inheritance and evolution pt 2 Flashcards
intraspecific competition
competition between SAME species
compete for identical resources in same niche
interspecific competition
competition between DIFF species
compete for e.g prey, water supply, light etc.
ecosystem
consist of a community
and non living components
has biotic and abiotic components
carrying capacity
ecosystem can only support certain size of population of a species
what creates variation in population size
- effect of abiotic (non-living) factors
- interactions between organisms
- interspecific + intraspecific competition
- predation
biotic
living component
abiotic
physical non-living component
biotic producers
- plants convert light energy to chemical energy in photosynthesis
-form the basis of all food chains
-biological molecules produced by photosynthesis consumed by other organisms
biotic consumers
animals, bacteria or fungi
break down large insoluble molecules into smaller soluble ones
to provide energy for growth
primary consumers: herbivores
secondary/tertiary: carnivores
saprobionts
consists of bacteria and fungi
which break down dead organisms
crucial for recycling nutrients in environment
abiotic factors that affect population size
light ( affects photosynthesis + affects n.o of plants species in ecosystem)
pH ( affects enzyme activity - affecting growth)
temperature ( affects plants + animals)
low temp- limits photosynthesis
high temp - enzymes denature
random abiotic factors
oxygen
water
pollution
community
formed by populations of diff species
species occupy a niche
what is a niche?
adaptation to biotic and abiotic conditions
(abiotic requirements in habitat and position in food web)
how organism fits into ecosystem
no 2 species will occupy same niche
how can we estimate the size of a population
- randomly placed quadrats or quadrats along belt transect
- mark-release-recapture method
random sampling
1) divide study area into a grid
2) generate coordinates from a random number generator via computer
3) ensuring NO BIAS in results
4) place large number of quadrats at the intersection of each pair of coordinates and record the number of individuals (e.g) of each species present within each quadrat
5) calculate a mean per quadrat
6) multiply by area of m² of field
why is it essential to use a large number of quadrats
so results are representative of population
using belt transect during sampling
when environments changing e.g light intensity
when theres a change in habitats and communities
can determine change in species distribution
quadrats placed at intervals along transect
how can the abundance of an organism be measured
using its frequency or % cover (in quadrat)
how can frequency of an organism be measured
- likelihood of it occurring in quadrat
- number of individuals in each quadrat
using quadrats to estimate mean density
mean density= total n.o of individuals counted (divided by) no. quadrats x area of each quadrat
when is the mark-release-recapture method used
measure abundance of mobile (moving species)
desrcibe mark-release-recapture method
and include equation
1) CAPTURE: representative sample of organisms from population and record the number captured
2) MARK: then they should be marked in a suitable way which doesnt affect their survival e.g no toxic dye, no visible colour for predators to see
3) RELEASE: marked organisms released back into habitat + left to mix randomly within population
4) after suitable amnt of time, 2nd samples captured and n.o of marked individuals is counted to estimate population size
estimated population size =
n.o captured and marked in 1st sample x n.o captured in second sample
DIVIDED BY
n.o captured in 2nd sample and marked
what is assumed during mark-release-recapture method to give reliable results
- no migration
- no reproduction
- large sample
- random mixing in population
- sufficient time between releasing and recapture so dont catch same in 2nd sample
- marking doesnt affect survival
what does low species diversity mean for the ecosystem
ecosystem is not v stable
what does higher diversity of species mean for the ecosystem
more stable - more resources available
describe predation
type of interspecifc interaction
control population sizes
increase in predator population = causes decrease in prey population (as theyre eaten by more predators)
increase in prey population = increase in predator population
decrease in prey population ( as theyre consumed by predators) = decrease in predator population (less food)
decrease in predator = increase in prey
primary succession
gradual change in plant + animal communities from colonisation (by pioneer species) to the climax community
stages of primary succession
1) pioneer species colonise an area first- slow growers- less hostile
2) change an abiotic factor in environment e.g soil - change environment
3) environment becomes less hostile -more suitable for new species - so more species can grow and outcompete the pioneer species - increasing biodiversity - increasing habitats
4) climax communities formed - usually consists of large plants , trees - blocks light so less smaller plants - higher biodiversity - most stable
5) more variety of foods ( more predators + prey) , more competition for survival - more stable
what prevents succession
- fires
- floods
- grazing- seedlings eaten
- ploughing- prevent germination - uses herbicides
conservation
maintenance of biodiversity + genetic diversity within species
maintains habitats and ecosystems variety
preserves species that’d be extinct by formation of climax community
conserve habitats by managing succession
why might smth not survive in climax community
small size
more competition
little food
abiotic factors not efficient for them
