weeks 8-10 Flashcards
(28 cards)
population
all the individuals of a given species that live ^ reproduce in a particular place
3 key features of a population
size, range, density
population size
the number of individuals of all ages alive at a particular time in a particular place
geographic range
the area over which that population is spread
-reflects in part the range of climates a population can tolerate & determines how many other species the population encounters
population density
population’s size divided by its range
-how crowded or dispersed the individuals are that make up the population
mark & recapture
a method in which individuals are captured, marked in a way that doesn’t affect their function or behavior, and then released. the percentage of marked individuals recaptured later enables ecologists to estimate population size.
what is population size affected by
birth, death, immigration, and emigration
per capita growth rate
the rate of population growth per individual; it equals the change in population size in a given period of time, divided by the size of the population (N).
-average number of offspring per individual
continuous growth
population increases or decreases continuously
-assumes there are no constraints on population size & the growth rate is constant
exponential growth
occurs when the growth rate is constant, meaning the population grows in proportion to the number of individuals
- J shape
-typical of small populations when resources are abundant
intrinsic rate of increase
the per capita growth rate; the maximum rate of growth when no environmental factors limit population increase
discrete growth
the population size increases or decreases in one discrete step at the beginning of each generation
- typical of organisms that breed seasonally or annually
geometric growth
when the growth rate is constant and the population increases or decreases in steps (discretely)
carrying capacity (K)
the maximum number of individuals a habitat can sustain without degrading the environment
logistic growth
the pattern of population growth that results as growth potential slows down as the population size approaches K, its maximum sustainable size
density-dependent factors
describes processes affecting populations that are influenced by the number of individual organisms, such as the use of resources or susceptibility to predation or parasitism
density-independent factors
influence population size without regard for the population’s density
carbon cycle
the intricately linked network of biological and physical processes that shuttles carbon among rocks, soil, oceans, air, and organisms
-traces the transfer of energy through ecosystems
-focuses on the ways that physical & biological processes together determine the properties of ecosystems
how is carbon dioxide added to the atmosphere
(1) geologic inputs (volcanoes & mid-ocean ridges) (2) biological inputs, especially respiration (3) human activities, including deforestation and the burning of fossil fuels
how is carbon dioxide removed from the atmosphere
(1) geologic removal, especially by chemical weathering (2) biological removal (photosynthesis)
what are 2 key processes in short-term carbon cycle
photosynthesis and respiration
ecology
the study of how organisms interact with each other & with their physical environment
short-term carbon cycle
exchanges over days, years and decades driven by the biological processes of photosynthesis and respiration & altered in recent times by human activities
long-term carbon cycle
links Earth’s physical & biological processes
-considers physical processes’ contributions to the carbon cycle, including volcanism & climate change
