Populations Flashcards
What is a population?
A group of organisms from the same species in the same area, chose to breed and share a gene pool
What is the best way to determine population size?
Collect an absolute number
What is indirect sampling?
Looks at evidence left behind
What are the patterns of disposal?
Clumped, spaced and random
What are reasons for clumped dispersal?
Safety, social grouping or uneven resources
What are reasons for spaced dispersal?
Territory and high intraspecific competition
What is random dispersal?
Least common where dont interact much
What do survivorship curves show?
Pattern of lifespan in a population
What does a positive survivorship curve show?
Most individuals reach adulthood and there is a large die-off of individuals as the population nears the end of a normal lifespan
What does a straight survivorship curve show?
A fairly constant mortality rate though the lifespan of the population
What does a negative survivorship curve show?
High mortality rate of the young, but those individuals that do reach maturity live a long life with a low death rate
What do population dynamics investigate?
Population size
What is the growth rate?
Number of organisms born over time
What affects growth rate?
Birth rate and death rate
What is biotic potential?
If all organisms reproduce as much as possible and none of the offspring die
What are issues with small populations?
Low genetic diversity, subject to inbreeding, less likely to adapt to environmental changes and low mates
What are issues with large populations?
Increased food shortages and diseases, decrease in space and clean water and live at carrying capacity so can experience huge crash
What are the stages on a population curve?
Log, exponential and stationary
What does the lag phase look like?
An exponential curve
What is happening at the lag phase?
The rate is accelerating and there is slow growth due to few reproducing individuals
What does the exponential phase look like?
A straight line
What is happening at the exponential phase?
The rate is the fastest, there is rapid growth and nothing is limiting
What does the stationary phase look like?
A wavy line with small fluctuations
What is happening in the stationary phase?
Small fluctuations are due to resources, environmental resistance as something is limiting and birth = death
