Mimicry--whereby warning signals in different species evolve to look similar--has long served as a paradigm of convergent evolution. Little is known, however, about the genes that underlie the evolution of mimetic phenotypes or to what extent the same or different genes drive such convergence. Here, we characterize one of the major genes responsible for mimetic wing pattern evolution in Heliconius butterflies. Mapping, gene expression, and population genetic work all identify a single gene, optix, that controls extreme red wing pattern variation across multiple species of Heliconius. Our results show that the cis-regulatory evolution of a single transcription factor can repeatedly drive the convergent evolution of complex color patterns in distantly related species, thus blurring the distinction between convergence and homology.

Bumble bees ( Bombus Latreille) occupy a wide diversity of habitats, from alpine meadows to lowland tropical forest, yet they appear to be similar in morphology throughout their range, suggesting that behavioural adaptations play a more important role in colonizing diverse habitats. Notwithstanding their structural homogeneity, bumble bees exhibit striking inter-and intraspecific variation in colour pattern, purportedly the outcome of mimetic evolution. A robust phylogeny of Bombus would provide the framework for elucidating the history of their wide biogeographical distribution and the evolution of behavioural and morphological adaptations, including colour pattern. However, morphological studies of bumble bees have discovered too few phylogenetically informative characters to reconstruct a robust phylogeny. Using DNA sequence data, we report the first nearly complete species phylogeny of bumble bees, including most of the 250 known species from the 38 currently recognized subgenera. Bayesian analysis of nuclear (opsin, EF-1 α , arginine kinase, PEPCK) and mitochondrial (16S) sequences results in a highly resolved and strongly supported phylogeny from base to tips, with clear-cut support for monophyly of most of the conventional morphologybased subgenera. Most subgenera fall into two distinct clades ( short-faced and long-faced ) associated broadly with differences in head morphology. Within the short-faced clade is a diverse New World clade, which includes nearly onequarter of the currently recognized subgenera, many of which are restricted to higher elevations of Central and South America. The comprehensive phylogeny provides a firm foundation for reclassification and for evaluating character evolution in the bumble bees.

Identifying the genomic changes that control morphological variation and understanding how they generate diversity is a major goal of evolutionary biology. In Heliconius butterflies, a small number of genes control the development of diverse wing color patterns. Here, we used full genome sequencing of individuals across the Heliconius erato radiation and closely related species to characterize genomic variation associated with wing pattern diversity. We show that variation around color pattern genes is highly modular, with narrow genomic intervals associated with specific differences in color and pattern. This modular architecture explains the diversity of color patterns and provides a flexible mechanism for rapid morphological diversification.

Bumble bees (Bombus) are a cold-adapted, largely alpine group that can elucidate patterns of Holarctic historical biogeography, particularly in comparison to the alpine plants with which they likely coevolved. A recently published molecular phylogeny of bumble bees provides uniquely comprehensive species sampling for exploring historical patterns of distribution and diversification. Using this phylogeny and detailed data on extant distributions, I reconstruct the historical distribution of bumble bees in a temporal framework, estimating divergence times using fossil data and molecular rates derived from the literature. The nearly comprehensive phylogeny allows assessment of the tempo of diversification within the bumble bees using lineage-through-time plots and diversification statistics, which have been performed with special consideration to confidence intervals. These analyses reveal movements of Bombus concordant with geographic and climatic events of the late Cenozoic. The initial diversification of extant bumble bee lineages was estimated at around 25 to 40 Ma, near the Eocene-Oligocene boundary 34 Ma, a period of dramatic global cooling. Dispersal-vicariance analysis (DIVA) predicted an Old World Bombus ancestor, with early diversification events largely restricted to the eastern Old World. The numerous intercontinental dispersal events occurred mostly in the direction of Old World to New World and North America to South America. Early movements from the Palearctic into the Nearctic most likely took place after 20 Ma and may have coincided with a period of Miocene cooling that gave rise to taiga habitat across Beringia. Subsequent dispersal between these regions is estimated to have occurred among boreal and tundra-adapted species mostly in the last 5 million years. Radiations are estimated in both Nearctic and Neotropical regions at approximately 6 to 8 Ma and after 3.5 Ma, concordant with the opening of land corridors between the continents.

