organism population community ecosystem biosphere Population Ecology AP

organism population community ecosystem biosphere Population Ecology AP Biology

Life takes place in populations § Population u group of individuals of same species in same area at same time § rely on same resources § interact § interbreed AP Biology Ecology: What factors affect a population? Population

Why Population Ecology? § Scientific goal u understanding the factors that influence the size of populations § general principles § specific cases § Practical goal u management of populations § increase population size w endangered species § decrease population size w pests § maintain population size w fisheries management n AP Biology maintain & maximize sustained yield

Characterizing a Population: 3 fundamental characteristics of a population are Density, Dispersion and Demography. 1970 1966 1964 1960 1965 § Describing a population 1961 Equator 1958 population range u pattern of spacing u § density AP Biology 1951 range 1943 1937 1956 1970 Immigration from Africa ~1900 density

1. Density is the number of individuals per unit area of volume. § Abiotic factors u u u sunlight & temperature precipitation / water soil / nutrients § Biotic factors u other living organisms § prey (food) § competitors § predators, parasites, disease § Intrinsic factors u AP Biology adaptations

At risk populations § Endangered species u limitations to range / habitat § places species at risk Devil’s hole pupfish Iiwi Hawaiian bird Catalina Island mahogany tree AP Biology Socorro isopod Iriomote cat New Guinea tree kangaroo Northern white rhinoceros

§ DENSITY increases with immigration and birth and decreases with emigration and death. AP Biology

Measuring population density § How do we measure how many individuals in a population? number of individuals in an area u mark & recapture methods u Difficult to count a moving target AP Biology sampling populations

Mark and recapture § N=# marked in 1 st catch x total # In 2 nd catch § _____________________ § # of recaptures AP Biology

2. Dispersion or Population Spacing Provides insight into the § Dispersal patterns within a population environmental associations & social interactions of individuals in population clumped random AP Biology uniform

Clumped Pattern AP Biology (most common)

Uniform May result from direct interactions Clumped patterns between individuals in the population territoriality AP Biology

3 DEMOGRAPHICS: is the study of the vital statistics of a population especially birth and death rates, § Factors affecting population growth rate u sex ratio § how many females vs. males? u generation time § at what age do females reproduce? u AP Biology age structure § how females at reproductive age in cohort?

Why do teenage boys pay high car insurance rates? Demography § Factors that affect growth & decline of populations u Life table vital statistics & how they change over time females AP Biology males What adaptations have led to this difference in male vs. female mortality?

Survivorship curves § Graphic representation of life table The relatively straight lines of the plots indicate relatively constant rates of death; however, males have a lower survival rate overall than females. Belding ground squirrel AP Biology

Survivorship curves § Generalized strategies Survival per thousand 1000 Human (type I) Hydra (type II) 100 1 0 AP Biology 25 I. High death rate in post-reproductive years II. Constant mortality rate throughout life span Oyster (type III) 10 What do these graphs tell about survival & strategy of a species? 50 75 Percent of maximum life span 100 III. Very high early mortality but the few survivors then live long (stay reproductive)

Trade-offs: survival vs. reproduction § The cost of reproduction u increase reproduction may decrease survival § age at first reproduction § investment per offspring § number of reproductive cycles per lifetime AP Biology Natural selection favors a life history that maximizes lifetime reproductive success

Population growth /biotic potential change in population = births – deaths Exponential model (ideal conditions) d. N = ri. N growth increasing at constant rate dt N r ri t d = # of individuals = rate of growth = intrinsic rate = time = rate of change intrinsic rate = maximum rate of growth AP Biology every pair has 4 offspring every pair has 3 offspring

Exponential growth rate § Characteristic of populations without limiting factors u introduced to a new environment or rebounding from a catastrophe Whooping crane coming back from near extinction AP Biology African elephant protected from hunting

