Factors limiting population growth

Question 1

Carrying capacity(K) of the habitat influenced by

Answer 1

the most limiting resource

Question 2

Density- dependent pop. regulation is due too

Answer 2

intrinsic factors, the population numbers depend on activity of individuals ex.birth rate, over-grazing, death rate

Question 3

In a density dependent pop. reg. regulation occurs with..

Answer 3

with decreased birth rate and increased mortality

Question 4

Mechanisms for density-dependent effects when pop exceeds K

Answer 4

1.Intraspecific competition
2.Delayed breeding or reduced offspring production
3.Maintain larger territories when resources become limiting
4.Dispersal(migration)
5.Parasites/disease
6.Predators

Question 5

Intraspecific competition-?

Answer 5

Occurs when required resources are limited (food, space, or mates)

Question 6

Two types or things in Intraspecific competition

Answer 6

Interference competition-individuals directly interferes
Differential ability to secure resources

Question 7

Delayed breeding or reduced offspring production, elk studies?

Answer 7

When populations density’s are high it results in
-increased agonistic encounters
-increased stress in sub-dominant animals
-stress triggers secretion of growth and sex hormones
-leads to suppression of body growth and reproduction
-odour of urine from females delays puberty in baby’s born during periods of high pop. density

All of this leads to lower birth rate and reduction of pop, growth rate

Question 8

Mech. for density dependent effects when pop. exceed k-
Maintain larger territories when resources become limiting

Answer 8

Larger territories by dominant individuals leads to less recources for sub-domainant individuals

This leads to reduced in non-territorial individuals

Question 9

Mechanisms for density-dependent effects when populations exceed K-

Dispersal

Answer 9

When in enclosed area animals can be excess predation and starvation but with migration Number of animals dont go above carrying capacity

Question 10

Mechanisms for density-dependent effects when populations exceed K

Parasites

Answer 10

parasites do not appear to have a major effect on host survival but in females to become pregnant

fish has least parasite
mammals and trees most parasites

Question 11

Mechanisms for density-dependent effects when populations exceed K

Predators

Answer 11

predators are major sources of mortality in the survivorship curve for most species

increased density allows predators to expand in numbers and distribution

Predator foraging rates-predators spend more time in habitats where prey are abundant

Question 12

Insects in density-dependent pop. die mostly from..

Answer 12

Parasites and disease

Question 13

Small animals and birds die mostly from what in a density-dependent pop.

Answer 13

Limited space or overcrowding

Question 14

Large animals die mostly from what in a density-dependent pop.

Answer 14

Mortality from limited food

Question 15

Extrinsic factors is from..?

Answer 15

Density-independent population regulation

Question 16

Density-independent population regulation?

Answer 16

reduction of carrying-capacity
mortality due to severe external conditions
independent of amount of individuals in population

ex. fire, cold, hot , hurricane

Question 17

Cycles of predator and prey abundance are correlated going up and down in a 11 year cycle, why?

Answer 17

1.Sunspots- concentrated portion of the sun’s magnetic field pokes through the surface- are localized zones of reduced heat output but mostly greater solar output

2. Stressful for predators when hunts are not successful= less reproduction/ weak offspring

3.Nights without darkness peak over 9.3 years