Browsing by Subject "DISPERSAL"

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  • Macias-Hernandez, Nuria; Ramos, Cândida; Domènech, Marc; Febles, Sara; Santos, Irene; Arnedo, Miquel A.; Borges, Paulo A. V.; Emerson, Brent C.; Cardoso, Pedro (2020)
    Background There is an increasing demand for databases including species trait information for biodiversity and community ecology studies. The existence of trait databases is useful for comparative studies within taxa or geographical regions, but there is low availability of databases for certain organisms. Here we present an open access functional trait database for spiders from Macaronesia and the Iberian Peninsula, recording several morphological and ecological traits related to the species life histories, microhabitat and trophic preferences. New information We present a database that includes 12 biological traits for 506 spider species present in natural forests of the Iberian Peninsula (Spain) and three Macaronesian archipelagoes (Azores, Madeira and Canary Islands). The functional trait database consists of two sections: 1. individual-level data for six morphological traits (total body size, prosoma length, prosoma width, prosoma height, tibia I length and fang length), based on direct measurements of 2844 specimens of all spider species; and 2. species-level aggregate data for 12 traits (same 6 morphological traits as in the previous section plus dispersal ability, vertical stratification, circadian activity, foraging strategy, trophic specialization and colonization status), based on either the average of the direct measurements or bibliographic searches. This functional trait database will serve as a data standard for currently ongoing analyses that require trait and functional diversity statistics.
  • Ovaskainen, Otso; Somervuo, Panu; Finkelshtein, Dmitri (2020)
    Agent-based models are used to study complex phenomena in many fields of science. While simulating agent-based models is often straightforward, predicting their behaviour mathematically has remained a key challenge. Recently developed mathematical methods allow the prediction of the emerging spatial patterns for a general class of agent-based models, whereas the prediction of spatio-temporal pattern has been thus far achieved only for special cases. We present a general and mathematically rigorous methodology that allows deriving the spatio-temporal correlation structure for a general class of individual-based models. To do so, we define an auxiliary model, in which each agent type of the primary model expands to three types, called the original, the past and the new agents. In this way, the auxiliary model keeps track of both the initial and current state of the primary model, and hence the spatio-temporal correlations of the primary model can be derived from the spatial correlations of the auxiliary model. We illustrate the agreement between analytical predictions and agent-based simulations using two example models from theoretical ecology. In particular, we show that the methodology is able to correctly predict the dynamical behaviour of a host-parasite model that shows spatially localized oscillations.
  • Palacio, Facundo X.; Callaghan, Corey T.; Cardoso, Pedro; Hudgins, Emma J.; Jarzyna, Marta A.; Ottaviani, Gianluigi; Riva, Federico; Rodrigues Leandro Roza, Caio Graco; Shirey, Vaughn; Mammola, Stefano (2022)
    The widespread use of species traits in basic and applied ecology, conservation and biogeography has led to an exponential increase in functional diversity analyses, with > 10 000 papers published in 2010-2020, and > 1800 papers only in 2021. This interest is reflected in the development of a multitude of theoretical and methodological frameworks for calculating functional diversity, making it challenging to navigate the myriads of options and to report detailed accounts of trait-based analyses. Therefore, the discipline of trait-based ecology would benefit from the existence of a general guideline for standard reporting and good practices for analyses. We devise an eight-step protocol to guide researchers in conducting and reporting functional diversity analyses, with the overarching goal of increasing reproducibility, transparency and comparability across studies. The protocol is based on: 1) identification of a research question; 2) a sampling scheme and a study design; 3-4) assemblage of data matrices; 5) data exploration and preprocessing; 6) functional diversity computation; 7) model fitting, evaluation and interpretation; and 8) data, metadata and code provision. Throughout the protocol, we provide information on how to best select research questions, study designs, trait data, compute functional diversity, interpret results and discuss ways to ensure reproducibility in reporting results. To facilitate the implementation of this template, we further develop an interactive web-based application (stepFD) in the form of a checklist workflow, detailing all the steps of the protocol and allowing the user to produce a final 'reproducibility report' to upload alongside the published paper. A thorough and transparent reporting of functional diversity analyses ensures that ecologists can incorporate others' findings into meta-analyses, the shared data can be integrated into larger databases for consensus analyses, and available code can be reused by other researchers. All these elements are key to pushing forward this vibrant and fast-growing field of research.
