Studied by 4 people
adaptation
process where, over time, characteristics (trait) that lead to better reproductive success become more prevalent in the population
adaptive trait
a trait that provides reproductive success
mutations
accidental changes in DNA that may be passed on to the next population
directional selection
drives a feature in one direction
convergent evolution
unrelated species may acquire similar traits because they live in similar environments (related species may acquire similar traits bc they live in similar environments)
artificial selection
the process of selection conducted under human direction (ex: dog breeds and food crops)
allopatric speciation
"geographic isolation" - species formation due to physical separation of populations (by glaciers, rivers, mountains) each population gets its own set of mutations
phylogenetic trees
diagrams that show relationships among species, groups, genes etc (scientists can trace how certain traits evolved, see how many times trait evolved and were passed on)
cladistics (clades)
means of classification using derived characteristics (shows when a particular major event occurred) (taxonomy)
derived character
trait which evolves overtime in which each next generation will have
fossil
an imprint in stone of a dead organism
fossil record
the cumulative body of fossils worldwide (shows life existed on earth for at least 3.5 bill years, earlier organisms evolved into later ones)
speciation-extinction
endemic species
a species that only exists in a certain, specialized area- very susceptible to extinction, small populations, island species
population ecology
investigates the dynamics of population change (affecting the distribution and abundance
community ecology
focuses on patterns of species diversity and interactions
ecosystem ecology
studies living and nonliving components of systems to reveal patterns
habitat
the environment where an organism lives (living + nonliving elements)
habitat use
each organism thrives in certain habitats, but not others (nonrandom use)
habitat selection
process by which organisms actively select habitats in which to live (availability + quality are crucial to an organism's well being)
vary with body size
population size
number of individuals present at a given time -grow when resources are abundant and predators are few
population density
the number of individuals in a population per unit area
high population density
areas where its easier to find mate, increased competition, vulnerability to extinction, increased transmission of disease
low population density
access to plentiful resources and space, make it harder to find mates
population distribution (dispersion)
spatial arrangement of organisms
random dispersion
haphazardly located individuals, with no pattern (ex: trees separating populations)
uniform dispersion
individuals are evenly spread (territoriality, competition) (ex: penguins at a territory)
clumped dispersion
organisms found close to other members of population (most common in nature, clustering around organisms, mutual defense) (ex: schools of tuna or fish)
sex ratio
proportion of males to females
monogamous species
1 to 1 sex ratio maximizes population growth, one partner
age distribution (structure)
the relative number of organisms of each age in a population
survivor ship curve
graphs that show the likelihood of death varying with age
type 1 survivor ship curve
higher death rate at older ages, larger animals like humans
type 2 survivor ship curve
same death rate at all ages, medium sized animals like birds
type 3 survivor ship curve
higher death rate at young ages, small animals, plants, insects and amphibians (fish can be 2 or 3 depending on species)
natality
births within the population
mortality
deaths within the population
immigration
arrival of individuals from outside the population
emigration
departure of individuals from the population
crude birth/death rates
natural rate of population increase
(crude birth rate) - (crude death rate)
population growth rate
(crude birth rate + immigration rate) - (crude death rate + emigration rate)
growth rate as a percent
population growth rate x 100%
exponential growth
when a population increases by a fixed percent (J-shaped curve) -occurs w small populations, low competition, introduced species, can't be sustained indefinitely
limiting factors
physical, chemical, and biological attributes of the environment that restrain population growth ex) space, food, water, mates, shelter, suitable breeding sites, temp, disease
carrying capacity
the maximum population size of a species that its environment can sustain (limiting factors slow and stop exponential growth: S-Shaped curve)
density-dependent factors
limiting factors whose influence is affected by population density -increased density increases risk of predation, disease, and competition results in logistic growth curve
logistic growth curve
larger populations have strong effects
biotic potential
an organisms capacity to produce offspring
K-selected species
species with long pregnancy periods, few offspring, and strong parental care -low biotic potential, most mammals; stabilizes at/near carrying capacity
R-selected species
species that reproduce quickly and offer little or no care for offspring -high biotic potential, population fluctuate greatly, insects, amphibians ex) turtles laying eggs and leaving them at the beach, tuna/salmon leaving eggs
ecotourism
the phenomenon of people visiting the islands to experience the natural areas -climate change altering how we protects species and habitats
infant mortality rate
the death rate in children -has dropped dramatically
Thomas Malthus - An essay on the principles of population (1798)
philosophist that believed humans will outstrip food supplies, have war, disease, starvation
IPAT model
model that links sustainability
IPAT model - (P)
population, individuals need space and resources
IPAT model - (A)
affluence, greater per capita resource use
IPAT model - (T)
technology, increased exploitation of resources, but also pollution controls and renewable energy
IPAT model - (S)
sensitivity, how sensitive an area is to human pressure (arid land vs rainforest)
demography
the application of population ecology to the study of change in human populations
what do demographers study?
population size, density, distribution, age structure, sex ratio, birth, death, immigration and emigration
age structure
describes the relative numbers in each age class within a population
total fertility rate (TFR)
the average number of children born to each female -has been decreasing due to industrialization, improved women's rights, quality health care, contraceptives
replacement fertility
the TFR that keeps the size of a population stable (about 2.1)
natural rate of population change
change due to birth and death rate alone (no migration)
life expectancy
average number of years that an individual is likely to continue to live
demographic transition
a model of economic and cultural change - 4 stages
preindustrial stage
in these societies, birth and death rates were both high
transitional stage
declining death rates due to increased food production and medical care (birth rates remain high)
industrial change
birth rates dell as jobs provided opportunities for women outside the home and children are not needed in the workforce (pop growth slows)
post-industrial stage
birth and death rates are low and stable (stabilizes or shrinks)
family planning
efforts to control the number and spacing for children, the greatest single factor slowing population growth
birth control
effort to control the number of children born by reducing the frequency of pregnancy
contraception
deliberate prevention of pregnancy through a variety of methods
reproductive window
time frame where a woman can become pregnant
biocapacity
the amount of biologically productive land and sea available to us
ecological deficit
ecological footprint > biocapacity
ecological reserve
ecological footprint < biocapacity
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Flashcard (37)