Lec 14- Populations Flashcards
population
individuals of same species that co-occur in space and time
patterns and processes (4)
disease ecology: spread and changes
invasion: spread of new species (invasive)
conservation biology: extinction risk in species (most important)
restoration: intro of species
density
of individuals per unit area
distribution
size, shape, location of area occupied
absolute density
number of individuals of population per unit area (# moose per hectare)
ecological density
of individuals of population per unit area of suitable habitat (# moose per hectare forest) (specific habitat)
dispersal
permanent movement of individuals (propagules) from one population to another
- alter species distributions and local population densities
migration
seasonal movement of individuals from one location to another
seed dispersal modes (6)
gravity
ballistic
wind
water
animals
humans
gravity dispersal
large seed size
short dispersal distances
ballistic dispersal
explosive dispersal
short dispersal distances
wind dispersal
seeds with appendages
short to long dispersal distances
water dispersal
seeds with floating
capabilities short to long dispersal distances
animals dispersal
ingestion or defecation or hooks
short to long distances
humans dispersal
breeding and transportation
short to long distances
dispersal (2)
immigration: movement into a local population
emigration: movement out of a local population
does density change in response to food supply?
yes
functional response
increase and decrease in feeding rate (short-term response)
numerical response
change in density of predator populations in response to changes in prey density
what are the 2 drivers of numerical responses?
reproduction
dispersal (aggregative response)
reproduction
time lag b/w peak prey population and peak predator population
- non-synchronized dynamics b/w predator and prey
- lag due to time needed for predators to produce offspring
- wolves
dispersal (aggregative response)
no time lag b/w peak prey population and peak predator population
- synchronized predator and prey dynamics
- no time lag as species are highly mobile and can track prey across landscape
- birds of prey
voles vs kestrels/owls
if responses were structured by repro then there would be a lag
- driven by dispersal so no lag
distribution
- geographic distribution of species as limited by physical enviro and species niche requirements
- species can only exist in areas where niche requirements are fulfilled
smaller scale distribution
individuals of pop are distributed in random, reg or clumped
- result of abiotic or biotic environment
random distribution
individuals have equal chance of living anywhere within area
- neutral interaction b/w individuals and b/w individuals and local environment
- uniform distribution of resources
regular/even
individuals are uniformly spaces
- antagonistic interactions b/w individuals or local depletion of resources
- uniform distribution of resources
clumped
individuals have higher probability of being in some areas vs others
- attraction b/w individuals or to a common resource; limited dispersal
- positive interactions (attraction)
- patchy resources
larger scales
area over which there is substantial environmental change
- clumped species
- the broader the niche. the wider a species large-scale distributions usually is
- hotspots
- American and Fish crow
why aren’t all species in all places?
- limited energy and resources
- takes extra energy to survive/reproduce in regions at edge of niche
how does climate shape species distribution?
E vs W grey kangaroo vs red kangaroo
eastern grey kangaroo
habitat niche encompasses tropical forests
western grey kangaroo
temperate woodland and shrubland type (most rain in winter)
red kangaroo
savanna and desert species adapted to hot, dry, arid and semi-arid conditions
range expansion in response to climate change
maple trees disperse faster and colonized larger area due to broader climate niche
range expansion in invasive species
Africanized honeybee
- hybrid
- aggressive
- efficient foragers
- create larger colonies b/c excess food
- form massive swarms
dispersal of expanding population (honeybees)
no populations of bc of dispersal lag or unfavorable climate
- too cold for now (climate change)
dispersal lag
phenomenon where species has not had enough time to colonize area (will occur eventually)
range expansion in pest species
mountain pine beetle
- lay eggs under bark
- introduce blue-stain fungi
- larval feeding and fungal infection stop water and nutrient flow
- dispersal will allow species ranges to move along with climate but only if climate slows enough for them to keep up
mountain pine beetle dispersal
spreading to AB
- northern limit of beetle: cold winter temp and cool summers
- recent outbreaks linked to favorable weather in both summer and winter
- warm + dry summer = good for development and dispersal and drought stress reduces tree defenses
metapopulations
made up of group of subpopulations living in patches of habitat connected by exchange of individuals
- exist when individuals can disperse from one pop to another
- no dispersal b/w populations then not a metapopulation
rocky mountain parnassian butterfly
very specific set of niche requirements distributed as patches
- patches appear to form metapopulation
mark and recapture survey:
- pop size correlated with meadow size
- individuals immigrating from smaller population and moving into larger ones
- global warming could lead to forest encroachment and shrink habitat
- pop will likely decline
