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1、ECOLOGY chapter 50,Ecology: Study of interactions between organisms and their environment.Environment includes both abiotic (non-living) and biotic (living) components.Abiotic: light, water, nutrients, chemicals, rocks, weather, etc.,Biotic: organisms. Organisms compete with, parasitize, eat or are
2、eaten by and change the environment for other organisms.,Ecology explores a wide range of questions about what factors control the distribution, abundance and behavior of organisms.For example, Red Kangaroos occur primarily in the Australian interior in semiarid regions.,Distribution of Kangaroos su
3、ggests an abiotic factor (precipitation) influences it, but perhaps populations also influenced indirectly by biotic factors such as competitors, predators, food availability and parasites.Ecologists have to consider multiple factors to explain patterns of abundance and distribution.,Ecology has man
4、y subfields of study ranging from ecology of individual organisms to dynamics of landscapes Organismal Ecology Population Ecology Community Ecology Ecosystem Ecology Landscape Ecology We will explore these sequentially,Distribution of species,Biogeography: study of the broad patterns of distribution
5、 of organisms across the globe.Patterns strongly influenced by historical factors such as continental drift (see chapter 26) and barriers including mountain ranges and seas.,For example, Australia populated by marsupial mammals (e.g. kangaroos, wombats, koalas) because placental mammals did not colo
6、nize it before it separated from other landmasses.Tapirs found only in southeast Asia and South America. Ancestral populations separated when land masses diverged.,Role of dispersal in distribution,Ability to cross barriers affects distribution.Thus, species of birds often more widely distributed th
7、an mammals.,However, inability to reach an area not only factor that limits distribution. Ability to survive in new area is critical.To survive and thrive species must be able to cope with both biotic and abiotic factors.,Biotic factors,The presence of competitors or predators may limit an organisms
8、 ability to establish itself.For example, algae are eaten by sea urchins and limpets, which limits the ability of seaweeds to establish themselves on rocks,Biotic factors,Conversely, absence of predators and competitors has allowed many organisms introduced into new areas to increase so much they be
9、come pests.E.g. Japanese beetles (from Asia), zebra mussels and purple loosestrife from Europe) (Melaleuca (Eucalyptus trees from Australia) and many other invasive species have spread widely in the U.S.,Abiotic factors,The major factor affecting distribution of terrestrial organisms is climate, whi
10、ch incorporates temperature, sunlight, wind and precipitation.,Abiotic factors,Climate is determined by global factors such as inputs of solar energy and the movement of the earth through space.Study discussion of climate patterns pages 1088 and 1089,Climate,Local factors such as the presence of mou
11、ntains and large bodies of water also affect climate.Mountains force up moist air moving across them. As the air cools the water condenses and falls as rain. The result is that one side of the mountain range is wet and the other side is drier (and perhaps a desert e.g. Mojave and Gobi Deserts.),Clim
12、ate,Large bodies of water moderate climate. Land heats faster than water and warm air rises. Cooler air over water moves in and replaces the warm air. The warm air that was over land cools at high altitude and sinks over water. Results is steady flow of cool air over land.,Terrestrial Biomes,Biomes
13、are major types of ecosystems that cover large areas of the earth and are classified by their dominant vegetation types.(an ecosystem is the community of organisms in an area and their physical environment),Each biome also is populated by a diverse array of animals, fungi and microorganisms adapted
14、to that environment.,Major terrestrial biomes include,Tropical forest Desert Temperate Grassland Savanna Temperate broadleaf forest Coniferous forest (Taiga) Tundra (see descriptions pages 1100-1104),Savannah,Terrestrial biomes,Terrestrial biomes often vertically stratified. Layers defined by differ
15、ent size plants (e.g. in forests there is an upper canopy of tall trees, low tree layer, shrub layer, ground layer of herbaceous plants, litter layer and root zone).,Stratification provides multiple different habitats for animals which occupy specialized feeding niches.,Convergent evolution,Actual s
16、pecies in a biome differ from one area to another but they possess similar adaptations.This is convergent evolution (development of same evolutionary solutions to ecological problems),Convergent evolution,For example vegetation in all deserts worldwide characterized by extensive root systems, long-t
17、erm water storage capability, thick waxy coverings to reduce water loss, and extremely small (if any) leaves,Biomes often maintained by disturbance.Wildfires are an essential factor in maintaining many biomes (e.g. grasslands, savannahs, some coniferous forests). Fire favors trees such as longleaf pine whose bark resists fire and grasses, which recover quickly after burning.,
