Abstract:

Background & Aims: Alfred Russel Wallace is widely known for his work alongside Charles Darwin on natural selection, and for his foundational work in biogeography. Specimen collecting in different regions and extensive knowledge of natural history enabled Wallace to explore the relationship between species traits and the associated environments in which they evolve. His work in the Malay Archipelago led to the establishment of what is now known in biogeography as the “Wallace Line”, which separates the Oriental Realm from the Australasian Realm in zoogeographic terms. Beyond these well-known achievements, this paper reviews Wallace’s contributions to the study of animal body coloration, in particular his pioneering articulation of animal coloration, including crypsis and mimicry in animals, and his initial proposal of the evolutionary mechanisms behind them.

Progress: Wallace’s work on the division of animal body colors and their mechanisms is still relatively comprehensive. This is likely due to his extensive fieldwork, his collection of insect and bird specimens, and his deep understanding of the principles of natural selection. The definitions and hypotheses he proposed encouraged generations of ecologists to explore animal body colors through experiments and theoretical models. For instance, Wallace’s definition of protective colors has been confirmed by many classic behavioral experiments; his hypothesis on warning colors initiated Ronald Fisher’s theory on the evolution of aposematism; and his observations on the mimicry of insects and birds have led to several taxa becoming classical systems in understanding the evolution of trait convergence, which prompted later scholars to formulate compelling hypotheses explaining their functions and evolutionary trajectories. Remarkably, in some animal taxa the mimicry mechanism has been investigated at the genomic level, leading to recent confirmation that supergene (supergene) and adaptive introgression are important contributors in the mimicry patterns among multiple species.

Prospects: As research methods continue to improve, Wallace’s work on the evolution of animal body coloration will continue to promote in-depth studies from contemporary scholars. In addition to quantifying body coloration more precisely and unravelling the mechanisms of body coloration from a genomic perspective, this paper emphasizes the need for more studies that concentrate on the distributional patterns and co-evolution of body coloration, which are still not clearly linked to how species adapt to their environments. This is a key area for further research, especially given today’s rapidly changing environment.

Key words: Wallace, animal coloration, crypsis, mimicry, genome, global change