Lecture 8: Populations: Characteristics & Structure

Question 1

define populations in a genetic view

Answer 1

reproduction within a population defines a distinct gene pool where a high level of genetic mixing occurs via sexual reproduction

Question 2

range of ecological consequences in a population

Answer 2

1. Suitable habitat
2. dispersal
3. population structure

Question 3

ecological consequence - suitable habitat

Answer 3

a suitable habitat might be patchily distributed within the larger area where it is found, creating sub-populations with distinct spatial structure.

Question 4

suitable habitat - niche

Answer 4

The range of conditions populations of a species can tolerate, which also defines its functional role within the environment it occupies.

Question 5

what is a fundamental niche

Answer 5

the full range of habitat conditions that a population of organisms can tolerate and persist

Question 6

what is a realized niche

Answer 6

• the actual range of habitat conditions a species can tolerate
• is small bc of predators, competitors, and pathogens put a limit on the population

Question 7

define dispersal

Answer 7

The movement of individuals from one area of suitable habitat to another

Question 8

how is a geographical range determined

Answer 8

The suitable habitat ultimately determines geographic range, but only if populations can reach all suitable habitat.

Question 9

what are dispersal limitations

Answer 9

• absence of a population from suitable
  habitat because of barriers to movement
• are overcome naturally
• natural founding populations that reach new suitable habitat tend to be small and represent a rare colonization event

Question 10

How do humans influence dispersal?

Answer 10

• humans can intentionally and unintentionally move organisms in large numbers and with high frequency.
• they can facilitate larger founding populations
  and multiple founding events in a short period of time

Question 11

what is an invasive species

Answer 11

A non-native species in the ecological system under consideration that causes economic losses, environmental harm, or harm to human health

Question 12

geographic range - what is migration

Answer 12

Dispersal of populations to track suitable habitat.

Question 13

what are two examples of migration (geographical range)

Answer 13

• Seasonal changes in the population’s lifecycle needs
• Seasonal shifts in location of suitable habitat

Question 14

population structure - 3 key properties

Answer 14

1. Abundance
2. Density
3. Dispersion

Question 15

define abundance in population structure

Answer 15

Total number of individuals within a defined area.

Question 16

define density in population structure

Answer 16

Number of individuals per unit area or volume

Question 17

define dispersion in population structure

Answer 17

• The spacing of individuals within the geographic range of a population
• Can be different under the same abundance and density conditions.

Question 18

what is random dispersion

Answer 18

• no influence of biotic or abiotic interactions on spacing among individuals
• Uncommon and usually a null hypothesis in studies of dispersion within a population

Question 19

what can be indicative of different population-level interactions

Answer 19

changes/differences in dispersion, density, and abundance

Question 20

what can clustered dispersion result from?

Answer 20

• Clustered resources.
• Social interactions — family, mating, protection, etc
• Limited dispersal of offspring

Question 21

what can even dispersion result from?

Answer 21

• Direct interactions among individuals.
• Especially competitive interactions under high resource limitation