  • Tolvanen, Jere; Pakanen, Veli-Matti; Valkama, Jari; Tornberg, Risto (2017)
    Capsule: Mark-recapture data suggest low apparent survival and sex- and population-specific site fidelity and territory turnover in adult Northern Goshawks Accipiter gentilis breeding in northern Europe.Aims: To understand how species cope with global environmental change requires knowledge of variation in population demographic rates, especially from populations close to the species' northern range limit and from keystone species such as raptors. We analyse apparent survival and breeding dispersal propensity of adult Northern Goshawks breeding in northern Europe.Methods: We used long-term mark-recapture data from two populations in Finland, northern Europe, and Cormack-Jolly-Seber models and binomial generalized linear models to investigate sex- and population-specific variation in apparent survival, territory turnover and site fidelity.Results: We report low apparent survival (53-72%) of breeding adult Goshawks. Breeding dispersal propensity was higher in females than males, especially in northern Finland, contrasting with previous studies that suggest high site fidelity in both sexes.Conclusion: Low apparent survival in females may be mainly due to permanent emigration outside the study areas, whereas in males the survival rate may truly be low. Both demographic aspects may be driven by the combination of sex-specific roles related to breeding and difficult environmental conditions prevailing in northern latitudes during the non-breeding season.
  • Jamoneau, Aurelien; Passy, Sophia I.; Soininen, Janne; Leboucher, Thibault; Tison-Rosebery, Juliette (2018)
    1. Understanding the mechanisms that drive beta diversity (i.e. beta-diversity), an important aspect of regional biodiversity, remains a priority for ecological research. beta-diversity and its components can provide insights into the processes generating regional biodiversity patterns. We tested whether environmental filtering or dispersal related processes predominated along the stream watercourse by analysing the responses of taxonomic and functional diatom beta-diversity to environmental and spatial factors. 2. We examined the variation in total beta-diversity and its components (turnover and nestedness) in benthic diatom species and ecological guilds (motile, planktonic, low-and high profile) with respect to watercourse position (up-, mid-and downstream) in 2,182 sites throughout France. We tested the effects of pure environmental and pure spatial factors on beta-diversity with partial Mantel tests. Environmental factors included eight physicochemical variables, while geographical distances between sites were used as spatial factors. We also correlated a and c-diversity, and the degree of nestedness (NODF metric) with environmental variables. 3. Total beta-diversity and its turnover component displayed higher values upstream than mid-and downstream. The nestedness component exhibited low values, even when NODF values increased from up-to downstream. Pure environmental factors were highly significant for explaining total beta-diversity and turnover regardless of watercourse position, but pure spatial factors were mostly significant mid-and downstream, with geographical distance being positively correlated with beta-diversity. Across sites, nutrient enrichment decreased turnover but increased the degree of nestedness. Motile and low profile diatoms comprised the most abundant guilds, but their beta-diversity patterns varied in an opposite way. The lowest guild beta-diversity was observed upstream for low profile species, and downstream for motile species. 4. In conclusion, environmental filtering seemed to play a major role in structuring metacommunities irrespective of site watercourse position. Filtering promoted strong turnover patterns, especially in disconnected upstream sites. The greater role of spatial factors mid-and downstream was consistent with mass effects rather than neutral processes because these sites had lower total beta-diversity than upstream sites. Motile species were most strongly affected by mass effects processes, whereas low profile species were primarily influenced by environmental conditions. Collectively, these findings suggest that partitioning of total beta-diversity into its components and the use of diatom ecological guilds provide a useful framework for assessing the mechanisms underlying metacommunity patterns along the stream watercourse.
