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Healthy ecosystems support the well-being of all organisms on Earth. Yet, the overexploitation of natural resources for human needs and profit has resulted in widespread ecosystem degradation, loss of biodiversity, and climate emergency, which pose fundamental threats to planetary well-being. Impoverished ecosystems may become dysfunctional and fail to provide for the needs of many organisms, including humans and wildlife. Changes in ecosystem functioning and wildlife distributions affect the prevalence and spread of pathogens, with consequences for the health and well-being of human and wildlife communities alike. Increasing contact between humans and domestic and wild animals enable pathogen spillover, while global trade and travel distribute pathogens to new areas. Human activities thus provide favourable conditions for pandemics and trigger cascading consequences for ecosystems worldwide. A better integration of ecosystem health into public health and conservation planning could alleviate disease burden and improve well-being of all organisms on the planet. peerReviewed

1. Traits related to reproduction and dispersal drive the assembly and dynamics of species communities and can explain and predict how species respond to habitat loss and fragmentation and to the changing climate. For fungi, such links remain poorly known. 2. We examine how spore production rate, a key demographic trait, is influenced by the interaction between environmental conditions and species traits. We monitored the spore production of 97 wood-inhabiting fungal species on 107 decaying logs for two years and analyzed the data with a hierarchical community model. 3. Our analysis demonstrates clear species differences in seasonal patterns, with spring and summer release dominating in perennial species, contrary to the commonly held view of autumn as the primary ?mushroom season?. Many species follow a diurnal pattern with a higher spore release rate during the night. Such patterns in release timing have important implications for dispersal, as shown by recent model simulations. 4. The overall level of spore release was negatively correlated with spore size, providing new evidence that fungi face the classic trade-off of investing either in the number or size of offspring. 5. We found that different species within the functional group of wood-inhabiting fungi display alternative strategies in spore release timing and along the trade-off between offspring size and number. Linking our findings to previously reported correlations between spore size and other traits, we propose a new conceptualization of life history strategies in wood-inhabiting fungi, with implications for species? ability to survive the ongoing biodiversity crisis.

Männynjuurikäävän aiheuttama tyvitervastauti on riesa Etelä- ja Keski-Suomen männiköissä erityisesti kasvupaikoilla, joilla puulajin vaihto männynjuurikääpää kestävälle lehtipuulle ei ole mahdollista. Luonnonvarakeskuksessa tehty tutkimus osoitti, että tuhot saattavat lisääntyä merkittävästi seuraavassa mäntysukupolvessa. Tutkimuksessa seurattiin yhdeksän vuoden ajan juurikääpäsienten leviämistä männyn taimikossa, joka oli istutettu tyvitervastaudin vaivaamalle kasvupaikalle. Ensimmäiset taimet kuolivat juurikääpätartuntaan viisi vuotta istutuksen jälkeen. Kolmetoista vuotta istutuksesta taimia oli kuollut 1,2 hehtaarin alueella kaikkiaan 672 ja tyvitervastautipesäkkeiden määrä oli lisääntynyt edellisen puusukupolven yhdeksästä 48:aan. Juurikäävän tappamista taimista yli puolessa oli lisäksi juurikäävän itiöemiä eli kääpiä, mikä lisää itiötartuntariskiä erityisesti kesäaikaisessa taimikon harvennuksessa.

Active dispersal is driven by extrinsic and intrinsic factors at the three stages of departure, transfer and settlement. Most empirical studies capture only one stage of this complex process, and knowledge of how much can be generalized from one stage to another remains unknown. Here we use genetic assignment tests to reconstruct dispersal across 5 years and 232 habitat patches of a Glanville fritillary butterfly ( Melitaea cinxia ) metapopulation. We link individual dispersal events to weather, landscape structure, size and quality of habitat patches, and individual genotype to identify the factors that influence the three stages of dispersal and post-settlement survival. We found that nearly all tested factors strongly affected departure probabilities, but that the same factors explained very little variation in realized dispersal distances. Surprisingly, we found no effect of dispersal distance on post-settlement survival. Rather, survival was influenced by weather conditions, quality of the natal habitat patch, and a strong interaction between genotype and occupancy status of the settled habitat patch, with more mobile genotypes having higher survival as colonists rather than as immigrants. Our work highlights the multi-causality of dispersal and that some dispersal costs can only be understood by considering extrinsic and intrinsic factors and their interaction across the entire dispersal process.

nonPeerReviewed

Monitoring of arthropods focuses typically on changes in population and range size over time. Yet, there are a myriad of other aspects that could and should be monitored under the ongoing global and local environmental change. Stable isotope analysis, widely employed in short-term ecological studies, has potential in long-term monitoring of arthropods. Here we discuss the use of stable isotopes in monitoring terrestrial arthropods, provide some empirical examples of the use of bulk tissue samples in stable isotope analysis, and outline future directions in using compound-specific stable isotope analysis in monitoring. We performed a literature search for 2012–2021 to see if stable isotopes have been specifically used in monitoring of terrestrial arthropods. The literature shows that stable isotopes have been successfully used to reveal ecological phenomena (dispersal, trophic interactions, resource use) that would have been difficult or impossible to detect by other means. Yet, stable isotopes have been underused in arthropod monitoring programs, but the growing number of basic studies on stable isotope ecology and methodology provides crucial basis needed for developing monitoring programs. Stable isotopes provide technically, economically and ecologically feasible addition to the traditional monitoring methods of terrestrial arthropods. peerReviewed

