Homologous and Analogous Structures

Structures that are similar but has different functionsShows common ancestry

Homologous structures

Acquiring the same biological trait independentlyExample: FlightHumming bird and moth - last common ancestor

did not have wingsThey acquired these traits separately

Only very few designs for a wing would allow for hovering

Convergent Evolution

Porpoises

Sharks

Similar functions but differ in structureEx: wings of a hummingbird and humming

moth – both can hover to feed

Analogous Structures

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

bones

Vestigial Structures

Vestigial Structures

Closely related organisms often have similar stages in their embryonic developmentAll vertebrate embryos are similarVertebrates share a common ancestor

Comparative Embryology

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!!

CoevolutionChange of two or more species in close

association with each otherPredators and their prey sometimes co-evolvePollinators

Bees can’t see red, but can see in blue, yellow, and UV

Bee landing pad!

Divergent EvolutionTwo 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 RadiationMany related species evolve from a single

ancestral species ex: Galapagos finches

Canis familiarisartificial selection: all domestic dogs are the

same species “Canis familiaris”