Ecology Exam 2
Cooperative Breeding
social system: offspring receive care from their parents plus additional non-breeding group members
Inclusive Fitness
(direct fitness plus indirect fitness)
-Total effect an ind. has on proliferating its genes via own offspring and helping close relatives
Direct Fitness
benefits that improve the reproductive success of the actor
Indirect Fitness
benefits that improve the reproductive output of closely-related individuals
Reasons for helping
-Poor conditions/low food supply
-lack of good places to burrow/nest
-lack of suitable partners
Group living Benefits
Defense, hunting, survival in harsh conditions, home building, dilution of losses
Group living Drawbacks
Fight for dominance, increased parasitism, visibility to predators
Pop. growth without limits
-Exponential: pop. reproduce continually dN/dt= rN
-Geometric: pop. have no overlap in reproduction
Logistic Growth
dN/dt= rN(1-N/K)
– r decreases as N increases
– If N=K, r=0, pop growth stops
Density dependence
-Competition for food, space, mates
-disease, parasites, waste accumulation
Allee Effect
-as pop size decreases, r also decreases (inverse density dependence)
-Sets of spatially isolated populations are linked by dispersal
-Characterized by repeated extinctions and colonization
Source vs Sink pop
-Source populations exist in high quality patches with births>deaths
-Sink is low quality patch with deaths>births
Rescue effect
High rates of immigration that protect a pop from extinction
Demography Fundamental Parameters
-pop size and density
-Fecundity and mortality
-Age structure
-Sex ratio
Cohort (dynamic) life table
Follows the fate of a group of individuals all born at the same time(a cohort)
Nx (life table)
Number alive at start of an age interval or stage
Dx (life table)
Ix (life table)
Survivorship Curves
-Type 1: low death rate
-Type 2: mod. death rate
-Type 3: High death rate
Mx (life table)
fecundity (# of females)
Reproduce once
Reproduce several times
Life History Key traits
-Survival and mortality rates
-Amount and timing or reproduction
-Age and size of adult at maturity
-Deterioration with age/decline in physiological function
Fundamental Niche
Potential env conditions tolerated by a species
Realized Niche
Conditions of env where species is actually found
Production of chemicals by plants that inhibit growth of neighboring plants
Aggressive behavioral exclusion of organisms from specific units of defended space
Preemptive competition
When a physical resource is occupied by one organism and therefore unavailable to others
Intra vs interspecific competition
competition for resources among individuals of the same species vs different species
a (competition coefficient)
Per capita effect of one species on the pop. growth of another species
cumulative effect
Comp. coefficient x # of individuals
Character displacement
Differences among similar species are accentuated where the species co-occur, but are minimized where they don’t
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