Chapter 11: population distributions Flashcards
Fundamental niche
range of abiotic conditions under which species can persist
- Range of temp, humidity, salinity conditions that allow population for survive, grow, and reproduce
Realized niche
range of abiotic and biotic conditions under which a species persists
Geographic range
measure of the total area covered by population
- Climate, topography, soils, vegetative structure
ecological niche modeling
process of determining the suitable habitat conditions for a species
ecological envelope
range of ecological conditions that are predicted to be suitable for a species
- prediction of where a species could potentially live
- global warming impacts suitable habitats
5 important characteristics for population distributions:
geographic range, abundance, density, dispersion, and dispersal
Geographic range
all areas its members occupy during their life
- how large an area a population occupies
endemic species
species that live in 1 isolated location
- if restricted to specific area, population is susceptible to extinction by natural disaster
cosmopolitan
species w/ very large geographic ranges that can span several continents
abundance
total number of individuals in a population that exist w/in a defined area
- measure of whether a population is thriving or on brink of extinction
density
number of individuals (in 1 population) in a quantified area or volume
- density = (abundance) / (area)
- how many individuals packed into specific location
if density is greater than what habitat can support, individuals will have to ____
leave area or population will experience less growth and survival
dispersion
describes the spacing of individuals w/ respect to one another w/in geographic range of a population
3 different types of dispersion
clustered (aggregated/clumped), evenly space (uniformly), random
Dispersal
mvmt of individuals from 1 area to another to colonize areas outside of their geographical range
- w/ good conditions, can be a method for speciation
- To avoid competition or high predation
- NOT migration; dispersal = Do NOT return
Census
count of every individual in a population
Survey
counting a subset of the population
- Representative of population
Area-and-volume-based surveys
surveys define the boundaries of an area or volume and then count all the individuals in the space
- size = rated to abundance and density of population
- can estimate total population size
Line-transect surveys
surveys count the number of individuals observed as one moves along a set line (randomization and replication)
- sample survey technique
Mark-recapture surveys
researchers capture and mark a subset of a population from an area, return it to the area, and then capture a second sample population after time has passed
- sample survey technique
Lifetime dispersal distance
avg distance an individuals moves from where it was hatched/born to where it reproduces
Population abundance vs geographic range:
Populations w/ high abundance = large geographic range
Population density vs adult body size:
Density of a population is negatively correlated w/ body size
- Smaller individuals live in highest densities, larger individuals live in lowest densities
Dispersal limitation
absence of a population from suitable habitat because of barriers to dispersal
- common barriers: physical barriers, ice, climate, altitude, food, water, competition
- Humans can assist animals/plants in overcoming limitations
Habitat corridors
strip of favorable habitat located b/w 2 large patches of habitat that facilitates dispersal
Ideal free distribution
individuals distribute themselves among different habitats in a way that allows them to have the same per capita benefit
- How individuals should distribute themselves among habitats of differing quality
Subpopulations
larger population is broken up into smaller groups that live in isolated patches
Basic metapopulation model
model describes a scenario in which there are patches of suitable habitat embedded w/in a matrix of unsuitable habitat
Source-sink metapopulation model
population model that builds on basic metapopulation model; accounts of the fact that not all patches of suitable habitat are of equal quality
Source subpopulations
in high-quality habitats, subpopulations that serve as a source of dispersers w/in a metapopulation
Sink subpopulations
in low-quality habitats, subpopulations that rely on outside dispersers to maintain the subpopulation within a metapopulation
Landscape metapopulation model
population model that considers both differences in the quality of the suitable patches and the quality of the surrounding matrix
Density-dependent population
density is a factor
- maximum carrying capacity for population
Density-dependent population
density is a factor
- maximum carrying capacity for population is a factor
Density-independent population
density is not a factor
- maximum carrying capacity is not a factor
- abiotic and biotic factors limit density
3 major types of spatial distribution
aggregated, uniform, random
Aggregated spatial distribution
members of population live in groups; family or social grouping
- Many eyes to lookout for predation
- Resources are localized (water holes, etc.)
Uniformly spatial distribution
maintain relatively constant distance b/w individuals
- Defending resources, breeding sites, nutrients/water
- Animals defend their territories
- Some plants and animals have chemical markers for spacing
Random spatial distribution
individuals do not form social groups; resources are equally spaced and abundant
- Less common
- Not helpful for breeding; some are random for most of the year and come together for mating
isolation
restrict gene flow, allow for speciation
- isolation = speciation depends on: distance factors, time factor, area factor, habitat factor, the flow factor, chance/random events
Key processes in ecosystem change
dispersal, drift, selection, speciation
- Ideal way to categorize ecological data
spatial structure
pattern of density and spacing of individuals in a population
most introduced species are…
not invasive and likely won’t survive
- if they do survive, they are invasive species
Clustered dispersion
pattern of dispersion in which individuals are aggregated in discrete groups (ex: social groups or around resources)
Evenly spaced dispersion (uniformly)
pattern of dispersion in which each individual maintains a uniform distance b/w itself and its neighbors
Random dispersion
pattern of dispersion in which the position of each individual is independent of the position of other individuals in the population
vicariance
splitting range; extinction of middle population
ultimate cause of dispersal
avoidance of inbreeding and inbreeding depression over time
costs of dispersal
- greater risk of death due to increased energy expenditure, unfamiliar habitat, or predation risk
- reduced survival or reproductive success bc if of unfamiliarity with new environments
costs of dispersal
- greater risk of death due to increased energy expenditure, unfamiliar habitat, or predation risk
- reduced survival or reproductive success bc if of unfamiliarity with new environments
active dispersal
mvmnt of organism from 1 location to another on its own (by its own means)
passive dispersal
mvmnt of organism from 1 location to another by means of a stronger force
- ex: water flow, wind, other organism, etc.
equation to estimate total population size w/ mark-recapture survey
N = (M x C) / R
- N = population size
- M = initially captured individuals
- R = marked recaptured individuals
quantifying dispersal
technique to measure how far individuals travel from 1 source location
- can determine life-time dispersal difference
3 types of dispersal barriers
- physiological
- ecological
- behavioral
common physiological barriers
- physical environments outside of organisms tolerance range
land-water, salinity, temperature
common ecological barriers
- predation, mating, competition
dispersal routes
corridors (most things through), filters (some things and not others), sweepstake route (few cross, but success for those that do)
