AN INTRO TO ECOLOGY & THE BIOSPHERE ch 34

1. AN INTRO TO ECOLOGY & THE BIOSPHERE ch34 Scope of ecology: • Ecology – studies of interactions b/t org & their env • Difficulty in studying? • Env includes… • Interactions affect orgs & env • Ex: first photosyn bacteria added O to atm, trees blocking sunlight …

2. 4 levels of ecology 1. organismal ecology – concerned w/ behavioral, physiological, & morphological ways individuals deal w/ their abiotic env. 2. population ecology – group of individuals of same species living in an area. [ ] on factors that affect pop size & composition 3. community – all orgs in an area. [ ] on interactions among species 4. ecosystem – all abiotic & community of species in an area. [] on E flow & cycling of chemicals

3. Abiotic factors of biosphere temp – affects biological processes. If cold blooded: • below 0 C – cells rupture • above 45 C – proteins denature • some have adapted water – essential to life but availability varies over earth sunlight – provides E that powers all ecosystems. • shading in forests • absorption in water • Amount of light per day – effects flowering & migration wind – amplifies effects of temp. • evaporative cooling • transpiration rocks & soil – affect plant growth which affects animal distribution periodic disturbances – fires, hurricanes, tornadoes, volcanoes

4. Climate & the distribution of orgs • climate – prevailing weather conditions in an area • temp, water, light, wind are most important & based on annual means • biome – major types of ecosystems

5. Major terrestrial biomes tropical forests – high rain, warm temps savanna – grasses & scattered trees, herbivores, dry & rainy seasons desert – sparse rainfall, cold or hot, plants & animals adapted to low water Ex: cacti chaparral – midlatitude coastal areas, dense spiny evergreen shrubs, mild rainy winters, long hot dry summers temperate grassland – fires, drought, grazing of mammals keep shrubs & trees from growing, soil is deep & nutrient rich, little exists today in US cause of farming Temp deciduous forests – midlatitudes with good rain, drop leaves in fall when temps too low for photo & water loss isn’t replaced from frozen soil, recover well after disturbances Coniferous forest – cone bearing trees (pine, spruce, fir, hemlock), temperate rain forest (Washington state, taiga which is the largest terrestrial biome) Tundra – permafrost, cold, high winds, no trees

6. Concepts of organismal ecology • Orgs strive to maintain homeostasis. There are benefits & costs: • Ex: panting or sweating when hot can serve to cool but it can also cause dehydration. • Regulators – orgs that use behavioral & physiological mechanisms to achieve homeostasis • Conformers – allow internal conditions to vary with external • principle of allocation – each org has a limited amount of E that can be allocated for getting food, escaping predators, coping, growth & reproduction • Some have more E left over than others – like having a budget

8. An orgs short term responses to env variations operate within a long term evolutionary framework. • Ex: all plants change stomata size in response to transpiration but only desert plants have additional adaptations like stomata in pits – why? • physiological responses to env change • Ex: blood vessels in skin constrict when in cold – occurs fast • Ex: some occur slow – called acclimation – moving from sea level to high elevations you increase the number of RBC you make Why?