1. Fragmentation of tropical forests is increasing globally, with negative impacts for biodiversity. In Southeast Asia, expansion of oil palm agriculture has caused widespread deforestation, forest degradation and fragmentation. 2. Persistence of forest-dependent species within these fragmented landscapes is likely to depend on the capacity of individuals to move between forest patches. In oil palm landscapes, riparian buffers along streams and rivers are potential movement corridors, but their use by moving animals is poorly studied. 3. We examined how six dung beetle species traversed riparian buffers connected to a continuous forest reserve area within an oil palm plantation in Sabah, Malaysian Borneo. We used a mark–release–recapture study and a new Bayesian Joint Species Movement Modelling (JSMM) approach, extended to a continuous capture process model. 4. Dung beetle species were fairly generalist in their habitat use, but two species showed a statistically supported preference for riparian buffer forest over oil palm, and one species showed a strong preference for forest reserve over riparian buffer, indicating the importance of forested areas within oil palm landscapes for some species. 5. A land-use change simulation indicated that the loss of riparian buffers in oil palm will result in reduced movement by forest-dependent species. 6. Synthesis and applications. Our results provide evidence for the use of riparian buffers in oil palm plantations for forest-dependent dung beetle species, strengthening the case for their retention, restoration and re-establishment. Furthermore, our study demonstrates the wider applicability of the Joint Species Movement Modelling (JSMM) framework to assess movement behaviour of species in fragmented landscapes, a vital tool for future forest and landscape management and conservation prioritisation exercises.

International audience; Globalization has led to the introduction of thousands of alien species worldwide. With growing impacts by invasive species, understanding the invasion process remains critical for predicting adverse effects and informing efficient management. Theoretically, invasion dynamics have been assumed to follow an "invasion curve" (S-shaped curve of available area invaded over time), but this dynamic has lacked empirical testing using large-scale data and neglects to consider invader abundances. We propose an "impact curve" describing the impacts generated by invasive species over time based on cumulative abundances. To test this curve's large-scale applicability, we used the data-rich New Zealand mud snail Potamopyrgus antipodarum, one of the most damaging freshwater invaders that has invaded almost all of Europe. Using long-term (1979-2020) abundance and environmental data collected across 306 European sites, we observed that P. antipodarum abundance generally increased through time, with slower population growth at higher latitudes and with lower runoff depth. Fifty-nine percent of these populations followed the impact curve, characterized by first occurrence, exponential growth, then long-term saturation. This behaviour is consistent with boom-bust dynamics, as saturation occurs due to a rapid decline in abundance over time. Across sites, we estimated that impact peaked approximately two decades after first detection, but the rate of progression along the invasion process was influenced by local abiotic conditions. The S-shaped impact curve may be common among many invasive species that undergo complex invasion dynamics. This provides a potentially unifying approach to advance understanding of large-scale invasion dynamics and could inform timely management actions to mitigate impacts on ecosystems and economies.

Species can adapt to climate change by adjusting in situ or by dispersing to new areas, and these strategies may complement or enhance each other. Here, we investigate temporal shifts in phenology and spatial shifts in northern range boundaries for 289 Lepidoptera species by using long-term data sampled over two decades. While 40% of the species neither advanced phenology nor moved northward, nearly half (47%) -used one of the two strategies. The strongest positive population trends was observed for the minority of species (13%) that both advanced flight phenology and shifted their northern range boundaries northward. We show that, for Boreal Lepidoptera, a combination of phenology and range shifts is the most viable strategy under a changing climate. Effectively, this may divide species into winners and losers based on their propensity to capitalize on this combination, with potentially large consequences on future community composition.

1. The occupancy and abundance of species are jointly driven by local factors, such as environmental characteristics and biotic interactions, and regional‐scale factors, such as dispersal and climate. Recently, it has been shown that biotic interactions shape species occupancies and abundances beyond local extents. However, for small ectothermic animals, particularly for those occurring in freshwater environments, the importance of biotic interactions remains understudied. Species‐to‐species associations from joint species distribution models (i.e. species associations while controlling for environmental characteristics) are increasingly used to draw hypotheses of which species possibly show biotic interactions. 2. We studied whether species‐to‐species associations from joint species distribution models show signs of competition using a hypothesis testing framework in stream macroinvertebrate communities at regional extent. 3. We sampled aquatic macroinvertebrates from 105 stream sites in western Finland encompassing a latitudinal gradient of ca. 500 kilometers. We hypothesized that if competition drives these associations (H1) functionally similar species are mostly negatively associated, whereas functionally dissimilar species show random associations. We further hypothesized that the relationship between functional dissimilarity and the strength of association is more pronounced (H2) for abundances rather than occupancies, (H3) at small grain (i.e. stream site) rather than at large grain (i.e. river basin), and (H4) among species having weak dispersal ability than among species with high dispersal ability. 4. Stream macroinvertebrates showed both negative and positive species‐to‐species associations while controlling for habitat characteristics. However, the negative associations were mostly at large grain (river basin) rather than at small grain (stream site), in occupancy rather than abundance, and not related to species functional dissimilarity or to their dispersal ability. Thus, all our hypotheses considering possible competition (H1‐H4) were rejected. 5. Competition does not appear to be a major driving force of stream macroinvertebrate communities at the spatial grain sizes considered. The observed positive associations in occupancy at small grain (stream site) may be attributed to species’ similar microhabitat preferences, whereas at large grain (river basin), they may stem from metacommunity dynamics. Our results highlight that species traits were necessary to interpret whether or not species‐to‐species associations from joint species distribution models resulted from biotic interactions. peerReviewed

