Chapter 10 - Population Ecology Flashcards
What are the three types of population dispersal? Give one example for each.
Clumped (caribou), uniform (trees in forest), and random (dandilions).
What is a metapopulation?
A population that is not always taking up all of the space available to them. An example is caribou, they move around.
What is a source-sink population?
This population breeds at the source, but do not remain there, they move to the “sink,” where they also die.
This is a type of metapopulation.
What are four ways in which plants disperse?
Coconuts that grow next to water, where coconuts are washed away onto other islands where they grow new trees.
Some plants also have seeds that stick to fur and clothes next to paths, where they are carried by other beings further along the path, where new trees can grow from the seeds.
Other plants like dandilions have seeds that blow away with the wind allowing them to disperse.
Another method of dispersal is in some fruits which are attractive to birds, who will eat them and poop out the seeds, or the fruits might stick to the birds’ claws and be transported to a new location.
What are the 2 imput and 2 output factors of population demography?
Immigration and births are imput.
Emigration and deaths are output.
Describe the generation time vs body size curve.
This curve is a log scale, where generally, bigger organisms have longer generations than smaller organisms. Humans are exceptions, as they are rather small but live very long lives.
Length of generation is determined by how quickly you are able to reproduce.
What are survivorship curves? What are the three types? Give examples for each.
Curves that describe how likely individuals are to die as a function of the percentage of their maximum life span.
Some species have more risk of death very early in their live span, as they are vulnerable soon after birth, but after, they become more resistant to predators or disease for example.
Type I survivorship is like humans and most large animals, which usually do not have many predators and die of old age. They are much more likely to die as they get older.
An example of Type II survivorship is in rodents, where they are equally likely to die at any age.
An example of type III survivorship is in oysters, where when they are young, they have no shell, and are therefore extremely vulnerable. Once they build their shells, they are very well protected and very rarely die as they have little predators.
What is the difference between logistic growth and geometric/exponential growth?
Geometric growth describes the biotic potential, which is how fast a population could grow if there were no limits to their growth. In this case, growth is independant of density of population.
Logistic growth is dependant on the density of the population, which is why the population size settles at its carrying capacity as the population grows denser.
What are semelparity and iteroparity?
Semelparity is when there is only one reproductive event in a lifetime, where many babies are made. Little to no attention is given to each offspring.
Iteroparity is when there are many reproductive events in a lifetime, each making only a few offspring or just one. A lot of attention is given to each. Example: humans.
What are r-Selected and K-selected species? Which one are humans?
R-Selected species follow exponential growth, they have many offspring at a time that get little to no attention, have a large mortality rate and grow to be relatively small.
K-Selected species have a population size that varies along their carrying capacity. They have less children at a time, but each receives more attention and grows to be larger. The mortality rate of children is lower, and they reproduce many times in their lifetimes.
Humans are K-Selected but currently behave as R-Selected as they overcome many constraints.
What is eutrophication?
When there is an excess of phosphorus in the water which causes an algal bloom. This is terrible for the environment, as many aquatic species die for lack of oxygen.
What factors regulate populations?
What affects population growth?
Density-independant factors, such as climate.
Density-dependant factors, such as predation, toxic wastes, competition, stress, diseases, territoriality.
Generation time (how fast the offspring is ready to mate) and sex ratio.
What are boom-bust cycles?
When they population of two species are interdependant. Hare and lynx example.
When there are many hares, the lynx population grows, as there is a large source of food. When there are many lynx, the hare population decreases, which causes the lynx population to decrease. This causes the hare population to increase, and we start over again.
