Population ecology examines populations as units of study. A population has characteristics like density, size, age structure, and dispersion. The four basic population parameters that affect density are natality, mortality, immigration, and emigration. Techniques to estimate population density include using quadrats, capture-recapture methods, and calculating relative density with tools like traps or roadside counts. Life tables can describe mortality schedules by tracking age-specific cohort survival. Population growth rates depend on birth and death rates, and can be modeled exponentially or logistically depending on environmental constraints.

1. Population Ecology

4. immigration emigration natality mortality Four basic population parameters DENSITY

5. Density : no of organisms per unit area or per unit volume Natality : the reproductive output of a population (birth, reproduction) Mortality : the death of organisms in a population Immigration : the no of organisms moving into area occupied by the population Emigration : the no of organisms moving out of the area occupied by the population Immigration and Emigration are referred to as Migration

8. 2 attributes Size -small animals/plants are usually more abundant than large animals/plants Mobility -based on movements of these organisms

10. 2 broad approaches to estimate pop density Absolute density No of individual per area/ per volume Important for conservation and management Relative density Comparative no of organisms Two areas of equal sizes, which area has more organism e.g, between area x and y Area x has more organism than area y

15. Capture recapture method Capture, marking, release, and recapture-important for mobile animals Why?-it allows not only an estimate of density but also estimates of birth rate and death rate for the population being studied Capture animal, mark (tag) them and then release them Peterson method: Involves 2 sampling periods Capture, mark and release at time 1 Capture and check for marked animals at time 2 Time intervals between the 2 samples must be short because this method assumes a closed population with no recruitment of new individuals into the Population between time 1 and 2 and no losses of marked individuals

16. Formula for capture-recapture method Marked animals in 2 nd sample = Marked animals in 1 st sample Total caught in 2 nd sample Total population size

28. Population dispersion patterns 3 types random uniform clumped

32. DEMOGRAPHIC TECHNIQUES

33. A technique to summarize how mortality occurs in a population Is mortality high among juveniles? Do older organisms have a higher mortality rate than younger organisms?

37. e.g of cohort life table for the song sparrow - - 0.0 0 6 1.0 1 0.009 1 5 0.50 1 0.017 2 4 0.83 10 0.104 12 3 0.37 7 0.165 19 2 0.24 6 0.217 25 1 0.78 90 1.0 115 0 Rate of mortality (qx) No dying within age interval x to x+1 (dx) Proportion surviving at start of age interval x (lx) Observed no of birds alive (nx) Age in years (x)

39. Types of survivorship curves Type 1- low type of mortality for most of the life span and then high losses of older organisms Humans and large mammals Type 2- constant per capita rate of mortality independent of age eg birds, squirrels Type 3-High per capita mortality early in life, followed by a period of much lower and relatively constant loss Fishes, invertebrates, parasites

41. Fig. 10.14

42. Fig. 10.15

43. Fig. 10.16

45. Age Distribution

47. Fig. 11.24

48. POPULATION GROWTH

61. 2 types of pop growth Exponential population growth dN = r max N dt Logistic population growth dN = r max N (K-N) dt K Population Growth Mathematically Defined

62. N=K/2

70. Fig. 11.9

82. Human Growth

86. Fig. 11.24