Zoology 101 – McIntyre – Ecological Thinking - 30 Apr 2012Time scales of evolutionary vs. ecological processesEcology – the study of the interactions betweenorganisms & the environment and how these interactionsdetermine distribution & abundance of speciesOrganismal ecology – how an organism’s structure,physiology, & behavior meet environmental challengesPopulation ecology – controls on how many individualsof a species live in an area (integrates all individuals)Community ecology - interactions among species withinthe same area (integrates all populations)Ecosystem ecology – energy flow & chemical cyclingamong biotic & abiotic components (integrates allcommunities)Landscape ecology – consequences of the arrangementof ecosystems in a region (integrates all ecosystems)Global ecology – distribution & dynamic of species,energy, and materials throughout the biosphere; on thebiosphere scale (integrates all landscapes)Biogeography: current geographic range of anyspecies depends on past & presentenvironments, and its capacity to disperseKey factors: 1) History – past environmental conditions2) Dispersal – ability to reach a place3) Fitness – survival & reproduction inpresent environmental conditionsBiogeographic control #1: DispersalDispersal – movement of individuals from high-density area to low-density areas- Arises from natural responses to population pressures- Can also result from human activitiesContinental drift – Earth’s crust is dynamic in geological timeThere’s evidence of original “supercontinent” of Pangaea in fossils as well as extent taxa. Some organisms show evidence of being from Pangaea (time range); Fossils show cosmopolitan dispersal similar to Pangaea or even Laurasia or from Gondawana. Natural differences in dispersal – the dispersal scalevaries widely (1st graph). Herbivores usually dispersefarther than plants (2nd graph). Dispersal in ocean (1st graph) futher than dispersalon land (3rd graph)x-axis = Estimated dispersal scaley-axis = # of taxaSome things can’t move very far within or acrossgenerations. 1st graph – doesn’t disperse very far;plants can’t be targeted by organisms that can’t moveAnimals can disperse further than plants (3rd graph). Marine patterns – algaea can disperse further than terrestrial plants. Herbivore insects may move more (averagely) than marine invertebrates; dispersal for marine plants is more than terrestrial plantsDispersal potential (Examples: pollen attaching to clothes or “burrs” attaching to animal skin, carrying plant seeds). The cow is the agent of dispersal. Rats were able to disperse on boats. Now they’re everywhere. One rat eluded capture on New Zealand for 18 weeks. It swam 400m between the islands of New Zealand. Rats eat baby birds, and they our decreasing the populations of the native species there.Species invasions (Invasive species – organisms that become established outside their native range)Global reach of shipping and roads – Enable humans to introduce species worldwide. (In lecture there was a map where the shipping lanes were light red and the road networks were dark red). There in no limit of the capacity of dispersion for species. ZEBRA MUSSELS EXAMPLE!Zebra mussels (a tramp species) are a recent example of an unstoppable invasion in North America. They colonize crayfish exoskeleton or native mussel (any hard surface). First site was Lake Erie, and 20 years later they spread all the way west. They zygotes have a larvae stage (can move anywhere). There is almost unlimited expansion for zebra mussels. Pattern: incremental expansion limited only by calcium in water for exoskeleton (can’t grow in places in low levels of calcium in the water)Biogeography has always shifted slowly but is now changing rapidly under human influenceBiogeographic control #2: Habitat selectionMost organisms do not occupy all of their potential rangeIn animals, habitat selection behaviors often decline the specific boundaries of the actual rangeBiogeographic control #3: Biotic factorsBiotic factors: interactions within and among speciesTypes of interactions (all aspects of community ecology)- Predation- Competition- Parasitism- Disease Biogeographic control #4: Abiotic factors- Chemical factors (i.e. calcium limitation of zebramussels)- Temperature (i.e. precipitation) - Physical factors Fundamental abiotic factors affecting the distribution of species include soil, temperature, water, and sunlight.Equinox graph/diagram – peak solar energy at equator (at 0degrees); creates warming effect, air rises, and it condensates(rainfall)- Climate: long-term, prevailing weather patterns in an areaTemperature, precipitation, and seasonalitySpatial heterogeneityMacroclimate – climate patterns on the global, regional, and landscape levelMicroclimate – climatepatterns that are very fine,and localized; patterns thatare encountered by thecommunity of the organismsthat live in the microhabitats(i.e. beneath a fallen log)- Climate changeSpecies distribution: abiotic controls; futuregeographic range depends on rate of climate change.American beech tree (needs human intervention tomove to the area they need to be due to climatechange)Climograph – a plot of the annual mean temperatureand precipitation in a particular region (IMAGE TORIGHT)Biomes: large regions of Earth where climate conditions are associated with a particular kind of ecological communities; often associated using the types of plants present (grassland, forest, tundra, etc.)Terrestrial Biomes Tropical Forest – (Borneo, Africa, Central America, Asia, South America, and Australia) Rainfall is relatively constant (200-400 cm annually). High temperature year round (25-29°C); layered canopy. Up to 5-30 million species of insects, spiders, and arthropods. It has the highest diversity of animals. Agriculture has diminished the tropical forestsDeserts – (North America, South America, Africa, Asia, and Australia) occur in bands near 30° north and south latitude or at other latitudes in the interiors of continents (i.e. the Gobi Desert in Mongolia). Precipitation and rainfall is low. Temperatures range from 50°C to -30°C. There is low vegetation (high water retention) & animals (lizards, snakes, scorpions, ants). Savanna – (South America, Africa, Australia & Asia) in the tropical belt. Rainfall is seasonal which averages 30-50cm per year. Scattered trees, large herbivores (zebras &wildebeests), large
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