Animal Distribution and Zoogeography

Zoogeography studies where animals live and why, explaining the patterns of animal distribution across the globe through ecology, history, and the movement of continents.

Definition

Animal distribution and zoogeography is the study of the geographic ranges of animals and of the ecological and historical processes, including dispersal, vicariance, and plate tectonics, that determine where animal groups occur on Earth.

Scope

This topic covers the geographic distribution of animals and the processes that shape it. It describes the world's major faunal regions, each with a distinctive animal community, and explains distribution patterns through present-day ecological factors such as climate and habitat, through dispersal across and around barriers, and through history, including continental drift, past climate change, and the rise and fall of land connections. It distinguishes ecological from historical biogeography.

Core questions

• What are the major faunal regions of the world, and how do their animals differ?
• Which ecological factors set the limits of an animal's geographic range?
• How do dispersal and barriers shape distributions?
• How have continental drift and Earth history molded animal distributions?

Key theories

Faunal regions

The land surface can be divided into biogeographic regions, each characterised by a distinctive assemblage of animals, a scheme founded on the observation that major barriers separate sharply different faunas.

Dispersal, vicariance, and Earth history

Distributions are explained both by the spread of animals across barriers, dispersal, and by the splitting of once-continuous ranges when barriers such as drifting continents arise, vicariance, so present patterns reflect both ecology and deep history.

Mechanisms

An animal's range is bounded by where conditions permit survival and reproduction and by the dispersal that brings it to suitable places. Physical and climatic factors, such as temperature, moisture, and habitat type, set ecological limits, while barriers like oceans, mountains, and deserts impede movement and isolate faunas, producing the distinct biogeographic regions. Over geological time, the movement of continents has carried animals apart and brought once-separated lands into contact, so that vicariance, the fragmentation of a range by a new barrier, and dispersal, the crossing of barriers, together explain why related animals occur where they do. Past climate change and the formation or loss of land connections add further layers to these patterns.

Clinical relevance

Zoogeography underpins conservation planning and the identification of biodiversity hotspots, the prediction of how species and their ranges respond to climate change, and the understanding and management of invasive species and the geographic spread of disease vectors. This is educational context, not clinical advice.

History

Philip Sclater proposed biogeographic regions based on bird distributions in 1858, and Alfred Russel Wallace developed and synthesised the field, mapping the world's faunal regions and identifying the sharp faunal boundary now called Wallace's Line. The mid-twentieth-century acceptance of plate tectonics gave zoogeography a powerful historical explanation, allowing many distributions to be understood through continental drift and vicariance.

Key figures

• Alfred Russel Wallace
• Philip Sclater
• Joseph Dalton Hooker

Seminal works

• hickman2020
• cox2016

Frequently asked questions

What is zoogeography?

Zoogeography is the branch of biogeography concerned with the geographic distribution of animals and the ecological and historical processes that explain where different animal groups are found.

What is Wallace's Line?

Wallace's Line is a sharp biogeographic boundary in the Malay Archipelago, identified by Alfred Russel Wallace, that separates the strikingly different animal faunas of Asia and Australia.