Data from: Testing potential selective agents acting on leaf shape in Ipomoea hederacea: predictions based on an adaptive leaf shape cline

Leaf shape is a highly variable phenotype, and is likely influenced by
many sources of selection. Ipomoea hederacea exhibits an adaptive
latitudinal cline in leaf shape, which is controlled by a single Mendelian
locus: lobed individuals dominate the north with entire-shaped individuals
mostly in the south. We test if the following candidate selective agents,
suggested by the literature, are responsible for the cline: differential
insect herbivory, genetic correlations with other clinal traits like
flowering time and growth rate, and thermoregulatory differences. We
planted 1680 F3 individuals, segregating for leaf shape, in the north of
I. hederacea's range, where we expected lobed genotypes to have
higher fitness. Individuals were assigned to insect removal or control
treatments, and we scored herbivory, flowering time, growth rate, leaf
temperature, and fitness (seed number). Herbivory, flowering, and growth
rate had significant fitness effects, but none differed between leaf
shapes. Lobed leaves were consistently warmer at night, but no performance
advantage was detected. Finally, we detected no overall fitness
differences between leaf shape genotypes, whether we controlled for other
traits under selection or not. Our data suggest these candidate selective
agents may not be important contributors to the cline, and alternative
approaches to understanding the mechanisms maintaining the leaf shape
cline in I. hederacea may be necessary.