Editorial: evolutionary innovation and morphological novelty

Abstract

New York Medical College, Valhalla, New York, NY, USAOOThere are fashionable problems and thereare neglected problems in any Þeld of re-search. The problem of the emergence ofevolutionary novelties has undoubtedly beengreatly neglected during the past two or threedecades, in spite of its importance in thetheory of evolution.OOWith these words, Ernst Mayr introduced his1960 contribution to the volume edited by Sol Taxon the occasion of the University of Chicagosymposium that commemorated the centennial ofthe publication of On the Origin of Species .Indeed, innovation had been thoroughly consid-ered by Darwin, in particular after MivartOsobjections, and by several individual workersthereafter, such as Romanes, Weisman, Berrill,Baldwin, and Gregory. In general, however, thesuccess of population genetics in the Þrst half ofthe twentieth century quelled any concertedattempts to delve further into these questions inevolutionary research. The variation of the exist-ing was much easier to study than the originationof the unprecedented. The result was that whatcame to be referred to as the neo-DarwinianSynthesis contained no research program to studythe origin of morphological novelties and theunderlying mechanisms of innovation. Mayr wasright, the problem was neglected, but theorydetermines what we study, and since the leadingparadigm was one of small, gradual, and contin-uous variation, anything really new was notperceived or recorded as such. Even though Mayrrecognized in his 1960 article that the problemof morphological novelty was one of qualita-tive rather than of quantitative change, hestrived to provide a gradualist explanation thatinvoked no mechanisms beyond the standard neo-Darwinian ones of populational shifts in variantsof small effect.The situation began to change with the rise ofEvoDevo in the 1980s. Although many trace thebeginnings of this Þeld to the successes ofdevelopmental molecular genetics and the discov-ery of the homeobox, efforts toward this expansionof the scope of evolutionary theory began wellbefore. It was precisely the inability of the neo-Darwinian synthesis to account for many phenom-ena of higher-level phenotypic organization thatstimulated interest in the mechanistic processesthat generate these phenomena, novelty centralamong them. A major step towards taking innova-tion seriously was the 1988 Spring SystematicsSymposium, Evolutionary Innovations: Patternsand Process , held at the Field Museum of NaturalHistory in Chicago (Nitecki, 1990). Here, a groupof evolutionary biologists, who had been consider-ing the problems of innovation and novelty from avariety of perspectives and disciplines, werebrought together with developmental biologistswho contributed knowledge of mechanisms inhe-rent to developmental systems that could con-tribute to the explanation of novelty generation.A second meeting was held in the following yearon the role of symbiosis as a source of evolutionaryinnovation at Bellagio, Italy. (Margulis and Fester,1991). A theoretical reframing of the noveltyproblem, focused largely on its mechanistic,developmental aspects, began to take shape atthe same time (Mu ¬ ller and Wagner, 1991).The main reason for convening the symposiumMorphological Innovations at the 2003 NewOrleans meeting of the Society of Integrative andComparative Biology was that both contentand context in the discourse around evolutionarybiology has changed since the two earlier inno-