Four Darwinian themes on the origin, evolution and preservation of island life

The above excerpts of quotations from Charles Darwin’s writings, which I present and discuss in detail below, capture themes that proved seminal for generations of scientists who were equally captivated by both the marvels and the perils of island life. Although presented as I have done so above as disarticulated and seemingly unrelated metaphors and observations, these passages from Darwin’s publications serve as mile markers along a professional and personal journey shared by most scientists who study island life: one that progresses from an innate attraction for insular biotas, to an astonishment over their distinct and seemingly bizarre character, a quest to explain these phenomena in the most fundamental terms, and finally to a sobering understanding of the fragility of island life and of our obligations as scientists and the planet’s only global stewards to conserve these imperilled biotas. Darwin, of course, was not the first naturalist to study the diversity and singular nature of island life, but his classic works clearly constitute a seminal nexus in the reticulating phylogeny of island theory. Perhaps just as important, Darwin remarked on the decline of nature over a century before ‘biodiversity’ and ‘conservation biology’ were first articulated. Here I provide an historical and prospective overview of the development of theory on the ecological and evolutionary assembly of insular biotas and, in particular, the continuing capacity of island studies to provide fundamental insights for conserving the diversity and natural character of native biotas. In forming his theory of natural selection, Darwin drew heavily on studies of the effects of artificial selection on domestic livestock. Thus, I see fitting irony and symmetry in the prospect that the tables should now be turned; that our abilities to predict and hopefully mitigate the effects of artificial selection incurred through species introductions, overharvesting and anthropogenic insularization (via habitat loss and fragmentation) rest heavily on the revelations of Darwin and generations of countless others who studied the effects of natural selection on isolated biotas. The relevance of island studies is only likely to increase as their native biotas become ever rarer, and as an increasing proportion of continental biotas become more restricted to island-like ecosystems (e.g. wildlife parks, nature reserves and other remnants of once expansive and continuous, native ecosystems). My purpose here is to discuss four themes inspired by the research and writings of Charles Darwin; themes on the assembly (and disassembly) of insular biotas which continue to hold great promise for providing insights into their ecological and evolutionary development, and for conserving the natural character and evolutionary potential of species restricted to isolated ecosystems (natural or anthropogenic). The first theme describes how selective pressures on islands are often College of Environmental Science and Forestry, Syracuse, NY 13210, USA