Unit 2 - The Living World: Biodiversity

biodiversity

the diversity of life forms in an environment

genetic diversity

a measure of the genetic variation among individuals in a population

population bottleneck

when a large population decline in number, the amount of genetic diversity carried by the surviving individuals is greatly reduced

species diversity

the number of species in a region or in a particular ecosystem

habitat diversity

the variety of habitats that exist in a given ecosystem

specialists

species that only live under a narrow range of biotic or abiotic conditions

ecosystem diversity

the variety of ecosystems that exist in a given region

species richness

the number of different species in a given area

species evenness

the relative proportion of individuals within the different species in a given area

ecosystem services

the processes by which life supporting resources such as clean water, timber, fisheries, and agricultural crops are produced

provision

a good produced by an ecosystem that humans can use directly

aquaculture

the farming of fish, shellfish, and seaweed

island biography

the study of how species are distributed and interacting on islands

species-area curve

a description of how the number of species on an island increase with the area of the island

ecological tolerance (fundamental niche)

the suite of abiotic conditions under which a species can survive, grow, and reproduce

realized niche

the range of abiotic antibiotic conditions under which is species actually lives

geographic range

areas of the world in which a species lives

mass extinction

a large number of species that when extinct over relatively short period of time

periodic distribution

occurring regularly, such as the cycles of day and night or the daily and monthly cycles of the moon’s effect on ocean tides

episodic distribution

occurring somewhat regularly, such as cycles of high rain and low rain that occur every 5 to 10 years

random distribution

occurring with no regular pattern, such as volcanic eruptions or hurricanes

resistance

in an ecosystem, a measure of how much a disruption can affect the flows of energy and matter

resilience

the rate at which an ecosystem returns to its original state after a disruption

intermediate disturbance hypothesis

the hypothesis that ecosystems experiencing intermediate levels of disturbance will favor a higher level of diversity of species than those with high or low disturbance levels

evolution

a change in the genetic composition of a population over time

microevolution

evolution at the population level

macroevolution

evolution that gives rise to new species, genera, families, classes, or phyla

evolution by artificial selection

the process in which humans determine which individuals to breed, typically with a preconceived set of traits in mind

evolution by natural selection

the process in which the environment determines which individuals survive and reproduce

fitness

an individual’s ability to survive and reproduce

adaptation

a trait that improves an individual’s fitness

evolution by random processes

the processes that alter the genetic composition of a population over time, but the changes are not related to differences in fitness among individuals

allopatric speciation

the process of speciation that occurs with geographic isolation

sympatric speciation

the evolution of one species into two species, without any geographic isolation

genetically modified organism (GMO)

an organism produced by copying genes from a species with some desirable trait and inserting them into other species of plants, animals, or microbes

ecological succession

the predictable replacement of one group of species by another group of species over time

primary succession

ecological succession occurring on surfaces with bare rock and no soil

pioneer species

in primary succession, species that can survive with little or no soil

secondary succession

the succession of plant life that occurs in areas that have been distributed but have not lost their soil

climax community

historically described as the final stage of succession

keystone species

a species that is not very abundant but has large effects on an ecological community

indicator species

a species that demonstrates a particular characteristic of an ecosystem

endemic species

species that live in a very small area of the world and nowhere else, often in isolated locations such as the Hawaiian Islands

biodiversity hotspots

isolated areas that are home to so many endemic species, that they contain a high proportion of all the species found on Earth