Evolution in Process 15.3 pp. 289-292

Evolution is a continuous process that is always going on, just really slowly (needs lots of time)

Evolution in Process 15.3 pp. 289-292

Homologous structure = similar feature found in many different species• Comes from some common

ancestor• Examples: different beaks

for different birds• Forelimbs (arms) in high order

animals

• Similar species,different job

Evolution in Process 15.3 pp. 289-292

Analogous structure = feature that does the same job but is very different in structure• Wings on birds (arms) vs.

wings on insects (just wings)

• Webbed feet on ducks vs. fins on fish

• Different species, same job

Evolution in Process 15.3 pp. 289-292

Coevolution = 2 different species in close relationship that evolve together• Predator – prey : gazelle

get faster to escape, cheetah get faster to catch the gazelle

• Plant – pollinator: hummingbirds and the flowers they feed on

Evolution in Process 15.3 pp. 289-292

Convergent evolution = different species evolve features to do a similar job in a similar environment• The conditions they live in

are similar so they need to do similar things to survive

• Sharks – dolphins : these have converged

• Different species, same job

What does it mean to converge?

Related to analogous structure.

Evolution in Process 15.3 pp. 289-292

Divergent evolution = very similar species evolve different features to do different jobs• Different habitats so they

evolve different ways to survive

• Sea snakes – desert snakes• Penguins -- ducks• Artificial selection: dog

breeding, cattle breeding (these are done by humans, not nature)

• Similar species, different job

Related to homologous structure.

Evolution in Process 15.3 pp. 289-292

Examples of divergent evolution.

Where on the graph to species diverge?