Population Growth & life histories

Question 1

Life table types

Answer 1

dynamic / cohort and time specific

Question 2

What are cohort life tables?

Answer 2

Cohorts of individuals born in a specific year or over multiple years are followed.

Question 3

What are time specific life tables?

Answer 3

A single time period is used to construct a distribution of age or stage classes.
Easier to do but assumptions:
Sample of each class represents the population; age specific mortality and birth rates constant over time.

Question 4

What is age-specific mortality represented by?

Answer 4

q

Question 5

What is survivorship?

Answer 5

Differences in survivorship curves between males and females.

Some organisms exhibit a combination of different survivorship types during their lifetimes.

Question 6

What is type 1 survivorship?

Answer 6

generally very few offspring
high parental care
and high survivorship
live with low mortality until you hit a point where there is a high die-off.

Question 7

What is type 2 survivorship

Answer 7

Constant decline in the populations
relatively high survivorship.

Question 8

What is type 3 survivorship?

Answer 8

Low survivorship
mostly sprays and pray strategies.
only a few offspring make it to “old age”

Question 9

What is birth rate?

Question 10

How does birth rate vary?

Answer 10

can vary with age

Question 11

What influences the repoductive rate?

Answer 11

• Birth rate
• survivorship

Question 12

What is Life history?

Answer 12

lifetime pattern of growth, development, and reproduction.
patterns that are adpations that evolve through natural selection.

Question 13

Why would these adaptions limit an orgnisms’ ability to do equally well under a variety og different evironmental conditions?

Answer 13

Individuals have a limted amount og resources that can be allocated to specific aspects of thier life history.
An allocation to one aspect reduces the resourece availabel resources for other aspects.
Allocating resources to reproduction reduces the amount of resrouces available for growth.

Question 14

what is Trade-off?

Answer 14

beneficial change in one trait results in a detrimental change in another.
slow vs fast growing/lived
large vs small reproductive output
early vs late maturing
semelparous vs iteroparous.

Question 15

what are reproduction effort governed by trade-offs between fecundity and survival?

Answer 15

Reproductive effort: total energetic cost of reproduction per unit time is closely related to adaptive responses to age at maturity.

Energy invested in reproduction varies.
Allocation to reproduction leads to a decrease in growth.
Allocation to reproduction may increase mortality:
example in deer of Scotland - Milk hinds - higher mortality
Yeld hinds - lower mortality.

Question 16

Age at maturity vs fecundity.

Answer 16

natural selection will favour the age at maturity that results in the greatesr number iog offspring produced over the individual’s lifetime.

The primary fittness advantage if delaying maturity is the larger the body size at first reproduction.

The primary cost is the chance of dying before reproduction or before the advantage above is full realised.

Question 17

What is r strategy?

Answer 17

many off spring with little or no parental care; density - independant growth limitation

Question 18

What is k strategy?

Answer 18

few larger offsrping with more parental care

Question 19

What is the role of the environment?

Answer 19

Variety of niches that the individuals are existing in and a variety of pressures that are exerted on them.

Question 20

Fast-slow continuim hypothesis?

Answer 20

Species with high adult mortality evolve shorter lifespans, faster development, early reproduction, and high fecundity.

Species with low adult mortality evolve longer lifespans, slower development, delayed reproduction, and low fecundity.

Question 21

How do life histories adapt to environmental adaptability?

Answer 21

VAraibel / short-lived habitats select for r-strategists.

Stable / long-lives species habitats select for K-strategies.

Question 22

What are examples of r-species?

Answer 22

Weedy speices
Speices in unstable environments.

Question 23

Examples of K-species?

Answer 23

Competitive species
Stable population sizes.

Question 24

Explain Grime’s CSR model?
[ triangle ]

Answer 24

Competitive species such as birch predominate under conditions of low disturbance and low stress.

Stress-tolerant species predominate under conditions of low disturbance and high stress.

Ruderals are dominant under conditions of high disturbance and low stress.

Question 25

What is included in the “stress”?

Answer 25

availability of water, nutrients, and light, along with growth-inhibiting influences like temperature and toxins

Question 26

What is included in “disturbances”?

Answer 26

herbivory, pathogens, anthropogenic interactions, fire, wind, etc

Question 27

What are competitors?

Answer 27

species with high relative growth rate, short leaf-life, relatively low seed production, and high allocation to leaf construction. They persist in high nutrient, low disturbance environments, and “rapidly monopolize resource capture by the spatially-dynamic foraging of roots and shoots.

Question 28

What are stress-tolerators?

Answer 28

found in high stress, low disturbance habitats, allocate resources to maintenance and defences, such as anti-herbivory. Species are often evergreen with small, long-lived leaves or needles, slow resource turnover, and low plasticity and relative growth rate. Due to high stress conditions, vegetative growth and reproduction are reduced.

Question 29

What are ruderals?

Answer 29

Rudiral species inhabit low-stress, high-disruption regimes, allocate resources mainly to seed reproduction, and are often annuals or short-lived perennials. Common characteristics of ruderal species include a high relative growth rate, short-lived leaves, and short-statured plants with minimal lateral expansion.