B16 Adaptations, interdependence, and competition Flashcards
Community
A group of interdependent living organisms in an ecosystem
Ecosystem
Made up of a community of organisms interacting with abiotic and biotic elements
Interdependence
If one species is removed or increased it can impact the whole community
Population
The number of individuals of the same species living in a certain habitat
What factors affect population size?
- Competition
- Disease
- Predators
- Migration
Describe how animals and plants are interdependent within a community
- Plants produce food by photosynthesis
- Animals eat plants
- Animals pollinate plants
- Animals eat other animals
- Animals use plant and animal materials to build nests and shelters
- Plants need the nutrients from animal droppings and decay
Species
A group of organisms that can breed together and produce fertile offspring
A stable community
One where all the species and environmental factors are in balance so that population sizes remain fairly constant
Examples of stable communities
- Tropical rainforests
- Ancient oak woodlands
- Mature coral reefs
Abiotic
Non-living conditions
Abiotic factors affecting communities
- Temperature
- Light intensity
- Moisture content of the soil
- Soil pH and mineral content
- Availability of oxygen
- Availability of carbon dioxide
- Wind intensity and direction
Affect of wind intensity and direction
In areas with strong prevailing winds, the shape of the trees and the whole landscape is affected by the wind. It also means plants transpire fast
Affect of oxygen concentration
- The availability of oxygen has a huge impact on water-living organisms
- Some invertebrates can survive in water in low oxygen levels. However, most fish need a high level of dissolved oxygen
- The proportion of oxygen in the air varies very little
Affect of light intensity
- Light limits photosynthesis, so light intensity also affects the distribution of plants and animals
- Some plants are adapted to living in low light levels, for example, they may have more chlorophyll or bigger leaves
- Nettles growing in the shade of other bushes have leaves with a much bigger surface area than nettles growing in the open
- However, most plants need plenty of light to grow well
- The breeding cycles of many animal and plant species are linked to day length and light intensity
Affect of temperature
- Temperature is a limiting factor on photosynthesis and therefore growth in plants
- In cold climates, temperature is always limiting. For example, the low Arctic temperatures mean the plants are all small
- This in turn affects the numbers of herbivores that can survive and so the number of carnivores in the community
Affect of moisture levels
- If there is no water, there will be little or no life
- As a rule, plants and animals are relatively rare in a desert as the availability of water is limited
- However, after it rains, many plants grow, flower, and make seeds very quickly while the water is available
Affect of soil pH and mineral content
- The level of mineral ions has a considerable impact on the distribution of plants
- Carnivorous plants such as sundews thrive where nitrate levels are very low because they can trap and digest animal prey
- The nitrates they need are provided when they break down the anima protein
- Most other plants struggle to grow in areas with low levels of mineral ions
- The pH of the soil also has a major effect on what can grow in it and on the rate of decay and therefore on the release of mineral ions back into the soil
- low acidic pH inhibits decay
Affect of carbon dioxide concentration
- The level of carbon dioxide acts as a limiting factor for photosynthesis and plant growth
- It can also affect the distribution of organisms e.g. mosquitoes are attracted to their food animals by high carbon dioxide levels
Biotic
Living conditions
Biotic factors affecting communities
- Food availability
- Arrival of new predators
- New pathogens or parasites
- Competition
Affect of food availability
When there is plenty of food, organisms breed successfully. When food is in short supply, animals struggle to survive and often do not breed
Affect of new pathogens or parasites
When a new pathogen or parasite emerges, organisms have no resistance to the disease. A new pathogen can damages and even wipe out populations in a community
Affect of the arrival of new predators
Organisms that have no defences against new predators may be quickly wiped out
Affect of interspecific competition
- A new species may outcompete another to the point where numbers become too low for successful breeding
- The grey squirrels that were introduced to Britain and outcompeted the native red squirrels are a good example
- Another example is Japanese knotweed, which has become a very invasive plant pest
