Coeffects of diet and neonicotinoid exposure on honeybee mobility and food choice

Malnutrition and pesticide exposure are severe factors contributing to the current losses of honeybee colonies. As these stressors often occur combined, we studied the synergistic effects of different diets and pesticide exposure on food choice and mobility of Apis mellifera. We fed beehives with different food sources and exposed the bees to sublethal doses of thiacloprid. After that three different types of honey and pollen were offered in separate choice assays and behaviour towards food was recorded. Thiacloprid significantly affected the food choice in the honey assay, increasing the bees' preference of polyfloral honey, while pre-pesticide diet had no influence. The pollen choice remained similar regardless of treatments, as bees always preferred polyfloral pollen. Interestingly, pesticide exposure affected bee mobility differently, depending on the previous diet. These results indicate that the diet is an important factor influencing the susceptibility to pesticides.Peer reviewe

Evolution of dispersal in ants (Hymenoptera: Formicidae) : a review on the dispersal strategies of sessile superorganisms

The extreme diversity of dispersal strategies in ants is unique among terrestrial animals. The nature of ant colonies as social, perennial, and sessile superorganisms is the basis for understanding this diversity, together with the inclusive-fitness framework for social evolution. We review ant dispersal strategies, with the aim of identifying future research directions on ant dispersal and its evolution. We list ultimate and proximate determinants of dispersal traits and the ecological and evolutionary consequences of dispersal for population structures and dynamics, as well as species communities. We outline the eco-evolutionary feedbacks between the multitude of traits affecting dispersal evolution and the likely evolutionary routes and ecological drivers in transitions among the diverse ant dispersal strategies. We conclude by presenting a research framework to fill the gaps in current knowledge, including comparative studies of colony life histories and population structures and theoretical models of the eco-evolutionary dynamics affecting dispersal, in an inclusive-fitness framework.Peer reviewe

Strong Gene Flow Undermines Local Adaptations in a Host Parasite System

The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve

Strong Gene Flow Undermines Local Adaptations in a Host Parasite System

The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve

An Expanded Evaluation of Protein Function Prediction Methods Shows an Improvement In Accuracy

Background: A major bottleneck in our understanding of the molecular underpinnings of life is the assignment of function to proteins. While molecular experiments provide the most reliable annotation of proteins, their relatively low throughput and restricted purview have led to an increasing role for computational function prediction. However, assessing methods for protein function prediction and tracking progress in the field remain challenging. Results: We conducted the second critical assessment of functional annotation (CAFA), a timed challenge to assess computational methods that automatically assign protein function. We evaluated 126 methods from 56 research groups for their ability to predict biological functions using Gene Ontology and gene-disease associations using Human Phenotype Ontology on a set of 3681 proteins from 18 species. CAFA2 featured expanded analysis compared with CAFA1, with regards to data set size, variety, and assessment metrics. To review progress in the field, the analysis compared the best methods from CAFA1 to those of CAFA2. Conclusions: The top-performing methods in CAFA2 outperformed those from CAFA1. This increased accuracy can be attributed to a combination of the growing number of experimental annotations and improved methods for function prediction. The assessment also revealed that the definition of top-performing algorithms is ontology specific, that different performance metrics can be used to probe the nature of accurate predictions, and the relative diversity of predictions in the biological process and human phenotype ontologies. While there was methodological improvement between CAFA1 and CAFA2, the interpretation of results and usefulness of individual methods remain context-dependent

An expanded evaluation of protein function prediction methods shows an improvement in accuracy

