Evolution by Means of Natural Selection: The Development of Adaptations to Survive

Evolution by Means of Natural Selection: The Development of Adaptations to Survive Important Vocabulary 1. Fit or Fitness: success at surviving & reproducing 2. Gene Pool: all alleles (forms of genes) shared within a species 3. Frequency: how often an allele is seen in the gene pool How does its coloration help the Snowy Owl survive in its habitat? What other adaptations does it have that makes it “fit” for its environment?

Convergent Evolution Convergent evolution 1. Different lineage, exposed to similar selection pressures 2. Example: Bats and butterflies. Evolved through different mutations. 3. Convergent evolution produces analogous structures (similar in function, different in structure (bat's wing and butterfly's wing).

Coevolution Co-evolution 1. Two species evolve in response to each other. 2. Examples: predator/prey host/parasite species bees & flowers

Requirements for Natural Selection: Variation Exists in Nature Slide # 4 Requirements for Natural Selection: Variation Exists in Nature Variation is inheritable New variations come from mutations in DNA. Some mutations are harmful & some are helpful.

Requirements for Natural Selection: More offspring are produced than will survive. Tendency towards overpopulation b. Strategy for survival: Many species produce an over-abundance of offspring so that some survive and reproduce

Requirements for Natural Selection: There is a constant struggle for survival. Competition for limited resources food, space, territory, shelter (nesting sites) & mates Wolf chasing raccoon

Requirements for Natural Selection: Some individuals in the species will have variations that cause them to be the most fit in a particular environment. The fittest individuals will survive the longest & produce more offspring than less “fit” individuals. The most “fit” individuals are best adapted to that particular environment. If environment changes, different variations may be selected to be more fit

Requirements for Natural Selection: Vast amount of time is required for a species to change After many generations there will be enough genetic change in the population to produce a new species. Separated by a glacier during the last Ice Age, two different species of meadowlark evolved. Eastern Meadowlark Western Meadowlark

Mutations in Genes: the Source of all new Variations 1. Helpful mutations lead to adaptation by increasing fitness & decreasing the death rate Frequency of helpful mutation will increase in the population as more individuals survive & leave offspring 2. Harmful mutations decrease fitness of the individual in that environment & cause a higher mortality rate Frequency of the mutation will decrease & might or might not disappear from the gene pool How is the fruit fly on the bottom different from the fruits above?

Adaptations: A Result of Compromise An adaptation may work really great for some things (reaching food) , but they may prose a problem for other things (drinking water)

Camouflage 1. Camouflage: having a shape / color that blends in with the environment

Mimicry Mime- mimic (to copy) -ry: indicates quality or action Mimicry Viceroy: nonpoisonous Monarch is poisonous 1. Mimicry: when a harmless individual looks like a similar, harmful (poisonous) individual 2. Predators learn to avoid both