Chapter 52 Population Ecology

I. Population Density, Dispersion and Demography Dynamic biological processes –Birth rates/death rates; immigration/emigration –Patterns: Clumped, Uniform, Random Demography –Life tables –Survivorship curves (figures 52.4 and 52.5) –Reproductive rates

LE 52-2 Population size Emigration Deaths Immigration Births

LE 52-3 Clumped. For many animals, such as these wolves, living in groups increases the effectiveness of hunting, spreads the work of protecting and caring for young, and helps exclude other individuals from their territory. Uniform. Birds nesting on small islands, such as these king penguins on South Georgia Island in the South Atlantic Ocean, often exhibit uniform spacing, maintained by aggressive interactions between neighbors. Random. Dandelions grow from windblown seeds that land at random and later germinate.

II. Life History and Natural Selection Life history variables –When reproduction begins, how often, how many Life history diversity –Semelparity (Big bang reproduction) –Iteroparity (Repeated reproduction Trade offs

LE 52-5 III II 100 Percentage of maximum life span Number of survivors (log scale) , I

LE 52-8 Most weedy plants, such as this dandelion, grow quickly and produce a large number of seeds, ensuring that at least some will grow into plants and eventually produce seeds themselves. Some plants, such as this coconut palm, produce a moderate number of very large seeds. The large endosperm provides nutrients for the embryo, an adaptation that helps ensure the success of a relatively large fraction of offspring.

III. Exponential vs. Logistic Growth Exponential –Unlimited resources Logistic –Carrying capacity

LE Year Elephant population 8,000 4,000 6,000 2,

LE Number of generations Population size (N) K = 1,500 1,500 2,000 1, Logistic growth Exponential growth = 1.0N dN dt = 1.0N dN dt 1,500 – N 1,500

LE 52-13b Time (days) Number of Daphnia/50 mL A Daphnia population in the lab

LE 52-13c Time (years) Number of females A song sparrow population in its natural habitat

IV. Regulation of Populations Density-dependent and density- independent Dynamics of population growth -> variation Population cycles

LE Year Moose population size 2,500 Steady decline probably caused largely by wolf predation 2,000 1,500 1, Dramatic collapse caused by severe winter weather and food shortage, leading to starvation of more than 75% of the population

LE Year Commercial catch (kg) of male crabs (log scale) 730, ,000 10,

LE Year Hare population size (thousands) 1850 Snowshoe hare Lynx population size (thousands) Lynx

V. Human Population Figure Regional –Demographic transition –Age structure Global Carrying Capacity

LE B.C. Human population (billions) B.C B.C B.C B.C. The Plague A.D A.D.

LE B.C. Human population (billions) B.C B.C B.C B.C. The Plague A.D A.D.

LE Rapid growth Afghanistan Age Male Percent of population Female –49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0– –84 75–79 70–74 65–69 60–64 55–59 50–54 Slow growth United States Age Male Percent of population Female –49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0– –84 75–79 70–74 65–69 60–64 55–59 50–54 8 Decrease Italy Male Percent of population Female

LE Infant mortality (deaths per 1,000 births) Developed countries 60 Developing countries Life expectancy (years) Developed countries 60 Developing countries