APS11007 Principles of Ecology and Conservation

Question 1

What 6 key processes drive distribution and abundance?

Answer 1

• Colonisation and extinction
• Emigration and immigration
• Births and deaths

Question 2

Unitary organisms

Answer 2

• Easy to recognise genetically separate individuals
• Form is determinate, programmed by birth
• Variation smaller than in modular organisms
• Strong programming means local damage has serious consequences

Question 3

Modular organisms

Answer 3

• Genetic individual, genet, starts life as a single celled zygote but doesn’t follow set developmental programme
• Growth occurs by repeated production of modules (leaves, polyps etc)
• Indeterminate growth and development, not predictable
• Individual not dead until all modules are dead, local damage is unimportant

Question 4

The Life History

Answer 4

“Life history theory predicts how natural selection should shape the way organisms parcel their resources into making babies” Reznick, D. N. (2010)

Question 5

Life history questions

Answer 5

• When start producing?
• How often?
• How many offspring?
• Many small or few large offspring?

Question 6

‘Parity’

Answer 6

Number of times a female has reproduced

Question 7

Key traits of life history

Answer 7

• Rates, e.g. somatic growth and senescence
• Timing, e.g. maturation and frequency of reproduction
• Allocation, e.g. offspring size and number

Question 8

Somatic growth

Answer 8

Growth of body exclusive of gametes

Question 9

Senescence

Answer 9

• Process of deterioration with age

- Loss of a cell’s power of division and growth

Question 10

Semelparity

Answer 10

• Large number of offspring produced in a single reproductive event
• After which the individual soon dies
• E.g. many annual plants, some perennial plants, a few vertebrates

Question 11

Iteroparity

Answer 11

• Reproduction is spread out
• Produce offspring during repeated reproductive episodes
• E.g. most mammals, most perennial plants, many insects

Question 12

Annual life history

Answer 12

• Simplest
• An adaptation to living in seasonal environments
• One ‘generation’ per year, growth, seed and death
• Spend part of life as dormant seeds, can be viable for 10-100s of years

Question 13

Ephemerals

Answer 13

• Adult lifespan lasts only few weeks or months
• Desert annual plants (dormant seeds)
• Some amphibia (dormant eggs)
• Remain dormant most of life
• Emerge and reproduce in occasional years that conditions are good
• Complete life cycle in <8 weeks

Question 14

Population

Answer 14

• Group of organisms of one species that interbreed and live in same place at same time
• Compete for food, breeding sites and partners

Question 15

Metapopulation

Answer 15

• Larger scale

- Collections of populations linked via dispersal

Question 16

Survivorship

Answer 16

• How many individuals are expected to survive to any specific age (x), donated by lx
• Plotting the log of this number on y-axis and age on x gives survivorship curve

Question 17

Types of survivorship curves

Answer 17

• Type I, relatively high mortality later in life
• Type II, constant mortality throughout life
• Type III, relatively high mortality earlier in life

Question 18

Life tables

Answer 18

• Summarise births and deaths for organisms at different ages of lives. Shows quantities like survivorship for different ages
• Cohort life table, represents age-specific rates over the lifetime of a cohort of organisms born during a short time period
• Period life table, age-specific rates during specific time period of certain pop (different age groups born at different times)

Question 19

Column in a cohort table

Answer 19

• Survivorship, survival from age 0 to age x
• Survival (Sx), age-specific survival from age x to age x + 1
• Fertility (mx), mean number of offspring produced by each surviving individual over the age of x-1 to x
• Lx x Mx
• X x Lx x Mx

Question 20

What can be calculated from life tables?

Answer 20

• Measures of population growth
• Net reproductive rate
• Annual growth rate
• Generation time

Question 21

Net reproductive rate: R0

Answer 21

• Average number of female offspring produced by one individual over her lifetime
• R0<1, population declines, R0 >1, population grows, R0 = 1, stable
• Measure of per-generation population growth
• Measure of fitness
• Sum of lx x mx

Question 22

Generation time: T

Answer 22

• Average time between successive generations (birth of individual and birth of offspring)
• A weighted average of age (x) at reproduction of cohort
• Weights (lx mx) are the expected contributions from birth to the next generation arising at each future age
• Sum of x lx mx, all over R0

Question 23

Population growth rate:  (lambda)

Answer 23

• R0 tells if population is growing, but not how fast per unit of time
• Population growth gives amount by which a population will grow each year
• R0 to the power of 1/T