Photic niche invasions: phylogenetic history of the dim-light foraging augochlorine bees (Halictidae)

Abstract

Most bees rely on flowering plants and hence are diurnal foragers. From this ancestral state, dim-light foraging in bees requires significant adaptations to a new photic environment. We used DNA sequences to evaluate the phylogenetic history of the most diverse clade of Apoidea that is adapted to dim-light environments (Augochlorini: Megalopta, Megaloptidia and Megommation). The most speciose lineage, Megalopta, is distal to the remaining dim-light genera, and its closest diurnal relative (Xenochlora) is recovered as a lineage that has secondarily reverted to diurnal foraging. Tests for adaptive protein evolution indicate that long-wavelength opsin shows strong evidence of stabilizing selection, with no more than five codons (2%) under positive selection, depending on analytical procedure. In the branch leading to Megalopta, the amino acid of the single positively selected codon is conserved among ancestral Halictidae examined, and is homologous to codons known to influence molecular structure at the chromophorebinding pocket. Theoretically, such mutations can shift photopigment l max sensitivity and enable visual transduction in alternate photic environments. Results are discussed in light of the available evidence on photopigment structure, morphological specialization and biogeographic distributions over geological time.

Variation in opsin genes correlates with signalling ecology in North American fireflies

“…; Tierney et al . ). The presence of elevated rates of evolution at these sites across butterflies, bees and fireflies suggests that, even if our homology model is inaccurate, there may be similar selective pressures at work across these diverse lineages.…”

A molecular and morphological phylogeny of the extant Augochlorini (Hymenoptera, Apoidea) with comments on implications for biogeography

“…The Augochlorini is monophyletic and most closely related to the tribe Halictini (Alexander & Michener, ; Danforth & Eickwort, ; Pesenko, , ; and Engel, for morphological evidence, Danforth et al ., , for molecular evidence). Hypotheses to explain generic affinities have been proposed (see later, and Danforth & Eickwort, ; Engel, ), yet current topologies, most of which are based on morphological characters, are not congruent and the few molecular studies do not resolve these topologies due the limited number of genera studied (Danforth et al ., ; Tierney et al ., ).…”

“…and Corynurina (Gonçalves, ). Also, the analysis of molecular data has become more common (Danforth et al ., ; Tierney et al ., ). According to Tierney et al .…”

Evolution and Expression Plasticity of Opsin Genes in a Fig Pollinator, Ceratosolen solmsi

“…Not surprising, insects have a concomitantly diverse array of visual receptors [2]. Many studies reveal adaptations of insects to their specific light environment or behavior by analyzing the opsin genes [10]–[20].…”