Morph-specific selection on floral traits in a polymorphic plant

Area of Science:

• Evolutionary Biology
• Plant Ecology
• Population Genetics

Background:

• Phenotypic correlations are common, but the roles of selection versus nonadaptive mechanisms in their evolution are unclear.
• Polymorphic species can exhibit morph-specific trait differences due to divergent selection pressures.
• Primula farinosa, a herb with short- and long-scaped morphs, experiences differential herbivory, predation, and pollination limitation.

Purpose of the Study:

• To investigate if morph-specific selection acts on floral display and pollination traits in Primula farinosa.
• To determine if biotic interactions explain differences in selection between short- and long-scaped morphs.
• To assess the consistency between current selection and observed trait differences between morphs.

Main Methods:

• Studied three populations of Primula farinosa polymorphic for scape length.
• Examined selection on floral display traits (flower number, petal size) and pollination efficiency (corolla tube width).
• Assessed morph-specific differences in biotic interactions and their association with selection gradients.

Main Results:

• Morph-specific selection differences were detected in one of the three populations.
• In that population, selection favored more flowers and larger petals in the short-scaped morph.
• Selection for narrower corolla tubes occurred in the short-scaped morph, but not significantly in the long-scaped morph.

Conclusions:

• Evidence suggests morph-specific selection on traits related to floral display and pollination efficiency.
• Current selection pressures are only partially consistent with the observed trait differences between morphs.
• Biotic interactions likely play a role in shaping trait evolution in polymorphic species like Primula farinosa.