Logistic rate of growth § Can populations continue to grow exponentially? Of course not! no natural controls K= carrying capacity What happens as N approaches K? AP Biology effect of natural controls

u varies with changes in resources What’s going on with the plankton? AP Biology Number of cladocerans (per 200 ml) population size that environment can support with no degradation of habitat Number of breeding male fur seals (thousands) Carrying capacity § Maximum 10 8 6 4 2 0 1915 1925 1935 Time (years) 1945 500 400 300 200 100 0 0 10 20 30 40 Time (days) 50 60

Changes in Carrying Capacity § Population cycles u predator – prey interactions At what population level is the carrying capacity? K K AP Biology

Reproductive strategies § K-selected u u u late reproduction few offspring invest a lot in raising offspring § primates § coconut § r-selected u u u K-selected early reproduction many offspring little parental care § insects § many plants AP Biology r-selected

Life strategies & survivorship curves K-selection Survival per thousand 1000 Human (type I) Hydra (type II) 100 Oyster (type III) 10 r-selection 1 0 25 50 75 Percent of maximum life span AP Biology 100

Parental survival Kestrel Falcons: The cost of larger broods to both male & female parents AP Biology

Trade offs Number & size of offspring vs. Survival of offspring or parent r-selected K-selected “Of course, long before you mature, AP Biology most of you will be eaten. ”

Regulation of population size marking territory = competition § Limiting factors u density dependent § competition: food, mates, nesting sites § predators, parasites, pathogens u density independent § abiotic factors w sunlight (energy) w temperature w rainfall APcompetition Biology for nesting sites swarming locusts

Introduced species § Non-native species u u transplanted populations grow exponentially in new area out-compete native species § loss of natural controls § lack of predators, parasites, competitors u u reduce diversity examples § § AP Biology African honeybee gypsy moth zebra mussel purple loosestrife kudzu

Zebra mussel ~2 months u u AP Biology ecological & economic damage u reduces diversity loss of food & nesting sites for animals economic damage

Purple loosestrife 1968 1978 u u AP Biology reduces diversity loss of food & nesting sites for animals

FOREIGN INVADERS OF PEI AP Biology

Age structure PYRAMIDS § Relative number of individuals of each age What do these data imply about population growth in these countries? AP Biology

Population of… China: 1. 3 billion India: 1. 1 billion Human population growth Doubling times 250 m 500 m = y () 500 m 1 b = y () 1 b 2 b = 80 y (1850– 1930) 2 b 4 b = 75 y (1930– 1975) What factors have contributed to this exponential growth pattern? Is the human population reaching carrying capacity? adding 82 million/year ~ 200, 000 per day! 2005 6 billion Significant advances in medicine through science and technology Industrial Revolution Bubonic plague "Black Death" 1650 500 million AP Biology

Distribution of population growth 6 5 4 3 ty ili the world takes… World total the effect of income What is K & education for humans? 10 -15 billion? y it l i t r fe m u i d me ity l i t r e f low Developing countries 2 1 AP Biology rt hi gh 9 uneven distribution of resources: 8 consumes ~90% wealthiest 20% of resources There are choices as increasing gap poor which future path 7 between rich & to fe World population in billions 11 uneven distribution of population: 10 are in developing countries 90% of births 0 1900 Developed countries 1950 Time 2000 2050

Ecological Footprint USA 30. 2 Germany 15. 6 Brazil 6. 4 Indonesia 3. 7 Nigeria 3. 2 India uneven distribution: wealthiest 20% of world: 86% consumption of resources 53% of CO 2 emissions 2. 6 0 2 4 AP Biology over-population or over-consumption? 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Acres Amount of land required to support an individual at standard of living of population

Ecological Footprint deficit surplus Based on land & water area used to produce all resources each country consumes & to absorb all wastes it generates AP Biology

Any Questions? AP Biology 2007 -2008

Evolutionary adaptations § Coping with environmental variation u regulators § endotherms § homeostasis § (“warm-blooded”) u conformers § ectotherms § (“cold-blooded”) AP Biology

Bright blue marble spinning in space Ecology AP Biology

Studying organisms in their environment organism population community ecosystem AP Biology biosphere