Biology subjects

Helantera, H.

Publications and source records attributed to Helantera, H..

5 recordsLinked to original sources

bioRxiv2025

Dispersal behavior rather than dispersal morphology creates social polymorphism in Formica ants

O_LIDispersal evolution and social evolution are interlinked. Dispersal is necessary for avoiding kin competition and inbreeding, but limited dispersal also allows beneficial social interactions with kin. In ants, a correlation between poor dispersal and complex societies, where a big proportion of queens are philopatric, is well documented, but the underlying causal mechanisms are not clear. C_LIO_LIIn this study we investigate the dispersal ability of six Formica species that vary in their colony queen number and nest founding mode, from three different subgenera. Investigating resource allocation in the bodies of young queens and males allows us to analyze the evolutionary causalities between dispersal ability and social organization. We measured the body ratios including wing-muscle ratio; glycogen, triglyceride and protein resources with colorimetric assays; and microscopic wing muscle structures with transmission electron microscopy, with an overall sample size of 1515 individual males and queens. C_LIO_LIOur results suggest that the physical condition of individuals does not strongly correlate with the dispersal patterns of the species, contrary to assumptions based on earlier studies in both ants and other insects. There was still a minor effect of social organization on male wing-muscle ratio, which is an interesting case of sexual coevolution of dispersal traits: it is likely that the queen philopatric behavior is reflected in male behavior and consequently in male morphology - even when our overall results support the hypothesis that ant dispersal is male biased regardless of social organization. Further, our intraspecific analyses in two of the six species reveal different patterns in their flight abilities in connection to their social organization, further pointing towards a mismatch between dispersal behavior and ability. C_LIO_LIIn Formica queens, philopatry seems to be a behavioral trait of the individuals rather than a consequence of colony-level resource allocation into dispersal ability, pointing towards a "behavior first" evolutionary route. The queens may selfishly choose not to disperse even when their society provides them with the resources for it. This raises new questions about conflicts over dispersal in these highly social systems. C_LI

evolutionary biology↗

bioRxiv2024

Introgression and divergence in a young species group

The process of speciation concerns often not only pairs of species but rather groups of diverging and interacting taxa, as highlighted by recent research. Hence, to understand the evolution of species diversity and their persistence, it is crucial to understand how gene flow and evolution of reproductive isolation shape groups of closely related species. Using resequencing data, we disentangle here genomic patterns of divergence and introgression in five Formica rufa group wood ant species that are at the early stage of speciation. We first revise earlier mitochondrial phylogenies with a nuclear genomic tree, and demonstrate then introgression that is in line with observations of their current day natural hybridisation. Investigating the genome-wide differentiation and divergence we find correlations between population genetic parameters of divergence, differentiation, and diversity, that are in line with theoretical expectations for young species. Despite previously found evidence for polygenic species barriers, our data lacks the genome-wide correlation between differentiation and divergence that would be expected under a model of polygenic barriers. The likely explanation for this lack is the dominating effect of ancestral diversity at these early stages of speciation. As hybridisation has led to both deleterious and adaptive consequences within the group, we examined the signatures of introgression. We find no strong positive correlation between introgression and recombination, suggesting introgression does not have a predominantly deleterious effect. We also infer low diversity in the genomic regions with high proportions of introgression, consistent with the idea that selection has locally favoured introgression. This could be due to sharing of adaptive alleles or reduction of genetic load in the receiving species. Interestingly, gene flow in this group could potentially cross multiple species boundaries even in the absence of direct interbreeding between all the species. We discuss the long-term benefits and costs of introgression in young species, including the effect of environmental fluctuations and multi-species introgression.

evolutionary biology↗

bioRxiv2023

Strong purifying selection in haploid tissue-specific genes of Scots pine supports the masking theory