Background: A major bottleneck in our understanding of the molecular underpinnings of life is the assignment of function to proteins. While molecular experiments provide the most reliable annotation of proteins, their relatively low throughput and restricted purview have led to an increasing role for computational function prediction. However, assessing methods for protein function prediction and tracking progress in the field remain challenging. Results: We conducted the second critical assessment of functional annotation (CAFA), a timed challenge to assess computational methods that automatically assign protein function. We evaluated 126 methods from 56 research groups for their ability to predict biological functions using Gene Ontology and gene-disease associations using Human Phenotype Ontology on a set of 3681 proteins from 18 species. CAFA2 featured expanded analysis compared with CAFA1, with regards to data set size, variety, and assessment metrics. To review progress in the field, the analysis compared the best methods from CAFA1 to those of CAFA2. Conclusions: The top-performing methods in CAFA2 outperformed those from CAFA1. This increased accuracy can be attributed to a combination of the growing number of experimental annotations and improved methods for function prediction. The assessment also revealed that the definition of top-performing algorithms is ontology specific, that different performance metrics can be used to probe the nature of accurate predictions, and the relative diversity of predictions in the biological process and human phenotype ontologies. While there was methodological improvement between CAFA1 and CAFA2, the interpretation of results and usefulness of individual methods remain context-dependent. Keywords: Protein function prediction, Disease gene prioritizationpublishedVersio

Sosiaalinen monimuotoisuus ja levittäytyminen suomumuurahaisilla (Formica)

