Andrew Flashcards
population
a group of individuals of the same species living and interacting in a particular geographic area
population ecology…
examines factors that LIMIT and REGULATE population size and composition
community
all the individuals of all species that inhabit a geographic area
community ecology…
examines the INTERACTIONS AMONG POPULATIONS and sees how factors such as predation, disease and environmental factors affect COMMUNITY STRUCTURE and ORGANISATION
6 key processes that drive distribution and abundance
- Births
- Deaths
- Immigration
- Emigration
- Colonisation
- Extinction
unitary organisms
- easy to recognise genetically separate individuals
- their form is determined from birth/determinate
modular organisms
- genetic individual (genet) starts life as a single zygote
- growth occurs by the repeated production of modules
- growth is intermediate
- structure and programme of development is not predictable
- individual genet is not dead until all modules are dead
2 key reproductive patterns
- Semelparity
2. Iteroparitary
Semelparity
- big bang reproduction
- large numbers of offspring are produced in on life event, then the organism dies
Iteroparitary
- produce several offspring during repeated reproductive episodes
generation time =
average time between birth of the individuals and the birth of their offspring - age at which members of the cohort are expected to reproduce
generation time equation
XIxMx/R0
XIxMx = sum of age ‘weighted’ reproduction
R0 (Ix*Mx)= average number of offspring produced
Px
survivorship of age x females to age x+1
birth pulse
Px*Mx+1
pre-breeding
Fx = P0*Mx
P0= those surviving to age 1
Mx = making babies now
everyone counted just before next baby making time
every baby that survives to 1 is counted - no newborns
population growth can be increased by:
- increased reproduction
- increased survival
- decreased generation time
exponential
describes an idealised population in an unlimited environment
exponential population growth
- no limit on available energy resources
- no restriction on growth or reproduction
- a population of a few individuals
- in an environment with no limiting factors
notation
dN/dt = bN - dN dN/dt = change in population/ per change in time bN = per capita birth rate times population size (N) dN = per capita death rate times population size (N)
R =
the intrinsic rate of increase
K =
carrying capacity - energy/resource limitation is the most common determinate of K; k= equilibrium where births = deaths
3 rules of population limitation
rule 1 - the carrying capacity of a habitat is the maximum stable population size that can be supported over a long period of time
rule 2 - as density increases, per capita resource declines
rule 3 - as density increases and capita resource declines, births decrease and deaths increase
competitive exclusion principle -Gause
- no 2 species can share the same resource
- no 2 species can occupy the same niche
- 2 species cannot coexist when they identical needs of the same limiting resource
exploitation
depleting resources
pre-emptive
using space (deleting space)
overgrowth
species growing over another and depriving the other of light
chemical
production of toxins
territorial
behaviour of fighting in defence of space
encounter
transient (short term) interactions directly over a specific resource
importance of predation:
ecology - structure and dynamics of communities
evolution - morphology, physiology, behaviour
agriculture - pest control
conservation - predator controls vs reintroductions
biodiversity- richness, evenness, diversity, gradients
tangent
maximises the ratio between resource intake and time spent traveling and foraging
diet breadth predicted by:
- energy (E)
- handling time (h)
- encounter rates (funny triangle symbol)
vertical transmission
transmission between generations from parent to offspring
horizontal transmission
transmission within one generation between unrelated individuals
horizontal transmission methods:
sexual waterborne transmission e.g. cholera soil borne- with or without long-lived resting stages vector transmission e.g. malaria aerially transmitted e.g. common cold
