ESS 3.1 Biodiversity and Evolution

Biodiversity

The total diversity of living systems, composed of species, habitat diversity, and genetic diversity.

Genetic Diversity

The range of genetic material present in a population of a species, crucial for resilience to change.

Gene Pool

The collection of different versions of genes within a species, indicating its resilience to change.

Species Diversity

The diversity of species in a given unit of area for a given period of time, a product of species richness and evenness.

Species Richness

The number of species in a community.

Species Evenness

The relative proportions of different species in a given area, reflecting the similarity of population sizes for each species.

Habitat Diversity

The range of different habitats in a given area, impacting overall biodiversity by providing varied microclimates and niches.

Resilience (Ecosystem)

The ability of a system to resist change and to return to an equilibrium despite inputs that could push it away from that stable state.

Ecosystem Complexity

Characterized by more connections in a food web, which leads to stability as consumers can switch to other food sources.

Negative Feedback Loops

Mechanisms within a system that help return it to equilibrium and resist change.

Positive Feedback Loops

Inputs that trigger a cascade, potentially increasing system resilience or pushing it away from an equilibrium.

Trophic Cascade

An ecological process that starts at the top of the food chain and has effects throughout lower trophic levels, such as in rewilding projects.

Keystone Species

A species that provides a bigger than expected impact on its habitats and whose protection improves the resilience of the whole ecosystem.

Genetic Drift

Random events that can cause changes in a population's gene pool, particularly problematic in smaller populations.

Population Bottleneck

A sharp reduction in the size of a population due to environmental events, leading to a significant loss of genetic diversity.

Inbreeding Depression

A phenomenon where rare deleterious alleles come together in smaller, inbred populations to cause genetic problems.

Evolution

The cumulative change in the heritable characteristics of a population or species over time.

Biological Variation

Differences in characteristics within a species that arise from random mutations to DNA, providing the raw material for diversity.

Mutations

Changes in the sequence of DNA bases that can be harmless, negative, or beneficial, leading to genetic diversity.

Natural Selection

A process where individuals with adaptations better suited to an environment are more likely to survive and reproduce, passing on advantageous genes.

Carrying Capacity

The maximum population size of a species that an ecosystem can sustain indefinitely given the available resources.

Adaptation

A heritable characteristic that enables an individual to survive and reproduce more effectively in its environment.

Speciation

The generation of new species through evolutionary processes, typically occurring slowly over many generations.

Adaptive Radiation

A process where a single ancestral species evolves into multiple diverse species, each adapted to fill different ecological niches, often seen on islands.

Geographical Isolation

The physical separation of populations by external barriers (e.g., mountains, rivers), preventing gene flow and potentially leading to speciation.

Reproductive Isolation

The inability of populations to interbreed and produce fertile offspring, a key factor in the formation of new species.

DNA (Deoxyribonucleic Acid)

The genetic material of life, passed from one generation to the next, carrying the instructions for an organism's development and function.

Chromosomes

Structures located in the nucleus of eukaryotic cells that contain condensed DNA.

Alleles

Different variants of the same gene, found at the same locus on homologous chromosomes.

Meiosis

A type of cell division that reduces the number of chromosomes in the parent cell by half, creating four gamete cells, and involves crossing-over for genetic variation.

Environmental Mutagens

Agents in the environment, such as certain chemicals or high-energy radiation (e.g., UV, X-rays), that can cause mutations in DNA.

Simpson's Reciprocal Index (D)

A mathematical formula used to quantify species diversity in an ecosystem, with higher values indicating greater diversity.

Sampling Strategies

Methods such as random sampling, quadrats, or transects used to estimate species diversity and abundance in an ecosystem when a complete count is not feasible.

Allopatric Speciation

Speciation that occurs due to the geographical isolation of populations.

Sympatric Speciation

Speciation that occurs within the same geographical area without physical separation, often driven by ecological or behavioral differences.

Parapatric Speciation

Speciation that occurs along a continuous habitat boundary where populations share a hybridization zone but evolve distinct characteristics.

Endemism

The condition of a species being unique to a specific geographic region and found nowhere else in the world.

Biodiversity Hotspot

A biogeographic region with significant levels of biodiversity that is threatened by human habitation, defined by criteria of endemic plants and habitat loss.

Artificial Selection

The process by which humans selectively breed organisms for particular desirable characteristics, increasing their frequency in subsequent generations.

Mass Extinction Event

A period in Earth's history characterized by the rapid and widespread disappearance of a significant proportion of species across the globe.

Background Rate of Extinction

The natural, ongoing rate at which species become extinct over geological time, typically measured as one species per year based on fossil records.

6th Mass Extinction Event

The current period identified by scientists where extinction rates are significantly higher than the background rate, largely driven by human activities.

Anthropocene

A proposed new geological epoch characterized by profound and widespread environmental changes caused by human activities.

Global Boundary Stratotype Section and Point (GSSP)

A 'golden spike' location that serves as an internationally agreed-upon reference point for the lower boundary of a geological stage or epoch.

The Great Acceleration

A period beginning around the 1950s, marked by a sharp increase in human socio-economic and Earth system trends, a strong candidate for the start of the Anthropocene.