Homologous and Analogous Structures

Homologous structures Structures that are similar but has different functions Shows common ancestry

Convergent Evolution Acquiring the same biological trait independently Example: Flight Humming bird and moth - last common ancestor did not have wings They acquired these traits separately Only very few designs for a wing would allow for hovering

Porpoises

Sharks

Analogous Structures Similar functions but differ in structure Ex: wings of a hummingbird and humming moth – both can hover to feed

Vestigial Structures Features that were useful to an ancestor, but they are not useful to the modern organism that has th. tailbone in humans Appendix Some snakes have tiny pelvic bones and limb bones

Vestigial Structures

Comparative Embryology Closely related organisms often have similar stages in their embryonic development All vertebrate embryos are similar Vertebrates share a common ancestor lemur pig human

Vertebrate Embryos

Similarities in Macromolecules: The more similar homologous proteins are in different species, the more closely related the species are thought to be. Ex: the amino acid sequence in human hemoglobin and gorilla hemoglobin differ by ONE amino acid While the Hb of humans and frogs differ by 67 amino acids!!

Coevolution Change of two or more species in close association with each other Predators and their prey sometimes co-evolve Pollinators Bees can’t see red, but can see in blue, yellow, and UV Bee landing pad!

Divergent Evolution Two or more related populations or species become more and more dissimilar. Divergence is nearly always a response to differing habitats and can result in new species

Adaption Radiation Many related species evolve from a single ancestral species ex: Galapagos finches

Canis familiaris artificial selection: all domestic dogs are the same species “Canis familiaris”