How can animals that are not closely related be similar in appearance? EVOLUTION IN ACTION How can animals that are not closely related be similar in appearance? How can animals that are closely related be dissimilar in appearance?

EVOLUTION DEFINED… Evolution of a population is due to environment and the interaction of other species

Ex: shark and dolphin, bird and insect wing

  sailfin fish flying squirrel

Types of Evolution 1. CONVERGENT EVOLUTION: Organisms with very different ancestors become more alike due to a common environment Compare analogous structures: same functions but different development

Case 3 bat  insect Wing  

2. DIVERGENT EVOLUTION: Populations become more and more dissimilar to adapt to the environment They share a recent common ancestor compare homologous structures: similar body part but may have different functions

When the dinosaurs died out, mammals evolved to fit niches once used by dinosaurs Darwin’s Finches are an example of adaptive radiation. They can be found in all areas of the island: the ground, in bushes, in all levels of the trees.

Adaptive Radiation: Population undergoes divergent evolution until it fills all areas of the environment

Rough-skinned newt and garter snake Newt evolved to produce neurotoxins then the snake evolved resistance to this toxin through genetic mutations. Birds and flowers, Humans and bacteria are other examples

3. COEVOLUTION: When two species each evolve in response to each other over a long period of time.  This leads to a close relationship

Rate of evolution Phyletic gradualism: populations of species diverge slowly by accumulating differences in response to the environment Punctuated Evolution: most populations of species go through long periods of stasis (not changing) then a sudden shift in the environment causes a rapid change

WhaT is the rate of plant evolution?