Unit 3 APES

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

# of species in existence

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

# of births/deaths per 1000 individuals per year

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