Biology subjects

Hakala, S. M.

Publications and source records attributed to Hakala, S. M..

4 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

Plasticity and evolution of metabolic division of labour within families

Fluids produced by parents for dependent young, such as milk or regurgitate, carry molecules that assist offspring with growth, immunity and digestion, allowing the metabolic burden of development to be shared between parents and offspring. We tested whether this division of metabolic labour changes plastically and evolves when offspring are experimentally deprived of their parents metabolic assistance. In the burying beetle Nicrophorus vespilloides parents deposit oral fluids on their carrion nest during pre-hatching care, and facultatively transfer fluids to larvae through oral trophallaxis as post-hatching care. We analysed the oral fluid proteomes of replicate experimental populations that had been evolving for 50 generations with or without post-hatching care, and which were then allowed to raise larvae with or without post-hatching care for one experimental generation. We found that parents and larvae plastically and evolutionarily adjusted the proteins in their oral fluids when we prevented post-hatching care. When reared in the absence of post-hatching care, larvae that evolved without post-hatching care were also more capable of consuming carrion proteins than larvae that had evolved with post-hatching care, and had higher survival. Our results suggest that metabolic division of labour within families is plastically modulated, and that the extent of socially modulated plasticity can evolve rapidly when social conditions change.

evolutionary biology↗

bioRxiv2021

Dynamic variation in a socially exchanged fluid indicates a role in the regulation of ant colony development and maturation

Socially exchanged fluids, like seminal fluid and milk, allow individuals to molecularly influence conspecifics. Many social insects have a social circulatory system, where food and endogenously produced molecules are transferred mouth-to-mouth (stomodeal trophallaxis), connecting all the individuals in the society. To understand how these endogenous molecules relate to colony life, we used quantitative proteomics to investigate the trophallactic fluid within colonies of the carpenter ant Camponotus floridanus. We show that different stages of the colony life cycle circulate different types of proteins: young colonies prioritize direct carbohydrate processing; mature colonies prioritize accumulation and transmission of stored resources. Further, colonies circulate proteins implicated in oxidative stress, ageing, and social insect caste determination, potentially acting as superorganismal hormones. Brood-caring individuals that are also closer to the queen in the social network (nurses) showed higher abundance of oxidative stress-related proteins. Thus, trophallaxis behavior provides a mechanism for distributed metabolism in social insect societies.

evolutionary biology↗

bioRxiv2020

Limited dispersal and an unexpected aggression pattern in a native supercolonial ant

Understanding how social groups function requires studies on how individuals move across the landscape and interact with each other. Ant supercolonies are extreme cooperative units that may consist of thousands of interconnected nests, and their individuals cooperate over large spatial scales. However, the inner structure of suggested supercolonial (or unicolonial) societies has rarely been extensively studied using both genetic and behavioral analyses. We describe a dense supercolony-like aggregation of more than 1 300 nests of the ant Formica (Coptoformica) pressilabris. We performed aggression bioassays and found that, while aggression levels were generally low, there was some aggression within the assumed supercolony. The occurrence of aggression increased with distance from the focal nest, in accordance with the genetically viscous population structure we observe by using 10 microsatellite markers. However, the aggressive interactions do not follow any clear pattern that would allow specifying colony borders within the area. The genetic data indicate limited gene flow within and away from the supercolony. Our results show that a Formica supercolony is not necessarily a single unit but can be a more fluid mosaic of aggressive and amicable interactions instead, highlighting the need to study internest interactions in detail when describing supercolonies.

animal behavior and cognition↗