ch. 4 environmental

biological evolution

biological evolution

process by which species change genetically overtime

natural selection

process by which individuals with certain genetic traits are more likely to survive and reproduce under a specific set of environmental conditions, thereby passing these traits on to their offspring

fossil

preserved remains or traces of prehsitoric

biodiversity

Variety of life on Earth, including species diversity, genetic diversity, ecological diversity, and functional diversity.

ecosystem diversity

Earth’s diversity of biological communities such as deserts, grasslands, forests, lakes, rivers, and wetlands.

insurance hypothesis

Hypothesis stating that biodiversity ensures ecosystems against a decline in their functioning because many species provide greater guarantees of functioning even if others fail.

species diversity

Variety of species present in a specific ecosystem and their abundance within that ecosystem.

biome

Geographical area composed of different ecosystems and characterized by a distinct climate and certain species (particularly vegetation) that are able to survive there.

genetic diversity

Variety of genes found in a population or in a species.

functional diversity

functional diversity Variety of processes that occur with ecosystems. Examples include energy flow and cycles of matter.

ecological niche

Role that a species plays in an ecosystem, encompassing everything that affects its survival and reproduction.

specialist species

Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or eat only one type or a few types of food.

keystone species

Species that preserves an ecosystem by controlling the populations of prey animals which could otherwise consume enough plant matter to devastate the ecosystem. Examples include wolves, sea otters, alligators, and sharks.

habitat

Area that provides the abiotic and biotic factors a species needs to survive.

native species

Species that naturally originated in a given ecosystem and have become suited to the environmental conditions there.

indicator species

Species whose presence or absence indicates the quality or characteristics of certain environmental conditions.

generalist species

Species with a broad niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions.

nonnative species

Species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans.

genetic variability

Variety in the genetic makeup of individuals in a population.

mutation

Permanent change in the DNA sequence within a gene in any cell.

adaptation

Any heritable trait that gives an individual some advantage over other individuals in a given population.

speciacion

Formation of a new species from a branch of an existing species through reproductive isolation.

geographic isolation

Separation of populations of a species into different areas. It may occur because of a search for food, a natural event (such as a hurricane, earthquake, or volcanic eruption), or a physical barrier, either natural (such as a mountain or valley) or created by humans (such as a dam or a clearing in a forest).

reproductive isolation

Halt in the exchange of genes due to the separation of populations. Eventually, members of isolated populations may have very different genetic makeup and no longer be able to interbreed, meaning they have become two distinct species.

biological extinction

Complete disappearance of a species from Earth. It happens when a species cannot adapt to survive and reproduce in response to changes in their environment and cannot move to a new environment with more favorable conditions

endemic species

Species that is found in only one area. Such species are especially vulnerable to extinction.

background extinction rate

Naturally low rate at which species have disappeared throughout most of Earth’s history.

mass extinction

Significant rise in extinction rates well above the background extinction rate.

artificial selection

Process by which humans select one or more desirable genetic traits in the population of a plant or animal species and then use selective breeding to produce populations containing many individuals with the desired traits.

genetic engineering

Scientific manipulation of genes in order to select desirable traits or eliminate undesirable ones. It allows scientists to alter an organism’s genetic material by adding, deleting, or changing segments of its DNA in a process called gene splicing.

synthetic biology

Technology that enables scientists to make new sequences of DNA and to use such genetic information to design and create new cells, tissues, organisms, and devices, and to redesign existing natural biological systems.