[19.1] populations and ecosystems

the study of the inter-relationships between organisms and their environment, which includes abiotic and biotic factors

interaction between abiotic and biotic factors in a given area

the number of members of a given species in a specific habitat at the same time

the maximum sustainable population of a species in an ecosystem given the available resources

a combination of all factors in an ecosystem eg. predation, inter / intraspecific competition

• effect of abiotic factors • interactions between organisms eg. intra / interspecific competition and predation

all of the populations of different species in a given habitat living and interacting at the same time

where an organism normally lives

• how an organism fits into the environment • where an organism lives and what it does there • includes all the biotic and abiotic conditions an organism is adapted to survive in, reproduce and maintain a viable population

the idea that no two species occupy exactly the same niche

living aspects of an ecosystem

• non-living aspects of an ecosystem • influences biotic factors • determines what organisms can live in an ecosystem

• wind • light intensity • wavelength of light absorbed by pigments for photosynthesis • soil pH • soil water content • soil mineral content (eg. nitrates, phosphates) • soil structure • oxygen concentration • carbon dioxide concentration • rain levels

• competition • predation • parasites • mutualism

the range of conditions where a species could theoretically survive, set by abiotic factors only

where a species actually does live once biotic factors are introduced eg. competition, predation, disease on top of the other abiotic factors