Plant species exhibiting polymorphisms with respect to flower color are widespread. Our understanding of the selection pressures that may maintain these color polymorphisms has primarily been confined to one set of organisms—pollinators. Yet, selection on flower color may also be driven by other agents, such as herbivores, especially in cases where pollinators and herbivores are using the same or correlated traits to select plants. A wealth of studies have documented pollinator preference for anthocyanin‐recessive color morphs (A−; yellow and white flowers) of wild radish, Raphanus sativus, over anthocyanin‐dominant morphs (A+; pink and bronze flowers); yet, differences in pollination alone do not explain the maintenance of the flower color polymorphism. Here, we ask whether variation in flower color in R. sativus influences the preference and performance of herbivores for A− flower color morphs vs. A+ flower color morphs in four types of herbivores (generalist and specialist Lepidoptera, slugs, aphids, and thrips). We found that all herbivores except for aphids and thrips preferred flowering A− color morphs compared to A+ morphs of R. sativus. Furthermore, all herbivores except larvae of specialist and generalist Lepidoptera performed better on A− color morphs. Differences in plant secondary chemistry may play a role in differential herbivore preference and performance on the anthocyanin flower color morphs. Chemical analyses of leaf secondary compounds (indole glucosinolates) revealed that A+ color morphs produced higher concentrations of indole glucosinolates than A− morphs in the presence of herbivore damage. Therefore, herbivores may exhibit lower preference for A+ color morphs, and these morphs may support lower herbivore performance because they are heavily defended once damaged. This is the first study, to our knowledge, to document differential preference and performance of herbivores for different flower color morphs. Previous studies have shown that increased herbivore damage can have profound negative direct and indirect effects on the reproduction of R. sativus. The data presented here suggest that differential preference and performance of herbivores for R. sativus color morphs may counter selection on flower color exerted by pollinators.

Delimiting the boundaries of species involved in radiations is critical to understanding the tempo and mode of lineage formation. Single locus gene trees may or may not reflect the underlying pattern of population divergence and lineage formation, yet they constitute the vast majority of the empirical data in species radiations. In this study we make use of an expressed sequence tag (EST) database to perform nuclear (nDNA) and mitochondrial (mtDNA) genealogical tests of species boundaries in Ambystoma ordinarium, a member of an adaptive radiation of metamorphic and paedomorphic salamanders (the Ambystoma tigrinum complex) that have diversified across terrestrial and aquatic environments. Gene tree comparisons demonstrate extensive nonmonophyly in the mtDNA genealogy of A. ordinarium, while seven of eight independent nuclear loci resolve the species as monophyletic or nearly so, and diagnose it as a well-resolved genealogical species. A differential introgression hypothesis is supported by the observation that western A. ordinarium localities contain mtDNA haplotypes that are identical or minimally diverged from haplotypes sampled from a nearby paedomorphic species, Ambystoma dumerilii, while most nDNA trees place these species in distant phylogenetic positions. These results provide a strong example of how historical introgression can lead to radical differences between gene trees and species histories, even among currently allopatric species with divergent life history adaptations and morphologies. They also demonstrate how EST-based nuclear resources can be used to more fully resolve the phylogenetic history of species radiations.

The relationship between worker body size and the shape of their body parts was explored in the polymorphic ant, Solenopsis invicta . The data consisted of 20 measurements of body parts as well as sums of some of these measurements. Size-free shape variables were created by taking the ratios of relevant measures. After log-transformation, these ratios were regressed against the logarithm of total body length, or against the log of the size of the parent part. Slopes of zero indicated that shape did not change with size, and non-zero slopes signaled a size-related change of shape. Across the range of worker sizes, the head length retained a constant proportion to body length, but relative headwidth increased such that head shape changed from a barrel-profile to a somewhat heart-shaped profile. Antennae became relatively smaller, with the club contributing more to this decline than the other parts. The alinotum became relatively shorter and higher (more humped), and the gaster increased in both relative width and length, and therefore in volume. All three pairs of legs were isometric to body length. The component parts of the legs, with one exception, were isometric to their own total leg length. The body of S. invicta is therefore dominated by mostly modest allometries, giving large workers a somewhat different shape than small ones. None of these size-shape relationships was different for different colonies. The functional meaning of these shape changes is unknown, but that does not stop us from speculating. HL head length BL body length HW1 width across the eyes HW2 width above the eyes HW3 width below the eyes

The relationship between worker body size and the shape of their body parts was explored in the polymorphic ant, Solenopsis invicta. The data consisted of 20 measurements of body parts as well as sums of some of these measurements. Size-free shape variables were created by taking the ratios of relevant measures. After log-transformation, these ratios were regressed against the logarithm of total body length, or against the log of the size of the parent part. Slopes of zero indicated that shape did not change with size, and non-zero slopes signaled a size-related change of shape. Across the range of worker sizes, the head length retained a constant proportion to body length, but relative headwidth increased such that head shape changed from a barrel-profile to a somewhat heart-shaped profile. Antennae became relatively smaller, with the club contributing more to this decline than the other parts. The alinotum became relatively shorter and higher (more humped), and the gaster increased in both relative width and length, and therefore in volume. All three pairs of legs were isometric to body length. The component parts of the legs, with one exception, were isometric to their own total leg length. The body of S. invicta is therefore dominated by mostly modest allometries, giving large workers a somewhat different shape than small ones. None of these size-shape relationships was different for different colonies. The functional meaning of these shape changes is unknown, but that does not stop us from speculating.HLhead lengthBLbody lengthHW1width across the eyesHW2width above the eyesHW3width below the eyes