There are intricate links between the evolution of sociality and the spatial population structures created by dispersal. In ants, the evolution of the most complex societies, supercolonies, is strongly connected to limited dispersal. The supercolonies consist of hundreds of interconnected nests where thousands of queens and their workers cooperate over large areas. Supercolonies arise from simpler family units when large proportions of daughter queens are philopatric and stay in their natal colony as additional reproducing queens instead of dispersing by wing. This allows the colonies to grow quickly and colonize large areas, but also increases social conflicts due to very low local relatedness in these societies. In this thesis I inspect the evolution and maintenance of ant supercolonies, by focusing on dispersal traits and the consequences of dispersal in socially polymorphic Formica ants. Formica have both simple family-based monodomous colonies and complex supercolonies, and some species have also intraspecific variation. To lay a sound theoretical background for my work, I began by synthesizing current knowledge of dispersal evolution in ants. In my literature review I showed how eco-evolutionary feedbacks link the evolution of ant dispersal strategies and social organization, and pinpointed the most relevant future research directions. Next, to be able to inspect some of the hypotheses formulated in the review, I clarified the species identification of one of my intended study species, Formica fennica with molecular methods, and concluded that the populations I studied should be treated as conspecific to Formica exsecta. I analyzed the individual dispersal traits of six socially variable species of Formica ants to assess whether dispersal ability varies between monodomous and supercolonial societies in accordance to the observed behavioral difference. According to my results the dispersal behavior of these species is likely not restricted by their morphology or resources the individuals get from their natal colonies. The traits of all species and both sexes indicate good flight ability, with overall male bias and large variation both among and within species. The increased philopatry in supercolonial species and populations is more a behavior change: the queens are philopatric even though the society provides them resources for dispersal. However, I observed a small decrease of male flight muscle ratio in supercolonial species, which indicates strong coevolution of the sexes. In order to better understand the outcomes of limited dispersal in supercolonial Formica, I analyzed the behavioral and genetic structure of a dense supercolonial population of Formica pressilabris. The population is genetically viscous at a small spatial scale, but still not genetically structured by location on a larger spatial scale. This indicates that although dispersal is limited within the population, a large enough proportion of individuals do disperse to keep the local populations connected. Interestingly, when analyzing worker behavior among the polydomous nests, the observed aggression pattern indicates that they are not a single cooperative unit – but also not clearly separate colonies. The sensitive behavioral assay developed for this study shows that workers allow a proportion of individuals from outside nests to enter their own nest material, but are slightly more aggressive towards individuals from further away. This indicates the population is only partially cooperative over the whole nest aggregation, and shows that the inner structures of supercolonies should be analyzed in more detail. This thesis sheds light on ants’ dispersal ability and behavior, and demonstrates the crucial role of dispersal in the evolution of their different social structures. My results also raise new questions about possible conflicts over dispersal in ant societies.Sosiaalisuuden evoluutio linkittyy vahvasti siihen, kuinka eliöt hajaantuvat elinympäristöönsä levittäytymisen seurauksena. Muurahaisten monimutkaisimpien yhteiskuntien, superkolonioiden, evoluutio on yhteydessä rajoittuneeseen levittäytymiseen. Superkoloniat koostuvat sadoista toisiinsa yhteydessä olevista pesistä, joissa tuhannet kuningattaret ja niiden työläiset tekevät yhteistyötä laajoilla alueilla. Superkoloniat syntyvät yksinkertaisemmista perheyksiköistä, kun suuri osuus tytärkuningattarista jää synnyinkoloniaansa ylimääräisiksi lisääntyviksi kuningattariksi sen sijaan, että lentäisivät muualle. Tämän seurauksena yhteiskunnat voivat kasvaa nopeasti ja suurille alueille, mutta samalla sosiaaliset ristiriidat lisääntyvät, koska paikallinen sukulaisuus laskee hyvin alas. Tässä väitöskirjassa tutkin superkolonioiden evoluutiota ja toimintaa sosiaalisesti monimuotoisilla suomumuurahaisilla (Formica), keskittyen levittäytymisominaisuuksiin ja levittäytymisen seurauksiin. Formica-muurahaisilla on sekä yksipesäisiä perheryhmiin perustuvia kolonioita että monimutkaisia superkolonioita, ja joillakin lajeilla on myös lajinsisäistä vaihtelua. Luodakseni työlleni vahvan teoreettisen pohjan, aloitin kokoamalla yhteen nykytietämyksen muurahaisten levittäytymisen evoluutiosta. Kirjallisuuskatsauksessani osoitan kuinka eko-evolutiiviset takaisinkytkennät liittävät levittäytymisstrategioiden evoluution ja sosiaalisen rakenteen toisiinsa. Hahmottelen myös tärkeimpiä tulevaisuuden tutkimussuuntia. Voidakseni tutkia katsausartikkelissa muotoilemiani hypoteeseja, varmistin suomenloviniskan (Formica fennica) lajintunnistuksen molekulaarisin metodein. Totesin, että geneettisen samankaltaisuuden vuoksi tutkimuspopulaatioitani tulee käsitellä karvaloviniskan (Formica exsecta) kanssa samaan lajiin kuuluvina. Analysoin kuuden sosiaalisesti erilaisen Formica-lajin yksilöiden levittäytymisominaisuuksia selvittääkseni, vaihteleeko niiden yksipesäisten ja superkoloniaalisten yhteiskuntien levittäytymiskyky samalla tavalla kuin niiden levittäytymiskäyttäytymisen tiedetään vaihtelevan. Osoitan, että näiden lajien käyttäytyminen ei todennäköisesti riipu yksilöiden morfologiasta tai resursseista, joita ne saavat synnyinkolonioiltaan. Kaiken kaikkiaan jokaisen tutkimani lajin ominaisuudet viittaavat siihen, että sekä koiraat että kuningattaret osaavat lentää hyvin. Koirailla on parempi lentokyky kuin kuningattarilla, ja sekä lajien välillä että lajien sisällä yksilöiden välillä on suurta vaihtelua. Se, että superkoloniaalisten lajien kuningattaret jäävät synnyinkoloniaan on siis käyttäytymispiirre: ne jäävät, vaikka yhteiskunta antaa niille tarvittavat resurssit levittäytymiseen. Havaitsin kuitenkin, että superkoloniaalisilla lajeilla koiraiden lentolihasten koko on pienentynyt, mikä viittaa sukupuolten yhteisevoluutioon. Ymmärtääkseni rajoittuneen levittäytymisen seurauksia superkoloniaalisilla Formicoilla, analysoin rämeloviniskan (Formica pressilabris) tiiviin, superkoloniaalisen populaation käyttäytymistä ja geneettistä rakennetta. Osoitan, että populaation sisällä läheiset pesät ovat geneettisesti samankaltaisempia kuin kaukaisemmat pesät, mutta että suuremmassa mittakaavassa populaatiot eivät silti eroa geneettisesti toisistaan. Tämä viittaa siihen, että vaikka levittäytyminen on rajoittunutta populaation sisällä, tarpeeksi suuri joukko yksilöitä silti lentää alueelta toiselle, ja suuremmassa mittakaavassa populaatiot ovat yhteydessä toisiinsa. Superkolonian sisäisen käyttäytymisen analysoiminen osoitti mielenkiintoisen seikan: työläisten vaihtelevasti aggressiivinen käytös viittaa siihen, että kaikki pesät eivät kuulu samaan yhteistyössä olevaan yksikköön - mutta pesien välille on silti mahdoton osoittaa selkeitä rajoja. Tätä tutkimusta varten kehitetty herkkä käyttäytymisanalyysi osoittaa, että työläiset sallivat muiden pesien työläisten tulla omalle pesämateriaalilleen, mutta ovat hiukan aggressiivisempia mitä kauempaa vierailijat ovat peräisin. Tämä viittaa siihen, että populaatio on vain osittain yhteistyössä koko pesärykelmän alalla. Formica-superkolonioiden sisäistä rakennetta pitäisi jatkossa tutkia aiempaa yksityiskohtaisemmin. Tämä väitöskirja valottaa muurahaisten levittäytymiskykyä ja -käyttäytymistä, sekä näyttää kuinka vahvasti levittäytyminen liittyy sosiaalisten rakenteiden evoluutioon. Tulokseni herättävät myös uusia kysymyksiä levittäytymiseen mahdollisesti liittyvistä ristiriidoista muurahaisyhteiskunnissa

