EVIDENCE OF EVOLUTION

So, what are we doing today? - Look at Evidence of evolution - Do a comprehensive Chapter 15 Review (Quest on Tuesday)

Pay close attention What is discussed in the next session is critical in understanding your research project!

MORE EVIDENCE? We have already examined how fossils, but in Science we ALWAYS look for more evidence to confirm our understanding.

HOMOLOGOUS STRUCTURES Similar features that originated in a shared ancestor are described as HOMOLOGOUS Beaks of Darwin’s Finches Limbs (15.7 in Textbook) Homologous structures indicate that different species may share a fairly recent common ancestor.

Although these differ in function, structurally they are very similar…

ANALAGOUS FEATURES Serve identical functions, and can look similar. However may differ in internal anatomy, or embryological development Figure 15.8 E.g. wing of a butterfly, and a bird

Vestigial Structures Apparently useless features are said to be Vestigial Human appendix*, pelvic bones of some snakes and whales A vestigial structure in a modern organism, is evidence that the structure was functional to some ancestor of that organism May share a common ancestry with an existing organism that has use for that structure.

Similarity in Embryology Early stages of vertebrate embryo development are strikingly similar…

Similarities in Macromolecules Like we have discussed, humans and all living things share common genetic sequences Ex. Human gene for the protein hemoglobin (red blood cell protein) and gorilla gene for hemoglobin differ by 1 amino acid. Human and frog hemoglobin by 67 a.a. More recent common ancestry, more similar genetic sequence/ proteins.

In your Journal Define and Provide examples (NOT DISCUSSED IN CLASS preferably) Homologous structure Analogous structure Vestigial structure Natural selection

Patterns of Evolution So now that we’ve discussed the theories and evidence of evolution, we are ready to start looking at how species evolve…

Coevolution Change of two or more species, in close association (think of our classroom example!) evolving together. Predators– Prey, Hosts – Parasites, Plants – Animals that eat them* Figure 15.10 in textbook Bats have evolved long tongue which allow them to feed on the nectar in the flower. The fur on the bat picks up the pollen, which the bat will take to the next flower (allowing for reproduction of the flowering plant)

Convergent Evolution Shark, Porpoise, Icthyosaur – Similar, but very different! Result of a convergent evolution Environment selects for advantageous phenotypes (physical traits), in spite of different ancestry Analogous structures typically arise from convergent evolution

Divergent Evolution Two or more related populations/species become more and more dissimilar. Divergence is a response to differing habitats, usually resulting In a new species (more on this later) How homologous structure arise.

Divergent Evolution Adaptive Radiation Many related species evolve from a single ancestral species. E.g. Galapagos Finches. Diverged in response to the different types of food in their environment.

Divergent Evolution Artificial Selection Process of divergent evolution sped up artificially! All dogs are the same species Canis familaris Bred by humans for certain phenotypic characteristics Resulting in different breeds with different traits (fig 15.11)

To Do Now What type of evolution pattern pairs with the “homologous structures” and which type pairs with the “analogous structures” 15.3 Review sheets Chapter 15 Review p294