  • Rosa, Elena; Saastamoinen, Marjo (2020)
    Cold developmental conditions can greatly affect adult life history of ectotherms in seasonal habitats. Such effects are mostly negative, but sometimes adaptive. Here, we tested how cold conditions experienced during pupal development affect adult wing melanization of an insect ectotherm, the Glanville fritillary butterfly, Melitaea cinxia. We also assessed how in turn previous cold exposure and increased melanization can shape adult behaviour and fitness, by monitoring individuals in a seminatural set-up. We found that, despite pupal cold exposure inducing more melanization, wing melanization was not linked to adult thermoregulation preceding flight, under the conditions tested. Conversely, wing vibrating behaviour had a major role in producing heat preceding flight. Moreover, more melanized individuals were more mobile across the experimental set-up. This may be caused by a direct impact of melanization on flight ability or a more indirect impact of coloration on behaviours such as mate search strategies and/or eagerness to disperse to more suitable mating habitats. We also found that more melanized individuals of both sexes had reduced mating success and produced fewer offspring, which suggests a clear fitness cost of melanization. Whether the reduced mating success is dictated by impaired mate search behaviour, reduced physical condition leading to a lower dominance status or weakened visual signalling remains unknown. In conclusion, while there was no clear role of melanization in providing a thermal advantage under our seminatural conditions, we found a fitness cost of being more melanized, which potentially impacted adult space use behaviour. (c) 2020 The Authors. Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY-NC-ND license ( licenses/by-nc-nd/4.0/).
  • Quesada, J.; Chavez-Zichinelli, Carlos A.; Garcia-Arroyo, Michelle; Yeh, Pamela J.; Guevara, R.; Izquierdo-Palma, J.; MacGregor-Fors, I. (2022)
    Bold or shy? Examining the risk-taking behavior and neophobia of invasive and non-invasive house sparrows. Behavior provides a useful framework for understanding specialization, with animal personality aiding our understanding of the invasiveness of birds. Invasions imply dispersion into unknown areas and could require changes in behavior or spatial clustering based on personality. Reduced neophobia and increased exploring behavior could allow individuals to colonize new areas as they test and use non-familiar resources. Here, we hypothesized that house sparrow (Passer domesticus) individuals from invasive populations would exhibit bolder behavior than in non-invasive populations. We assessed risk taking and neophobia in male house sparrows in Barcelona (where it is considered native) and in Mexico City (where it has become widely invasive), captured in two different habitats, urban and non-urban. We assessed latency to enter an experimental cage and to explore it, and latency to feed and feeding time in the presence of a novel object. We found that sparrows from Mexico City, both from urban and non-urban areas, were quicker to enter the experimental cage than the sparrows from Barcelona. The time it took the birds to start exploring the cage gave a similar result. We found no differences between cities or habitats in the latency to feed and feeding time while exposed to a novel object. Our results partially support the view that the invader populations from Mexico City are bolder than those from Barcelona. Behavior is an important component of plasticity and its variability may have an important effect on adaptation to local situations. Future studies should disentangle the underlying mechanisms that explain the different personalities found in populations of different regions, contrasting populations of different densities, and taking different food availability scenarios into account.
  • Mammola, Stefano; Pétillon, Julien; Hacala, Axel; Monsimet, Jérémy; Marti, Sapho-Lou; Cardoso, Pedro; Lafage, Denis (2021)
    Aim Species distribution models (SDMs) have emerged as essential tools in the equipment of many ecologists, useful to explore species distributions in space and time and answering an assortment of questions related to biogeography, climate change biology and conservation biology. Historically, most SDM research concentrated on well-known organisms, especially vertebrates. In recent years, these tools are becoming increasingly important for predicting the distribution of understudied invertebrate taxa. Here, we reviewed the literature published on main terrestrial arthropod predators (ants, ground beetles and spiders) to explore some of the challenges and opportunities of species distribution modelling in mega-diverse arthropod groups. Location Global. Methods Systematic mapping of the literature and bibliometric analysis. Results Most SDM studies of animals to date have focused either on broad samples of vertebrates or on arthropod species that are charismatic (e.g. butterflies) or economically important (e.g. vectors of disease, crop pests and pollinators). We show that the use of SDMs to map the geography of terrestrial arthropod predators is a nascent phenomenon, with a near-exponential growth in the number of studies over the past ten years and still limited collaborative networks among researchers. There is a bias in studies towards charismatic species and geographical areas that hold lower levels of diversity but greater availability of data, such as Europe and North America. Conclusions Arthropods pose particular modelling challenges that add to the ones already present for vertebrates, but they should also offer opportunities for future SDM research as data and new methods are made available. To overcome data limitations, we illustrate the potential of modern data sources and new modelling approaches. We discuss areas of research where SDMs may be combined with dispersal models and increasingly available phylogenetic and functional data to understand evolutionary changes in ranges and range-limiting traits over past and contemporary time-scales.
