Project description:Using an organ-specific RNA-sequencing approach, we explore the role of supergene genotype and social environment on unmated, reproductive females Solenopsis invicta ants as they depart on their mating flights.
Project description:Here we reveal evidence of a shared genetic toolkit across the full spectrum of social complexity found in Vespid wasps, from simple group living where castes remain plastic throughout life, to complex superorganismal societies comprised of mutually dependent insects with irreversible castes determined during development. We generated brain transcriptomic data for castes in nine representative species; using a machine learning approach we identified thousands of shared orthologs which consistently describe castes (queens and workers), from species with the simplest (Mischocyttarus paper wasps) to the most complex (e.g. Vespine wasps) levels of social organisation. The top 400 genes were enriched in synaptic transport genes, suggesting that these changes could affect brain neural function and connectivity. Fine-scale dissection of these patterns revealed that the molecular processes underpinning the simpler societies (which likely represent the origins of social living) are conserved throughout the major transition, but that additional processes may come into play in the more complex societies, especially at the point of no return where societies transition to be committed superorganisms. These analyses provide the first evidence of a conserved toolkit regulating social behaviour across the full spectrum of social complexity in any social insect. Importantly, they also provide evidence that there may be fundamental differences discriminating superorganismal societies from non-superorganismal societies. We suggest that the evolution of irreversible caste commitment (in superorganisms) is accompanied by a fundamental shift in the underlying regulatory molecular machinery; such shifts may also typify other major evolutionary transitions that are characterised by the emergence of a committed division of labour, such as the evolution of multicellularity.
2021-01-31 | GSE159973 | GEO
Project description:The evolution of social parasitism in Formica ants revealed by a global phylogeny
Project description:This experiment was performed to investigate the effect of the manipulation of social rank on gene expression. Fire ants newly mated queens were paired and placed in nesting chambers. After emergence of workers, queensM-^R behavior was monitored. Once the behavioral observation revealed the social rank of the two cofoundresses (winners and losers), queens were weighed again and re-paired with a different partner. We created the following three groups of queens: a) winner + winner (similar weight), b) loser + loser (similar weight), and c) winner + loser (different weights). Again, we monitored the behavior until the social rank of the newly coupled specimens was evident and we collected 4 new behavioral phenotypes in the same way as above: a) winners switched into losers (win/los), b) losers switched into winners (los/win), c) continuing winners (win/win) and d) continuing losers (los/los).
Project description:In fire ants, a complex colony level phenotype, colony queen number, is completely associated with a single Mendelian factor marked by the gene Gp-9. The first aim of this study was to investigate whether variation in the genomic region marked by Gp-9 is associated with differences in patterns of expression of genes other than Gp-9 in workers. The second aim was to study how the social environment (i.e., presence or absence of nestmate workers with the b allele) can alter individual gene expression patterns. Keywords: Genotype comparison and social form comparison
Project description:This SuperSeries is composed of the following subset Series: GSE31344: smRNA sequencing of queen and virgin queen of two ants: Camponotus floridanus and Harpegnathos saltator GSE31346: Transcriptome sequencing of queen and virgin queen of two ants: Camponotus floridanus and Harpegnathos saltator GSE31576: Single base resolution methylome of two ants: Camponotus floridanus and Harpegnathos saltator Refer to individual Series
Project description:Social interactions are typically characterised by conflict and competition. This antagonism can play a critical role in evolutionary processes, such as promoting diversity through maintenance of alternative strategies or driving accelerated evolution through arms-race like escalation. However, despite our sophisticated understanding of how conflict shapes social traits, we still have limited knowledge of how it impacts molecular evolution across the underlying ‘social genes’. To address this problem, we analysed the genome wide impact of social interactions in a microbe. To understand broad-scale processes shaping molecular evolution at social genes we have used four different, but complementary, approaches to identify sets of social genes. For ease, we have named these sets ‘sociality’, ‘chimerism’, ‘antagonism’ and ‘cheater’ genes. Chimerism genes are defined as those up-regulated in chimeric aggregations in comparison to clonal aggregations. This is based on the logic that chimeric development will be characterised by conflict, and hence these genes will show the signatures of conflict driven evolution. Using genome sequences from 67 Dictyostelium discoideum strains, we find that social genes often exhibit enhanced polymorphism and accelerated evolution. However, these patterns are not consistent with the expectation of conflict driven processes, but instead reflect relatively relaxed purifying selection. This pattern reflects the fact that social interactions are conditional, and therefore selection on genes expressed in social interactions is diluted by generations of inactivity. This results in the ‘Red King’ process, wherein dilution of selection by inactivity enhances the role of drift, resulting in increased polymorphism and accelerated evolution.
Project description:DNA methylation is an important chromatin modification that is necessary for the structural integrity and proper regulation of the genome for many species. Despite its conservation across the tree of life, little is known about its contribution to complex traits. Reports that differences in DNA methylation between castes in closely related Hymenopteran insects (ants, bees and wasps) contributes to social behaviors has generated hypotheses on the role of DNA methylation in governing social behavior. However, social behavior has evolved multiple times across insecta, and a common role of DNA methylation in social behavior remains outstanding. Using phylogenetic comparative methods we sought to better understand patterns of DNA methylation and social behavior across insects. DNA methylation can be found in social and solitary insects from all orders, except Diptera (flies), which suggests a shared loss of DNA methylation within this order. The lack of DNA methylation is reflected in the absence of the maintenance and de novo DNA methyltransferases (DNMT) 1 and 3, respectively. Interestingly, DNA methylation is found in species without DNMT3. DNA methylation and social behavior (social/solitary) or with division of labor (caste+/caste–) for 123 insect species analyzed from 11 orders are not evolutionary dependent, which is further supported by sequencing of DNA methylomes from 40 species.
Project description:The emergence of eusociality is one of the major transitions in evolution. There have been several investigations into the reasons for shaping caste differentiation and social behavior of eusocial insects, such as ants and honeybees. However, the molecular mechanisms governing the sociality of these insects remain obscure. In this study, we profiled the transcriptome and chromatin accessibility of brain tissues in all castes: queens, males, gynes and workers in Monomorium pharaonis which is a typical caste-dependent eusocial insect. We created a comprehensive dataset including 16 RNA-seq and 16 ATAC-seq profiles from 4 biological replicates. We also demonstrated strong reproducibility of the datasets and identified specific genes and open chromatin regions in the genome that may be associated with caste differentiation. Overall, our data will be a valuable resource for further study of the mechanisms underlying eusocial insect behavior, particularly the role of the brain in the control of eusociality.
Project description:Social status is one of the strongest predictors of disease risk and mortality in humans, and often influences Darwinian fitness in social mammals more generally. To understand the biological basis of these effects, we combined a functional genomics approach with sequential social status manipulations in rhesus macaques to investigate how social status alters immune function. We demonstrate causal, but largely plastic, effects of social status on immune cell proportions, cell type-specific gene expression levels, and the gene expression and cytokine response to infection. Further, we identify specific transcription factor signaling pathways that explain these differences, particularly status-associated polarization of the TLR4 signaling pathway towards pro-inflammatory versus anti-viral responses. Our findings provide an unprecedented level of insight into the direct biological effects of social inequality on immune function, thus contributing to an improved understanding of social gradients in health and the evolution of social hierarchies. For social status, please refer to table S1 in the manuscript.