An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an organism into unitary ‘traits’ and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analysed as integrated wholes, with Baupläne so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin’s own pluralistic approach to identifying the agents of evolutionary change.

The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme

An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an organism into unitary 'traits' and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the onlv brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analysed as integrated wholes, with Bauplane so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of nonadaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin's own pluralistic approach to identifying the agents of evolutionary change.

/pdf/the-spandrels-of-san-marco-and-the-panglossian-paradigm-a-19fdlsieru.pdf

Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.

/pdf/ocean-acidification-the-other-co-2-problem-4h18mw2cpj.pdf

Ocean Acidification: The Other CO 2 Problem

We review the biogeography of microorganisms in light of the biogeography of macroorganisms A large body of research supports the idea that free-living microbial taxa exhibit biogeographic patterns Current evidence confirms that, as proposed by the Baas-Becking hypothesis, 'the environment selects' and is, in part, responsible for spatial variation in microbial diversity However, recent studies also dispute the idea that 'everything is everywhere' We also consider how the processes that generate and maintain biogeographic patterns in macroorganisms could operate in the microbial world

/pdf/microbial-biogeography-putting-microorganisms-on-the-map-1k7e5do5pn.pdf

Microbial biogeography : putting microorganisms on the map

Darwin (1859, pp. 11-14, 143-150) stressed the evolutionary importance of covariation between characters in populations and its "most imperfectly understood" connection with correlated responses to artificial and natural selection. After the turn of the century the discoveries of pervasive pleiotropy and linkage of Mendelian factors revealed the underlying genetic mechanisms. Existing theory on the dynamics of correlated characters has been developed in the limited framework of practical plant and animal breeding. Methods of multivariate analysis, functional analysis and optimality criteria popular among evolutionists, do not account for dynamical constraints imposed by the pattern of genetic variation within populations. Consideration of phenotypic variation often does not suggest any clear mechanism connecting growth patterns or adult variation to interspecific evolution. When there is individual variation in development, no necessary correspondence exists between ontogenetic and adult variation in a population (Cock, 1966, pp. 148-15 1). It is also common for the pattern of adult variation within a species to differ from that at higher taxonomic levels (Simpson, 1953, pp. 25-29). An example which will be investigated here is the brain weight:body weight relationship. At various taxonomic levels, brain and body weights tend to follow the allometric equation

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1558-5646.1979.tb04694.x

Quantitative genetic analysis of multivariate evolution, applied to brain:body size allometry.

In this text, the author addresses, from a palaeobiologist's perspective, the question of whether punctuated equilibria - the view, popularized by Stephen Jay Gould among others, that species remain evolutionarily static for long periods of time, with substantial genetic changes and the development of new adaptive strategies occurring only during speciation, or gradualism - the view that large-scale changes result from continual and successive small-scale changes, offers the best account of the history of life. Coming down on the side of those who favour the model of punctuated equilibria, Stanley argues that only "quantum speciation" (rapid and radically divergent), can explain the story of life revealed in the fossil record; macroevolution, he contends, cannot be attributed to microevolutionary forces such as mutation, genetic drift and natural selection. Instead, he posits a series of processes, including species selection, phyletic drift and directed speciation, to accounnt for large-scale patterns.

Macroevolution, pattern and process

Relation of Shell Form to Life Habits of the Bivalvia (Mollusca)

Secular oscillations in the carbonate mineralogy of reef-building and sediment-producing organisms driven by tectonically forced shifts in seawater chemistry

Gradual evolutionary change by natural selection operates so slowly within established species that it cannot account for the major features of evolution. Evolutionary change tends to be concentrated within speciation events. The direction of transpecific evolution is determined by the process of species selection, which is analogous to natural selection but acts upon species within higher taxa rather than upon individuals within populations. Species selection operates on variation provided by the largely random process of speciation and favors species that speciate at high rates or survive for long periods and therefore tend to leave many daughter species. Rates of speciation can be estimated for living taxa by means of the equation for exponential increase, and are clearly higher for mammals than for bivalve mollusks.

https://www.pnas.org/content/pnas/72/2/646.full.pdf

A theory of evolution above the species level.

Cope's Rule is the name customarily applied to the widespread tendency of animal groups to evolve toward larger physical size. According to Kurten (1953), this paleontologic rule of evolution "is second in repute only to 'Dollo's Law' of . . .irreversibility." Although the rule was never concisely formulated by Cope, it is generally implicit in his writings (Cope, 1887, 1896). Like many other evolutionary generalizations extracted from the fossil record, Cope's Rule was derived primarily from study of mammalian phylogeny. Writers like Deperet (1909), Newell (1949), and Rensch (1959) have added diverse examples of evolutionary size increase to the mammalian trends discussed by Cope. Because numerous exceptions are known, recognition of the concept as a law has been rejected by most workers. Still, it has been widely upheld as a valid empirical generalization, and of the definitions for "rule" listed by Webster, "a generally prevailing condition," describes it accurately. Most modern interpreters of Cope's Rule have attributed its validity solely to certain fundamental advantages of size increase, at least one of which is alleged to have operated within most evolutionary lineages (Newell, 1949, p. 122-123; Kurten, 1953, p. 105; Simpson, 1953, p. 151; Rensch, 1959, p. 210-211; Gould, 1966b, p. 1138). Most of the proposed advantages of evolutionary size increase have been reviewed by Newell (1949), Kurten (1953), Rensch (1959), and Gould (1966a). Among the more salient are: improved ability to capture prey or ward off predators, greater reproductive success, increased intelligence (with increased brain size), better stamina, expanded size range of acceptable food, decreased annual mortality, extended individual longevity, and increased heat retention per unit volume. Certainly when evolutionary size increase occurs, it is in response to selection pressure resulting from one or more advantages. As Bonner (1968) pointed out, however, a net trend toward increased size within a higher taxon usually produces an increase in mean and maximum animal size, but not necessarily in minimum animal size. Selection pressure favoring size decrease is not rare but only less common than pressure favoring size increase. Reliance solely on inherent advantages of larger size to explain the high incidence of size increase suffers from deficiencies resembling some of those attached to the discarded concept of orthogenesis. The "inherent advantage" idea attempts only to account for directional evolution, without reference to limits. Clearly when size increase occurs in a

https://www.jstor.org/stable/pdfplus/2407115.pdf

Steven M. Stanley

Papers

Macroevolution, pattern and process

Relation of Shell Form to Life Habits of the Bivalvia (Mollusca)

Secular oscillations in the carbonate mineralogy of reef-building and sediment-producing organisms driven by tectonically forced shifts in seawater chemistry

A theory of evolution above the species level.

An explanation for cope's rule.