  • Mammola, Stefano; Piano, Elena; Cardoso, Pedro; Vernon, Philippe; Dominguez-Villar, David; Culver, David C.; Pipan, Tanja; Isaia, Marco (2019)
    Scientists of different disciplines have recognized the valuable role of terrestrial caves as ideal natural laboratories in which to study multiple eco-evolutionary processes, from genes to ecosystems. Because caves and other subterranean habitats are semi-closed systems characterized by a remarkable thermal stability, they should also represent insightful systems for understanding the effects of climate change on biodiversity in situ. Whilst a number of recent advances have demonstrated how promising this fast-moving field of research could be, a lack of synthesis is possibly holding back the adoption of caves as standard models for the study of the recent climatic alteration. By linking literature focusing on physics, geology, biology and ecology, we illustrate the rationale supporting the use of subterranean habitats as laboratories for studies of global change biology. We initially discuss the direct relationship between external and internal temperature, the stability of the subterranean climate and the dynamics of its alteration in an anthropogenic climate change perspective. Owing to their evolution in a stable environment, subterranean species are expected to exhibit low tolerance to climatic perturbations and could theoretically cope with such changes only by shifting their distributional range or by adapting to the new environmental conditions. However, they should have more obstacles to overcome than surface species in such shifts, and therefore could be more prone to local extinction. In the face of rapid climate change, subterranean habitats can be seen as refugia for some surface species, but at the same time they may turn into dead-end traps for some of their current obligate inhabitants. Together with other species living in confined habitats, we argue that subterranean species are particularly sensitive to climate change, and we stress the urgent need for future research, monitoring programs and conservation measures.
  • Siqueira, Tadeu; Saito, Victor S.; Bini, Luis M.; Melo, Adriano S.; Petsch, Danielle K.; Landeiro, Victor L.; Tolonen, Kimmo T.; Jyrkänkallio-Mikkola, Jenny; Soininen, Janne; Heino, Jani (2020)
    Ecological drift can override the effects of deterministic niche selection on small populations and drive the assembly of some ecological communities. We tested this hypothesis with a unique data set sampled identically in 200 streams in two regions (tropical Brazil and boreal Finland) that differ in macroinvertebrate community size by fivefold. Null models allowed us to estimate the magnitude to which beta-diversity deviates from the expectation under a random assembly process while taking differences in richness and relative abundance into account, i.e., beta-deviation. We found that both abundance- and incidence-based beta-diversity was negatively related to community size only in Brazil. Also, beta-diversity of small tropical communities was closer to stochastic expectations compared with beta-diversity of large communities. We suggest that ecological drift may drive variation in some small communities by changing the expected outcome of niche selection, increasing the chances of species with low abundance and narrow distribution to occur in some communities. Habitat destruction, overexploitation, pollution, and reductions in connectivity have been reducing the size of biological communities. These environmental pressures might make smaller communities more vulnerable to novel conditions and render community dynamics more unpredictable. Incorporation of community size into ecological models should provide conceptual and applied insights into a better understanding of the processes driving biodiversity.
  • Valanko, Sebastian; Heino, Jani; Westerbom, Mats; Viitasalo, Markku; Norkko, Alf (2015)
    The majority of studies in metacommunity ecology have focused on systems other than marine benthic ecosystems, thereby providing an impetus to broaden the focus of metacommunity research to comprise marine systems. These systems are more open than many other systems and may thus exhibit relatively less discrete patterns in community structure across space. Metacommunity structure of soft-sediment benthic invertebrates was examined using a fine-grained (285 sites) data set collected during one summer across a large spatial extent (1700km(2)). We applied the elements of metacommunity structure (EMS) approach, allowing multiple hypothesis of variation in community structure to be tested. We demonstrated several patterns associated with environmental variation and associated processes that could simultaneously assemble species to occur at the sites. A quasi-Clementsian pattern was observed frequently, suggesting interdependent ecological relationships among species or similar response to an underlying environmental gradient across sites. A quasi-nested clumped species loss pattern was also observed, which suggests nested habitat specialization. Species richness declined with depth (from 0.5 to 44.8m). We argue that sensitive species may survive in shallower water, which are more stable with regard to oxygen conditions and present greater habitat complexity, in contrast to deeper waters, which may experience periodic disturbance due to hypoxia. Future studies should better integrate disturbance in terms of temporal dynamics and dispersal rates in the EMS approach. We highlight that shallow water sites may act as sources of recruitment to deeper water sites that are relatively more prone to periodic disturbances due to hypoxia. However, these shallow sites are not currently monitored and should be better prioritized in future conservation strategies in marine systems.
