Populations In Ecosystems Flashcards
define ecosystem
all the organisms living in a community plus all the abiotic conditions in the area in which they live
define community
a group of interacting populations of different species living in the same place at the same time
define population
a group of organisms belonging to the same species found in the same area at the same time and potentially able to interbreed
define habitat
the environment in which an organism or population of organisms usually live
define biotic
the living features of an ecosystem e.g. the presence of predators or food
define abiotic
the non-living features of an ecosystem e.g. temperature and the soil
define niche
the role of a species within its habitat e.g. what it eats, when and where it feeds
explain competitive exclusion
if 2 species try to occupy the same niche, there will be competition. one species will be more successful and survive and reproduce
define adaptation and whats it caused by?
-a characteristic that members of a species have that increase their chance of survival and reproduction
-caused by random and spontaneous mutations
define natural selection
when adaptations become more common in a population increasing allele frequency
define carrying capacity
the max population size that can remain sustainable in an ecosystem
give an example on the effect of abiotic factors on plants
a plant will grow much quicker if there is a higher temperature, higher light intensity, water and space available
how might a abiotic factor of colder temp effect mammals?
-having the use a lot of energy to maintain the correct body temperature
-so less energy available for growth so slower growth
-less reproduction
-so population size will decrease
what are the 3 main types of biotic effects that can influence population?
- interspecific competition
- intraspecific competition
- predation
describe interspecific competition
-competition that occurs between different species
-can be competing to occupy the same niche
-one species will have a competitive advantage = competitive exclusion principle
(inter= think intergalactic (outside different) from beastie boys)
describe intraspecific competition
-competition between members of the same species
-causes fluctuations in population size around the carrying capacity = cyclical pattern
-as population increase, there are less resources for a larger population
-more intraspecific competition so now less food/energy for growth and reproduction
-population decreases so recourses increase
-less intraspecific competition
-more food/energy for growth and population so population increases
describe predation on population size
-predation is where a predator kills and eats its prey.
-prey and predator pop sizes are inter-linked
-the relationship between them creates a selection pressure
-means those members of the species that are better adapted to hide or escape from predators are more likely to survive and reproduce
why will predators never have higher population than prey?
biomass is lost so less energy to grow and reproduce
what’s the advantage in knowing cyclical predation patterns?
carry out research at a more advantaged time when populations are higher
why do we use logs?
-compare values with a very large range
-diff to plot on y axis
-to find the original value
-values in order of magnitude not numbers
what does the log10 number tell you?
how many times 10 has been multiplied by itself to give that value
factors 2 effecting bacteria growth
food and space available
whats a broth culture?
a liquid broth containing bacteria
whats a liquid broth?
a liquid containing nutrients a bacteria needs to grow
how can we messure how much bacteria is present in a broth
-colorimeter to meassure light that can pass through.
scattered because bacteria is present
the more bacteria present, the more light is absorbed so higher absorbance value (less light transmitted)
what type of graph is an absorbance against time?
exponential
-it shows the bacteria doubling at certain intervals of time
define abundance
the number of individuals of one species in a particular area
2 ways abundance can be measured
frequency- number of samples a species is recorded in
percentage cover- how much of the area is covered
define distribution
how a species is spread across a habitat
describe how to carry out random sampling
1.randomlu place quadrats using coordinates from a random number generator
2.count the total number in many quadrats
3. multiply to give estimate for total area
give advantages of random sampling
-larger sample more representative
-random so prevents any bias
-saves time
whats a quadrat?
frame made of small dividing sqaures in a larger square
investigates slow moving/non-motile
what 3 things can quadrats messure?
1.species frequency = counting. shows likelihood of the species occuring
3. number of individuals = time-consuming.
4. percentage cover = count number of squares covered, include if more than half square covered. calculate a percentage
what are the 2 types of transects?
- belt transect = quadrats are placed next to each other along the line. can calculate species frequency and percentage cover
- interrupted belt transects = place quadrats at regular intervals along the line
give 4 examples for methods of investigating motile populations
-sweeping nets
-pooters/fall traps
-baited traps
-tranquilizers
equation for total population size
(Number in 1st sample x number in 2nd sample)
divide
number marked in 2nd sample
examples of making non-toxic
-non-toxic paint
-using tags
-cut thier hair
-dna samples
principles of mark-release-recapture
- marked sample needs enough time to mix with the non-marked population
2.the marking not affected chance of survival - no population size changes dues to births, deaths and migration
give 2 ethical issues in mark-release-recapture
1.organism could be stressed after being captured so could lead to a reduce in chance of survival
2. some organisms may be more likely to enter a trap again if previously caught