Depending on their reproductive strategy, different fish species aim to aggregate or disperse eggs and larvae in their reproductive habitat. Many pelagic species disperse their eggs widely around the potential nursery areas. Larval dispersion or aggregation affects population sub‐structuring, which has important implications in fisheries management and conservation of the natural spatial diversity in populations. The dispersion of larval vendace (Coregonus albula) was quantified in two oligotrophic Finnish lakes, and effects of density and environmental variables on the inter‐annual variation in the larval distribution were examined by analysing spatial abundance data from the lakes from 1999 to 2017. A 3‐D hydrodynamic egg distribution model was used to simulate the larval transport after hatching. Vendace larvae dispersed lake‐wide to both littoral and pelagic zones but, in some littoral hot spots, more larvae aggregated year after year. However, in years of high larval number, the densities increased not only in the hot spots, but generally at all sampling plots. An overall increase in abundance was observed at all sampling sites. The simulations of the egg distribution model supported the hypothesis that the dispersion of the eggs occurs by spawners, i.e. by spawning at several different spawning sites, which are located all around the lake. The dispersion of vendace eggs and larvae can be seen as a bet‐hedging strategy in space and time since in boreal oligotrophic large lakes with fragmented morphology, weather and other environmental factors in spring during hatching varies from year to year spatially in unpredictable manner. Lake‐wide larval dispersion suggests that the subpopulations of adjacent lake deeps may swap considerable amounts of individuals during early life and may not be closed units. Conservation of particular habitats seems unnecessary for Finnish vendace populations where large potential spawning areas in lakes are available.

Both cognitive abilities and dispersal tendencies can vary strongly between individuals. Since cognitive abilities may help dealing with unknown circumstances, it is conceivable that dispersers may rely more heavily on learning abilities than residents. However, cognitive abilities are costly and leaving a familiar place might result in losing the advantage of having learned to deal with local conditions. Thus, individuals which invested in learning to cope with local conditions may be better off staying at their natal place. In order to disentangle the complex relationship between dispersal and learning abilities, we implemented individual‐based simulations. By allowing for developmental plasticity, individuals could either become a 'resident' or 'dispersal' cognitive phenotype. The model showed that in general residents have higher learning abilities than dispersers. Dispersers evolve higher learning ability than residents when dispersers have long life spans and when dispersal occurs either early or late in life, thereby maximizing the time in one habitat patch. Time is crucial here, because the longer an individual resides in a location where it can use its learned knowledge or behavior, the more often it profits from it and thus eventually obtains a net benefit from its investment into learning. Both, longevity and the timing of dispersal within lifecycles determine the time individuals have to recoup that investment and thus crucially influence this correlation. We therefore suggest that species' life history will strongly impact the expected cognitive abilities of dispersers, relative to their resident conspecifics, and that cognitive abilities might be an integral part of dispersal syndromes., Using individual‐based simulations, we show that dispersal and learning abilities can be either positively or negatively correlated, depending critically on the time span individuals have to recoup their investment into learning. Both longevity and timing of dispersal crucially determine this time span. We thus conclude that these life‐history traits crucially determine this correlation and suggest that in order to better understand animal dispersal patterns and success one should take the cognitive abilities of investigated species into account.

The evolution of dispersal tendencies and of cognitive abilities have both been intensely studied. Yet little attention has been given to the question of how these two aspects may relate to each other, as a result of their joint evolution. On the one hand, learning abilities may help dispersers to cope with their new habitat. On the other hand, dispersal may sometimes reduce the need for learning, because local environments may differ in how much there is to learn. To get a better understanding of this relationship, we built an individual‐based simulation in which both learning speed and dispersal tendency were free to evolve. We found that both positive and negative correlations could evolve between these traits, depending on properties both of local patches and of the metapopulation as a whole. We also found that dispersal stabilized the co‐existence of different cognitive types in the metapopulation, underscoring its importance for maintaining biodiversity within species. peerReviewed

According to ecology theory, isolated habitat fragments cannot maintain populations of specialized species. Yet, empirical evidence based on monitoring of the same fragments over time is still limited. We studied the colonization–extinction dynamics of eight wood-decaying fungal species in 16 old-growth forest fragments (Phellinus nigrolimitatusPhellinus ferrugineofuscus

Highlights • Data quality is very important for conducting a reliable risk assessment. • Same locations should be confined to smallest practicable areas within a port. • Nearly all shipping routes with adequate data resulted in high-risk outcomes. • Pelagic larval traits are key factors in natural dispersal modelling assessments. The International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention) aims to mitigate the introduction risk of harmful aquatic organisms and pathogens (HAOP) via ships’ ballast water and sediments. The BWM Convention has set regulations for ships to utilise exceptions and exemptions from ballast water management under specific circumstances. This study evaluated local and regional case studies to provide clarity for situations, where ships could be excepted or exempted from ballast water management without risking recipient locations to new introductions of HAOP. Ships may be excepted from ballast water management if all ballasting operations are conducted in the same location (Regulation A-3.5 of the BWM Convention). The same location case study determined whether the entire Vuosaari harbour (Helsinki, Finland) should be considered as the same location based on salinity and composition of HAOP between the two harbour terminals. The Vuosaari harbour case study revealed mismatching occurrences of HAOP between the harbour terminals, supporting the recommendation that exceptions based on the same location concept should be limited to the smallest feasible areas within a harbour. The other case studies evaluated whether ballast water exemptions could be granted for ships using two existing risk assessment (RA) methods (Joint Harmonised Procedure [JHP] and Same Risk Area [SRA]), consistent with Regulation A-4 of the BWM Convention. The JHP method compares salinity and presence of target species (TS) between donor and recipient ports to indicate the introduction risk (high or low) attributed to transferring unmanaged ballast water. The SRA method uses a biophysical model to determine whether HAOP could naturally disperse between ports, regardless of their transportation in ballast water. The results of the JHP case study for the Baltic Sea and North-East Atlantic Ocean determined that over 97% of shipping routes within these regions resulted in a high-risk indication. The one route assessed in the Gulf of Maine, North America also resulted in a high-risk outcome. The SRA assessment resulted in an overall weak connectivity between all ports assessed within the Gulf of the St. Lawrence, indicating that a SRA-based exemption would not be appropriate for the entire study area. In summary, exceptions and exemptions should not be considered as common alternatives for ballast water management. The availability of recent and detailed species occurrence data was considered the most important factor to conduct a successful and reliable RA. SRA models should include biological factors that influence larval dispersal and recruitment potential (e.g., pelagic larval duration, settlement period) to provide a more realistic estimation of natural dispersal.