  • Korhonen, Aku; Seelan, Jaya Seelan Sathiya; Miettinen, Otto (2018)
    We propose a taxonomic revision of the two closely related white-rot polypore species, Skeletocutis nivea (Jungh.) Jean Keller and S. ochroalba Niemela (Incrustoporiaceae, Basidiomycota), based on phylogenetic analyses of nuclear ribosomal internal transcribed spacer (ITS) and translation elongation factor EF-1 alpha sequences. We show that prevailing morphological species concepts of S. nivea and S. ochroalba are non-monophyletic and we delineate new species boundaries based on phylogenetic inference. We recognise eleven species within the prevailing species concept of S. nivea (S. calida sp. nov., S. coprosmae comb. nov., S. futilis sp. nov., S. impervia sp. nov., S. ipuletii sp. nov., S. lepida sp. nov., S. nemonzlis sp. nov., S. nivea sensu typi, S. semipileata comb. nov., S. unguina sp. nov. and S. yuchengii sp. nov.) and assign new sequenced epitypes for S. nivea and S. semipileata. The traditional concept of S. ochroalba comprises two independent lineages embedded within the S. nivea species complex. The Eurasian conifer-dwelling species S. cummata sp. nov. is recognised as separate from the North American S. ochroalba sensu stricto. Despite comprehensive microscopic examination, the majority of the recognised species are left without stable diagnostic character combinations that would enable species identification based solely on morphology and ecology.
  • Goncalves, Vitor; Ritter, Catarina; Marques, Helena; Teixeira, Dinarte Nuno; Raposeiro, Pedro M. (2021)
    Background Freshwater diversity, and diatoms in particular, from Desertas Islands (Madeira Archipelago, Portugal) is poorly known, although the Islands are protected and became a Natural Reserve in 1995. During two field expeditions in 2013 and 2014 to Deserta Grande Island, several freshwater and terrestrial habitats were sampled. The analysis of these samples aims to contribute to the biodiversity assessment of the freshwater biota present in Deserta Grande Island. Here, we present the diatom diversity in Deserta Grande Island resulting from that survey. This study contributes to improve the knowledge of Madeira Archipelago freshwater diversity, particularly in the Desertas sub-archipelago. New information To our knowledge, we present the first diatom data for the Desertas sub-archipelago. This work resulted in a list of 60 diatom taxa for Deserta Grande, from which 57 were identified to species level. From the 60 new records for Desertas sub-archipelago, 30 of them were also new records for Madeira Archipelago. Several specimens could not be assigned to a known species and may be new diatom species not yet described.
  • Liao, Wenfei; Venn, Stephen; Niemelä, Jari (2022)
    Context: Structural and functional connectivity, as subconcepts of landscape connectivity, are key factors in biodiversity conservation and management. Previous studies have focused on the consequences of connectivity for populations of terrestrial organisms, which may not be appropriate for aquatic organisms. Objectives: As landscape connectivity critically affects the potential value of ponds for biodiversity, here we used diving beetles (Dytiscidae), an indicator taxon of wetland biodiversity, to investigate how structural connectivity affects functional connectivity to aquatic invertebrates in an urban landscape. Methods: We assessed pairwise similarities of dytiscid community, i.e. the variation of species composition between clustered and isolated ponds in the Helsinki Metropolitan Area, Finland. We investigated how dytiscid community similarity is affected by Euclidean distances between ponds, as an indicator of structural connectivity. Results: We found that clustered ponds shared more species than isolated ponds. Dytiscid species community similarity responded negatively to increasing Euclidean distance between ponds. Effectively dispersing species were widely distributed across the landscape, while poor dispersers were scarcely distributed in the same landscape. Conclusions: Structural connectivity determines which species are able to disperse successfully, with poor dispersers restricted to well-connected ponds. The different responses of effective dispersers and poor dispersers to the same structural connectivity indicate that functional connectivity determines species composition. We recommend providing well-connected aquatic habitats in urban landscapes and the implementation of measures to reduce isolation of wetland assemblages. Even clustered ponds need dispersal from other habitats to ensure their contribution to urban biodiversity.
