ORDANO Mariano Andres
Phenotypic integration: between zero and how much is too much
JUAN FORNONI; MARIANO ORDANO; KARINA BOEGE; CÉSAR A. DOMÍNGUEZ
Blackwell Publishing Ltd.
Lugar: Oxford, UK; Año: 2009 vol. 183 p. 248 - 248
The hypothesis that flowers constitute mechanical devicesdesigned by natural selection to ensure pollen donation/reception through the concerted action of a suite of correlated(integrated) traits is an appealing and broadly accepted idea(Bell, 1985). Two questions derive from this hypothesis. Thefirst is whether flowers are, in fact, integrated modules. Moststudies evaluating this question have found significant levelsof floral integration and a marked heterogeneity amongspecies (Armbruster et al., 1999, 2004; Pérez et al., 2007;Pérez-Barrales et al., 2007; Ordano et al., 2008). Thus, theavailable evidence already indicates that flowers are indeedintegrated (Ordano et al., 2008). A different, but equallyrelevant, question is whether or not flowers exhibit relativelyhigh levels of phenotypic integration. Because in most plantspecies flower functioning depends on the interaction betweenfloral and pollinator morphologies, it has been suggested thatflowers should have relatively high levels of phenotypicintegration (Stebbins, 1950, 1970; Faegri & van der Pijl, 1966).Obviously, responses to these two questions require differentapproaches and rely on distinct biological reasons.In his letter to New Phytologist, Harder (2009) argues thatour conclusion that flowering plants have lower floral integrationthan expected by a randomly generated distribution(Ordano et al., 2008, p. 1189) is flawed because of theinappropriateness of our analysis. He further concluded that:floral integration is the rule, rather than the exception. Whilewe agree with his general conclusion regarding the ubiquity offloral integration, we believe that his criticism is based on confusingthe two questions presented above. Accordingly, thedisagreement presented by Harder (2009) merits a thoroughdiscussion of these two questions. In doing so, we attempt toclarify possible sources of misinterpretation in the paper byOrdano et al. (2008).