The study was supported by the COST Action CA15113 Science and Management of Intermittent Rivers and Ephemeral Streams (http://www.smires.eu), funded by COST (European Cooperation in Science and Technology). NC was supported by the French research program Make Our Planet Great Again. MC-A was supported by the MECODISPER project (CTM2017-89295-P) funded by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO) - Agencia Estatal de Investigacion (AEI) and cofunded by the European Regional Development Fund (ERDF). AC-R acknowledges funding by MINECO-AEI-ERDF (CGL2014-53140-P). CG-C was supported by the EDRF (COMPETE2020 and PT2020) and the Portuguese Foundation for Science and Technology, through the CBMA strategic program UID/BIA/04050/2019 (POCI-01-0145-FEDER-007569) and the STREAMECO project (Biodiversity and ecosystem functioning under climate change: from the gene to the stream, PTDC/CTA-AMB/31245/2017). JH was supported by the project 'Global taxonomic, functional and phylogenetic diversity of stream macroinvertebrate communities: unravelling spatial trends, ecological determinants and anthropogenic threats' funded by the Academy of Finland. PP and MP were supported by the Czech Science Foundation (P505-20-17305S). ZC was supported by the projects EFOP-3.6.1.-16-2016-00004, 20765-3/2018/FEKUTSTRAT and TUDFO/47138/2019-ITM. We thank two anonymous reviewers for insightful feedback that improved an earlier draft of this manuscript., Dispersal is an essential process in population and community dynamics, but is difficult to measure in the field. In freshwater ecosystems, information on biological traits related to organisms’ morphology, life history and behaviour provides useful dispersal proxies, but information remains scattered or unpublished for many taxa. We compiled information on multiple dispersal-related biological traits of European aquatic macroinvertebrates in a unique resource, the DISPERSE database. DISPERSE includes nine dispersal-related traits subdivided into 39 trait categories for 480 taxa, including Annelida, Mollusca, Platyhelminthes, and Arthropoda such as Crustacea and Insecta, generally at the genus level. Information within DISPERSE can be used to address fundamental research questions in metapopulation ecology, metacommunity ecology, macroecology and evolutionary ecology. Information on dispersal proxies can be applied to improve predictions of ecological responses to global change, and to inform improvements to biomonitoring, conservation and management strategies. The diverse sources used in DISPERSE complement existing trait databases by providing new information on dispersal traits, most of which would not otherwise be accessible to the scientific community., COST Action Science and Management of Intermittent Rivers and Ephemeral Streams - COST (European Cooperation in Science and Technology) CA15113, French research program Make Our Planet Great Again, MECODISPER project - Spanish Ministerio de Economia, Industria y Competitividad (MINECO) - Agencia Estatal de Investigacion (AEI) CTM2017-89295-P, European Union (EU), MINECO-AEI-ERDF CGL2014-53140-P, EDRF (COMPETE2020), Portuguese Foundation for Science and Technology, through the CBMA strategic program UID/BIA/04050/2019 (POCI-01-0145-FEDER-007569), STREAMECO project (Biodiversity and ecosystem functioning under climate change: from the gene to the stream) PTDC/CTA-AMB/31245/2017, project 'Global taxonomic, functional and phylogenetic diversity of stream macroinvertebrate communities: unravelling spatial trends, ecological determinants and anthropogenic threats' - Academy of Finland, Grant Agency of the Czech Republic P505-20-17305S, EDRF (PT2020), EFOP-3.6.1.-16-2016-00004, 20765-3/2018/FEKUTSTRAT, TUDFO/47138/2019-ITM

During winter insects face energetic stress driven by lack of food, and thermal stress due to sub-optimal and even lethal temperatures. To survive, most insects living in seasonal environments such as high latitudes, enter diapause, a deep resting stage characterized by a cessation of development, metabolic suppression and increased stress tolerance. The current study explores physiological adaptations related to diapause in three beetle species at high latitudes in Europe. From an ecological perspective, the comparison is interesting since one species (Leptinotarsa decemlineata) is an invasive pest that has recently expanded its range into northern Europe, where a retardation in range expansion is seen. By comparing its physiological toolkit to that of two closely related native beetles (Agelastica alni and Chrysolina polita) with similar overwintering ecology and collected from similar latitude, we can study if harsh winters might be constraining further expansion. Our results suggest all species suppress metabolism during diapause and build large lipid stores before diapause, which then are used sparingly. In all species diapause is associated with temporal shifts in storage and membrane lipid profiles, mostly in accordance with the homeoviscous adaptation hypothesis, stating that low temperatures necessitate acclimation responses that increase fluidity of storage lipids, allowing their enzymatic hydrolysis, and ensure integral protein functions. Overall, the two native species had similar lipidomic profiles when compared to the invasive species, but all species showed specific shifts in their lipid profiles after entering diapause. Taken together, all three species show adaptations that improve energy saving and storage and membrane lipid fluidity during overwintering diapause. While the three species differed in the specific strategies used to increase lipid viscosity, the two native beetle species showed a more canalized lipidomic response, than the recent invader. Since close relatives with similar winter ecology can have different winter ecophysiology, extrapolations among species should be done with care. Still, range expansion of the recent invader into high latitude habitats might indeed be retarded by lack of physiological tools to manage especially thermal stress during winter, but conversely species adapted to long cold winters may face these stressors as a consequence of ongoing climate warming. peerReviewed

Air carries a vast number of bacteria and viruses over great distances all the time. This leads to continuous introduction of foreign genetic material to local, established microbial communities. In this perspective, I ask whether this silent rain may have a slowing effect on the overall evolutionary rates in the microbial biosphere. Arguably, the greater the genetic divergence between gene ‘donors’ and ‘recipients’, the greater the chance that the gene product has a deleterious epistatic interaction with other gene products in its genetic environment. This is due to the long-term absence of check for mutual compatibility. As such, if an organism is extensively different from other bacteria, genetic innovations are less probable to fit to the genome. Here, genetic innovation would be anything that elevates the fitness of the gene vehicle (e.g. bacterium) over its contemporaries. Adopted innovations increase the fitness of the compatible genome over incompatible ones, thus possibly tempering the pace at which mutations accumulate in existing genomes over generations. I further discuss the transfer of bacteriophages through atmosphere and potential effects that this may have on local dynamics and perhaps phage survival.

