Population dynamics Flashcards
1
Q
What affects distribution of a population and therefore population density
A
Resources: food and water and shelter/land
Interactions between members of the populations: Positive or negative
2
Q
Describe clumped populations
A
- Working in groups to catch prey gathered near water or clustered plants
- Positive interactions, highly socialized, cooperative feeding, minimizes chances of being caught by a predator
- ex. Meerkats
3
Q
Describe uniform populations
A
- Distributed evenly, but scarce resources
- Negative interactions –> territorial or competition for resources
- Ex. wolverines
4
Q
Describe randomly distributed populations
A
- resources are plentiful and evenly distributed
- No need for competition or defense so interactions between species are neutral
- ex. thistle
5
Q
Determining population size and density
A
- Population size (N): Number of individuals of the same species, living in a specific geographic area
- Population density (Dp): Number of individuals per unit of volume or area
6
Q
Transects
A
- samples taken from a long rectangular line of a specific length
- starting point is determined randomly
- average of transects is counted, then multiplied by the total area of the space
- useful for measuring low density species
7
Q
Quadrats
A
- an area of a specific size is used (such as 1M^2)
-Best used for sessile (imoble) organisms - Dp = N/A
8
Q
Mark recapture
A
- Used to measure populations of moving organisms. In this case, tracks, nests, burrows and scats can be used to estimate population
- Animals are caught, tagged and released. They are then recaptured and used to measure marked animals to unmarked using the formula
N= M x n/m
9
Q
Life history
A
- It’s the survivorship and reproductive pattern of indivuduals
- Includes; Age when organism sexually matures, how often it reproduces, how many offspring it has
- varies between species and favours evolutionary fitness
10
Q
Fecundity
A
- the average number of offspring produced by a female over her lifetime and represents an output of energy
- Animals that reproduce and die often have a large number of offspring (high fecundity)
- Animals that survive often care for their young for many years (low fecundity)
- (Number of offspring is usually inversly related to the care that parents provide)
- Is also affected by the age at which an organism sexually matures
11
Q
Defensive mechanisms to avoid predation
A
- thorns, quills, toxins, protective colouration
11
Q
Survivorship
A
- proportion of organisms that live to a given age in a population
- Type 1 has a high rate of juvenile surival, individuals live beyond when their young are born. Offspring are well cared for. (ex. humans)
- Type 2 is a mix between type 1 and 3. Mortality is a constant risk throughout the organisms lifetime. (ex. squirrels)
- Type 3 has a low rate of juvenille survival. Large amounts of offspring are produced to compensate (ex. salmon)
12
Q
Protective colouration
A
- camouflage (ex stick insect), body colouration as a warning (ex. poison dart frogs) and mimicry (ex. scarlet king snakes)
13
Q
Batesian Mimicry
A
When a species has colouration to look like another that is dangerous to predators
14
Q
Symbiosis
A
- and ecological relationship between two species in direct contact with one another
- includes parasitism, mutualism and commensalism
15
Q
Parasitism
A
- One population increases while another decreases
- Ex. Wasp larvae in catepillars will feed in it until they are ready to leave by drilling out of its body. Then strangely, when wasps enter their cocoons, the catepillar will protect them until it eventually starves to death.
