1. Chapter 9 con’t March 14th

2. Founder Principle Founder principle – populations founded by a very small number of individuals generally contain a small subset of the total genetic variability of the main population and are prone to allopatric speciation Genetic bottleneck – decreased genetic diversity resulting from decreased population size

3. Peripatric speciation – when peripheral populations become geographically isolated from the main population and undergoes speciation and genetic divergence Tanysiptera galatea Tanysiptera sylvia Tanysiptera carolinea

4. Natural Selection favors traits that increase survival and reproduction Flightless birds, insects, and seeds Continental relatives can fly Guam railHawaiian Goose “nene”

5. Vicariance Event Populations split by geographic barrier initiating allopatric speciation Boreal biome split by Laurentide Ice Complex Species differentiation slower in larger populations

6. Adaptive Radiation Adaptive radiation – the development of many species from a single species – new species fill all available niches in the colonized region Example: Hawaiian honeycreepers have variety of beaks to take advantage of different foods

7. Species of Hawaiian honeycreepers descended from a common ancestor, some of which are shown here, have evolved many different bill shapes and food sources. (Paintings copyright H. Douglas Pratt, The Hawaiian Honeycreepers: Drepanidinae. Oxford: Oxford University Press, 2003. Diagram adapted from T.J. Givnish and K.J. Sytsma, eds., Molecular Evolution and Adaptive Radiation. Cambridge: Cambridge University Press, 1997.)

8. Adaptive radiation in cichlid fish from Lake Malawi in East Africa

9. Convergent Evolution

10. Evolutionary convergence; (From Top to Bottom) An ichthyosaur Ophthalmosaurus icenicus, a Porpoise, and a Spiny Dogfish (Squalus acanthias)

11. Parallel Evolution

12. Extinction Extinction is the loss of all individuals in the population of a given species, genus, family, or order –Local extinctions: American buffalo (Bison bison)

13. Global extinction – loss of species or higher taxonomic order over its entire range Abundant in North America, Europe, and Asia before 12,000ya Extinction caused by combination of over hunting (Pleistocene overkill hypothesis) and climate change

14. Trophic cascades – when the loss of a prey species causes further ecosystem disruptions because of the loss of food for higher predators

15. Phyletic extinction – pseudoextinction – species evolve into new species with many of its genes persisting in descendant species Example: Hyracotherium to Equus

16. Mass Extinctions Late Devonian (360 mya) Permian (250 mya) –50-96% of land and marine species becoming extinct –Large extinction of insects –Caused by (?) climate cooling or poisoned oceans Late Triassic (200 mya) Late Cretaceous (65 mya) –Extinction of dinosaurs –Caused by meteor Late Tertiary (2 mya) –Climate cooling

17. Dinosaur Extinction KT Boundary – geologic boundary between the Cretaceous and Tertiary 65 mya A large amount of iridium at this boundary indicated large meteor or comet slamming into Earth Large amounts of shock quartz and evidence of large fires found at this boundary The collision of meteor and Earth caused fires, tsunamis, followed by nuclear winter, and then extreme greenhouse effect

18. Red Queen Hypothesis – If a species cannot evolve fast enough to keep up with competing species, it will become extinct Could lead to an evolutionary trap – overspecializing in an isolated area Or blind alleys – when genetic diversity is lost during evolution, making environmental changes more problematic

19. Those prone to extinction: –Larger animals –Species with complex behavioral, morphological, or physiological adaptations –Predators at the top of food chain –Specialists species –Species with small population size –Species with low birth rates, or long gestation periods –Species with small geographic ranges –Poor dispersal capabilities