IB Environmental systems and societies 3.1 Biodiversity and Evolution Key Definitions

Adaptation is a heritable trait that increases an organism’s chances of survival and reproduction in a particular environment.

Anthropocene means “the age of humans”, emphasizing the unprecedented role humans play in altering Earth’s geology, atmosphere, and biosphere.

Artificial selection, unlike natural selection, is a human-driven process in which specific traits are chosen for breeding in plants and animals.

Biodiversity refers to the variety of life in an ecosystem, encompassing different levels of biological organization.

A biogeographic region that has exceptionally high levels of species richness and endemism but is also under significant threat from human activity.

Ecosystem resilience refers to an ecosystem’s ability to recover from disturbances and return to its original state or adapt to a new equilibrium.

Endemism refers to species that exist only in one geographic location, such as an island, mountain range, or isolated ecosystem.

Evolution is the cumulative change in the heritable characteristics of a population over generations.

Fossils are preserved remains, traces, or imprints of ancient organisms found in sedimentary rocks.

Genetic diversity is the variety of genes within a species, allowing for adaptation to environmental changes.

Genetic recombination refers to the random mixing of parental genes during meiosis and fertilization, creating genetically unique offspring.

Habitat diversity is the range of different habitats present in an ecosystem or within a geographical area.

The International Union for Conservation of Nature (IUCN) is the global authority on the conservation status of species.

A keystone species is an organism that has a disproportionately large impact on its ecosystem relative to its population size.

A mutation is a random change in DNA that introduces new genetic variants (alleles).

Natural selection is the primary mechanism behind evolutionary change, shaping species over time and leading to the incredible biodiversity we see on Earth today.

Reproductive isolation is the prevention of gene flow between populations due to physical, ecological, or behavioral barriers.

Selective pressure refers to any environmental factor (natural or human-made) that influences which traits are favorable for survival and reproduction in a population.

Simpson’s Reciprocal Index (D) is a quantitative measure of species diversity, used to: compare biodiversity between different ecosystems, monitor changes in biodiversity over time within a specific area and assess ecosystem health,

Speciation is the process by which new species evolve from an existing population due to isolation and adaptation.

Species diversity is the variety of species in an ecosystem, including both species richness (the number of species) and species evenness (the relative abundance of each species).

Species evenness is the relative abundance of each species in a community.

Species richness is the total number of different species present in a community.

Variation refers to the differences in traits among individuals of a population, resulting from genetic and environmental factors.