Phenotypic integration in style dimorphic daffodils (Narcissus, Amaryllidaceae) with different pollinators

Abstract

Different pollinators can exert different selective pressures on floral traits, depending on how they fit with flowers, which should be reflected in the patterns of variation and covariation of traits. Surprisingly, empirical evidence in support of this view is scarce. Here, we have studied whether the variation observed in floral phenotypic integration and covariation of traits in Narcissus species is associated with different groups of pollinators. Phenotypic integration was studied in two style dimorphic species, both with dimorphic populations mostly visited by long-tongued pollinators (close fit with flowers), and monomorphic populations visited by short-tongued insects (loose fit). For N. papyraceus , the patterns of variation and correlation among traits involved in different functions (attraction and fit with pollinators, transfer of pollen) were compared within and between population types. The genetic diversity of populations was also studied to control for possible effects on phenotypic variation. In both species, populations with long-tongued pollinators displayed greater phenotypic integration than those with short-tongued pollinators. Also, the correlations among traits involved in the same function were stronger than across functions. Furthermore, traits involved in the transfer of pollen were consistently more correlated and less variable than traits involved in the attraction of insects, and these differences were larger in dimorphic than monomorphic populations. In addition, population genetic parameters did not correlate with phenotypic integration or variation. Altogether, our results support current views of the role of pollinators in the evolution of floral integration.

Demographic compensation among populations: what is it, how does it arise and what are its implications?

“…Pérez‐Barrales et al . ). In this section, we compare the methodological approaches we have used to examine demographic compensation with approaches used in trait‐based studies to examine trait correlations.…”

“…Cheverud et al 1989) or to identify suites of traits that have been selected as a whole (e.g. P erez- Barrales et al 2014). In this section, we compare the methodological approaches we have used to examine demographic compensation with approaches used in trait-based studies to examine trait correlations.…”

“…Another approach that has been applied in the trait literature is to conduct a non-parametric bootstrap from the original data to place confidence limits on the mean correlation between pairs of traits involved in the same vs. different functions, such as insect attraction vs. pollen transfer (Conner & Sterling 1995;P erez-Barrales et al 2014). This approach could be applied in studying demographic compensation.…”

Evolutionary transition between bee pollination and hummingbird pollination inSalvia: Comparing means, variances and covariances of corolla traits

“…Empirical evidence suggests that unlike hovering foraging pollinators, those that perch and physically handle flowers likely exert stronger selection pressures on floral morphology increasing the magnitude of covariation of floral traits (Pérez‐Barrales, Simon‐Porcar, Santos‐Gally, & Arroyo, ; Pérez‐Barrales et al., ). Although most bees must land on the flowers and have a stronger physical contact, hummingbirds are able to hover around the flower with no need of a landing platform.…”

“…Empirical evidence suggests that unlike hovering foraging pollinators, those that perch and physically handle flowers likely exert stronger selection pressures on floral morphology increasing the magnitude of covariation of floral traits (Pérez-Barrales, Simon-Porcar, Santos-Gally, & Arroyo, 2014;Pérez-Barrales et al, 2007).…”