Life processes in the biosphere Flashcards
How do species become better adapted to habitats?
Random mutation, natural selection (evolution)
What abiotic factors affect species distribution?
Light, pH, water and mineral nutrients
What biotic factors affect species distribution?
Food supply, pollination, seed dispersal and disease
What is a taxon?
A taxonomic group
What is an ecological niche?
The role an organism plays in its habitat
What is a population?
A group of one species occupying a defined area
What is a biome?
A large geographical region with specific climatic conditions within which a unique community of species lives
What is ecological succession?
The process of change in the species structure of an ecological community over time
What are the stages of ecological succession?
A ‘pioneer’ species of extremophiles colonises, the population grows and changes the habitat, making it more suitable for other species and this continues until the climax community develops
What is the climax community?
The final species to colonise that remains dominant unless the climate changes
How do temperature extremes change during ecological succession?
High to low
How does water availability change during ecological succession?
Variable to reliable
How do light levels change during ecological succession?
High to low
How does nutrient availability change during ecological succession?
Low to high
How do rate of change change during ecological succession?
Rapid to slow
How does main pollination method change during ecological succession?
Wind pollination to insect pollination
How does main seed dispersal method change during ecological succession?
Wind dispersal to animal dispersal
How does the importance of inter-species relationship change during ecological succession?
Low to high
How does biomass change during ecological succession?
Low to high
How does biodiversity change during ecological succession?
Low to high
What are the critical determinants of a biome?
Temperature and rainfall
What is a sere?
The conditions under which the first stages of ecological succession occurs
What are the three seres?
Hydrosere
Lithosere
Psammosere (sand)
What are the stages of hydrosere?
Pioneer species includes algae and water floating plants
Larger plants colonise in shallow waters
Rooted plants colonise
Marsh plants colonise the margins
Terrestrial plants as soil builds up, water content drops and conditions become more aerobic
Terrestrial plants out compete the water plants and they die out
How are spores and seeds brought into the freshwater?
Birds, such as herons and ducks, and flying incests, such as water beetles and pond skaters
How can rooted plants colonise?
As other plants die naturally, they leave dead organic matter, that and sediment and soil build up
What trees survive in waterlogged soils?
Alder and willow
What are the stages of lithosere?
Simple autotrophs colonise, mosses colonise, grasses and ferns colonise, layers of soil start to build up, larger plants and trees start to colonise
What are the initial conditions of the lithosere?
Bare rock, created by a cliff fall, the retreat of a glacier or volcanic eruption, which is under extreme temperatures with limited water availability and no soil
What autotrophs first colonise the lithosere?
Lichens and algae
What trees have wind-blown seeds?
Birch