Genetic analysis reveals Finnish Formica fennica populations do not form a separate genetic entity from F. exsecta

Coptoformica Muller, 1923 is a subgenus of Formica Linnaeus, 1758 that consists of c. a dozen species of ants that typically inhabit open grassy habitats and build small nest mounds. The most recent addition to the group is Formica fennica Seifert, 2000. The description was based on morphological characters, but the species status has not been confirmed by molecular methods. In this study, we use thirteen DNA microsatellite markers and a partial mitochondrial COI gene sequence to assess the species status of F. fennica, by comparing the genetic variation among samples identified as F. fennica and six other boreal Formica (Coptoformica) species. Most of the species studied form separate, discontinuous clusters in phylogenetic and spatial analyses with only little intraspecific genetic variation. However, both nuclear and mitochondrial markers fail to separate the species pair F. exsecta Nylander, 1846 and F. fennica despite established morphological differences. The genetic variation within the F. exsecta/fennica group is extensive, but reflects spatial rather than morphological differences. Finnish F. fennica populations studied so far should not be considered a separate species, but merely a morph of F. exsecta.Peer reviewe

Evoluutio vaikuttaa muurahaisten tulevaisuudennäkymiin

Muurahaisten yhteiskunnat ovat perherakenteiltaan monimuotoisia. Joskus pesässä on vain yksi kuningatar, jolloin yhteiskunta on tiivis ydinperhe. Joskus kuningattaria voi olla useita satoja. Tämä muuntelu on keskeinen osa muurahaisten ekologiaa, sillä kuningatarmäärän säätely liittyy siihen, miten muurahaiset levittäytyvät uusille alueille ja kuinka geneettisesti monimuotoisia muurahaisyhteiskunnat ovat. Tässä artikkelissa käsittelemme perherakenteiden vaihtelun syitä ja seurauksia. Erityisesti tarkastelemme Suomessa elävien ja paljon tutkittujen Formica-suvun muurahaisten yhteiskuntien sisäisiä konflikteja ja lajien tulevaisuudennäkymiä

Socially transferred materials: why and how to study them

When biological material is transferred from one individual's body to another, as in ejaculate, eggs, and milk, secondary donor-produced molecules are often transferred along with the main cargo, and influence the physiology and fitness of the receiver. Both social and solitary animals exhibit such social transfers at certain life stages. The secondary, bioactive, and transfer-supporting components in socially transferred materials have evolved convergently to the point where they are used in applications across taxa and type of transfer. The composition of these materials is typically highly dynamic and context dependent, and their components drive the physiological and behavioral evolution of many taxa. Our establishment of the concept of socially transferred materials unifies this multidisciplinary topic and will benefit both theory and applications