Question

In a paragraph discuss four differences between r-strategists to K-strategists. Give one example of a plant and one animal that exhibits each strategy and explain in a sentence for each what traits inform you that they exhibit that strategy.

In two sentences differentiate between density-dependent and density-independent forces and their impact on population size.

In a paragraph discuss the key differences between the three types of survivorship curves (Type I, Type II and Type III); give one example of an organism that exhibits each pattern and state in a sentence for each what traits inform you that it exhibits that strategy.

State seven ways humans make an impact on the environment through population size and/or the ecological footprint of its citizens.

Answer 1

A population has energy investment for maintenance and surplus energy invested in reproduction. Maintenance energy involve, energy invested against predator, competetor, pathogens and in basal metabolism.

under conditions of under crowded population natural selection favours, population having more energy investment in reproductive stretegy. They are called r- selected populations. Phytoplanktons in eutrophic ponds. r- selected populations are opportunists and take the advantage of favorable conditions and boom.

In over crowded and unfavourable environment, natural selection favours, population having high maintenace energy so that population can ensure survival under extreem biotic stress. They are called K- selected populations. k- selected populations are equilibrium species and better competetors. For example annual plants.

Characters	r- selection	k-selection
Environment Natural selection favours survivorship curve Growth curve Mortality Migration Social character	Variable and unpredictable temperature High biotic potential large clutch size small body size early age of reproduction Type III J- shaped High in young stage, density independent High degree Low degree	stable and predictable tropical climate Low biotic potential small clutch size large body size delayed age of reprodution Type II and I Sigmoid Low at Young stage Low degree High degree of sociability

Survivorship Curves

Type I	Type II	Type III
Highly convex curve death threat in young stage is very low or infant mortality rate is very low High degree of parental care. For example Humans	Highly concave curve High mortality rate in young stage very low parental care for example Fishes, oak tree	Diagonal curve constant mortality Death threat constant throughout the life span. it is not found in natural population.