The masking theory states that genes expressed in haploid stage will be under more efficient selection. In contrast, selection will be less efficient in genes expressed in diploid stage, where the fitness effects of recessive deleterious or beneficial mutations can be hidden from selection in heterozygous form. This difference can influence several evolutionary processes such as maintenance of genetic variation, adaptation rate, and genetic load. Masking theory expectations have been confirmed in single-cell haploid and diploid organisms. However, in multicellular organisms, such as plants, the effects of haploid selection are not clear-cut. In plants, the great majority of studies indicating haploid selection have been carried out using male haploid tissues in angiosperms. Hence, evidence in these systems is confounded with the effects of sexual selection and intra-specific competition. Evidence from other plant groups is scarce and results show no support for the masking theory. Here we have used a gymnosperm Scots pine megagametophyte, a maternally-derived seed haploid tissue, and four diploid tissues to test the strength of purifying selection on a set of genes with tissue-specific expression. By using targeted resequencing data of those genes, we obtained estimates of genetic diversity, the site frequency spectrum of 0-fold and 4-fold sites, and inferred the distribution of fitness effects (DFE) of new mutations in haploid and diploid tissue-specific genes. Our results show that purifying selection is stronger for tissue-specific genes expressed in the haploid megagametophyte tissue, and that this signal of strong selection is not an artifact driven by high expression levels

evolutionary biology↗

bioRxiv2023

Extensive hybridisation between multiple differently adapted species may aid persistence in a changing climate

Hybridisation and gene flow can have both deleterious and adaptive consequences for natural populations and species. To better understand the extent and consequences of hybridisation in nature, information on naturally hybridising non-model organisms is required, including characterising the structure and extent of natural hybrid zones. Here we study natural populations of five keystone mound-building wood ant (Formica rufa group) species across Finland. No genomic studies across the species group exist and the extent of hybridisation and genomic differentiation in sympatry is unknown. Combining genome-wide and morphological data, we show that Formica rufa, F. aquilonia, F. lugubris, and F. pratensis form distinct gene pools in Finland. We demonstrate more extensive hybridisation than previously thought between all five species and reveal a mosaic hybrid zone between F. aquilonia, F. rufa and F. polyctena. We show that hybrids between these climatically differently adapted species occupy warmer habitats than the cold-adapted parent F. aquilonia. This suggests hybrids occupy a different microclimatic niche compared to the locally abundant parent. We propose that wood ant hybridisation may increase with a warming climate, and warm winters, in particular, may provide a competitive advantage for the hybrids over F. aquilonia in the future. In summary, our results demonstrate how extensive hybridisation may help persistence in a changing climate. Additionally, they provide an example on how mosaic hybrid zones can have significant ecological and evolutionary consequences because of their large extent and independent hybrid populations that face both ecological and intrinsic selection pressures.

evolutionary biology↗

bioRxiv2023

Evidence of phylosymbiosis in Formica ants

Insects share intimate relationships with microbes that play important roles in their biology. Yet our understanding of how host-bound microbial communities assemble and perpetuate over evolutionary time is limited. Ants host a wide range of microbes with diverse functions and are an emerging model for studying the evolution of insect microbiomes. Here, we ask whether phylogenetically related ant species have formed distinct and stable microbiomes. To answer this question, we investigated the microbial communities associated with queens of 14 Formica species from five clades, using deep coverage 16S rRNA amplicon sequencing. We reveal that Formica species and clades harbour highly defined microbial communities that are dominated by four bacteria genera: Wolbachia, Lactobacillus, Liliensternia, and Spiroplasma. Our analysis reveals that the composition of Formica microbiomes mirrors the phylogeny of the host, i.e. phylosymbiosis, in that related hosts harbour more similar microbial communities. Our analysis also revealed significant correlations between microbe co-occurrences, which suggests that synergistic and antagonistic interactions may contribute to the phylosymbiotic signal. Additional factors potentially contributing to the phylosymbiotic signal are discussed, including host phylogenetic relatedness, host-microbe genetic compatibility, modes of transmission, and similarities in host ecologies (e.g., diets). Overall, our results support the growing body of evidence that microbial community composition closely depends on the phylogeny of their hosts, despite bacteria having diverse modes of transmission and localisation within the host.

evolutionary biology↗