1. Species Interactions & Population Control

2. Five Major Interactions Interspecific Competition Predation Parasitism Mutualism Commensalism

3. Interspecific Competition Different species competing for the same resources Niche overlap – Greater overlap = more intense competition Outcomes: – Resource partitioning Evolution/speciation – Competitive exclusion Local Extinction

5. Resource Partitioning When species divide a niche to avoid competition for resources

7. Competitive Exclusion two species competing for the same resource cannot coexist at constant population values, if other ecological factors remain constant

8. Predation

9. Symbiosis Close long term associations between two or more species *Three types: 1.Mutualism 2.Commensalism 3.ParasitismParasitism

10. Brood Parasitism The manipulation and use of a host to raise the young of the brood parasite *Nest hypothesisNesthypothesis *Mafia hypothesis

11. Population A group of interbreeding individuals of the same species

12. Population Characteristics Size Density Dispersion Age distribution

13. Population Size Four variables determine population size: 1.Births 2.Deaths 3.Immigration 4.Emigration = (Births + Immigration) - (Deaths + Emigration) Population Change

14. Dispersion

15. Clumps -most popular 1. Cluster near resources 2. Groups increase chance of finding resources 3. Protection 4. Hunting

16. Dispersal Examples Clumped (elephants) Uniform (creosote bush) Random (dandelions) Territorial Solitary

17. Age Structure Distribution of individuals among various ages Dictates how rapidly a population Three groups: 1. Pre-reproductive stage not mature enough to reproduce 2. Reproductive stage capable of reproduction 3. Post-reproductive stage too old to reproduce

18. A B CD

19. Life table Life Tables  Shows life expectancies for age groups  Demography : Study of a populations vital statistics and how they change over time females males What adaptations have led to this difference in male vs. female mortality?

20. Survivorship curves Generalized life strategies What do these graphs tell about survival & strategy of a species? 025 1000 100 Human (type I) Hydra (type II) Oyster (type III) 10 1 50 Percent of maximum life span 10075 Survival per thousand I.High death rate in post-reproductive years II.Constant mortality rate throughout life span III.Very high early mortality but the few survivors then live long (stay reproductive)

21. Reproductive strategies  K-selected  late reproduction  few offspring  invest a lot in raising offspring  primates  coconut  r-selected  early reproduction  many offspring  little parental care  insects  many plants K-selected r-selected

22. Exponential Growth Constant growth of a population – Birth rate exceeds the death rate J shaped curve

23. Conditions for Exponential Growth Unlimited resources – Abundant space – Abundant food – Shelter – Decrease in predators – Decrease in disease – Reproduction

24. Rule of 70 How long does it take to double? – Resource use – Population size – Money in a savings account Rule of 70 – 70 divided by the percentage growth rate = doubling time in years – 70 / 7% means it takes ten years to double

25. Human Population

26. Logistic Growth Growth of a population slows or stops as resources become less available S curve

27. Carrying Capacity The largest number of individuals that a given environment can support at a given time

28. Regulation of population size marking territory = competition competition for nesting sites  Limiting factors  density dependent  competition: food, mates, nesting sites  predators, parasites, pathogens  density independent  abiotic factors  sunlight (energy)  temperature  rainfall

29. St. Matthew’s Island

30. Ecological Succession Predictable changes that occur in a community over time Two types: – Primary – Secondary

31. Primary Succession Begins in a place without any soil Examples: – Volcanos – Glacier retreats Process begins with pioneer species – lichens or cyanobacteria

32. Primary Succession Moss move in bringing insects Ferns & grasses Shrubs & Trees

33. Secondary Succession Organisms evades an ecosystem that already existed before Usually a result of disturbance – Human disturbance – Natural catastrophes

34. Steps in Secondary Succession Major disturbance – weeds come in Grasses Pines begin to grow – Grasses are shaded out Old pines die – hardwoods begin to replace

35. Secondary Succession

36. Climax Community A stable group of plants and/or animals that colonize an area after a succession event Ex: Old Growth Forest

37. Climax Community Climax communities are not always BIG trees! – Grasses in prairies – Cacti in deserts

38. Aquatic Succession Transition of aquatic habitats (mainly ponds) filling with sediments & the eventually becoming a terrestrial ecosystem