apes unit 3 (populations)

ecological succession

the process by which the mix of species and habitat in an area over time

primary succession

ecosystem starting from nothing, very beginnings or new land is cleared (causes: glaciers melting, lava cools and creates new rock, pioneer species include: lichen, moss which provide organic matter for soil when they die)

secondary succession

ecosystem starting/coming back from a disturbance with some foundation, first stages meaning there is still nutrient rich soil (causes: landslides, fire, flooding, windstorm, pioneer species include: shrubs, grasses which provide oragnic matter for the soil)

climax communities

the final stage of succession before the community is disturbed and secondary succession is triggered

mass extinction

when a large population dies off in a short amount of time

natural selection

primarily influenced by survival and reproductive success of individuals with advantageous traits

population size

total amount of individuals within a given area in a defined time

population density

number of individuals per unit area at a given time

population distribution

how individuals are distributed with respect to one another

random distribution

random clumps of a species scattered

uniform distribution

orderly distribution of species scattered

clumped distribution

species gathering in clumps

population sex-ratio

the ratio of males to females

population age structure

how many individuals fit into particular age categories

K-selected species

species that grow slowly until they reach carrying capacity

r-selected species

populations of species that grow actively and are often followed by overshoots and die offs

intrinsic growth rate

under ideal conditions, with unlimited resources, the maximum potential for growth

density dependent facotrs

depend on size of the population to influence the individuals probability of survival

density independent factors

size of the population has no effect on an individuals probability of survival

metapopulations

a group of spatially distinct individuals connected by occasional movements of individuals between them

type I

(late loss) mortality is very low until old age, usually associated with K-selected species

type II

(constant loss) no one age is more susceptible to mortality than another (random species like birds or squirrels)

type III

(early loss) mortality is very high for early stages followed by low death rate for those who reach adulthood, usually associated with r-selected species

habitat corridors

strips of natural habitat that connect the separated populations

growth rate

(crude birth rate - crude death rate)/10

percent change

(new - old)/old * 100

doubling time

70/growth rate as a %

population

(birth + immigration) - (death + emigration)

child mortality rate

the probability of death between birth and five years old (per 1,000 live births)

infant mortality rate

number of deaths under one year of age

higher rates if mortality…

are seen where there is limited access to clan water, poor nutrition and weak immune systems

total fertility rate

number of kids a wiman has during her reproductive years

replacement level fertility

number of kids a couple must have to replac e themselves (about 2.1 globally)

phase one

birth rate is high to compensate for high infant mortality rate. less developed countries are in this stage. women have many children and many do not survive to adulthood

phase two

access to food and improved healthcare lowers death rate

phase three

death rate drops due tp improved medicine and modernization. most developed countries are in this stage

phase four

birth rate drops to equal zero population growth

phase 5

birth rate falls below death rate and population decreases