergent evolution. ⸻ 3. Embryology Many vertebrate embryos look similar during development. Example: * Fish, birds, reptiles, and mammals have similar embryonic stages. ⸻ 4. Molecular Evidence DNA similarities reveal evolutionary relationships. Example: * Humans share about 98–99% of DNA with chimpanzees. ⸻ 5. Biogeography Study of species distribution. Example: * Unique species on islands often resemb...