Sweat bees (Hymenoptera: Halictidae) encompass a wide range of social behaviors, from solitary individuals that live and reproduce independently to eusocial colonies with overlapping generations and a non-reproductive worker caste. Some species are capable of producing both social and solitary nests, often depending on environmental context.
Within the sweat bees, there have been two independent gains and a dozen losses of eusociality. These replicated gains and losses of social behavior enable a comparative approach to identify the core factors that shape the emergence and breakdown of eusociality and provide insights into the most costly aspects of social life. We performed this exact comparative analysis in our latest preprint "Convergent selection on juvenile hormone signaling is associated with the evolution of eusociality in bees".
For these genomic comparisons we needed, you guessed it, genome assemblies. Today, together with the Kocher Lab at Princeton University we share 17 chromosome-length sweat bee genome assemblies that span solitary, eusocial and polymorphic species to accompany the preprint.
The assembled species include:
Bicolored striped sweat bee (Agapostemon virescens): www.dnazoo.org/assemblies/Agapostemon_virescens
Pure green sweat bee (Augochlora pura): www.dnazoo.org/assemblies/Augochlora_pura
Golden green sweat bee (Augochlorella aurata): www.dnazoo.org/assemblies/Augochlorella_aurata
Ligated furrow bee (Halictus ligatus): www.dnazoo.org/assemblies/Halictus_ligatus
Giant furrow bee (Halictus quadricinctus): www.dnazoo.org/assemblies/Halictus_quadricinctus
Orange-legged furrow bee (Halictus rubicundus): www.dnazoo.org/assemblies/Halictus_rubicundus
White-legged sweat bee (Lasioglossum albipes): www.dnazoo.org/assemblies/Lasioglossum_albipes
Common furrow bee (Lasioglossum calceatum): www.dnazoo.org/assemblies/Lasioglossum_calceatum
Figueres' sweat bee (Lasioglossum figueresi): www.dnazoo.org/assemblies/Lasioglossum_figueresi
White-banded sweat bee (Lasioglossum leucozonium): www.dnazoo.org/assemblies/Lasioglossum_leucozonium
Sharp-collared sweat bee (Lasioglossum malachurum): www.dnazoo.org/assemblies/Lasioglossum_malachurum
Margined sweat bee (Lasioglossum marginatum): www.dnazoo.org/assemblies/Lasioglossum_marginatum
Evening primrose sweat bee (Lasioglossum oenotherae): www.dnazoo.org/assemblies/Lasioglossum_oenotherae
Lobe-spurred sweat bee (Lasioglossum pauxillum): www.dnazoo.org/assemblies/Lasioglossum_pauxillum
Viereck's sweat bee (Lasioglossum vierecki): www.dnazoo.org/assemblies/Lasioglossum_vierecki
Zephyr sweat bee (Lasioglossum zephyrum): www.dnazoo.org/assemblies/Lasioglossum_zephyrum
Alkali bee (Nomia melanderi): www.dnazoo.org/assemblies/Nomia_melanderi
The same genome assemblies and gene annotations are also available through the Princeton Halictid Genome Browser.
We searched the chromosome-length genome assemblies for genes that both experienced positive selection when eusociality arose and relaxed selection when eusociality was secondarily lost in the sweat bees. Strikingly, the analysis highlighted proteins that bind and transport juvenile hormone – a key regulator of insect development and reproduction. Read more about this in the preprint, and see also the Kocher lab twittorial!
To give you some taste of the data, see a collage of chromosome-length contact maps below, and visit the individual assembly pages for more information!
Fun fact: these genome assemblies constitute our 200-216th assembled species. Can you beelieve it?!