Ecology Pt 1

1. Communities Ecology Pt 1 Organisms interacting with each other. Populations

2. Ecology Pt 1 • Ecology is the study of interactions between organisms and their environments. • Unit 10 will be focus on the first 2 levels of interaction. • Populations • Communities • Ecosystems

3. Unit 10: Concepts • Populations (E) • Communities (E) • Terrestrial and aquatic biomes (I) Unit 10 Test Unit 10 Project

4. Essential question 1.1: How do changes in size, density and dispersion affect the health of a population?

5. I.A populationis defined as all the individuals of a species that live together in one place at one time. • The humans in Mechanicsburg in 2001. • The bacteria in your colon during adolescence. • The grass on your front lawn this summer.

6. II. Features of populations are studied by ecologists. • Population Size • Population Density and Distribution • Population Growth

7. Population Size • Population size is the number of individuals in a population. • Large populations are more stable since small populations may be easily affected by the environment and evolutionary forces due a lack of variety in the gene pool. • If environmental conditions fluctuate, large populations with a lot of variation are easily adaptable. • In small populations, inbreeding causes a disproportionate increase in unfavorable alleles.

8. II./2. Population densityis the number of individuals that live in a given area. • Defined as: “one mountain lion per square mile” • Being spread out may be good or bad. • This can be used to determine a species health. • This is generally determined by random sampling.

9. II./3. Dispersionis the way that individuals of a population are arranged in space. • Clumped • Even spacing • Random

10. Question: Name one example of a population that is typically arranged in each of the 3 types. Random: Maple trees (or any wind dispersed plant). Even Spacing: Mountain lions maintaining a specific range (Or any large predator). Clumped: A herd of Buffalo (Or any herd animal).

11. Essential question 1.2: How do ecologists calculate rates of change in populations?

12. III. Models are used to explain how a population grows. Click to view model live • A population model is a hypothetical population that attempts to exhibit the characteristics of a real population. • The models are built mathematically, often using a computer simulation. • The model may be manipulated to study the effects of a change. • The more data that are include, the more predicative the model will become. Image captured 9/11/11 11am

13. III./4. There are several key variables to consider when attempting to model the growth rate of a population. • Natality (birth rate) • Mortality (death rate) • Immigration (individuals entering population) • Emigration (individuals leaving the population)

14. III./5. If resources are unlimited, a population should grow exponentially.

15. III./6.When logistical factors are taken into account, a true sense of the growth of a population may be gained. • This type of growth is called logistical growth. • Competition for food, shelter, mating sites, and other resources as well as accumulation of wastes will increase with population size. • Growth rate will slow when a population reaches it’s carrying capacity. • If a population exceeds its carrying capacity, the population size will decrease as density dependent factors become a problem. • Carrying capacity is defined as the maximum sustainable number of individuals that the ecosystem can support.

16. Logistical Growth

17. IV. Real populations exhibit a range of growth patterns influenced by non-logistical factors. • Density-independent factors like weather and climate limit many populations. • r-strategists reproduce rapidly when conditions are favorable, then die back to reasonable levels as conditions worsen. • Live in rapidly changing environments. • Quick generation time. • Reproduce early, and prolifically (with many young). • Little to no parental care. • Examples: insects, weeds and other pests.

18. The effect of weather (density independent) on an Aphid population

19. IV./3. K-strategists exist in stable populations that are near their carrying capacity. • Live in very stable environments. • Slow generation time. • Reproduce late, and in small numbers. • High degree of parental care. • Long living organisms like whales and gorillas.

20. Logistic growth curve Beginning growth Rapid growth Growth slows Carrying capacity Fluctuations 5. 4. 3. 2. 1.

21. Question: Are humans r-strategists or K-strategists? Humans are K-strategist animals that are growing like r-strategists. At some point in the near future, we will witness a sharp decline in the human population.

22. Question: What’s in store for the human population? • Scientists had predicted 12 billion people by 2030. • Since HIV has become a major global killer, and consequently and important limiting factor, current projections show a continued increase of population (but a steady decline in the population growth rate) with the population to reach between 7.5 and 10.5 billion by the year 2050.

23. Sustainable human population projections Population estimates vary for both peak and sustainable populations depending on consumptions levels and climate change.

24. Question: Which population has the biggest potential for growth in years to come? Question 2: Which country has higher natality? Mortality ? What accounts for these differences?

