Natural Selection, Adaptations, and Niches

1. Natural Selection, Adaptations, and Niches

2. Essential Targets: • Define the terms: Natural Selection, Adaptation, and Niche • Explain how adaptations benefit an organism • Identify and describe the three types of interactions between organisms in a community

3. What is Natural Selection? • Every organism has some unique characteristics that enable it to live in its Environment • In response to their environment, species evolve, or change over time • The changes that make organisms better suited to their environment become common in that species by a process called natural selection Charles Darwin 1809-1882

4. “Bummer of a birthmark, Hal.”

5. Example of Natural Selection

6. One of the first examples of selection in nature was provided by the peppered moth.

7. Up until 1850, the dark form of the peppered moth had been very rare in England.

8. By 1895, the dark form made up 98% of moth populations in some industrial areas.

9. What was the explanation for the increased frequency of the dark form in industrial areas? The hypothesis was that pollution had darkened the trees by killing the lichens, making the light phenotype more susceptible to bird predation.

10. We can test this hypothesis by asking what should be happening today since pollution has been reduced by legislation. What would you predict?

11. Do the data in this graph support the pollution/selection hypothesis?

12. Natural Selection • Those species that live longer live to reproduce and pass along those characteristics (traits)

13. Natural Selection leads to “?” • The results of natural selection are adaptations • The behaviors and physical characteristics of species that allow them to live successfully in their environment • Every organism has a variety of adaptations that are suited to its specific living conditions. These adaptations create a unique role for the organism in its ecosystem

14. Adaptations Adaptation: A physical feature or behavior that allows an organism to survive in its environment

15. Canada Lynx (Lynx lynx Bobcat (Lynx rufus ) Lynx vs. Bobcat

16. Lynx vs. Snowshoe Hare

17. Interaction of Organisms • Some adaptations involve how organisms interact. • Competition • Predation • Symbiosis

18. Competition Swift Fox Gray Wolf Coyote • Competition - the struggle between organisms to survive as they attempt to use the same limited resource.

19. Predation • Predation - one organism kills and eats another organism. The organism that does the killing is the predator. The organism that is killed is the prey. Predators have adaptations that help them catch and kill their prey. Prey organisms have adaptations that help them avoid being caught and eaten.

20. Symbiosis • Symbiosis - a close relationship between two species that benefits at least one of the species. • Mutualism (both species benefit) • Commensalism (one species benefits. Other is not effected) • Parasitism (one species benefits. Other is harmed)

21. Niche • An organism’s particular role in its habitat, or how it makes its living, is called its niche • A niche includes the type of food the organism eats, how it obtains this food, which other species use it as food, when and how the organism reproduces, and the physical conditions it requires to survive.

22. Understanding an ecological niche • The idea of an ecological niche is very simple. You just need to know where the animal or plant lives and what it does. • Oak trees live in oak woodlands. The oak woodland is the habitat. So if you were writing a letter to an oak tree you would address the letter to: • Mr. Deciduous Oak Tree,The Oak Forest,Maine, USA.

23. Understanding an ecological niche • What do oak trees do? If you can answer that question you know the oak trees "profession" or its ecological niche. Perhaps you think that oak trees just stand there looking pretty and not doing vey much, but think about it. • absorb sunlight by photosynthesis; • absorb water and mineral salts from the soil; • provide shelter for many animals and other plants; • act as a support for creeping plants; • serve as a source of food for animals; • cover the ground with their dead leaves in the autumn. • These six things are the "profession" or ecological niche of the oak tree; you can think of it as being a kind of job description. If the oak trees were cut down or destroyed by fire or storms they would no longer be doing their job and this would have a disastrous effect on all the other organisms living in the same habitat.

24. Understanding an ecological niche • Now you get to try: Where does this species live? What does this species do?

25. Understanding an ecological niche • Now you get to try: Where does this species live? What does this species do?

26. Questions?

27. Essential Targets: • Define the terms: Natural Selection, Adaptation, and Niche • Explain how adaptations benefit an organism • Identify and describe the three types of interactions between organisms in a community