4.3 Evolution and Adaptation

1. 4.3 Evolution and Adaptation

2. Evolution • Long periods of time • Millions of years • Species change over time • Due to genetic mutation of traits • Mutations passed to offspring • New offspring make populations

3. Charles Darwin • 1835 • Traveled on the Beagle • Studied life forms at each port • Wrote Origin of Species http://www.youtube.com/watch?v=vmphlbRhLu8

4. Finches • Darwin's finches are an excellent example of the way in which species' gene pools have adapted in order for long term survival via their offspring. • The Darwin's Finches diagram below illustrates the way the finch has adapted to take advantage of feeding in different ecological niche's. http://www.youtube.com/watch?v=lDX4gIUv9kI

5. Mutation • Genetic • DNA mistake • Leads to a new trait • Trait can be passed to offspring • Not always bad

6. Adaptation • Good genetic mutation • New trait • Inherited by offspring • Helps it to survive

7. Katydid • Mimicry of leaves by insects is an adaptation for evading predators.

8. creosote bush • Desert-dwelling plant • Produces toxins that prevent other plants from growing nearby, thus reducing competition for nutrients and water

9. Penguins • Dense layer of tiny, waterproof feathers that protect them in the water. http://www.youtube.com/watch?v=ciu9xFTvELQ

10. Natural Selection • Nature • Selects the organisms with the best traits to survive • Organisms with bad traits will not have offspring and will die • Bad traits eventually are removed from a population http://www.youtube.com/results?search_filter=1&search_category=27&search_query=natural+selection&search_duration=short&search_type=videos&suggested_categories=24%2C27%2C10%2C20%2C28&uni=3

11. Selective Breeding • Plants for food • Animals for food, pets, or competition • Breeders of animals and plants in today's world are looking to produce organisms that will possess desirable characteristics • high crop yields, resistance to disease, high growth rate and best looking http://www.youtube.com/watch?v=LyRA807djLc

12. Speciation • Process when one species becomes 2 • Species separates into 2 groups • 2 groups mutate over time • Genes get lost

13. Speciation • Allopatric • Sympatric • Parapatric

14. Allopatric

15. Northern Spotted Owl and the Mexican Spotted Owl • Exhibit regional “varieties” • Genetically and in appearance • Live in different geographic locations

17. Sympatric Speciation • Does not require large-scale geographic distance to reduce gene flow between parts of a population. • Exploiting a new niche may automatically reduce gene flow with individuals exploiting the other niche. • This may occasionally happen when, for example, herbivorous insects try out a new host plant

18. grass species Anthoxanthumodoratum • Some of these plants live near mines where the soil has become contaminated with heavy metals. • The plants around the mines have experienced natural selection for genotypes that are tolerant of heavy metals. • Meanwhile, neighboring plants that don’t live in polluted soil have not undergone selection for this trait. • The two types of plants are close enough that tolerant and non-tolerant individuals could potentially fertilize each other—so they seem to meet the first requirement of parapatric speciation, that of a continuous population. • However, the two types of plants have evolved different flowering times. This change could be the first step in cutting off gene flow entirely between the two groups.

19. Parapatric speciation • Barrier to gene flow • The population does not mate randomly • Individuals are more likely to mate with their geographic neighbors

20. apple maggot flies • For example, 200 years ago, the ancestors of apple maggot flies laid their eggs only on hawthorns—but today, these flies lay eggs on hawthorns and domestic apples • Females generally choose to lay their eggs on the type of fruit they grew up in, and males tend to look for mates on the type of fruit they grew up in. • So hawthorn flies generally end up mating with other hawthorn flies and apple flies generally end up mating with other apple flies. • This means that gene flow between parts of the population that mate on different types of fruit is reduced. • This host shift from hawthorns to apples may be the first step toward sympatric speciation—in fewer than 200 years, some genetic differences between these two groups of flies have evolved.

22. Interbreed • Speciation • Species separated for thousands of years will not be able to interbreed if reacquainted