5) The distribution of terrestrial biomes is based mainly on regional variations in climate. 1) Interactions between organisms and environment determine distribution and abundance: dispersal, habitat selection, biotic factors, abiotic factors (climate very important: temperature and water). 2) Temporal and spatial scales of studies are important. 3) Global climate mostly determined by solar energy and earth’s movement in space. Permanent tilt on Earth’s axis causes seasonal variation in light, temperature and wind patterns. Hence, seasonal variation in distribution and abundance of organisms. 4) Aquatic biomes occupy the largest part of the biosphere; oceans have a major effect on global and local climate; freshwater biomes are closely linked to terrestrial biomes.

Aquatic Biomes Largest component. Vertical stratification: light, temperature, salinity, density. Oceans (3% salt): rainfall, climate, wind. Give O 2 and take CO 2. Freshwater (< 1% salt): linked to soil and biota of terrestrial biomes. Fig pages

Ocean zonation Distance to shore & water depth, light penetration, substrate. pages Fig

Terrestrial Biomes Determined by climate: latitudinal and regional patterns. Vertical stratification based on vegetation. Characteristic life forms. Gradation in boundaries: ecotone. Dynamic, not stable. pages Fig

1- Are we going to be tested on material that you have not covered in lecture? SOME questions from February 8th 2- When will the review sheet be posted? Will we have a study/review session? 3- Will there be questions about the third article on the test? 6- What are the lowest points in the ocean? What could possibly live there? 4- Do any chemicals evaporate with water or does water always separate from anything it is mixed with? 5- What is the Ekman transport vector? Why is it important?

Organismal ecology coping Population ecology limiting factors Community ecology interspecific interactions and diversity Ecosystem ecology energy flow and chemical cycling Landscape ecology effects on interactions at lower levels Biosphere ecology global effects Chapter 52- Population Ecology

Population: Group of individuals of the same species occupying the same general area. 67, Census 71, Estimate Density. Dispersion. pages

Uniform Clumped Random Fig page 1153 Dispersion Patterns

Additions (+) Natality (births). Immigration. Changes in Population Size Demography: Studies vital statistics that affect population size. pages 1153 (1154) Life Histories pages Reproductive success. Number of surviving offspring produced by an individual and that reach reproductive age. Natural selection. Differences in reproductive success due to heritable differences in individuals. Life histories. Patterns of resource allocation to maintenance (survival), growth, and reproduction. Subtractions (-) Mortality (deaths). Emigration. Individuals expected to behave so as to promote their own RS. Fig Island of Rhum, Scotland

TID Three basic life history “decisions” (remember not conscious choice except us): -When to begin reproducing? -How often to breed? -How many offspring to produce during each reproductive episode? Life Histories Iteroparity. Semelparity (“once” and “beget”) (“repeat” and “beget”) page 1156

Population Growth population is growing ( >1 ) population is declining ( <1 ) zero population growth ( 1 ) λ = number of individuals at time t + 1 divided by number of individuals at time t Finite rate of increase population is growing ( r+ ) population is declining ( r- ) zero population growth ( r = 0 ) r = ln λ Instantaneous rate of change NtNt+1 λ r% change pages

Exponential model Population Growth r max = maximum growth rate for the species Intrinsic rate of growth rate dtdt dNdN = r max N Ideal conditions: population growth constrained only by life history. exponential population growth or geometric population growth pages

Logistic model There is a limit to number of individuals that can occupy a habitat. Carrying capacity (K). Maximum population size an environment can support at a time with no habitat degradation. Not a fixed value. Population growth rapid when population size well below K, slow when close to K and zero when at K. Population Growth K K - N K = 100; N = 1; (K-N)/K = 0.99 K = 100; N = 90; (K-N)/K = 0.1 K = 100; N = 100; (K-N)/K = 0 dtdt dNdN = r max N K K - N pages

Number of individuals Time r = 0.02 Population Growth S-shaped curve. Population growth levels off as population size approaches carrying capacity. r = 0.02 Exponential curve. Population grows indefinitely. pages

ICES J. Mar. Sci Halichoerus grypus J. Wildl. Manage Phoca vitulina Sable Island, CAN pages

Many factors cause changes in birth and death rates in relation to population density: increased predation, competition for food or space, stress, parasitism, etc; slowing population growth rate. Population-Limiting Factors Why do they represent an example of negative feedback? Food-limited pages Fig CRESLI Eubalaena glacialis Mandarte Isl., BC

Dynamics of Populations They result from the interaction between biotic and abiotic factors. Long-term studies indicate that such factors make natural populations unstable. Fig pages Assigned paper to read for Quiz IV. Isla Royale, Michigan

-Hare fluctuations. -Fluctuations of food species. -Predation by various species. Some populations have regular boom-and-bust cycles. Fig pages Geographic variations due to large- scale climate effects (apparent lack of lynx migration between regions). PNAS 2004