Evolutionary Biology

Ageing: biological mechanisms, evolutionary explanations, and societal effects Ageing A clear overview of ageing (senescence): its biological basis, evolutionary theories, population patterns, medical relevance, and distinctions between ageing, disease, and non‑agei…

Alfred Russel Wallace: naturalist, biogeographer and co-discoverer of natural selection Alfred Russel Wallace British naturalist (1823–1913) who independently proposed natural selection, mapped the Wallace Line, and pioneered biogeography through extensive fieldwork in the Amazon and Malay…

Amotz Zahavi: Israeli evolutionary biologist and originator of the handicap principle Amotz Zahavi Israeli evolutionary biologist Amotz Zahavi (1928–2017) proposed the handicap principle to explain honest biological signalling; he taught at Tel Aviv University and co-founded the…

Amphibian: biology, life cycle, evolution and conservation Amphibian Overview of amphibians (class Amphibia): major groups, anatomy, life cycle, fossil origins, diversity, habitats and modern conservation challenges.

Apomorphy (biology): derived traits and their role in phylogeny Apomorphy An apomorphy is a derived character state that distinguishes a clade. This article explains definitions, types (synapomorphy, autapomorphy), examples, phylogenetic use, and complic…

Archaea Archaea are a domain of microscopic single-celled life distinct from bacteria and eukaryotes, notable for unusual cell chemistry, early evolutionary importance, and many species ad…

B chromosome (supernumerary or accessory chromosome) B chromosome Extra chromosomes found in some individuals of a species that are not necessary for survival; often heterochromatic, variably inherited, and of evolutionary and ecological interest…

Beetle (Order Coleoptera): Diversity, Biology, and Importance Beetle Beetles (Coleoptera) are the largest order of insects, with hundreds of thousands of described species and great ecological, economic, and evolutionary significance worldwide.

Butterfly: biology, life cycle, evolution, and human interactions Butterfly An accessible overview of butterflies: their classification, anatomy, life cycle, evolution with flowering plants, roles as pollinators, and human interest and conservation.

Cambrian explosion: rapid diversification of animal life in the early Paleozoic Cambrian explosion The Cambrian explosion refers to the relatively brief geological interval around 541 million years ago when most major animal body plans first appear in the fossil record, promptin…

Charles Darwin's Books: scope, major works and lasting influence Charles Darwin's books Survey of Charles Darwin's principal books, their subjects, structure, historical context, and influence on sciences such as geology, zoology, botany and evolutionary biology.

Chelicerata: anatomy, evolution, diversity and ecological roles Chelicerata Chelicerata are a major arthropod subphylum including arachnids and horseshoe crabs, defined by chelicerae and a two-part body; they have a long fossil record and play key ecologic…

Cline (biology) — Gradients of variation across populations Cline A cline is a continuous change in a trait or gene frequency across geographic or environmental space, arising from selection, gene flow, and history. It helps explain adaptation, s…