Chapter # 4 Ecosystems and Living (Biotic) Organisms (pages 64 – 84)

1. Chapter #4Ecosystems andLiving (Biotic) Organisms(pages 64 – 84)

2. Overview of Chapter #4 • Evolution • Natural Selection • Domains and Kingdoms • Biological Communities • Primary & Secondary Succession • Symbiosis • Mutualism, Commensalism, Parasitism • Predation & Competition • Resource Partitioning • Keystone Species • Species Richness & Community Stability

3. Evolution and Natural Selection • The cumulative genetic changes that occur in a population of organisms over time • Current theories were proposed by Charles Darwin, a 19th century naturalist • Evolution occurs through natural selection • Natural Selection • Individuals with more favorable genetic traits are more likely to survive and reproduce • Frequency of favorable traits increase in subsequent generations

4. Natural Selection • Based on four observations about the natural world • Overproduction • Each species produces more offspring than will survive to maturity (David Lack, 1943) • Variation • Individuals in a population exhibit variation • Limits on Population Growth • Resource limitations will limit populations. • Differential Reproductive Success • Individuals with most favorable traits are more likely to reproduce

5. Natural Selection • Darwin’s finches exemplified the variation associated with natural selection

6. Domains and Kingdoms of Life Think of this variation (diversity) as different organisms (both plants and animals) with different traits, abilities and methods for surviving and reproducing.

7. Biological Communities • Communities vary greatly in size and lack precise boundaries • They are often nestled within each other, and dependent upon the abiotic resources in an area. • Q: How might changes in resource abundance affect communities?

8. Interactions Among Organisms • Symbiosis • An intimate relationship between members of 2 or more species • Participants may be benefited, harmed or unaffected by the relationship • Results of coevolution • Three types of symbiosis • Mutualism • Commensalism • Parasitism

9. Mutualism • Symbiotic relationship in which both members benefit • Ex: Mycorrihzal fungi and plant roots • Fungus grows around and into roots providing roots with otherwise unavailable nitrogen from soil • Roots provide fungi with food produced by photosynthesis in the plant Left: root growth without fungi Right: root growth with fungi

10. Commensalism • Symbiotic relationship where one species benefits and the other is neither harmed nor helped • Ex: epiphytes and tropical trees • Epiphytes anchors itself to the tree, but does not take nutrients from the tree • Epiphyte benefits from getting closer to sunlight, tropical tree is not affected

11. Parasitism • Symbiotic relationship in which one species is benefited and the other is harmed • Parasites rarely kill their hosts • Ex: Varroa mites and honeybees • Mites live in the breathing tubes of the bees, sucking their blood and weakening them

12. Predation • The consumption of one species by another • Many predator-prey interactions • Most common is pursuit and ambush • Plants and animals have established specific defenses against predation through evolution

13. Pursuit and Ambush • Pursuing prey simply means chasing it down and catching it • Ex: Day gecko and spider (see picture) • Ambush is when predators catch prey unaware • Camouflage • Attract prey with colors or light

14. Plant Defenses Against Predation • Plants cannot flee predators • Adaptations • Spikes, thorns, leathery leaves, thick wax • Protective chemicals that are poisonous or unpalatable

15. Animal Defenses Against Predation • Fleeing or running • Mechanical defenses • Ex: quills of porcupines, shell of turtles • Living in groups • Camouflage • Chemical defenses- poisons • Ex: brightly colored poison arrow frog

16. Competition • Interaction among organisms that vie for the same resource in an ecosystem • Intraspecific • Competition between individuals in a population • Interspecific • Competition between individuals in 2 different species

17. In-class Discussion Readers: Chapter #1 - Me Chapter #2 – Chapter #3 – Elizabeth Goodrich Chapter #4 – James McLeod Chapter #5 – Labecca Hampton and Jessica Vidal Chapter #6 – Patrick Grennan and Scott Arnold Chapter #7 – William Arnold and David Dudley Chapter #8 – Crissy Overgard Chapter #9 – Juan Rodriguez

18. Readings last Week and this Week: Chapter #5 – “Free Wealth” Facilitators: Labecca Hampton and Jessica Vidal Quizzes will be returned on Wednesday

19. Ecological Niche • The totality of an organisms adaptations, its use of resources, and the lifestyle to which it is fitted • Takes into account all aspect of an organisms existence • Physical, chemical, biological factors needed to survive • Habitat • Abiotic components of the environment • Ex: Light, temperature, moisture

20. Ecological Niche • Fundamental niche • Potential idealized ecological niche • Realized niche • The actual niche the organism occupies • Ex: Green Anole and Brown Anole

21. Ecological Niche • Green Anole and Brown Anole • Fundamental niches of 2 lizards initially overlapped • Brown anole eventually out-competed the green anole- reduced the green anole’s realized niche

22. Limiting Resources • Any environmental resource that, because it is scarce or at unfavorable levels, restricts the ecological niche of an organism (Leibig’s Law of Minimum)

23. Interspecific Competition

24. Competitive Exclusion & Resource Partitioning • Competitive Exclusion Principle • One species excludes another from a portion of the same niche as a result of competition for resources • Resource Partitioning • Coexisting species’ niche differ from each other in some way

25. Keystone Species • A species that exerts profound influence on a community • More important to the community than what would be expected based on abundance • The dependence of other species on the keystone species is apparent when the keystone species is removed • Protecting keystone species is a goal to conservation biologists

26. Species Richness • The number of species in a community • Tropical rainforests = high species richness • Isolated island = low species richness • Related to the abundance of potential ecological niches

27. Ecosystem Services • Important environmental benefits that ecosystems provide, such as: • Clean air to breathe • Clean water to drink • Fertile soil in which to grow crops

28. Ecosystem Services