Consequences of inter-population crosses on developmental stability and canalization of floral traits inDalechampia scandens(Euphorbiaceae)

Abstract

Congruence between changes in phenotypic variance and developmental noise in inter‐population hybrids was analysed to test whether environmental canalization and developmental stability were controlled by common genetic mechanisms. Developmental stability assessed by the level of fluctuating asymmetry (FA), and canalization by the within‐ and among‐individual variance, were measured on several floral traits of Dalechampia scandens (Euphorbiaceae). Hybridization affected canalization. Both within‐ and among‐individual phenotypic variance decreased in hybrids from populations of intermediate genetic distance, and strongly increased in hybrids from genetically distant populations. Mean‐trait FA differed among cross‐types, but hybrids were not consistently more or less asymmetric than parental lines across traits. We found no congruence between changes in FA and changes in phenotypic variance. These results suggest that developmental stability (measured by FA) and canalization are independently controlled. This study also confirms the weak relationship between FA and the breakdown of coadapted gene complexes following inter‐population hybridization.

Variational and Genetic Properties of Developmental Stability in Dalechampia Scandens

“…Hidden genetic variation may, however, be released following the breakdown of the canalizing system (Waddington 1959;Levin 1970;Eshel and Matessi 1998;Rutherford 2000). Increased levels of FA may thus result from drastic genetic changes, such as after hybridization events (Graham 1992; but see Pélabon et al 2004), or rapid adaptive responses to drastic environmental changes, such as the response to a novel pesticide in the Australian blowflies (Clarke and McKenzie 1987;Davies et al 1996).…”

Genetic constraints predict evolutionary divergence inDalechampiablossoms

“…Microsatellite analysis show that they fall out as well-separated groups on the phylogeny (figure 3). Despite many attempts, we have never managed to obtain fertile hybrids between these two species [45,46]. Judging from blossom morphology, the small-glanded species seems to be able to self-pollinate more easily than the large-glanded species.…”

The Evolution of Genetic Architecture

“…While theoretically plausible, a number of recent studies failed to find a link between canalization and measures of developmental stability such as fluctuating asymmetry (Debat et al 2000, Dworkin 2005a, Milton et al 2003, Pélabon et al 2004, Rutherford 2000.…”