Population Ecology Flashcards
Define population
a group of individuals of a single species living in the same general area, which are capable of interacting and interbreeding together – generally isolated from other populations
What 3 factors affect population rates
Births
Deaths
Migration
Describe the 3 types of survivorship curves
Type I = convex shape - fairly flat then falls
Type II = Fairly constant slope with individual dying evenly over time
Type III = Drops fast then flattens out
What are k selected species characterised by and give 2 species examples
They only have a few offspring but investing high amounts of parental care
- Humans, elephants, bison
What type of survivorship curves are seen in k selected species?
Type I
What does a Type I survivorship curve tell us about a population?
The death rate in juveniles is low, the individuals usually die in old age
What does a Type II survivorship curve tell us about a population?
Fairly constant threat of death throughout life from disease, predation, parasitism
Which type of species will usually have a Type II survivorship curve?
Rodents
Birds
Invertebrates
What does a Type III survivorship curve tell us about a population?
There is no parental care
Species reproduce abundantly but don’t survive long
Which types of organisms would usually have a Type III survivorship curve
Plants
Marine Invertebrates
Fish
What are r selected species? Give 2 examples of r species
They are species puts that only a small investment of resources into each offspring, but produces many such low effort babies. Such species are also generally not very invested in protecting or rearing these young
- Plants
- marine invertebrates
- fish
Which type of survivorship curve would r selected species have?
Type III
Define dispersion
The pattern of spacing among individuals within an area that the population occupies
What are the 3 types of dispersion?
Uniform
Random
Clumped
Which are the most and least common types of dispersion?
Most common = clumped
Least common = random
What is allelopathy?
It is a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms – can be beneficial or detrimental
What does random dispersal suggest about the interactions of a population
They lack strong interactions - are independent
They neither attract or repel one another
Give an example of how random dispersal can occur
Dandelion seeds being dispersed by wind - WIND POLLINATION
Give an example of uniform dispersal
Termite mounds in Kenya - dispersed 100-250ft apart for territorial activity
What kind of environment will random dispersal most likely occur?
Homogenous environments
What kind of conditions will result in clumped dispersal?
When there are patches of favourable conditions (i.e: patches of food) or interactions (e.g. shoaling)
What is an example of clumped dispersal?
Lions, Hyenas, giraffes, elephants, gazelles etc all clumped by a small water source in African dry season
