Populations and ecosystems-BP Flashcards
(28 cards)
What is a species?
group of organisms with similar characteristics that can interbreed to produce fertile offspring
What is a population?
all the individuals of a particular species in a habitat at a particular time
What is a community?
all the population of different species in a habitat
What is a habitat?
The place when organisms normally live which is characterised by the physical conditions and the other organisms present
What is an ecosystem?
all the organisms living in a particular area and the non-living (abiotic) conditions
What is ecological niche?
an organisms role/position in an ecosystem – in terms of its interaction with abiotic and biotic factors
Why can 2 different species not occupy the same ecological niche?
- interspecific competition will take place for the limiting factors/resources (abiotic & biotic factors)
- better adapted species will out compete the other = competitive exclusion principle
How to sample plant species over a large area?
obtain a map of the area
divide the map into grids
select a large number of coordinates using a running mean
select a random set of coordinates using a random number chart
in each coordinate place a quadrat
measure abundance of the plant species in each quadrat = frequency or percentage cover
calculate average for the whole area
How to sample plants species along a path?
use a transect
place a tape along the path, count number of plants touching tape (Line Transect)
or
place a tape along the path, at regular intervals along the tape place a quadrat, measure abundance within the quadrat (Belt Transect)
How to sample animal species in an area?
- collect the sample, mark and release them
- method is non-toxic and it does not make them visible to predators
- leave sufficient time for animals to re-distribute before collecting second sample
- (no in 1st sample x no in 2nd sample) ÷ number of marked individuals recaptured
Assumptions of Mark-release-recapture technique?
no births or deaths
no immigration or emigration
marked animals mix evenly with population
mark is not toxic
mark does not come off
large population
What are the 3 stages of population growth?
slow/lag phase: species becomes adapted to new environment
rapid/log phase: species adapted, abundant resources, doubling with reproduction, birth rate>death rate
stationary phase: resources become limited, intraspecific competition occurs, birth rate = death rate
How are resources/limiting factors grouped?
abiotic (non-living): light, temperature, water, O2/CO2, minerals, pH, living space
biotic (living): predator, prey, mates, competition, disease
What is competition?
when organisms compete for resources (abiotic and biotic)
What are the 2 types of competition?
- intraspecific
- interspecific
Describe the predator/prey relationship?
prey increases in number
more food available for predator
predator increases in number (more energy available for reproduction & growth)
predator eats more of the prey
prey decreases in number
less food available for predator
predator decreases in number
less of the prey are eaten
prey increases in number [cycle repeats]
What is succession?
- how an ecosystem changes over time (change in species diversity and habitat diversity)
- relies on environment being made less hostile by present species via death and decomposition leading to it being outcompeted and replaced by larger better adapted species
What are the 2 types of succession?
primary (occurs on new land) and secondary (occurs on previously colonised land that has become bare e.g. after a forest fire)
Describe Primary Succession?
- new land appears (glacier retreats exposing rock, lava cools, sand dunes)
- pioneer species settle [adapted to surviving in hostile conditions of bare land]
- the land then erodes and soil forms
- The pioneer species die and decompose, putting nutrients back into the soil.
- small plants can now grow
- they out compete the pioneer species
- over time more soil forms, small plants die and decompose adding more nutrients to the soil
- large plants can now grow, they out compete the small plants
- this process continues until the climax community is reached
- the climax community contains the best adapted species to the environment (they are the final community, there will be no more succession after them)
Primary succession vs Secondary succession?
- secondary succession starts from small plants not pioneer species (soil and nutrients already present)
- secondary succession is faster (soil, nutrients and seeds already present)
types of conservation?
- ex-situ conservation
- in-situ conservation
ex-situ conservation?
individual endangered species within zoos
in-situ conservation?
whole ecosystems and landscapes
specialised features of pioneer species?
- produce large quantities of wind-dispersing seeds or spores- can spread easily to remote areas
- short dormancy/fast germination
- not dependant on animal species (must photosynthesise)
- nitrogen fixing - poor soil quality
- tolerant of challenging conditions
