Flashcards in Lecture 7- Intro to population ecology Deck (25)
What is a population?
-group of individuals OF THE SAME SPECIES! occupying a particular location
-attributes are: abundance, genotypes, sizes
What is a major aspect of predator prey relationship?
Explain the cycle of predator-prey population.
-have lot of prey= predator population will expand
-that will have a negative effect on prey= decline
-that in turn will decrease the population of predators
-and that will lead to prey increasing in numbers
= cycling like this
-Lotka-Volterra model says the same thing
Are the cycles of predator/prey often observed in real life?
-no only rarely
-there more interactions than just the predator prey relationship that change it
Give an example of a prey-predator relationship which follows the oscillations?
-hare and lynx in North America
-10 year cycle
What are the three practical reasons why knowing population dynamics is important?
-fisheries management (whale conservation)-how many can we catch sustainably
-conservation of endangered species (what do we need to do to increase their numbers?)
-pest/weed management(how to control their numbers, prevent outbreaks)
What is population dynamics?
-understanding and predicting changes in the abundance and distribution of organisms
What does B stand for?
What does D stand for?
What does I stand for?
What does E stand for?
What does Nt stand for?
-abundance at time t
What is the equation for abundance at t+1?
minus D and E as those are the ones leaving
What does f stand for?
f=fecundity (offspring per parent)
What does d stand for?
d= proportion of adults dying
How can we change the Nt+1 equation with f and d?
Nt+1= Nt + fNt - dNt + I -E
replaces B-D by fNt-dNt
can be rearranged:
Nt+1= (1-d)Nt + fNt + I- E
How can the already changed Nt+1 equation be changed by s?
Nt+1= sNt + fNt + I -E
replaced (1-d)Nt by sNt
What does s stand for?
-proportion of adults surviving
What do we have to measure to know Nt+1?
Nt, f, d(or s), I , E
How can you study abundance and distribution (3 ways)?
-snap-shots:describe what you see and where;try to infer explanations
-time-sequence: describe what changes you see over time, and infer explanations
-do experimental manipulations: observe responses (=changes over time)
How do we measure the population number Nt?
-census: count every individual in the population
-problems: hard to do, only get ones you can find
How do you count the Nt if there are too many to count (census)?
-sample the population
-count no. in each square and estimate from that
-get density=abundance in the area
What are the issues with population sampling?
-can't find all in the quadrat, if small, young etc.
-cryptic species= in soil, fish, hiding in soil
How do you measure population abundance in a lake?
-mark and recapture
-capture some= mark
-later again capture= and see how many are marked and unmarked= proportion= estimate abundance