Much of our understanding of natural invasions is retrospective, based on data acquired after invaders become established. As a consequence, we know little about the characteristics of the early population growth and habitat use of the invaders during establishment. Here we report on experimental introductions of guppies into natural streams in which we conducted monthly censuses of each population. Two of the four introductions were in streams with thinned canopies, which mimics a common form of habitat disturbance. We conducted similar censuses of natural populations to characterize natural population densities and generate a null distribution against which we could test a priori hypotheses about the establishment of the experimental invaders. We constructed a pedigree for one population, which enabled us to quantify lifetime reproductive success. Population simulations predict that the nature of the introduced population’s life history, in combination with reduced risk of predation in the introduction sites, will result in explosive population growth; however, populations of introduced invaders instead grew to match densities observed in natural streams with intact canopies. Experimental populations in streams with thinned canopies grew to densities that often exceeded those of natural streams with intact canopies. High population densities were associated with the increased use of marginal habitat. Adult females and males that moved into marginal habitat suffered no apparent fitness loss, suggesting lower population densities found there compensated for lower habitat quality. Our results suggest that the ecological setting in which invasions occur plays a role at least comparable in importance to that of the invader’s inherent characteristics in shaping early population growth and habitat use. peerReviewed

Predicting population colonisations requires understanding how spatio‐temporal changes in density affect dispersal. Density can inform on fitness prospects, acting as a cue for either habitat quality, or competition over resources. However, when escaping competition, high local density should only increase emigration if lower‐density patches are available elsewhere. Few empirical studies on dispersal have considered the effects of density at the local and landscape scale simultaneously. To explore this, we analyze 5 years of individual‐based data from an experimental introduction of wild guppies Poecilia reticulata. Natal dispersal showed a decrease in local density dependence as density at the landscape level increased. Landscape density did not affect dispersal among adults, but local density‐dependent dispersal switched from negative (conspecific attraction) to positive (conspecific avoidance), as the colonisation progressed. This study demonstrates that densities at various scales interact to determine dispersal, and suggests that dispersal trade‐offs differ across life stages. peerReviewed

Parents can influence offspring dispersal through breeding site selection, competition, or by directly moving their offspring during parental care. Many animals move their young, but the potential role of this behavior in dispersal has rarely been investigated. Neotropical poison frogs (Dendrobatidae) are well known for shuttling their tadpoles from land to water, but the associated movements have rarely been quantified and the potential function of tadpole transport in dispersal has not been addressed. We used miniature radio-transmitters to track the movements of two poison frog species during tadpole transport, and surveyed pool availability in the study area. We found that parental males move farther than expected by the distance to the nearest pool and spread their offspring across multiple pools. We argue that these movement patterns cannot be fully explained by pool quality and availability, and suggest that adaptive benefits related to offspring dispersal also shape the spatial behavior of parental frogs. Electronic supplementary material The online version of this article (10.1007/s10682-019-09994-z) contains supplementary material, which is available to authorized users.

Invasive marbled crayfish Procambarus virginalis (Lyko, 2017) is spreading alarmingly fast across European countries and beyond. Early maturation, parthenogenetic reproduction mode and high growth rate contribute to a high potential invasiveness. Marbled crayfish can pose severe effects on native communities impacting the native crayfish populations being carrier of the crayfish plague disease caused by Aphanomyces astaci. Here we report the first record of marbled crayfish in Estonia. In total, 104 individuals were found in the artificially warm outflow channel of the cooling system of Balti Power Plant, entering to the water reservoir of the River Narva. Molecular analyses confirmed the morphological identification of captured specimens as a marbled crayfish. Four out of six marbled crayfish individuals exhibited the presence of crayfish plague agent, though at very low level. This suggests that marbled crayfish can potentially be a new vector of crayfish plague in Estonian freshwater ecosystems containing native noble crayfish Astacus astacus populations. Monitoring and eradication actions are urgently needed not only in the outflow channel where the species was found but in the whole water reservoir and River Narva itself. peerReviewed

Success rates for conservation translocations of species are low and there is a need for increased understanding of how this activity is best applied. Here, using static species distribution models and a spatially-explicit dynamic simulation model, RangeShifter, we examine the impacts of habitat cover in recipient landscapes, allocation of individuals into multiple sites and species trait characteristics on the long-term fate of hypothetical translocations of a grassland specialist butterfly, Maniola jurtina, in Finland. While persistence of populations introduced to climatically suitable locations northwards of the current range can be increased by selecting sites with increasing habitat cover and by allocation of individuals to multiple release sites, local population growth rate is shown to be the key parameter in determining likely translocation success. We conclude that the long-term persistence of translocated habitat specialist butterflies, particularly with low growth rates, appears to be uncertain in modern-day fragmented grassland networks and that translocation activities should prioritize management that improves local growth rate.

