DARWIN Charles Darwin - naturalist aboard HMS Beagle from 1831-1836 Galapagos Islands Survival of the fittest leads to… Natural Selection: mechanism for changes in a population ***NOT AT AN INDIVIDUAL LEVEL*** Opposite = artificial selection - breeding for a specific trait

www.gct.org/images/mainmap.jpg www.travelblog.org/pix/maps/south-america.jpg

Evidence for Evolution 0. Adaptations – response to environment, helps species survive. Mimicry – yellow jacket and syrphid fly Camouflage – walking sticks

www.intelligentdesignnetwork.org/.../Finches.jpg

Evidence for Evolution Fossils - provide a sort of timeline www.answersingenesis.org/.../camel-evolution.jpg

Evidence for Evolution 2. Anatomy - Homologous structures: similar in arrangement and/or function Analogous structures: do not have commonality; similar environments Vestigal structures: structure in present day organisms that no longer serves its original purpose. Eyes of mole rats Pelvic bone of baleen whale

Homologous and analogous structures images.encarta.msn.com/.../ilt/T010228A.gif Vestigial structures

Evidence for Evolution 3. Embryology - at early stages (embryo) many animals look alike and have similar features. nitro.biosci.arizona.edu/.../figures/embryo.gif

Evidence for Evolution Biochemistry - all organisms share similar DNA, ATP and enzymes Cytochrome c - amino acid sequence, similar organisms have fewer differences. citruscollege.edu/pic/46/0350al.jpg

Gene Pool Gene pool- all the genes in a population Allelic frequency – how often the allele appears Genetic equilibrium - if frequency remains the same over several generations (not evolving) CHANGES – 1.) mutations that are beneficial, 2.) by migration of people and 3.) Genetic Drift – chance events Hits small populations hardest

Natural Selection acts on VARIATIONS Variations can be good or bad Good variations help one survive (= naturally selected) REPRODUCE Change allele frequency in population equals change = evolution http://www.daviddarling.info/images/natural_selection.png

Mechanisms for Evolution Populations, not individuals, evolve. Stabilizing selection - n.s. favors the average www.gwu.edu/.../BiSc150/PopGen/stabilizing.GIF

Mechanism for Evolution Disruptive selection- n.s. favors both extremes (can lead to new species) Directional selection n.s. favors one extreme

Speciation Evolution of a new species They can’t breed and make FERTILE offspring Geographic Isolation = physical barrier 1995, 15 iguanas survived Hurricane Marilyn on a raft of uprooted trees. Colonized the Caribbean island, Anguilla. https://eapbiofield.wikispaces.com/file/view/speciation.jpg

Speciation Reproductive Isolation = cannot mate Behavioral – difference in mating time, location, rituals Physical – pieces don’t fit Genetic material differs too greatly; fertilization doesn’t occur

Speciation Rates Gradualism – gradual change Punctuated equilibrium - rapid burst of change with long periods of equilibrium Caused by environmental changes or a competitive species.

Patterns of Evolution Divergent evolution – once similar become different Adaptive radiation – one species evolves into several species Different habitats, niches Ex. Darwin’s finches Convergent evolution – unrelated species evolve similar traits Due to similar environments and pressures EX. Organ pipe cactus (N/S America) and the Euphorabia sp (Africa) tucsoncactus.org/.../convergent-evolution_eu.jpg