Unit 2 Test Study Guide

Explain why it is said that populations evolve not individuals.

Individuals alone do not evolve, they retain the same genes throughout their life. However, a population has many different genetic types and they’re constantly changing.

Describe the process of coevolution.

When populations of two different species interact over a long period of time they may coevolve. The evolution of one species influences the evolution of the other

What are the different ways that change can be introduced into the gene pool?

* Mutation and recombination


* Natural selection
* Genetic drift

What are the requirements for natural selection?

* Adaptive traits enhance the chances of survival
* Must be heritable and lead to differential reproduction.
* Survive and reproduce more offspring with these traits

What is the difference between habitat and niche?

A habitat is the place where an organism lives while a niche is that organism's role within the environment.

What is the difference between a specialist species and a generalist species?

Generalists can thrive in a range of habitats while specialists have a stricter habitat requirement.

Which one is more prone to extinction and why?

Specialists because they can only live in a certain place and eat certain things therefore if that place or thing gets destroyed that leads to them going extinct.

Explain the process of speciation.

Speciation is when a group within a species separates from other members of its specie and develops its own unique characteristics.

How is sympatric speciation different from the other forms of speciation?

Sympatric speciation is when groups from the same ancestral population evolve into separate species without any geographical relocation. Occurs through polyploidy. Polyploidy are reproductively isolated from diploid.

Explain the process of extinction and what events can precipitate it.

Extinction occurs when species are diminished because of environmental forced such as habitat fragmentation, climate change, natural disaster, humans, pollution etc. or Bec of evolutionary changes in their members, ex. Genetic inbreeding poor reproduction, and decline in population.

In what ways do human activities contribute to the extinction of a species?

Habitat destruction, pollution, the spread of invasive species, overharvest from the wild, climate change, population growth.

How would the movement of tectonic plates influence the evolution of species?

The movement of tectonic plates can move land masses a geographically isolated population. This promotes speciation of organisms.

Distinguish between species richness and species evenness. Give an example of an ecosystem that would best exemplify that term.

* Species richness- is a measure of the number of different types of species in an ecosystem and more diverse.
* Species evenness- is a measure of the relative abundance of each species.
* Ex. In a forest there may be a large number of different species (high species richness) but only a few members of each species (low species evenness).

What factors influence island biogeography.

* Climate
* Proximity to other land masses
* Age of island
* Size of the island
* Level of geographical isolation

Distinguish between a fundamental niche and a realized niche.

* The fundamental niche describes the full range of conditions and resources in which a species could survive and reproduce.
* The realized niche describes the actual conditions and resources in which a species exits due to biotic interactions.

Distinguish among ecosystem: inertia, constancy, resilience

* Inertia/persistence- is the ability of a living system to resist being disturbed or altered.
* Constancy- is the ability of a living system to keep its numbers within its limits.
* Resilience- is the ability of a living system to repair damage after an external disturbance.

Differentiate between primary and secondary succession. Give examples.

* Primary- occurs in an environment without pervious life (no soil)


* Ex. Abandoned parking lot
* Secondary- occurs in an area that had previously been inhabited but experienced disturbance. (soil)
* Ex. Wildfire

Nonnative species

Migrate or are introduced and find suitable niches

Native species

Indigenous to a given region or ecosystem

Keystone species

Their elimination may alter structure, function of community; typically low numbers.

Foundation species

The ecosystem engineers that may create or maintain habitat for other species.

Indicator species

Early warning of harmful environmental changes

Range of tolerance

Each population in an ecosystem has a ROT to variations in its physical and chemical environment.

Optimum range

level in which a population thrives

Limiting factor principle

too much or too little of any abiotic factor can limit or prevent growth of a population, even if all else is in optimal range.