Extreme environmental change and evolution: stress-induced morphological variation is strongly concordant with patterns of evolutionary divergence in shrew mandibles

Abstract

Morphological structures often consist of simpler traits which can be viewed as either integrated (e.g. correlated due to functional interdependency) or non-integrated (e.g. functionally independent) traits. The combination of a long-term stabilizing selection on the entire structure with a short-term directional selection on an adaptively important subset of traits should result in long historical persistence of integrated functional complexes, with environmentally induced variation and macroevolutionary change con¢ned mostly to non-integrated traits. We experimentally subjected populations of three closely related species of Sorex shrews to environmental stress. As predicted, we found that most of the variation in shrew mandibular shape was localized between rather than within the functional complexes; the patterns of integration did not change between the species. The stress-induced variation was con¢ned to nonintegrated traits and was highly concordant with the patterns of evolutionary changeöspecies di¡ered in the same set of non-integrated traits which were most sensitive to stress within each species. We suggest that low environmental and genetic canalization of non-integrated traits may have caused these traits to be most sensitive not only to the environmental but also to genetic perturbations associated with stress. The congruence of stress-induced and between-species patterns of variation in non-integrated traits suggests that stress-induced variation in these traits may play an important role in species divergence.

Genome-wide comparison of cyanobacterial transposable elements, potential genetic diversity indicators

“…Previous studies indicated that unique morphological, physiological and genetic characters were always found in organisms from the extreme environments [ (Badyaev and Foresman, 2000) and (Rothschild and Mancinelli, 2001)]. Zhou et al (2008) concluded that hot spring seems to be one of the favorite living environments for organisms with active IS elements (Zhou et al, 2008).…”

Evolutionary innovations in the fossil record: the intersection of ecology, development, and macroevolution

“…(e) Environmental stress: Many authors have argued for a link between evolutionary innovation and environmental stress, defined in terms of the physiological tolerances of the organism rather than any absolute measure of environmental variability (e.g., Parsons, '93;Hoffmann and Parsons, '97;Badyaev and Foresman, 2000;Hoffman and Hercus, 2000;Nevo, 2001). Although many potential mechanisms for the stress-novelty link have been proposed, the most striking have recently come from molecular biologists.…”

The Evolution of Sexual Dimorphism in the House Finch. I. Population Divergence in Morphological Covariance Structure

“…Of a special theoretical and empirical interest is the question of temporal persistence of genetic covariance structure. In particular, understanding temporal constancy of genetic covariance patterns can enable us to explore mechanisms behind population divergence (Lande 1985;Price and Grant 1985;Grant and Grant 1995;Cheverud 1996;Arnold and Phillips 1999;Camara and Pigliucci 1999;Badyaev and Foresman 2000).…”

“…If genetic covariance matrix remains constant over time since divergence and genetic drift is the primary cause of divergence, we expect (1) congruency or proportionality among population matrices (Lande 1980;Lofsvold 1988;Armbruster 1991;Bjö rklund 1994;Badyaev and Foresman 2000), i.e., the morphological diversification among house finch populations should occur in the directions predicted by within-population correlation or covariance structures (Schluter 1996); and (2) concordance in patterns of divergence in covariance matrices between males and females. Alternatively, if population divergence resulted from locally distinct selection pressures, no congruence would be expected both between within-and among-population covariance structures and between divergence of male and female covariance structures (Lande 1985;Riska 1985;Zeng 1988;Arnold and Phillips 1999;Camara and Pigliucci 1999).…”