26. Unit 10: Concepts Unit 10 Test • Populations (E) • Communities (E) • Terrestrial and aquatic biomes (I) Unit 10 Project

27. Essential question 2.1: How are symbiotic relationships important in biological communities?

28. Communities • Two or more interacting species in a defined habitat constitute a community. • An example of a community can be witnessed on the island of Isle Royale, Lake Superior Michigan. • Vegetation provides cover and food for birds. • Moose feed on trees changing the vegetation. • Wolves prey on Moose. • Fox scavenge of remaining carcasses • Ticks infest Moose and Wolves.

29. I. Species evolve in response to one another. • Coevolution occurs when two different organisms make back-and-forth adjustments necessary to continue their relationship.

30. Symbiotic relationshipsexist when organisms live in close proximity for their entire lives. There are 3 types of symbiotic relationships that we will focus on in this unit. • Mutualism • Commensalism • Parasitism

31. Mutualism Read page 103 in text • Mutualism occurs when both parties benefit (pollination).

32. Commensalism Read page 104 in text • Commensalism occurs when one party benefits and the other is neither harmed nor helped (Dung beetles and elephants).

33. Parasitism Read page 104 in text • Parasitism favors one, while it hurts the other (Ticks and you!).

34. Example1. Leaf cutter ants harvest leaves and feed them to colonies of fungus that produce a useful food resource. • Leaves are mulched and used to grow “fields” of fungi. • The fungi in turn produce specialized hyphal tips called gongylidia which the ants consume and feed to their larvae • A third layer of symbiosis exists, as colonies of bacteria on the ants bodies provide protection from mold infections that might harm the ants “crops” • This form of agriculture developed long before the first human farmers sowed their first seeds. • The needs of both the ants and the fungi are so specific that neither can survive without the other. • Watch clips from Evolution video. • Read article and answer questions.

35. Predator-Prey • Predator-Preyrelationships come about through co-evolution. Very often, both species benefit from the relationship.

36. Question: Why do predators and prey need each other? Predators need the prey as their food source. Without plentiful numbers, their population will decline. Prey need predators to keep their number limited. If unlimited growth occurs, the species will die back as resources are devoured.

37. Question: How is the coevolution of predators and prey similar to the Cold War between the United States and Russia? Biologists have often described the coevolution of predators and their prey as an “arms race”. During the Cold War, the U.S. and Russia competed in an arms race that saw them consistently attempt to gain an advantage over the other by developing newer, more powerful weapons.

38. Essential question 2.2: How is the niche of an organism related to the other organisms in the community?

39. II./2. The functional role of an organism in its ecosystem is its niche. • A niche is more than a habitat. • No two species can have the same exact niche, however, some niches may overlap. • If niches overlap, the organisms are in competition and a change is sure to occur. • One species might out compete the other, leading to extinction. • Both species may suffer and become extinct. • Species might successfully partition the resources in such a way as to co-exist.

40. II. Common use of scarce resources leads to competition. • When two species struggle to use the same scarce resource, they are in competition. • Many organisms in competition never come in contact (Shark species). • Some competitors actually fight for resources(lions and hyenas).

41. Competitive Exclusion in Paramecia

42. III./3. An organisms fundamental niche is often larger than its realized niche. F U N D A M E N T A L N I C H E • A bird population might feed only on insects on one small part of the tree (realized niche), even though it could feed throughout the whole tree (fundamental niche). • This prevents closely related species from competing with one another. Realized niche

43. A realized niche is just a portion of a fundamental niche.

44. III./4. If an organism can’t compete for resources, it will not be able to use its total fundamental niche. Question: What does this tell you about competition between these two species?

45. III./5. Competition without division of resources leads to extinction. • Competitive exclusion occurs when one species uses a resource more efficiently, and drives another into extinction. • If competitors find a way to divide (partition) the resources, they may coexist. • Predation may limit competition by keeping prey numbers down. • If competition stays low, biodiversity will be high. (We will discuss biodiversity more in part 2 of Ecology) • High biodiversity causes an ecosystem to be very stable and productive.

46. Resource partitioning in five Warbler species.

47. Question: What is the difference between a habitat and a niche? A habitat is just the place, while a niche is the organisms role in the environment? • What does it eat? • What eats it? • Does it alter the environment like an earthworm?

48. END OF UNIT 10 TEST MATERIAL • The following slides are information that can be used to create your presentations. • We will tour these slides in class but not teach the material explicitly. • You and a partner will be assigned a Biome to explore and present visually in the form of a power point presentation. • Class time will be provided but some work may need to be completed outside of the classroom.

49. Unit 10: Concepts • Populations (E) • Communities (E) • Terrestrial and aquatic biomes (I) Unit 10 Test

50. Essential question 3.1: How do temperature and precipitation determine the community that may live within a particular terrestrial biome?