Gliding motility facilitates the movement of bacteria along surfaces in many Bacteroidetes species and results in spreading colonies. The adhesins required for the gliding are secreted through a gliding motility-associated protein secretion system, known as the type IX secretion system (T9SS). The fish pathogen Flavobacterium columnare produces spreading (rhizoid [Rz], soft [S]) and non-spreading (rough [R]) colony types, of which only the spreading Rz type is virulent. In this study, we explored the spreading behavior of these colony types by microscopic imaging and measured the expression of genes associated with gliding motility and T9SS (gldG, gldH, gldL, sprA, sprB, sprE, sprF, sprT, and porV) under high and low resource levels by using RT-qPCR (reverse transcription quantitative PCR). The spreading colony types responded to the low resource level with increased colony size. The non-spreading colony type, as well as the cells growing under high nutrient level expressed only moderate cell movements. Yet, a low nutrient level provoked more active gliding motility in individual cells and increased spreading by cooperative gliding. The gene expression survey demonstrated an increased expression level of sprA (a core component of T9SS) and sprF (needed for adhesin secretion) under low nutrient conditions. Surprisingly, the expression of gliding motility genes was not consistently associated with more active spreading behavior. Furthermore, no genetic differences were found between spreading and non-spreading colony types in the studied genes associated with gliding motility. Our study demonstrates that environmental nutrient level is an important regulator of both gliding motility and the expression of some of the associated genes. These results may help to understand the connections between nutrient concentration, gliding motility, and virulence of F. columnare.

Sexual spores are important for the dispersal and population dynamics of fungi. They show remarkable morphological diversity, but the underlying forces driving spore evolution are poorly known. We investigated whether trophic status and substrate associations are associated with morphology in 787 macrofungal genera. We show that both spore size and ornamentation are associated with trophic specialization, so that large and ornamented spores are more probable in ectomycorrhizal than in saprotrophic genera. This suggests that spore ornamentation facilitates attachment to arthropod vectors, which ectomycorrhizal species may need to reach lower soil layers. Elongated spore shapes are more common in saprotrophic taxa, and genera associated with above ground substrates are more likely to have allantoid (curved elongated) spores, probably to lower the risk of wash out by precipitation. Overall, our results suggest that safe arrival on specific substrates is a more important driver of evolution in spore morphology than dispersal per se.

In Finland, massive signal crayfish introductions started towards the end of 1980s, with an estimated total of 2.2 million signal crayfish been stocked before year 2016. During that period, Finnish fisheries authorities have implemented three national management strategies setting guidelines for the crayfish introductions. The main aims of the strategies have been conservation of native noble crayfish stocks and a controlled spreading of the alien signal crayfish within a designated region. In this study, we report the current distribution of signal crayfish in Finland in comparison to the guidelines set in these three national strategies. The present distribution area of the signal crayfish covers most of the Southern Finland. The signal crayfish has been introduced with a stocking permits to over 480 water bodies. In addition, there have been numerous stockings without permits, which are often next to the region designated for the signal crayfish. Based on the results, we conclude that crayfish management strategies adopted in Finland have only had limited effect on the spread of signal crayfish. We presume that main causes for the uncontrolled spreading of the signal crayfish in Finland have been lack of strict official supervision and general lack of awareness about the risks associated with the alien species spreading. En Finlande, l'introduction massive d'écrevisses a commencé vers la fin des années 1980, avec un total estimé à 2,2 millions d'écrevisses signal stockées avant 2016. Au cours de cette période, les autorités finlandaises de la pêche ont mis en œuvre trois stratégies nationales de gestion fixant des lignes directrices pour l'introduction des écrevisses. Les principaux objectifs de ces stratégies ont été la conservation des stocks indigènes d'écrevisses nobles et la diffusion contrôlée des écrevisses exotiques dans une région désignée. Dans cette étude, nous présentons la répartition actuelle des écrevisses en Finlande par rapport aux lignes directrices établies dans ces trois stratégies nationales. L'aire de distribution actuelle de l'écrevisse signal couvre la majeure partie du sud de la Finlande. L'écrevisse signal a été introduite avec autorisation dans plus de 480 plans d'eau. De plus, il y a eu de nombreux cas sans permis, souvent à proximité de la région désignée pour les écrevisses signal. Sur la base des résultats, nous concluons que les stratégies de gestion des écrevisses adoptées en Finlande n'ont eu qu'un effet limité sur la propagation des écrevisses signal. Nous présumons que les principales causes de la propagation incontrôlée de l'écrevisse signal en Finlande sont le manque de surveillance officielle stricte et le manque général de sensibilisation aux risques associés à la propagation des espèces exotiques. peerReviewed

Natural populations often experience environments that vary across space and over time, leading to spatio-temporal variation of the fitness of a genotype. If local conditions are poor, organisms can disperse in space (physical movement) or time (dormancy, diapause). Facultatively sexual organisms can switch between asexual and sexual reproduction, and thus have a third option available to deal with maladaptedness: they can engage in sexual reproduction in unfavourable conditions (an ‘abandon-ship’ response). Sexual reproduction in facultatively sexual organisms is often coupled with dispersal and/or dormancy, while bet-hedging theory at first sight predicts sex, dispersal and dormancy to covary negatively, as they represent different escape mechanisms that could substitute for each other. Here we briefly review the observed links between sex, dormancy and dispersal, and model the expected covariation patterns of dispersal, dormancy and the reproductive mode in the context of local adaptation to spatio-temporally fluctuating environments. The correlations between sex, dormancy and dispersal evolve differently within species versus across species. Various risk-spreading strategies are not completely interchangeable, as each has dynamic consequences that can feed back into the profitability of others. Our results shed light on the discrepancy between previous theoretical predictions on covarying risk-spreading traits and help explain why sex often associates with other means of escaping unfavourable situations.This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences’.

