10.1 The effect of abiotic factors on populations Flashcards
what is a microclimate ?
This is a small area with a distinct climate that is different to surrounding areas.
how does light after populations ?
the amount of light in a habitat has a direct effect on the number of organisms found there. Plants are dependant on light for photosynthesis, so any plant populations that are going to survive in areas with low light levels need to be able to cope with this factor. some plants are adapted to survive in low light levels as they have extra chlorophyll or a different ratio of photosynthetic pigments that are sensitive to lower light. These plants can thrive in niches were others would die, giving them a survival advantage . Another strategy is having large leaves to collect light.
seasonal light changes effect reproductive patterns in animals and change circadian rhythms which control much of animals psychology and behaviour
how does temperature effect populations?’
every organism has a range of temperatures in which it can grow and successfully reproduce , it’s the extremes of temperature that determine where an organism can live .
the temp of an environment affects rate of enzyme-controlled reactions in plants and ectothermic In animals.
how does wind effect populations ?
wind causes an increase in water loss from the body and cooling so adds environmental stress to an organism, fewer species can survive in strong winds and it can destroy communities.
in currents, organisms must be able to ;
- be strong swimmer
- attach to surface and resist flow of water.
-flow with the current.
currents are most damaging to populations when strength increases suddenly.
how does water availability affect populations ?
water availability is affected by the amount of precipitation, rate of evaporation and edaphic factors e.g rate of loss of drainage through the soil. Water is vital for organisms so where the supply is limited will cause severe problems .
if water stress becomes too severe organisms will die unless like kangaroos rats and cacti they have special adaptions to enable them to survive and reproduce in very dry conditions.
in increase in water availability can lead to a huge change in habitat and massively increase population size of some organisms.
how does oxygen availability effect populations ?
when water is cold and fast flowing sufficient oxygen dissolves in it to support life. but if water temp rises or it becomes still oxygen content will drop, affecting survival of populations.
The spaces between soil particles contain air so there is enough oxygen for respiration of plant roots. however in waterlogged soil the air spaces are filled with water and plant roots may be deprived of oxygen, so plants may die. Some plants have special adaptions such as aerial roots that allow them to thrive in waterlogged conditions.
how does edaphic factors - soil structure and mineral content affect populations ?
sand has a loose shifting structure so allows little to grow on it . soils containing sand are very easily drained, water passed through them rapidly carrying with it minerals that may be needed by plant . this leaching of minerals reduces the population density of plants which can grow in the soil. however soils made up of tiny clay particles are hard to warm up and are easily waterlogged. the ideal soil has particles of a wide range of sizes. heavier and less prone to leaching than sandy soils but easier to warm and work than clay.
what is intraspecific competition?
occurs when individuals of the same species compete with each other for resources and a mate. competition for a mate links to courtship rituals. individuals that are fitter will have more energy to perform courtship rituals. The availability of resources determines the size of population
what is interspecific competition ?
occurs when individuals of different species compete with each other for resources. one will have a competitive advantage over the over / survival advantage , causing one population to increase and one to decrease .
this could lead to the removal of a species- known as the competitive exclusion principle.