  • Graco-Roza, Caio; Santos, Juliana B. O.; Huszar, Vera L. M.; Domingos, Patricia; Soininen, Janne; Marinho, Marcelo Manzi (2020)
    Environmental heterogeneity (EH) in space and time promotes niche-partition, which leads to high variation in biological communities, such as in algae. In streams, EH is highly related to the intensity of the water flow and may lead to community variation mainly during the low flow conditions. Despite the wide knowledge on the responses of phytoplankton communities to EH in lentic and semi-lentic systems, studies of riverine phytoplankton community variation are still scarce. Here, we first investigated the relationship between phytoplankton community variation and EH in different courses of the river and between seasons. We expected that under low or intermediate flow conditions, there is a positive correlation between community variation and EH. Alternatively, we did not expect any relationship between EH and community variation under high flow condition because stronger downstream transport would mask environmental filtering. We sampled nine sites monthly (May 2012 to April 2013) in a tropical river of Brazilian Southeast. We calculated EH from abiotic data whereas for community variation, here community distinctiveness (CD), we used Sorensen (CDSor) and Bray-Curtis (CDBray) dissimilarities. Differences in EH, CDSor and CDBray were tested at between-season and among-course levels. We found lower distinctiveness during the dry season when EH was the highest. Contrastingly, phytoplankton CD was the highest even when EH was low during the wet season. We found that this pattern raised from the increasing in individuals dispersal during the wet season, promoting mass effects. Finally, our results thus reject the first hypothesis and show a negative relationship between EH and distinctiveness. However, results support our alternative hypothesis and show that during the wet season, distinctiveness is not driven by EH. These results provide new insights into how EH drives community variation, being useful for both basic research about riverine algal communities and biomonitoring programs using phytoplankton communities as bioindicators. (C). 2019 Elsevier B.V. All rights reserved.
  • Vilmi, Annika; Zhao, Wenqian; Picazo, Félix; Li, Mingjia; Heino, Jani; Soininen, Janne; Wang, Jianjun (2020)
    Understanding the role of climatic variation on biodiversity is of chief importance due to the ongoing biodiversity loss and climate change. Freshwaters, one of the most threatened ecosystems in the world, offer a valuable context to study biodiversity patterns of distinct organism groups in relation to climatic variation. In the Tibetan Plateau biodiversity hotspot, we studied the effects of climate and local physico-chemical factors on stream microorganisms (i.e. bacteria) and macroorganisms (i.e. macroinvertebrates) in two parallel catchments with contrasting precipitation and temperature. Diversities and community structures were better explained by climatic and local environmental variables in the drier and colder catchment and at higher elevations, than in the warmer and wetter conditions and at lower elevations. This suggests that communities may be more strongly assembled by deterministic processes in the former, comparatively harsher conditions, compared to the latter, more benign conditions. Macroinvertebrates were more strongly affected by climatic and local environmental factors compared to bacteria, but the diversities and community structures of the two groups showed spatially similar responses to overall abiotic variation, being especially evident with their community structures’ responses to climate. Furthermore, bacterial and macroinvertebrate diversities were positively correlated in the drier and colder catchment, implying that these biologically and ecologically distinct organism groups are likely to be driven by similar processes in areas with such climatic conditions. We conclude that changes in climatic and local environmental conditions may affect the diversity of macroorganisms more strongly than that of microorganisms, at least in subtropical mountainous stream ecosystems studied here, but simultaneous responses of both groups to environmental changes can also be expected.
  • Dallas, Tad A.; Saastamoinen, Marjo; Ovaskainen, Otso (2021)
    The spatial arrangement of habitat patches in a metapopulation and the dispersal connections among them influence metapopulation persistence. Metapopulation persistence emerges from a dynamic process, namely the serial extinctions and recolonizations of local habitat patches, while measures of persistence are typically based solely on structural properties of the spatial network (e.g., spatial distance between sites). Persistence estimators based on static properties may be unable to capture the dynamic nature of persistence. Understanding the shape of the distribution of extinction times is a central goal in population ecology. Here, we examine the goodness of fit of the power law to patch persistence time distributions using data on a foundational metapopulation system-the Glanville fritillary butterfly in the angstrom land islands. Further, we address the relationship between structural measures of metapopulation persistence (i.e., metapopulation capacity) and our temporal distributional fits to patch persistence times based on a power law. Patch persistence time distributions were well fit by a power law for the majority of semi-independent networks. Power law fits to persistence time distributions were related to metapopulation capacity, linking structural and temporal measures of metapopulation persistence. Several environmental variables and measures of network topology were correlated with both measures of metapopulation persistence, though correlations tended to be stronger for the structural measure of metapopulation persistence (i.e., metapopulation capacity). Together, our findings suggest that persistence time distributions are useful dynamic properties of metapopulations, and provide evidence of a relationship between metapopulation structure and metapopulation dynamics.
