1. How do animals persist/increase in an area?

3. y

4. To keep every cog and wheel is the first precaution of intelligent tinkering If the biota in the course of eons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering A. Leopold

5. Variation Within a species, there is variation Ex. Morphology (size, shape, color), behavior Some of this is linked to genetic variation Heritable Different variations are better suited for certain conditions Those that are better suited for conditions do better (more food/different food; new nest sites, danger avoidance, etc…) When this variation is heritable, it is passed on to offspring and, if conditions remain the same, they gain an advantage.

6. Where does variation come from? Mutation – errors –Most are harmful or neutral Gene flow – migration followed by breeding –Add new alleles to population pool or change frequencies of alleles present Genetic drift – chance alterations in small populations –bottlenecks and founder effects Accumulates over time

7. Natural Selection Individuals within populations are variable for nearly all traits Individuals pass on their genes to offspring More offspring are produced than can survive Individuals that survive and go on to reproduce (the most) are those with the varieties (alleles) that best adapt them to their environment Outcome: alleles associated with higher fitness increase in frequency from one generation to the next

8. Evolution Any cumulative change in the characteristics of organisms or populations from generation to generation Evolutionary agents –Mutation –Gene flow –Genetic drift –Natural selection

9. It is not the strongest of the species that survive, nor the most intelligent, but the ones most responsive to change. C. Darwin

10. Dangers in context of our world today Losing large numbers of animals, can lose variation as well May limit individual’s ability to persist under current conditions Or future conditions...

11. Individuals belong to populations What is a population? a group of organisms of the same species occupying a defined area (habitat patch) at the same time Ostrich in the savannahs of the Loeli area, Sudan. Photo by Paul Elkan ©2007 Nat. Geo./ WCS

12. Density: amount per unit area (hectare, square kilometer, etc.) Example: 7 frogs/hectare (ha) 100 m (1 ha = 10,000 m 2 = 0.01 km 2 = 2.5 ac) Density

13. Niche: an n-dimensional hypervolume which includes the range of biological and physical conditions under which an organism can exist, including the resources that an animal must exploit for growth and reproduction A portion of the feeding niche of the Blue-gray Gnatcatcher (Smith & Smith 1998) Prey length (mm) Foraging height (m) Niche

14. “BIDE” Population size: N t = population size at time t N t+1 = population size at time t+1 N t+1 = N t + Births + Immigration – Deaths -Emigration Growth rates: r = exponential growth rate λ (‘lambda’) = intrinsic population growth rate Population size and rates of growth

15. Population Reproduction, births, natality (B) Mortality, death (D) Emigration (E) Immigration (I) “BIDE” Population growth

16. Study Area From 1999 to 2007, we studied songbird communities and populations within forest patches from 3 landscape types: Forest reserves (5) Developed Subdivisions (9) Changing landscapes (13)

17. Reserve sites are primarily forested. Changing sites are undergoing residential development during the study Developed sites are older residential areas built prior to the onset of study.

18. Closed System: r = (b - d) r = actual growth rate of population b = birth rate d = death rate Open System: r = (b - d) + (i - e) i = immigration e = emigration Population growth

19. Population Reproduction, births, natality (B) Mortality, death (D) Emigration (E) Immigration (I) Population growth

20. Length of gestation or incubation period & reproductive rate Sex ratios Breeding system (monogamous or polygamous) # of females that breed at each age # of young per female of various ages Influence of nutrition on reproduction Characteristics of birth rates

21. r-selected species (fast species) : shorter gestation period reproduce more frequently produce many offspring at a time K-selected species (slow species): longer gestation period reproduce less frequently produce few offspring at a time Reproductive rates

22. Length of gestation or incubation period & reproductive rate Sex ratios Breeding system (monogamous or polygamous) # of females that breed at each age # of young per female of various ages Influence of nutrition on reproduction Characteristics of birth rates

23. 1. Monogamy –Seasonal: same mate only for 1 year –Lifetime: same mate for life Canvasbacks Bald Eagles Sex ratios and mating systems

24. 2. Polygamy - polyandry: one female mates with several males - polygyny: one male mates with several females Red Phalaropes Fur Seals Sex ratios and mating systems

25. 3. Promiscuity: no pair bonds Sex ratios and mating systems

26. Length of gestation or incubation period & reproductive rate Sex ratios Breeding system (monogamous or polygamous) # of females that breed at each age # of young per female of various ages Influence of nutrition on reproduction Characteristics of birth rates

27. Age (yrs)N# Female births per pregnantfemale _____________________________________________ 0--0.000 160 20.017 236140.194 370520.371 448450.469 526190.365 619160.421 7 6 50.417 >710 70.350 ___________________________________________ A fecundity schedule for Chamois from New Zealand. Age-specific birth rates

