🗂️ Taxonomy &amp; Biodiversity

Taxonomy

The science of naming, describing and classifying organisms.

Binomial Nomenclature

Linnaeus's two-part naming system using genus and species, such as Homo sapiens.

Taxonomic Hierarchy

Domain, kingdom, phylum, class, order, family, genus and species form nested ranks.

Three Domains of Life

Bacteria, Archaea and Eukarya, based on fundamental cell differences and rRNA.

Kingdoms

Major groups of eukaryotes: animals, plants, fungi and protists, plus prokaryotes.

Species

A basic unit of classification; organisms that can interbreed and produce fertile offspring.

Biodiversity

The variety of life at the level of genes, species and ecosystems.

Dichotomous Keys

Step-by-step tools using paired choices to identify organisms.

Endemic Species

Species found naturally only in one specific geographic area, like lemurs in Madagascar.

Invasive Species

Non-native organisms that spread and harm local ecosystems and economies.

Endangered Species

Species at high risk of extinction, listed on the IUCN Red List.

Biodiversity Hotspots

Regions with exceptional endemic species that are highly threatened by habitat loss.

Conservation Biology

The scientific study and protection of biodiversity.

Habitat Loss

Destruction of natural habitats by farming, logging and urbanisation, the leading threat to species.

Living Fossils

Species like the coelacanth and ginkgo that resemble ancient lineages with few relatives.

Intermediate topics (17)

Linnaeus

Carl Linnaeus, the 18th-century Swedish scientist who established the modern hierarchical classification system.

Phylogenetic Classification

Groups organisms by evolutionary relationships so that taxa reflect common ancestry.

Monophyletic Groups

A group containing an ancestor and all of its descendants, called a clade.

Paraphyletic and Polyphyletic

Paraphyletic groups omit some descendants; polyphyletic groups lack the most recent common ancestor.

Cladograms

Branching diagrams showing patterns of shared derived traits among taxa.

Shared Derived Characters

Novel traits inherited from a recent common ancestor that define a clade.

Molecular Systematics

Uses DNA and protein sequences to infer relationships between organisms.

DNA Barcoding

Identifying species using short standardised gene regions such as COI in animals.

Species Richness and Evenness

Richness counts species; evenness describes how equally individuals are distributed among them.

Simpson and Shannon Indices

Mathematical measures that combine richness and abundance to quantify diversity.

Latitudinal Diversity Gradient

Species richness generally increases from poles toward the tropics.

Species-Area Relationship

Larger areas contain more species, commonly following a power law.

Genetic Diversity

Variation of alleles within a species that enables adaptation and resilience.

Ecosystem Diversity

The variety of habitats, communities and ecological processes in a region.

Threats to Biodiversity

Habitat loss, invasive species, pollution, overexploitation and climate change, often remembered as HIPPO.

Protected Areas

National parks and reserves that conserve species and habitats under legal protection.

Ex-situ Conservation

Protecting species outside natural habitat in zoos, seed banks and botanical gardens.

Advanced topics (20)

Species Delimitation

Methods integrating morphology, genetics and ecology to decide where species boundaries lie.

Cryptic Species

Distinct species that look nearly identical and are separated only by molecular or behavioural evidence.

Hybridisation and Species Boundaries

Gene exchange between species blurs lines, as in polar and grizzly bear hybrids.

Horizontal Transfer and the Tree of Life

Gene exchange among microbes makes their ancestry network-like rather than strictly tree-like.

PhyloCode

A proposed rank-free nomenclature that names clades by their ancestry.

Phylogenetic Diversity

Measures biodiversity by the total evolutionary history represented by a set of species.

Evolutionarily Distinct Species

Species with few close relatives, such as the tuatara, representing unique branches of evolutionary history.

Extinction Rate Estimation

Compares fossil background rates with current losses, suggesting a sixth mass extinction.

IUCN Red List Criteria

Quantitative thresholds for population size, decline and range classify species from Least Concern to Extinct.

Population Viability Analysis

Models estimate the probability a population persists given demographic and environmental risks.

Minimum Viable Population

The smallest population size with a high chance of long-term persistence.

Genetic Rescue

Introducing individuals from other populations to reverse inbreeding depression, as with Florida panthers.

Rewilding

Restoring ecosystems by reintroducing species and natural processes.

Conservation Genomics

Applies genome data to guide management, assess diversity and track illegal trade.

Biodiversity and Ecosystem Function

Experiments show richer communities often have higher productivity and stability.

Environmental DNA

DNA shed by organisms into water or soil allows detection of species without capturing them.

Community Phylogenetics

Uses phylogenetic distance among co-occurring species to infer assembly processes.

Citizen Science in Biodiversity

Public observations on platforms such as iNaturalist provide large-scale data on species distributions.

Biogeographic Regions

Wallace's realms divide the Earth by distinctive faunas shaped by plate tectonics and dispersal.

Systematics Software and Databases

Tools like GenBank and the Tree of Life Web Project organise and share biodiversity data.