Translocations have been advocated as a conservation tool helping species adapt to climate and land-use change, but well-documented examples of invertebrates’ translocations are rare. The paper describes a successful translocation of the threatened Clouded Apollo butterfly ( Parnassius mnemosyne ) in Finland, compares this to a specific failed translocation, and presents conclusions for conservation planning as to factors contributing to the success. Two apparent key characteristics of the successful translocation were greater abundance of larval resources and less open landscape. The successful site was surrounded by forest, which strongly restricted emigration, crucially supporting the survival of the small initial population. Based on 20 mated females’ translocation in 2000, the local population increased slowly, reaching 600 butterflies in 2011. A large translocation patch together with host-plant abundance enabled successful establishment of the local population. Availability of other suitable grassland patches sufficiently nearby was an additional key characteristic, facilitating the Clouded Apollo’s expansion. However, the expansion rate was low; it took seven years for the butterflies to colonise the five nearest patches, only 10–200 m from the translocation patch. By 2013, they had colonised all suitable semi-natural grassland patches within 2 km from the translocation site and established a seemingly viable metapopulation with 11 subpopulations. The results point to the significance of local habitat area and landscape quality, along with conditions restricting emigration, in determination of suitable translocation sites.

Assessment of the costs and benefits of dispersal is central to understanding species' life-history strategies as well as explaining and predicting spatial population dynamics in the changing world. While mortality during active movement has received much attention, few have studied the costs of passive movement such as the airborne transport of fungal spores. Here, we examine the potential of extreme environmental conditions to cause dispersal mortality in wood-decay fungi. These fungi play a key role as decomposers and habitat creators in forest ecosystems and the populations of many species have declined due to habitat loss and fragmentation. We measured the effect of simulated solar radiation (including ultraviolet A and B) and freezing at -25 degrees C on the spore germinability of 17 species. Both treatments but especially sunlight markedly reduced spore germinability in most species, and species with thin-walled spores were particularly light sensitive. Extrapolating the species' laboratory responses to natural irradiance conditions, we predict that sunlight is a relevant source of dispersal mortality at least at larger spatial scales. In addition, we found a positive effect of spore size on spore germinability, suggesting a trade-off between dispersal distance and establishment. We conclude that freezing and particularly sunlight can be important sources of dispersal mortality in wood-decay fungi which can make it difficult for some species to colonize isolated habitat patches and habitat edges.

Metacommunity paradigms are increasingly studied to explain how environmental control and spatial patterns determine variation in community composition. However, the relative importance of these patterns on biological assemblages among different habitats is not well known. We investigated the relative roles of local, catchment and spatial variables based on overland and watercourse distances in explaining the variation of community structure of lake and river macrophytes in two large river basins at two spatial extents (within and across river basins). Partial redundancy analysis was used to explore the share of variability in macrophyte communities attributable to local environmental conditions, catchment land cover and space (generated with Principle Coordinates of Neighbour Matrices). We found that local variables had the highest effect on both lake and river macrophyte communities, followed by catchment variables. Space had no or only marginal influence on the community structure regardless of used distance measure. Total phosphorus, conductivity and turbidity of the local variables contributed most for lake macrophytes, whereas pH and color had largest independent contribution for variation in river macrophytes. Size of catchment area and proportion of lakes and agriculture were the most important catchment variables in both habitats. The strong importance of environmental control suggests that both lake and river macrophyte communities are structured by species sorting. This finding gives support to the validity of assessment systems based on the European Water Framework Directive.

In ecology understanding variation in connectivity is central for how biodiversity is maintained. Field studies on dispersal and temporal dynamics in community regulating processes are, however, rare. We test the short-term temporal stability in community composition in a soft-sediment benthic community by determining among-sampling interval similarity in community composition. We relate stability to in situ measures of connectivity (wind, wave, current energy) and rates of dispersal (quantified in different trap types). Waves were an important predictor of when local community taxa are most likely to disperse in different trap-types, suggesting that wave energy is important for connectivity in a region. Community composition at the site was variable and changed stochastically over time. We found changes in community composition (occurrence, abundance, dominance) to be greater at times when connectivity and rates of dispersal were low. In response to periods of lower connectedness dominant taxa in the local community only exhibited change in their relative abundance. In contrast, locally less abundant taxa varied in both their presence, as well as in relative abundance. Constancy in connectivity and rates of dispersal promotes community stability and persistence, suggesting that local community composition will be impacted by changes in the spatial extent over which immigration and emigration operates in the region. Few empirical studies have actually measured dispersal directly in a multi-species context to demonstrate the role it plays in maintaining local community structure. Even though our study does not evaluate coexistence over demographic time scales, it importantly demonstrates that dispersal is not only important in initial recruitment or following a disturbance, but also key in maintaining local community composition.

Wind is the main dispersal agent for a wide array of species and for these species the environmental conditions under which diaspores are released can potentially modify the dispersal kernel substantially. Little is known about how bryophytes regulate spore release, but conditions affecting peristome movements and vibration of the seta may be important. We modelled airborne spore dispersal of the bryophyte species Discelium nudum (spore diameter 25 m), in four different release scenarios, using a Lagrangian stochastic dispersion model and meteorological data. We tested the model predictions against experimental data on colonization success at five distances (5, 10, 30, 50 and 100 m) and eight directions from a translocated point source during seven two-day periods. The model predictions were generally successful in describing the observed colonization patterns, especially beyond 10 m. In the laboratory we established spore release thresholds; horizontal wind speed sd > 0.25 m s(-1) induced the seta to vibrate and in relative humidity < 75% the peristome was open. Our dispersal model predicts that the proportion of spores dispersing beyond 100 m is almost twice as large if the spores are released under turbulent conditions than under more stable conditions. However, including release thresholds improved the fit of the model to the colonization data only minimally, with roughly the same amount of variation explained by the most constrained scenario (assuming both vibration of the seta and an open peristome) and the scenario assuming random release. Model predictions under realised experimental conditions suggest that we had a low statistical power to rank the release scenarios due to the lack of measurements of the absolute rate of spore release. Our results hint at the importance of release conditions, but also highlight the challenges in dispersal experiments intended for validating mechanistic dispersal models.

