Biol 3301 test 3

Population

group of interacting organisms of the same species living in the same place at the same time

What are populations bound by

geography, behavior, resources, and convenience

Population structure

features of population that characterize the population

Biotic structure

of individuals and density, age classes

Spatial structure

geographic distribution, and spatial arrangement of individuals

Geographic distribution

arrangement and size of habitats

Spatial arrangement of individuals

dispersion and spacing

Niche according to professor

what role they play in their ecosystem and how they affect the life in those ecosystems

Niches

summarized environmental factors that influence reproduction of species, growth, and survival

Hutchinsons niche

n dimensional hyper volume, which creates a huge group

N equates

number of environmental factors important to survival and reproduction of species

Limiting resources

one or few resources that establish maximum population size

Fundamental niche

hypervolume

Realized niche

includes interactions such as competition that may restrict envvironments where a species may live

Distribution limits

physical environment limits geopgraphic distribution of a species, organisms can only compensate so much for environmental variation

Geographic range (spatial structure)

measure of the total area covered by a population

Ecological range(spatial structure)

species range of conditions

Spatial structure constrained by

geographic barriers, distance, physical features, and competitions

Five important characteristics if population distributions

geographic range, abundance, density, dispersion, dispersal

Ubiquitous or cosmopolitan species

geographically widespread distribution

Endemic species

geographically restricted distribution, many endemic species have specialized habitat requirements

Density

number of individuals in an area

Abundance

actual number/biomass of organisms

Dispersion

spacing of individuals with respect to one another within the geographic range of a population

Clustered dispersion (clumped or aggregated )

patter of population dispersion in which individuals are aggregated in discrete groups

Factors of clustered dispersion

heterogenous resource distribution, abundant where found, mutual attraction between individuals, weak dispersal tendencies

Evenly spaced dispersion (regular, uniform, even)

pattern of dispersion in which each individual maintains a uniform distance between itself and its neighbors

Factors of evenly spaced dispersion

homogenous resource distribution, relatively common but likely somewhat limited, individuals avoid one another

Individuals avoid one another because

aggressive behaviors and competition, strong dispersal tendencies

Random dispersion

position of each individual is independent of the position of other individuals, it lacks patterm

Factor of random dispersion

random distribution of resources, lack of strong interactive or social forces

Random distribution of resources

resources not limiting overall, amounts vary across landscape

Lack of strong interactive or social forces

little competition or aggression, ambiguous dispersal tendencies, no mutual attraction

Range often divided by

life stages and temporal use

Migration

annual of seasonal movement of animals

Migration driven by

local climate and seasons, food availability, and variations in life cycle

Dispersal

one way movement of individuals, away from native or current habitat or existing population

Dispersal driven by

reproduction, resources, competition, changing environment (natural or man made), natural cycles

Dispersal limitation

absence of a population from suitable habitat because of barriers to dispersal

Habitat corridor

strip of favorable habitat located between two large patches of habitat that facilitates dispersal

Growth rate

number of new individuals produced in a given amount of time minus the number of individuals that die

Intrinsic growth rate

highest possible per capita growth rate for a population, not always achieved

Population doubling time

time needed for population to double in size

Reproduction

new individuals increases population growth, constant per capita rate of increase, more individuals reproducing

Immigration usually offset by emigration

Geometric growth occurs when

generations do not overlap, reproduction discrete, growth unlimited

Growth model is measured

geometrically

Nt in geometric growth model

number of individuals at the time t

N0

initial number of individuals

Lower y

geometric rate of individuals

t

number of time intervals or generations

Discrete growth

growth rate measured in discrete intervals

Geometric growth is appropriate for

discrete growth, non overlapping generations, unlimited growth

Exponential growth appropriate for populations

growing continuously, with overlapping generations, unlimited environment

Populations

exhibit growth, live in limited environment

What keeps populations in check, factors that shift balance, interactions of organisms, dynamics of resource use

Environment limits population growth by

altering birth and death rates

Regulations

control of population size with relation to population size

Density dependent factors

disease, resource competition, predation

Density dependent factors most important in

large animals, and constant environments

Density independent factors

natural disasters, environmental conditions

Regulation

control of population size with relation to population size

Density dependent

intensity influenced by density of organisms (density dependent)

Limitation

control of population size with no relation to population size (density independent)

Density independent factors

temperature, precipitation, severe storms, fires, floods, drought (influence birth and death rates but don’t regulate population growth

Environmental conditions exceed zone of tolerance it can affect

growth, age of maturity, reproduction, survival and movement

If conditions are extreme

population can go extinct

Competition

individuals use a common resource that is limited

No competition when

availability of resource is sufficient for all and does not affect survival, growth, and reproduction

Intraspecific competition

competition among individuals of the same species

As resources are depleted

population growth rate slows, eventually stops

Carrying capacity

number of individuals of a population the environment can support

Intrinsic rate of increase (biotic potential)

maximal per capita rate of increase possible in a population

Biotic potential

rarely achieved in nature, only occurs when no limits to growth exist

Instantaneous growth rate

per capita rate of increase at any time, varies based on conditions,

Logistic growth gives direct relationship between

r and population size

Density dependent also function through

growth, morphologically, activity, stress, dispersal, territoriality, and physiological

Allee effect

density dependent mechanism that reduce birthrate and survival when a population is at low density

Alle effect when there is difficulty finding a mate

pheromones carry a limited distance, pollination

Population dynamic influenced most by

density, reproduction, survival

Cohort life table

identify individuals born at same time, keeps records from birth

Static life table

record age at death of individuals, estimate number born and mortality rates

Age distribution

calculate difference in proportion of individuals in each age class, assumes differences from mortality

Age structure

relative proportion of a population in different age classes

Required to understand growth and regulation

age related birth rates, potential mortality

Populations divided into three ecologically important age classes

prereproductiove, reproductive, postreproductive

Age distribution reflects

history of survival, reproduction, and growth potential

Age structure

number of different age classes and number of individuals in each

RO is equal to 1.0

population is stable

RO is greater than 1.0

population is growing

RO is less than 1.0

population is declining