Lecture 7- Pop parameters, pop change Flashcards
Population
A group of potentiall interbreeding individuals of the same species at the same place at the same time (N)
Natality
Reproduction/fecundity, actual or potential
Mortality
Death, realized (actual lifespan) or potential (Max lifespan)
Imm/Emigration
dispersal, assumed to be equal
Age-structured pop
population made up of different age classes
Stage-Structured pop
pops made up of stages (used when age classes are not available, survival/reproduction are more dependant on stage than age)
Per capita rates
Average rates per individual in a population
Age-specific survival rates
Survival rate for a specific age class
Intrinsic rate of increase
The max rate of increase if there was no limit to resources, competition or predation (r^m or rmax)
instantaneous rate of increase (r)
The difference between birth and deaths (+=increasing, - = decreasing, and 0=nochange)
Finite rate of increase (lamda or R)
Rate of pop change (e^r), (lamda>1 =increasing, Lamda<1=decreasing, lamda=1 stable)
Carrying Capacity (K)
The natural limit to population size set by resource availability
Basic equation for population growth?
Nt+1 = Nt + B-D
What are the equations for per capita birth and death rate?
Per capita (B)= (total births during time t)/Nt Per capita (D)= (total deaths during time t)/Nt
What is the equation for rate of change?
r=B-D
Where r is pop growth rate
How does the finite rate of increase (lamda) relate to the instantaneous rate of increase (r) ?
(lamda) = (e^r)
express lamda as a result of a ratio of two censuses
lamda = Nt+1/ Nt
Where Nt+1 is the new census and Nt is the previous census
how do you find the population in the next time period using lamda?
(lamda)(Nt) = Nt+1
What 3 ways can r and lamda express pop change?
Stable- (r=0, Lamda= 1)
Increasing (r>0, Lam>0)
decreasing(r<0)
Given r=0.69 and No=50, what will N be after 20 years?
e^rt X No= Nt
(e^0.69x20) X 50 = N20
N20=~49 mil
Is rmax (intrinsic rate of increase) typically found in nature?
No, there are often limits to pop growth. Food, comp, pred
When can intrinsic rate of increase occur?
Colonizing new areas or recovering from over exploitation
How is carrying capacity built into other models (What equation uses L to relate to r or rmax)
r=rmax (1-N/K)
r- intantaneous rate of increa
rm- max rate of increase
How does pop ecology deal with variation in traits among individuals?
simplifying assumptions that individuals are identical in a pop. Some pop variations can be predicted as a function of stage/ age. can create models to account for differences.