Infectious diseases are amongst the ten major causes of human mortality worldwide, 60% of them being animal-borne. Variations of abiotic and biotic conditions are likely to modify the transmission of parasites and pathogens within reservoir species, and, as a consequence, alter the zoonotic risk for human. My thesis aims at elucidating the dynamics and mechanisms of the maintenance of ticks, tick-borne pathogens (TBPs) and the Puumala hantavirus (PUUV) in the reservoir host, the bank vole (Myodes glareolus, BV). In Northern Europe, tick-borne diseases are growing in importance to human because of the latitudinal expansion of the tick Ixodes ricinus. Field monitoring revealed that I. ricinus was the only species found in the vegetation in Central Finland. The abundance of immature I. ricinus in nature was positively associated with the BV abundance. The highest risk periods for tick bites on humans were May– June and September. Ixodes ricinus was positively associated with open water coverage and human density, which might offer suitable moisture conditions and anthropogenic modifications favouring the species. The infection of BV with the zoonotic B. burgdorferi s.l. was associated with the abundance of I. ricinus at the site, indicating that this tick species was required for the transmission and persistence of this pathogen. An experiment revealed, for the first time, that B. afzelii can modify the behaviour and the breeding success of its host, and these effects are both sex- and size-specific and density-dependent. Space-state modelling of longitudinal field data revealed that PUUV infection likelihood was the lowest in BV previously infested with vectors in comparison to Anaplasma phagocytophilum infected BV, or individuals without any previous infections. Altogether, this study shows how seasonality, co-infecting pathogens and host population density influence the risk of tick-borne pathogens and the zoonotic risk in Central Finland.

The consequences of the climate change on species are still uncertain, despite of intensive research. Currently, rising temperature is not the only concern, since the climate change scenarios also predict increases in the amount of disturbances, such as storms, floods, and thermal fluctuations. Disturbances have also been shown to affect species’ evolution, for example by selecting for traits that are advantageous in fluctuating environments but are also facilitating invasiveness. In this thesis, I study the consequences of evolving in a fluctuating thermal environment by utilizing bacterial microcosms. First I tested the effects of fluctuating vs. constant temperature on the evolution of temperature tolerance, both in one-species setting (I) and with multiple species (II). Then I studied how pre-adaptations to fluctuating vs. constant temperature, together with environmental conditions, affect invasion success (III). Additionally I also tested the effects of propagule pressure and genetic diversity on invasion success (IV). The results of the studies I and II show that constant and fluctuating thermal environments require different kinds of adaptations, as measurements taken in constant environments (traditional tolerance curve approach) did not reveal the adaptations to fluctuating environment. In study III, I found that fluctuations during invasion as well as pre-adaptations to fluctuating environment increased the invasion success of the invader. However, in study IV, I did not find any clear evidence that high propagule pressure or high genetic variance would have increased invasion success. To conclude, the results in this thesis demonstrate that adaptations that aid species to cope with disturbed environments can also lead to increased invasiveness. Furthermore, these adaptations might not be detectable using traditional measurement methods, which could, in the worst case, lead to incorrect conclusions and management actions, when considering climate-change driven extinction risks, or the effects of invasive species on natural environments.

Plant-associated microbes could play a role in plant colonization of sand dune ecosystems, but microbes associated with plants colonizing those ecosystems in the arctic are poorly known. I characterized Deschampsia flexuosa-associated microbiomes in two successional stages (early and late) of arctic inland sand dune differ in their plant species richness and soil physiochemical properties. The work based on culturable microbes showed that different plant parts harbour generalist and specific groups of endosphere microbes and most of the endosphere bacteria were closely related to other cold habitat microbes. Also, most of the endosphere bacteria possessed an important plant growth promoting property of solubilizing organic phosphate. Next generation sequencing methods showed that endosphere microbial species richness was determined by soil characteristics (succession) and plant compartment. Successional stage strongly affected the microbial community composition. Further, reciprocal transplantation experiment showed that endosphere microbial species richness was determined by successional stage rather than transplantation type (self or reciprocal). Irrespective of successional stage, after reciprocal transplantation microbial community compositions in most of the leaf and root compartments differed from local non-transplanted control. In contrast, the microbial community composition only in few root compartments was affected by self-transplantation. Further, leaf endosphere bacterial community composition was significantly affected by arbuscular mycorrhizal fungal (AMF) inoculation under greenhouse conditions. Overall, my work provided data from poorly characterized arctic biota and novel insight into endosphere bacterial and fungal community assemblage in arctic inland sand dune ecosystem. These results could be utilized when restoring vegetation in sand dunes and similar extreme ecosystems.

In this thesis, two bucephalid trematode parasites Rhipidocotyle campanula and R. fennica, which use the same first (Anodonta anatina) and second intermediate (Rutilus rutilus) host were studied. The aim was to investigate the effect of temperature on one of the key processes in the transmission of these parasites: 1) the emergence of cercarial larvae from A. anatina over short (1 h) and 2) long (throughout the annual cercarial shedding period, from May to October) time periods as well, as on 3) mussel survival and 4) the seasonal timing of cercarial release. In addition, the aim was to study how the cercarial shedding traits are linked to the 5) geographical occurrence and abundance of the Rhipidocotyle species. In the experimental studies, the cercarial emergence by R. fennica increased significantly with increasing temperature over short and long time periods, while that by R. campanula was unaffected by temperature. R. campanula clearly started seasonal cercarial release earlier and at a lower temperature than R. fennica. Survival of mussels, especially cercariae-shedding mussels, was lower at higher temperature, and the shedding of R. campanula cercariae was associated with higher mussel mortality than the shedding of R. fennica. The average duration of the seasonal cercarial release period of both species was unaffected by temperature at the individual host level, but at the host population level the cercarial shedding period of R. fennica (but not of R. campanula) was longer at higher temperature. The field study showed that the occurrence, mean prevalence and abundance of R. fennica – in accordance with the experimentally observed association of cercarial release with high temperature – decreased from the south (61–64 °N) to the low north (65–66 °N), but this pattern was not detected in R. campanula.