Behavioral and genetic mechanisms of social evolution: insights from incipiently and facultatively social bees

Abstract

Facultatively social species exhibit behavioral plasticity in response to changes in ecological conditions and social environment, and thus provide a natural experiment to compare solitary and social behaviors in a single genome. Such species can therefore provide empirical insights into the evolution of eusociality. The small carpenter bees (genus Ceratina) and sweat bees (Halictidae) are of special interest because they exhibit rich behavioral plasticity. Species range from solitary to eusocial, and both groups benefit from detailed behavioral research and well-established phylogenies. As such, small carpenter and sweat bees are poised to further comparative sociogenomic studies which emphasize the necessity of a molecular phylogeny for understanding the evolution of molecular architecture underlying social phenotypes and organizational complexity. Here, we review behavioral, transcriptomic and genomic data in bees across the social spectrum, highlighting the importance of simple societies and facultatively social taxa to examine the genetic basis of cooperative traits and social evolution.

Conserved Genes Underlie Phenotypic Plasticity in an Incipiently Social Bee

“…Instead, our results highlight evolutionary changes in gene regulation of deeply conserved genes as being of primary importance in the regulation of very basic sociality. These results are in general agreement with predictions of the social ladder hypothesis, but further data on an even wider spectrum of social species within the carpenter bees can elucidate whether regulation of conserved genes gives way to protein sequence change and novel genes in later stages of sociality ( Shell and Rehan 2018 ).…”

Genetic accommodation and the role of ancestral plasticity in the evolution of insect eusociality

“…Criterion 1: the focal trait can be environmentally induced in ancestral-proxy lineages Reproductive division of labor has been induced experimentally in multiple solitary and subsocial species through forced association studies, where typically non-associating females are forced to cohabit. Many examples come from the small carpenter bees (Sakagami and Maeta, 1984 and sweat bees (Jeanson et al, 2005(Jeanson et al, , 2008, groups that show high levels of social plasticity and may be especially useful for assessing genetic accommodation (Jones et al, 2017;Kocher and Paxton, 2014;Shell and Rehan, 2017). In some cases, a single species displays both solitary and social forms (Davison and Field, 2016;Smith et al, 2003;Soucy and Danforth, 2002), and in situations where these forms are Maeta, 1984, 1987), Ceratina okinawana (Sakagami and Maeta, 1989), Lasioglossum spp.…”

Effects of nutritional deprivation on development and behavior in the subsocial beeCeratina calcarata(Hymenoptera: Xylocopinae)

“…In primitively eusocial species, social dominance hierarchies are often determined by body size, where the smaller individual assumes a subordinate position (Smith et al, 2009); thus, poor larval nutrition would reduce competitive ability (Huntingford and Turner, 1987;Rehan, 2016, 2017). Comparisons of social complexity and life history between social species and their solitary relatives can offer insights into the evolution of social behavior (Michener, 1974;Rehan and Toth, 2015;Shell and Rehan, 2017). By understanding how maternal manipulation of larval nutrition affects growth, development and behavior of offspring in subsocial species, we can begin to understand the role maternal investment plays in the development of division of labor.…”