Population regulation
what is intraspecific competition?
competition among individuals of the same species
what is exploitation competition?
competition with individuals who do not directly interact with one another - individuals respond to the level of resource availability that is depressed by the presence and consumption of other individuals in the population ex. zebras eating all the grass in one field and then other animals cannot eat it
what is interference competition?
competition with individuals who interact directly with one another, preventing others from occupying a habitat or accessing resources with in it. ex. birds protecting their territory
what is the Allee Effect?
the reduction in reproduction or survival under low population densities ex. when its really hard to find a mate b/c of low population
what are some examples of density independent factors?
- temperature - precipitation - natural disasters ex. bark beetles
what are the two types of density dependent growth factors?
1. negative density dependence - intraspecific competition 2. postive density dependence - allee effect
What are the two types of intraspecific competition?
1. scramble 2. contest
what is an example of scramble competition?
animals foraging
what is negative density dependence?
anything that helps maintain population at constant levels (around K) - *population regulation*
what is an example of negative density dependence?
intraspecific competition
what is positive density dependence?
populations grow very slowly at low populations. - typically occurs at low population density *Allee Effect*
what are density dependent factors?
they affect the population growth rate in relation to population density - they function to slow the rate of population growth with increasing population density by increasing the rate of mortality or decreasing the rate of fecundity
what are density independent factors?
they can limit population size regardless of population density - leads to erratic, abrupt shifts in population size *population determination*
what is scramble competition?
this occurs when growth and reproduction are depresses equally across individuals in a population as the intensity of competition increases - everyone loses in the end
what is contest competition?
this takes place when some individuals claim enough resources while denying others a share - one winner
what is an example of contest competition?
two elephant seals fighting over who gets to mate