Chapter 19 - Populations in ecosystems Flashcards
what is ecology
studying the inter relationships between organisms and their environment
what are abiotic factors
non living
what are biotic factors
living
what are the two major processes to consider in an ecosystem
the flow of energy
the recycling of elements
what is a population
a group of individuals go one species that occupy the same habitat and have the potential to interbreed
what is carrying capacity
the size of a population an ecosystem can support
what is a community
different populations living and interacting in the same area at the same time
what is a habitat
the place where an organism usually lives
what are microhabitats
smaller units within a larger habitat each with its own microclimate
what is a niche
how an organism fits into its environment
what are adaptations
features that increase the chances of a species surviving and reproducing
what is population size
the number of individuals in a population
give two reasons why a population may fluctuate
the effect of abiotic factors
interaction between organisms
in what instance is it useful to use a logarithmic scale
where the population grows rapidly over a short period of time
how does a logarithmic scale differ from a normal one
log (population) is plotted rather than the population itself
give three reasons why a population may start to level out
consuming and using up mineral ions
winter brings lower temperature and levels of light intensity
bacteria collect at the surface and prevent light reaching those at the bottom
what are the 4 abiotic factors that influence the size of a population
temperature
ph
light intensity
water and humidity
how does temperature influence population size
enzymes to low means theres less kinetic energy for successful collisions and too high denatures the enzyme
warm blooded organisms have to expend energy in maintaining their temp levels
how does light influences population size
photosynthesis - more light means more photosynthesis
this increases their carrying capacity so more aninals can survive
how does water/humidity impact population size
too dry means that more evaporation occurs so there is no growth or food produced ]
too wet means that special adaptations are required to survive and so diversity is reduced
what are the two types of competition
interspecific and intraspecific
what is infraspecific
individuals of the same species competing for resources
how does intrapspeicfic competition impact a population
the availability of resources determines the carrying capacity and so population size
what is interspeicifc competition
individuals of different species competing for resources
how does interspecific competition impact a population
because the two species are occupying the same niche, one will have a competitive advantage over the other. this population will grow whilst the other will shrink and finally disappear
what is the competitive exclusion principle
where there are two species occupying the same niche, one will normally have a competitive advantage
the population of this species will grow and the population of the other will diminish
conditions remain the same leading to the removal of one species
when are you explaining how a factor influences population size what is it important to link your explanation to
the birth/death rate
what is predation
one organism consuming another
why is data gathered on predation in a lab generally not representative
the prey is usually exterminated by predators
this is because the size and type of habitat available is much less varied and smaller than in nature
there are also many more refuges in nature so although the prey population may fall to a low level, it rarely becomes extinct
what effect do predators and prey have upon eachothr
predators eat prey , reducing the prey population
the predators are in greater competition with each other for the prey that remains
the predator population then falls as there isn’t enough food to support a larger population
fewer prey are eaten and so reproduce to rebuild their population
the predator population increases as there is more food sources
why is the graph showing predator prey cycles normally exaggerated
in natural ecosystems predators normally eat a range of prey rather than just one species
What other factors can influence a population
disease and climate
why is the cyclical relationship of predators and prey important
the crashes in populations are important in evolution as they create selection pressures and only those adapted to the conditions can survive
what is abundance
the number of individuals in a specific area
what are the two types of sampling we use
random and systematic
what are the two types of quadrat
a point quadrat and a frame quadrat
what is a point quadrat
a horizontal bar supported by two legs. there are hokes along the length of the bar through which a pin is place. the species touching the pin is then recorded
what is a frame quadrat
a square frame divided into equal subdivisions
what are the three factors to consider when using quadrats
the size of the quadrat to use
the number of quadrat samples to conduct
the position of each quadrat in the study area
why is it important to consider the size of quadrats used
the size must be appropriate to the size of the area being studied
to get a representative sample, it is normally better to use a larger number of smaller quadrats
why is it important to consider the number of quadrats used
the greater the number of quadrats used the more reliable and representative your results will be. however this is a time consuming process
