biodiversity and succession Flashcards
(24 cards)
define carrying capacity
certain size of the population which can be maintained over long periods of time
what determines the carrying capacity 3
limiting features such as
limited resources
competition
limited space
define intERspecific competition
competition between different species
define intRAspecific competition
competition between the same species
what can competition within a species contain
competition for food
for space
light
minerals
water
breeding territory
what can intraspecific competition result in
stabilising effect of population
describe what a interrelationship is
predators eat prey
less prey = more competition for food
predators die
prey population increases
what is an ecological niche
a role a species serves in an ecosystem
what it eats how it behaves
explain the competitive exclusion principle
2 species occupy identicle niches
competition
eventually natural selection will drive one species to either extinction or to leave
biotic factors that may affect population size
competition
predation
disease/parasites
what are the 4 rules for a representative sample
- random + fair
- take lots of samples
- consistency in method
- where, when, how each sample was taken
define local frequency
The proportion of quadrats in which a particular species occurs within the sampled area
define density for quadrats
Counts the exact number of individuals per unit area
define % cover for quadrats
Estimating the proportion of ground covered by a species within each quadrat.
define ACFOR scale
Qualitative abundance scale categorizing species into Abundant, Common, Frequent, Occasional, and Rare
define succession
sequential change in a biotic community over time
what are the different levels of species during succession
pioneer species
intermediate species
climax community
what are the characteristics of a pioneer species
asexual reproduction
lots of seeds/spores
rapid germination
they can photosynthesise
nitrogen fixation
tolerance to extreme conditions
what happens after pioneer species arrive
lichen (fungi or bacteria) die and decompose
releasing sufficient nutrients to support the community
organic matter builds up
mosses/ferns start to grow
they die and decompose making conditions less hostile
what is stabilising selection
favouring intermediate phenotypes in the population
reducing variation
what happens after first plants die
topsoil/hummus becomes fertile and enables other species to grow
they die and decompose
leaving organic matter
everything repeats until animals come
what is management of succession
deflected succession
we can stop and start succession - secondary succession
what is directional selection
favours one extreme phenotype over the others causing a shift in the populations phenotypic distribution
often occurs when environment changes
what is disruptive selection
favours both extreme phenotypes over intermediate phenotypes
can lead to speciation as distinct phenotypes are selected in different environments
