Observing adaptive evolution is difficult. In the fossil record, phenotypic evolution happens much more slowly than in artificial selection experiments or in experimental evolution. Yet measures of selection on phenotypic traits, with high heritabilities, suggest that phenotypic evolution should also be rapid in the wild, and this discrepancy often remains even after accounting for correlations between different traits (i.e. making predictions using the multivariate version of the breeder's equation). Are fitness correlations with quantitative traits adequate measures of selection in the (...) wild? We should instead view fitnesses as average properties of genotypes, while acknowledging that they can be environment‐dependent. Populations will tend to remain at fitness equilibria, once these are attained, and phenotypes will then be stable. Thus, studying the causes of adaptive change at a genotypic rather than phenotypic level may reveal that, typically, it is occurring too slowly to be easily observed. (shrink)

Throughout the history of evolutionary theory a number of scientists have argued that evolution proceeds along a limited number of definite trajectories, a concept and group of theories known as “orthogenesis”. Beginning in the 1880s, influential evolutionists including Theodor Eimer, Edward Drinker Cope, and Leo Berg argued that a fully causal explanation of evolution must take into account the origin and nature of variation, an idea that implied orthogenesis in their views. This paper argues that these orthogenesis developed theories that (...) were more than highly technical and theoretically dubious hypotheses accessible only to elite specialists, as certain histories of these ideas might suggest. Some orthogenesists made their case to a non-specialist audience to gain support for their ideas in the face of widespread controversy over evolutionary theory. Through a case study analysis of three major books by Eimer, Cope, and Berg, this paper contends that they sought to re-orient the central tenets of the science of evolution to include the causal impact of variation on evolutionary outcomes. These orthogenesists developed novel and synthetic evolutionary theories in a publishing platform suited for non-specialist audiences in an effort to impact the debates over evolutionary causation prevalent in the late-19th and early 20th centuries. (shrink)

Raphael Meldola (1849-1915), an industrial chemist and keen naturalist, under the influence of Darwin, brought new German studies on evolution by natural selection that appeared in the 1870s to the attention of the British scientific community. Meldola's special interest was in mimicry among butterflies; through this he became a prominent neo-Darwinian. His wide-ranging achievements in science led to appointments as president of important professional scientific societies, and of a local club of like-minded amateurs, particularly field naturalists. This is an account (...) of Meldola's early scientific connections and studies related to entomology and natural selection, his contributions to the study of mimicry, and his promotion in the mid-1890s of a more theory driven approach among entomologists. (shrink)

In the life of any species, extinction is the final evolutionary process. It is a common one at present, as the world is entering a major extinction crisis. The pattern of extinction and threat is very non-random, with some taxa being more vulnerable than others. Explaining why some taxa are affected and some escape is a major goal of conservation biology. More ambitiously, a predictive model could, in principle, be built by integrating comparable studies of past and present extinctions. We (...) review progress towards both explanatory and predictive frameworks, comparing correlates of extinction in different groups at different times. Progress towards explanatory models for the current crisis is promising, at least in some well-studied taxa, but the development of a truly predictive model is hampered by the formidable difficulties of integrating studies of present and past extinctions. BioEssays 22:1123–1133, 2000. © 2000 John Wiley & Sons, Inc. (shrink)

This article analyzes the role, decisive but all-too unknown, played by the American paleontologist and embryologist Edward Drinker Cope in the argumentation, both biological and metaphysical, of Bergson in his Evolution créatrice. As in the cases of Weismann and, negatively, of Haeckel, this role is all the more important that it is less visible in the explicit references. It concerns three questions: that of aging, which is, for Bergson, the mark of the duration on the organism; that of photosynthesis, which (...) is the chemical phenomenon to which all life is suspended; and, above all, that of the difference between life and matter. This difference is seen by Bergson from the standpoint of a science to which Cope gives great importance too, namely the thermodynamics. (shrink)