why is it important to consider the positioning of each quadrat
random sampling must be used to avoid bias and make your results reliable
how do you conduct a random sample of an area
lay two long tape measures at right angles to each other
use a random number generator to generate your coordinates
place to quadrat at the intersection of these coordinates and record the species inside it
how do you conduct systematic sampling of an area
lay out a long piece of strong across the area you wish too study
lay down a frame quadrat at the beginning of the strong
record the species inside the quadrat
move the quadrat its own distance down the string and repeat the process
what is abundance
the number of a species in a given area
what are the two common measures of abundance we use
frequency and percentage cover
when is percentage cover useful
when a species is particularly abundant or difficult to count. this is because the species don’t need to be counted individually and can be conducted fairly quickly
what is percentage cover
an estimate of the area within a quadrat that a particular species occupies
what is frequency
the likelihood of a. species appearing in a quadrat
when is frequency useful
it is quick and gives information about the general area of a species particularly when it is difficult to count
when is calculating frequency not useful
it doesn’t provide information on the density of a species or its positioning
when are transects and quadrats not useful
for mobile animals
what method is used to calculate the abundance of aniamsl
mark
release
recapture
what is the equation for mark release recapture
population size = total no of individuals in 1st sample x total no in the 2nd sample / no of marked individuals recaptured
what are the size assumptions made for mark release recapture
- mark is not rubbed off
- few deaths and births within the pop
- method or marking isn’t toxic or marks animal more susceptible to predators
- no emigration or immigration
- the mark individuals have sufficient time to redistribute themselves throughout the population
- the proportion of marked- unmarked individuals in the second sample is the same as the proportion of marked : unmarked in the total population
what is conservation
managing the earths natural soreuces by humans in such a way that maximum use of them can be made in the future
what does conservation aim to preserve
ecosystem and biodiversity
what are the four main reasons for conservation
personal ethical economic and cultural aesthetic
why do we conserve the plant for personal reasons
we are supporting out life system
why do we conserve the plant for economic reasons
the organism we conserve have a huge pool of genes which enable the plants to make many of th eusbstances we use and profit form all the time
why do we conserve the planet for ethical reasons
we should respect the living organisms that have been on earth longer than us
why do we conserve the planet for cultural reasons
the variety of organisms that have been on earth longer than us
why might a pioneer species not feature in a climax community
their habitats have disappeared because of succession or the have been out competed
how do we conserve the planet by managing succession
we put factors in place to prevent further succession and so removal of habitats
what is succession
the changes that occur to a particular ecosystem over time
what is primary succession
occurs on land that has just been formed or exposed- there is no soil or organic material to start with
what is seoncdary succession
occurs on land that has been cleared by humans but soil and organic material remains
which type of succession is faster and why
secondary succession there is already some existing organic matter and soil so different species can be supported
what is important to remember when considering succession
competition
what is a pioneer species
a species that is adapted to living in extreme conditions and cans tart to colonise an area
what are some of the adaptations that a pioneer species might have
asxueal reproduction
rapid germination of seeds
tolerance of extreme conditions
ability to photosynthesis and grow own food
describe succession
- pioneer species- the first species to colonise an area have adaptations to withstand extreme conditions
- pioneer species penetrates and breaks up the rock, as the species dies and decomposes a layer of humus builds up allowing simple plants to grow
- these plants cast shade, preventing the pioneer species from growing. they have longer roots and so can break up men more rock. as they die the amount of nutrients and water in the soil increases so more complex plants can be supported
- larger plants grow so animals can inhabit them. this changes the soil and light conditions , linking the smaller plants
- a climax community Is reached and dominant plant species colonise an area
what is the most common climax in the uk
oak woodland
how to calculate the mean density
total no of individuals counted / total no of quadrats x area of one quadrat
what are the two factors that impact the succession of animals
habitats and food sources
how does succession in animals occur
over time, more complex animals can be supported by organic matter
this means that there are more food sources and larger animals come to the area
what five features emerge during succession
the abiotic environment becomes less hostile more habitats and niches increased biodiversity more complex food webs increased biomass
