ECOLOGY Flashcards
What is ecology
Study of interactions between organisms and their environments at various levels
Ecology can be studied in what ways
Individuals
Populations
Communities
Ecosystems
Why is a population perspective necessary in Ecology
Genetics changes over time within POPULATIONS and not individuals
What is growth rate
Understanding how populations will increase and decrease or stay the same over time
What is Exponential growth
Populations grow at a rate proportional to its size
The bigger the population the faster it grows
Cannot continue indefinitely
Population size quickly exceeds available resources
How is a population’s growth limited by its environment
It reaches CARRYING CAPACITY
Population growth is limited by the resources available for a particular habitat over a period of time
What happens as a population reaches its carrying capacity
Death rates increase
Emigration rates increase
Birth rates decrease
Th population reaches Logistic growth
What is logistic growth?
Population growth that is gradually reduces as the population nears the environments carrying capacity
What limits population growth?
Density - Dependent Factors
Food supply
Habitat for living and breeding
Parasite and disease risk
Predation risk
Density - Independent factors
Earthquakes
Fires
Floods
What is maximum stainable yield?
Individuals are utilized or harvested from a large population without impairing its growth rate
Who uses Maximum Stainable Yield?
Resource Managers
Used repeatedly
Yields more individuals in the long term than a one time harvest of all individuals
How does low hazard factor influence longevity?
Relatively low risks of death at each age
Individuals tend to reproduce later
Later aging
Longer life spans
How does high hazard factors affect longevity?
Relatively high risks of death at each age
Earlier aging
Individuals tend to reproduce earlier
Shorter life spans
What is the BIG BANG REPRODUCTION?
Reaches sexual maturity at one year
Mates intensely over a 3 week period
Males die shortly after mating period
What is SLOW GRADUAL REPRODUCTIVE INVESTMENT
Reaches sexual maturity at one year
Produces about one offspring per year
What is FAST, INTENSE REPRODUCTIVE INVESTMENT
Reaches sexual maturity at one month
Produces litters of six to ten offspring every month
What is a type 1
High survivorship until old age the rapidly decreasing survivorship
What is type 2
Survivorship decreases at a steady, regular pace
What is type 3
High mortality early in life, but those that survive the early years live long lives
Survivorship curves do what ?
Predicts the proportion of individuals of a age that are alive in a population
When resources are limited, populations must increase allocation to one of the following …
Growth, Reproduction, or survival
What is REPRODUCTION AND SURVIVAL
Big Bang reproducers such as salmon singe exceptionally high investment in reproduction, then die shortly afterward
Sacrifice survival for reproduction
What is REPRODUCTION AND GROWTH
Beech trees grow much more slowly in the years when they produce many seeds than they do in years when they produce few seeds
Sacrifice growth for reproduction
Number and size of offspring
Female lizards produce medium size eggs as a compromise between many small eggs ( with poor survival of offspring) and few large eggs (with better survival of offspring)
Sacrifice quality for quantity