  • Rossini, Michele; Vaz-de-Mello, Fernando Z.; Montreuil, Olivier; Porch, Nicholas; Tarasov, Sergei (2021)
    We describe a new species of dung beetle, Epactoides giganteus sp. nov., from a single female specimen allegedly collected in the 19th century on Reunion island and recently found at the Museum national d'Histoire naturelle, Paris. This species differs from other species of Epactoides by larger size and a set of other distinctive morphological characters. Epactoides giganteus sp. nov. is the first native dung beetle (Scarabaeinae) of Reunion, and its discovery expands the known area of distribution of the genus Epactoides, which was hitherto believed to be endemic to Madagascar. Like other taxa from Madagascar and peripheral islands (e.g., Comoro, Seychelles, Mascarenes), E. giganteus sp. nov. may have reached Reunion by over-water dispersal. Given the rapid loss of biodiversity on Reunion island and the fact that no additional specimens were re-collected over the last two centuries, it is very likely that E. giganteus sp. nov. has gone extinct. However, we have unconfirmed evidence that the holotype of E. giganteus sp. nov. might be a mislabeled specimen from Madagascar, which would refute the presence of native dung beetles on Reunion. We discuss both hypotheses about the specimen origin and assess the systematic position of E. giganteus sp. nov. by examining most of the described species of Madagascan Epactoides. Additionally, we provide a brief overview of the dung beetle fauna of Mascarene Archipelago.
  • Woestmann, Luisa; Kvist, Jouni Antero; Saastamoinen, Marjo Anna Kaarina (2017)
    Flight represents a key trait in most insects, being energetically extremely demanding, yet often necessary for foraging and reproduction. Additionally, dispersal via flight is especially important for species living in fragmented landscapes. Even though, based on life-history theory, a negative relationship may be expected between flight and immunity, a number of previous studies have indicated flight to induce an increased immune response. In this study, we assessed whether induced immunity (i.e. immune gene expression) in response to 15-min forced flight treatment impacts individual survival of bacterial infection in the Glanville fritillary butterfly (Melitaea cinxia). We were able to confirm previous findings of flight-induced immune gene expression, but still observed substantially stronger effects on both gene expression levels and life span due to bacterial infection compared to flight treatment. Even though gene expression levels of some immunity-related genes were elevated due to flight, these individuals did not show increased survival of bacterial infection, indicating that flight-induced immune activation does not completely protect them from the negative effects of bacterial infection. Finally, an interaction between flight and immune treatment indicated a potential trade-off: flight treatment increased immune gene expression in naive individuals only, whereas in infected individuals no increase in immune gene expression was induced by flight. Our results suggest that the up-regulation of immune genes upon flight is based on a general stress response rather than reflecting an adaptive response to cope with potential infections during flight or in new habitats.
  • Ramos, Danielle Leal; Pizo, Marco Aurelio; Ribeiro, Milton Cezar; Cruz, Rafael Souza; Morales, Juan Manuel; Ovaskainen, Otso (2020)
    In a rapidly changing world, it is important to understand how environmental modifications by humans affect species behavior. This is not a simple task, since we need to deal with a multitude of species and the different external contexts that affect their behavior. Here, we investigate how interpatch short-distance movements of 73 common forest bird species can be predicted by forest cover and forest isolation. We modeled bird movement as a function of environmental covariates, species traits - body mass and feeding habit - and phylogenetic relationships using Joint Species Movement Models. We used field data collected in forest edges and open pastures of six 600 x 600 m plots in the Atlantic Forest biodiversity hotspot. We found that birds fly larger distances and visit more forest patches and remnant trees with decreasing forest cover. Increasing landscape isolation results in larger flight distances, and it increases the use of trees as stepping-stones for most species. Our results show that birds can adjust their behavior as a response to spatial modification in resource distribution and landscape connectivity. These adjusted behaviors can potentially contribute to ecosystem responses to habitat modification.