28. Monitoring Songbird Productivity Productivity---Territory success and estimates of fledglings produced via spot mapping and nest monitoring. Monitored and color-banded individuals of 7 species: # Colorbanded Individuals # Territories/Nests Monitored American Robin289375 Bewick’s Wren160210 Dark-eyed Junco141339 Song Sparrow1177867 Spotted Towhee533848 Swainson’s Thrush647433 Winter Wren195552

29. Landscape specific productivity estimates : From spot-mapping data and nest monitoring Territory success rates Number of fledglings/ successful nest We used these numbers to get estimate of fecundity (number of young produced per female/year) ReservesChangingDeveloped Song Sparrow % Successful61.270.664.4 % 2 nd Brood7.516.40.16 Fledglings/nest attempt1.562.002.14 Fledgling/female0.781.001.07 From Oleyar et al. (in prep)

31. Length of gestation or incubation period & reproductive rate Sex ratios Breeding system (monogamous or polygamous) # of females that breed at each age # of young per female of various ages Influence of nutrition on reproduction Characteristics of birth rates

32. Reindeer (caribou) Bighorn sheep Population density (top) or size (bottom) # young produced

33. Population Reproduction, births, natality (B) Mortality, death (D) Emigration (E) Immigration (I) Population growth

34. 2 4 6 8 10 12 14 16 18 20 males females Age at Death (years) Survivors (l x ) Survivorship curves for male & female moose on Isle Royale

35. Estimating survival in different landscapes: Mark and recapture: Capture, mark, and release individuals in a population. Recapture or re-sight individuals at regular intervals (yearly) From this can estimate apparent survivorship and encounter rates. Photo by T. Unfried

36. Estimating survival in different landscapes: Yearly encounter histories based on recapture and resighting of colorbanded individuals. Encounter history: series of 0’s and 1’s denoting whether animal was seen during year or not. 100000 : marked and never seen again 101001 : marked and recaptured/resighted in yr 3 and 6 111111 : marked and recaptured/resighted in every yr Photo by T. Unfried

37. From Oleyar et al. (in prep)

38. Winter Wren American Robin Swainson’s Thrush From Oleyar et al. (in prep)

40. Population Reproduction, births, natality (B) Mortality, death (D) Emigration (E) Immigration (I) Population growth

41. Juvenile dispersal: movement from place of birth to place of breeding Breeding dispersal: movement by adults from one place of breeding to another –Birds: Female dispersing sex –Mammals: Male dispersing sex Emigration and Immigration

42. American Robin post-fledging movements

43. Adult survival, juvenile survival, and fecundity are what we need to estimate λ, the intrinsic population growth rate. Sink / declining Stable population Source/ growing populations

44. From Oleyar et al. (in prep)

45. No obvious response in growth rate by landscape.

46. Declining λ outside of reserves?

47. Possible sink during development for some species followed by recovery as subdivision ages?

48. How do these projections match up with what we see out there? Winter Wren numbers high and ‘stable’ in reserves, low and/or declining elsewhere Robin numbers ‘stable’ but low in reserves, highest in developed residential areas Are developed landscapes ecological traps for Robins?

49. Populations fluctuate due to Density dependent factors –Ex: Predation, competition, habitat availability –change population growth in predictable ways –N is driven by population density Density independent factors –Random or Stochastic events –Ex. Weather, accidents –Breeding 14 aug 2007

50. time # of Animals (N) Definitions Population regulation: the tendency of population sizes to stay within a certain range

51. time # of Animals (N) k Carrying capacity (k): the number of organisms that can be supported by a given area; the actual number of organisms fluctuates near this Carrying capacity

52. Population fluctuations Carrying capacity (k) Classic growth curve, unlimited resources Classic growth curve, limited resources (k) time NN k

53. Example of unlimited growth: Australian rabbit (European hare) 1859: 24 hares introduced (for human food?) 1865: over 20,000 hares were harvested, actual population much greater. Mid-1800’s to mid-1900’s: major problem with too many hares; caused habitat destruction and reduction in native mammals 2000: still present, local problems Population fluctuations

54. No rabbits Rabbits exceeded k Rabbit-proof fence Carrying capacity

55. High food addition Low food addition No food added Shaded area is winter Townsend’s vole Population regulation: food

56. Population cycles: Ex. peaks in lynx populations show time lag behind peaks in snowshoe hare populations Population size Snowshoe hare Lynx Time (years) Population regulation: food

57. Population regulation: climate

58. Competition – demand by 2 or more individuals of the same or different species for a common resource Between 2 individuals of same species: Intraspecific Between 2 individuals of different species: Interspecific Limited supply of resource: Exploitation Not limited but interaction detrimental: Interference Population regulation: competition

59. Inter- or Intraspecific competition? Exploitation or Interference competition?

60. Population regulation: competition