Imagine if we could compute across phenotype data as easily as genomic data; this article calls for efforts to realize this vision and discusses the potential benefits.

The mimetic butterflies Heliconius erato and Heliconius melpomene have undergone parallel radiations to form a near-identical patchwork of over 20 different wing-pattern races across the Neotropics. Previous molecular phylogenetic work on these radiations has suggested that similar but geographically disjunct color patterns arose multiple times independently in each species. The neutral markers used in these studies, however, can move freely across color pattern boundaries, and therefore might not represent the history of the adaptive traits as accurately as markers linked to color pattern genes. To assess the evolutionary histories across different loci, we compared relationships among races within H. erato and within H. melpomene using a series of unlinked genes, genes linked to color pattern loci, and optix, a gene recently shown to control red colorpattern variation. We found that although unlinked genes partition populations by geographic region, optix had a different history, structuring lineages by red color patterns and supporting a single origin of red-rayed patterns within each species. Genes closely linked (80-250 kb) to optix exhibited only weak associations with color pattern. This study empirically demonstrates the necessity of examining phenotype-determining genomic regions to understand the history of adaptive change in rapidly radiating lineages. With these refined relationships, we resolve a long-standing debate about the origins of the races within each species, supporting the hypothesis that the red-rayed Amazonian pattern evolved recently and expanded, causing disjunctions of more ancestral patterns.Müllerian mimicry | population genetics | phylogeography R esearchers typically rely on neutrally evolving loci to generate a phylogenetic and population genetic history of adaptive divergence. The rationale is that these markers provide an unbiased view of the relationships among divergent phenotypes and a better understanding of the evolutionary processes generating variation. However, the genome is a complicated mosaic shaped by an interplay of mutation, drift, selection, and recombination. Recombination allows different regions of the genome to experience alternative restrictions to gene flow, and thus develop different evolutionary trajectories. The closer a genetic marker is to the alleles responsible for adaptive differences, the more likely that it will trace the history of phenotypic change.Understanding how phenotypic variation is generated in nature is greatly enhanced by studying groups that are actively undergoing diversification. By deciphering the history of such diverse phenotypes we gain a clearer understanding of the evolutionary process, including the tempo and mode of phenotypic change. Heliconius butterflies present one of the most striking examples of a recent phenotypic radiation. The 40 species in the genus exhibit hundreds of wing patterns that are involved in Müllerian mimicry complexes, where distasteful species converge on a shared warning signal to avoid predation. Th...

-A system of subgenera has been widely used for nearly a century to communicate ideas of relationships among bumblebee species. However, with 38 subgenera in recent lists for about 250 species, the system has come to be seen as too complicated. In this paper we suggest four criteria to guide the process of simplifying the subgeneric system, so that ideally subgenera should become: (1) monophyletic; (2) fewer; (3) diagnosable from morphology; and (4) names for important behavioural and ecological groups. Using a new strongly-supported estimate of phylogeny for almost all bumblebee species, we apply these criteria to reduce the system to 15 subgenera, and we assess the consequences. Ten new subgeneric synonyms are recognised. Keys to identify adult bumblebees to the simplified subgenera are provided for both sexes.bumblebee / Bombus / subgenera / phylogeny / classification

Pollinator nutritional ecology provides insights into plant–pollinator interactions, coevolution, and the restoration of declining pollinator populations. Bees obtain their protein and lipid nutrient intake from pollen, which is essential for larval growth and development as well as adult health and reproduction. Our previous research revealed that pollen protein to lipid ratios (P:L) shape bumble bee foraging preferences among pollen host-plant species, and these preferred ratios link to bumble bee colony health and fitness. Yet, we are still in the early stages of integrating data on P:L ratios across plant and bee species. Here, using a standard laboratory protocol, we present over 80 plant species’ protein and lipid concentrations and P:L values, and we evaluate the P:L ratios of pollen collected by three bee species. We discuss the general phylogenetic, phenotypic, behavioral, and ecological trends observed in these P:L ratios that may drive plant–pollinator interactions; we also present future research questions to further strengthen the field of pollination nutritional ecology. This dataset provides a foundation for researchers studying the nutritional drivers of plant–pollinator interactions as well as for stakeholders developing planting schemes to best support pollinators.