1. Objective  Explain how population sizes are regulated.

2. Key Terms PopulationDispersion Growth rate Reproductive potential Carrying capacity

3. What Is a Population?  Group of organisms of the same species live in the same area live in the same area interbreed interbreed  Organisms usually breed with members of their own population.

4. Populations  “Population” refers to the group as a whole or the size - number of individuals (members) in the group.

5. Populations  Population Density - number of members that live in a specific area.

6. Populations  Dispersion - distribution of organisms in a population Clumped Clumped Uniform Uniform Random Random

7. Growth Rate  Population change over time can be represented by:

8. Growth Rate  Changes when birth rates and death rates increase or decrease.  Can be positive, negative, or zero.

9. Growth Rate  Positive – average number of births > average number of deaths  Negative - average number of births < average number of deaths  Zero - average number of births = average number of deaths

10.  Population sizes usually stay the same  Certain factors control the sizes of populations (limiting factors). spacespace diseasedisease immigration/emigrationimmigration/emigration predators and parasitespredators and parasites Growth Rate

11. Reproductive Potential  The maximum number of offspring a specific organism can produce.  Depends upon fecundity fecundity fertility fertility gestation gestation

12. Reproductive Potential  Increases when individuals produce more offspring at a time produce more offspring at a time reproduce more often reproduce more often reproduce earlier in life reproduce earlier in life shortens generation time – average age of reproductionshortens generation time – average age of reproduction

13. Reproductive Potential  Small organisms have short generation times can reproduce after few hours/few days can reproduce after few hours/few days populations grow quickly populations grow quickly

14. Reproductive Potential  Large organisms reach reproductive age after years have a much lower reproductive potential have a much lower reproductive potential populations grow slowly populations grow slowly

15. Exponential Growth  A large number of individuals is added to the population each generation.  Numbers increase by a certain factor (usu. 2).  Occurs in nature with plenty of resources and no predators.

16.  Only the best adapted members of a population will survive and reproduce.  Characteristics of a population may evolve over time. Limits to Population Growth

17. Carrying Capacity  Largest population an environment can support at any time.  Population can increase beyond this number but cannot stay elevated

18. Carrying Capacity  Estimated by average population sizes or by observing population crashes after a certain size has been exceeded.

19. Resource Limits

20.  Carrying capacity is reached when species consume a resource at the same rate that the resource is produced. resource consumption = resource creation resource consumption = resource creation  That natural resource is called a limiting resource. Food Food Water Water Light Light

21.  Resource competition increases as population approaches carrying capacity.  Competition within a population is part of the pressure of natural selection. Competition Within a Population

22.  Members of a species may compete indirectly for social dominance or for a territory.  A territory is an area defended by one or more individuals against other individuals. space space shelter shelter food food mates mates breeding sites breeding sites Competition Within a Population

23.  Causes of death in a population may be density dependent or density independent. Population Regulation

24.  Density dependent cause of death - deaths occur more quickly in a crowded population than in a sparse population. Limiting factors Limiting factors Predation Predation Emigration Emigration

25. Population Regulation

26.  Density independent cause of death – some of the population can die regardless of the population’s density. Severe weather Severe weather Natural disasters Natural disasters

27. Do Now/Objective – separate paper…Hand In (4 min)  Do all living organisms interact in the same way?  List the different ways organisms interact with each other.

28. Niche  Ecological role of an organism where it makes its home where it makes its home resources it needs to survive resources it needs to survive how it interacts with other organisms how it interacts with other organisms  A niche includes an organism’s habitat. habitat is an area within an ecosystem. habitat is an area within an ecosystem.

29. Niche Map All organisms use their habitats in a unique way. Think about your niche (where you fit into your community) and answer: Where do you gather your favorite resources?Where do you gather your favorite resources? Who do you compete or cooperate with?Who do you compete or cooperate with? Where do you live and where do you hang out?Where do you live and where do you hang out? Do you spend certain parts of the day in certain places?Do you spend certain parts of the day in certain places? Draw a niche bubble map that shows how your use your habitat. INCLUDE 4+ interactions and describe those interactions on your maps.

30. Key Terms NicheCompetitionPredationParasitismMutualismComensalismSymbiosis

31. Species Interaction  Five main types of interactions: Competition Competition Predation Predation Parasitism Parasitism Mutualism Mutualism Commensalism Commensalism

32. Competition  Organisms try to use the same limited resource  Members of the same species compete they require the same resources they require the same resources they occupy the same niche they occupy the same niche

33. Indirect Competition  Species can compete even if they never come into direct contact with each other.

34. Adaptations to Competition  Members of different species sometimes compete (niche overlap) each species use some of the same resources in a habitat. each species use some of the same resources in a habitat.

35. Adaptations to Competition  Law of Competitive Exclusion No two species can occupy the same niche (competing for the same resources) at the same time indefinitely No two species can occupy the same niche (competing for the same resources) at the same time indefinitely

36. Adaptations to Competition  The species will often divide up the niche by area by area by time of use by time of use

37. Adaptations to Competition  Niche restriction - each species uses less of the niche than they are capable of using. Actual niche may be smaller than potential niche. Actual niche may be smaller than potential niche.

38. Adaptations to Competition

39. Predation  One species kills and eats the other species predator predator prey prey

40. Predators  Some predators eat only specific types of prey. sizes of both populations have a direct relationship sizes of both populations have a direct relationship

41. Parasitism  An organism lives in or on another organism to feed on the other organism parasite parasite host host

42. Parasitism vs. Predation  Parasites depend on their hosts; usually don’t kill them.  The host is often weakened or diseased by the parasite.

43. Symbiosis  Relationship where two different organisms benefit from each other Mutualism Mutualism Commensalism Commensalism

44. Mutualism  Relationship between two species where both species benefit.

45. Commensalism  Relationship between two organisms where one organism benefits and the other is unaffected.

46. Coevolution  Can occur with species in symbiotic relationships. species may evolve adaptations that improve the benefits to each member. species may evolve adaptations that improve the benefits to each member.

47. Species Interactions Interaction Type Species A (harmed or benefited) Species B (harmed or benefited) Description Your own example 1. Competition HarmedHarmed Both parties struggle for a limited resource Coyote and kit fox both hunting kangaroo rat 2. 3. 4. 5.