Adapting to less: Revisiting the island syndrome through MacArthur’s blurry glasses
Köhler, Meike (Institut Català de Paleontologia Miquel Crusafont)

Date:	2026
Abstract:	What is the island syndrome, and why does it emerge repeatedly across taxa on small-to-medium islands, across latitudes, and throughout geological time? The wide range of interpretations surrounding this phenomenon often obscures broader evolutionary patterns—like a forest hidden by its trees. This paper approaches the island syndrome from a bioeconomic perspective and proposes a classification of its defining traits. To guide this analysis, I draw comparisons with troglomorphism—the cave equivalent of the island syndrome—which is better understood and offers a useful structural framework. Amid the complexities of island adaptation, the extinct Balearic caprine Myotragus, with its five-million-year evolutionary history and extreme insular traits—from metabolic to sensory, locomotor, digestive and life history adaptations—serves as a valuable model. Following a brief historical overview, I examine the ecological parallels between caves and islands and explore energy use from the perspective of metabolic economy. Because organ size and function strongly influence resting metabolic rate, I investigate reductions in energetically costly structures—such as brain regions—alongside compensatory expansions in others. Changes in field metabolic rate and behavioural adaptations are also considered. By tracing these bioeconomic shifts and momentarily adopting MacArthur’s “blurry glasses” to favour general patterns over fine detail, I propose a preliminary classification of island syndrome traits, organized into the categories of reduction, enhancement, and time. This framework, inspired by studies of cave evolution, highlights the directional nature of adaptation under constraint and offers a new perspective on how energy-limited environments shape life.
Grants:	Agencia Estatal de Investigación PID2020-117118GB-I00 Generalitat de Catalunya 2022/SGR-01184
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Bioeconomy ; Convergent evolution ; Low-energy environments ; Myotragus ; Single causal mechanism ; Trait classification
Published in:	Journal of Mammalian Evolution, Vol. 33, Num. 31 (June 2026) , ISSN 1573-7055

DOI: 10.1007/s10914-026-09806-6

45 p, 7.1 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Institut Català de Paleontologia Miquel Crusafont (ICP)
Articles > Research articles
Articles > Published articles