1: Individuals and populations

Question 1

Population

Answer 1

A group of individuals of the same species living and interacting in a particular geographic area

Question 2

population ecology

Answer 2

examines factors that limit & regulate population size and composition

Question 3

Community

Answer 3

a community consists of all the individuals of all the species that inhabit a particular geographic area

Question 4

Community ecology

Answer 4

examines the interactions among populations, and how factors such as predation, competition, disease and environmental factors affect community structure and organisation

Question 5

What 6 Key Processes Drive Distribution and Abundance?

Answer 5

Colonisation, Extinction, Birth, death, Immigration, Emmigration

Question 6

Life history

Answer 6

The typical schedule of survival and reproduction, along with the traits that impact these patterns

Question 7

Ephemerals

Answer 7

Ephemeral species are plants and animals whose ‘adult’ lifespan lasts only a few weeks or months

Question 8

Ephemeral examples

Answer 8

Dessert annual plants (dormant seeds)
Some amphibia (dormant eggs)

Question 9

Ephemeral life histories

Answer 9

adaptation to living in highly variable, harsh environments —wait out the bad times and take advantage of rare ‘good’ conditions:
They remain dormant for much of their life as seeds or eggs (just like annuals)
Emerge and reproduce rapidly in the occasional years that the conditions are good and usually complete life cycle in <8 weeks

Question 10

Annual life history

Answer 10

adaptation to seasonal environments - characterised by having one generation per year

Question 11

Frequency of reproduction - Iteroparity

Answer 11

Reproduction is spread out - repeated reproductive episodes

Question 12

examples of iteroparity

Answer 12

(most) mammals, the majority of perennial plants, many insects

Question 13

Frequency of reproduction - Semelparity

Answer 13

Big-bang reproduction - large number of offspring produced in a single reproductive event…
…after which the individual soon dies

Question 14

examples of Semelparity

Answer 14

many annual plants, some perennial plants, many insects, a few vertebrates

Question 15

Principle of allocation (Levins 1968)

Answer 15

each organism has a limited amount of energy that it can allocate for maintenance, survival, growth and reproduction

Question 16

Survivorship

Answer 16

describes how many individuals in a population are expected to survive to any specific age (x) — denoted lx (proportion of individuals surviving to each age for a given species or group)

Question 17

Survivorship curve

Answer 17

log of survivorship (y) against age (x)

Question 18

Type 1 survivorship

Answer 18

Relatively low mortality rate earlier in life - most individuals survive to old age

Question 19

Type 2 survivorship

Answer 19

Constant mortality throughout life

Question 20

Type 3 survivorship

Answer 20

Relatively high mortality rate earlier in life

Question 21

What does r represent

Answer 21

exponential / intrinsic population growth rate

Question 22

Period life table

Answer 22

represents age-specific rates during a specific time period of a certain population (meaning different age groups were born at different times)

Question 23

how is survival calculated?

Answer 23

Sx = (lx + 1) / lx

Question 24

Fertility

Answer 24

mx = mean number of offspring produced by each surviving individual over the age x-1 to age x period

Question 25

Net reproductive rate

Answer 25

The average number of female offspring produced by one individual female over her lifetime - R0 - tells you how much a population grows by per generation

Question 26

How is net reproductive rate calculated?

Answer 26

R0 = Σ lxmx

Question 27

Generation time calculation

Answer 27

T = = Σ (x lx mx) / R0

Question 28

Population growth rate: 𝜆 Definition + calculation

Answer 28

Population growth rate (𝜆) tells you how much a population will grow per unit time (e.g. years) in the long term - 𝜆≈𝑅0^(1∕𝑇)

Question 29

What values would basic population growth rate, reproductive rate and exponential growth rate have for population growth?

Answer 29

R0 > 1 λ > 1 r > 0

Question 30

What values would basic population growth rate, reproductive rate and exponential growth rate have for population decline?

Answer 30

R0 < 1 λ < 1 r < 0

Question 31

What values would basic population growth rate, reproductive rate and exponential growth rate have for a stable population?

Answer 31

R0 = 1 λ = 1 r = 0

Question 32

What represents population size?

Answer 32

N

Question 33

What is the change in population size over time equal to?

Answer 33

ΔN / Δt = bN - dN (number of births - number of deaths) during time interval or ΔN/ Δt = rN

Question 34

What is the carrying capacity?

Answer 34

K - maximum stable population size that can be supported over a long time determined by the energy/resource limitation

Question 35

What is the logistic growth equation?

Answer 35

ΔN/ Δt = rN - rN^2 / K rN^2 - density dependence

Question 36

What traits are associated with high density?

Answer 36

Large, few offspring (TRADE-OFF) Delayed reproduction Large size Long lived

Question 37

What traits are Associated with low density?

Answer 37

Many small offspring (TRADE-OFF) Early reproduction Small, Short lived