Investigating populations Flashcards
species
-closely related individuals which are capable of breeding
-to form fertile offspring
population
-all the individuals of a given species living together in the same area at the same time
carrying capacity
-the maximum equilibrium number of organisms of a particular species that can be supported indefinitely in each stable environment
-Birth rates death rates are in equilibrium
community
-is all the individuals of all the species living together in the same area at the same time
habitat
-place where an organism lives in an ecosystem
niche
-describes where an organisms lives and what it does
-what it feeds on and how it interacts with other organisms and the environment
biotic factors
-living factor which affects the distribution of an organism
-prey
-food availability
-disease
abiotic factors
-a non-living factor which affects the distribution of an organism
-temperature
-light intensity
-wind speed
conditions for estimating abundance
- data is not biased
-selected at random
-large sample must be taken
-method for collection must be appropriate to the species
Quadrats
-frame of known area which is placed on the ground and an estimate of the population sizes within them are made
How is abundance of a species measured
-actual count of all individuals
-percentage cover
-frequency
Using quadrats to find out the abundance
-use a grid
-use a random number generator to create co-ordinates
-plant quadrats in those co-ordinates
-count frequency of plants in quadrat
-calculate mean number per quadrat
How to know how many quadrants are in
-calculate a running mean
-when enough quadrants, mean levels out
-enough to carry out. a statistical test
-use a large number to make sure results are reliable
-need to make sire work can be carried out in the time available
Transect
recording what species are touching the line at each sampling point
Belt transect
placing two parallel lines across, a metre apart and recording what species are found between the two lines
interrupted belt transects
using one line and placing a quadrant down at equally spaced sampling point and recording abundance of species within the quadrant
describe how you would investigate the distribution of marram grass from one side of the dune to the other
-transect the area from one side to the other
-place the quadrants at regular intervals along the line
-count plants in quadrants
Mark-release-recapture
-animals of a particular species are ethically collected and counted
-animals are marked in some way
-animals are then released and left to redistribute into the population
-after a period of time a second capture is carried out
-total no. and marked no. are recorded
population size formula
(n1 x n2)/Nm
important considerations in MRR
- should be very few/no increase in birth/death/emigration/immigration rates
-marking should not make the animals more susceptible to predators or harm AS the formula is based on the ratio of marked to unmarked indiv. remaining the same
-the marking should not rub off or be lost
-sufficient time should be left after release to be fully dispersed BUT not too long that death may occur
MRR question points
-capture sample mark and release
-appropriate method of marking suggested
-take second sample and count marked organisms
-no in population=(no in sample 1 x no in sample 2) / no marked in sample two
abiotic factor: temperature
-temp too cold then enzymes have too low kinetic energy to catalyse reactions quickly
-overall activity will drop and may not be sufficient for survival
-temp too high causes enzymes to denature
-overall activity will drop and may not be sufficient for survival
-temp can be measured using a thermometer
abiotic factor: light intensity
-light needed for photosynthesis therefore the higher the intensity the more the growth via photosynthesis
-the more photosynthesis the more energy for spore production so increase in population
-the more the plants grow the more respiratory substrates is available for animal populations
-light intensity also effects leafing and flowering in plants along with reproductive cycles in animals
-water rapidly absorbs light
abiotic factors: water availability and humidity
-a solvent in cells
-organisms tend to lose water via evaporation but for thermoregulation eg. sweating or mass transport
-the lower the humidity the more water loss will occur
-humidity is measured using a whirling hygrometer
abiotic factors: pH
-the more extreme the pH the more the organism is affected and the lower the population size and range is
-pH can also affect the availability of mineral salts in the soil and therefore can affect growth in plants
biotic factors: competition
- the more individuals present the grater the competition for the resources
-competition increases when resources are limited
-INTRASPECIFC= between same species
-INTERSPECIFIC= between different species
intraspecific
between same species
interspecific
betwwen different species
biotic factors: predators
-one animal species feeding on another
-evolved mechanisms to improve capturing such as high speed, venomous secretions
-prey have also evolved defence mechanisms eg. camouflage and protective spines
