population and community ecology Flashcards
what is a population?
groups of individuals of the same species that inhibit a shared environment
since populations are dynamic, what makes them fluctuate?
-seasonal/yearly changes
-natural diasters
-competition for resources
-disease
what factors affect the size of a population?
-increases are due to births and immigration
-population decreases as a result of death and emigration
what is demography?
-statistical study of population dynamics and how populations respond to abiotic and biotic changes
what are the metrics of demography?
-population size which is the number of individuals
-population density which is the number of individuals in a specific area or volume
what is damuth’s law?
-There is an inverse relationship between body size and population density
-the bigger the species, the fewer number of individuals cohabitate a given area.
what are the methods used to determine population sizes?
-count
-quadrant
-mark and capture
What is the quadrant method of population determination?
looking at a sample population in a defined area and extrapolate
what is the mark and capture method?
involves catching-marking-releasing and recapturing of animals
-the ratio of marked to unmarked can determine population size
what is the equation of mark and recapture method?
(# marked on first catch)X(total # captured in second catch)/(# caught that were marked in second chance)
what are the types of spacing and dispersion patterns?
-uniform, which is common in plants that secrete toxins and animals with territory requirements
-random, which is common in plants with wind blown seeds
-clumped, which is common in plants where seed falls to ground, animals that form herds/groups
what is the type I of survivorship curve?
high percentage of offspring live in early years and middle years and die in old age
-usually organisms with low numbers of offspring and strong parental care
what is the type II of survivorship curve?
organisms that die equally at each age
what is the type III of survivorship curve?
few organisms survive younger age, but those that do make it to old age survive for a relatively long time
what is exponential growth of population?
growth with unlimited natural resources and populations grow rapidly
what is the logistic growth of population?
organisms will compete with members of their own species and members of other species until a carrying capacity is reached
what is a carrying capacity?
the maximum population size a particular environment can sustain
good for starting point
why is the human population growing exponentially?
because humans can alter the environment and thus the carrying capacity
what is the ecological footprint?
land and water area required to produce what is needed by each person per country
what is community ecology?
study of all populations occupying the same habitat at the same time and their interactions
what is the competitive exclusion principle?
two species cannot occupy the same niche and different species cannot coexist in the same community if they compete for same resources
what is an ecological niche?
a specific set of abiotic and biotic resources an organism uses in its environment
what is resource partitioning?
similar species can occupy the same niche if natural selection results in one species using a different or similar resources
how can a species niche be influenced by interspecies competition?
a species realized niche is much smaller than its fundamental niche because of the competition between species
what are the negative type of interactions in a community?
-predation where predator kills and eats prey
-herbivory where herbivore eats part of a plant
-parasitism where parasite derives nourishment from host
what are the types of prey defense adaption?
-mechanical defense
-chemical defense
-aposematic coloration
-cryptic coloration
-batesian mimicry
-mullerian mimicry
what are the types of plant defense adaption?
-chemical toxins
-thorns and spines
-bad taste (cloves, cinnamon, peppermint)
what are the types of positive interactions in a community?
-mutualism which benefits both species
-commensalism where one species benefits and other does not
what are some characteristics of communities?
-they are complex and characterized by the types and number of species and the dynamics of how it changes
what are foundation species?
base or bedrock species of a community that influences the overall community structure
what are the keystone species of a community?
a species whose presence is key to maintaining biodiversity within a ecosystem that are necessary
what are the invasive species of a community?
a non-native organism that is introduced to an area out of natural range and threatens balance of natural habitat
