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Journal Cover Proceedings of the Royal Society B: Biological Sciences
  [SJR: 2.375]   [H-I: 181]   [139 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0962-8452 - ISSN (Online) 1471-2954
   Published by Royal Society, The Homepage  [11 journals]
  • Adaptation in response to environmental unpredictability
    • Authors: Franch-Gras, L; Garcia-Roger, E. M, Serra, M, Jose Carmona, M.
      Pages: 20170427 - 20170427
      Abstract: Understanding how organisms adaptively respond to environmental fluctuations is a fundamental question in evolutionary biology. The Mediterranean region typically exhibits levels of environmental unpredictability that vary greatly in habitats over small geographical scales. In cyclically parthenogenetic rotifers, clonal proliferation occurs along with occasional bouts of sex. These bouts contribute to the production of diapausing eggs, which allows survival between growing seasons. Here, we studied two diapause-related traits in rotifers using clones from nine Brachionus plicatilis natural populations that vary in the degree of environmental unpredictability. We tested the hypothesis that the level of environmental unpredictability is directly related to the propensity for sex and inversely related to the hatching fraction of diapausing eggs. We found significant levels of genetic variation within populations for both traits. Interestingly, a positive correlation between pond unpredictability—quantified in a previous study from satellite imagery—and the propensity for sex was found. This correlation suggests a conservative, bet-hedging strategy that provides protection against unexpectedly short growing seasons. By contrast, the hatching fraction of diapausing eggs was not related to the level of environmental predictability. Our results highlight the ability of rotifer populations to locally adapt to time-varying environments, providing an evolutionarily relevant step forward in relating life-history traits to a quantitative measure of environmental unpredictability.
      Keywords: ecology, evolution
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.0427
      Issue No: Vol. 284, No. 1868 (2017)
       
  • The persistence of multiple strains of avian influenza in live bird
           markets
    • Authors: Pinsent, A; Pepin, K. M, Zhu, H, Guan, Y, White, M. T, Riley, S.
      Pages: 20170715 - 20170715
      Abstract: Multiple subtypes of avian influenza (AI) and novel reassortants are frequently isolated from live bird markets (LBMs). However, our understanding of the drivers of persistence of multiple AI subtypes is limited. We propose a stochastic model of AI transmission within an LBM that incorporates market size, turnover rate and the balance of direct versus environmental transmissibility. We investigate the relationship between these factors and the critical community size (CCS) for the persistence of single and multiple AI strains within an LBM. We fit different models of seeding from farms to two-strain surveillance data collected from Shantou, China. For a single strain and plausible estimates for continuous turnover rates and transmissibility, the CCS was approximately 11 800 birds, only a 4.2% increase in this estimate was needed to ensure persistence of the co-infecting strains (two strains in a single host). Precise values of CCS estimates were sensitive to changes in market turnover rate and duration of the latent period. Assuming a gradual daily sell rate of birds the estimated CCS was higher than when an instantaneous selling rate was assumed. We were able to reproduce prevalence dynamics similar to observations from a single market in China with infection seeded every 5–15 days, and a maximum non-seeding duration of 80 days. Our findings suggest that persistence of co-infections is more likely to be owing to sequential infection of single strains rather than ongoing transmission of both strains concurrently. In any given system for a fixed set of ecological and epidemiological conditions, there is an LBM size below which the risk of sustained co-circulation is low and which may suggest a clear policy opportunity to reduce the frequency of influenza co-infection in poultry.
      Keywords: computational biology, health and disease and epidemiology
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.0715
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Skill not athleticism predicts individual variation in match performance
           of soccer players
    • Authors: Wilson, R. S; David, G. K, Murphy, S. C, Angilletta, M. J, Niehaus, A. C, Hunter, A. H, Smith, M. D.
      Pages: 20170953 - 20170953
      Abstract: Just as evolutionary biologists endeavour to link phenotypes to fitness, sport scientists try to identify traits that determine athlete success. Both disciplines would benefit from collaboration, and to illustrate this, we used an analytical approach common to evolutionary biology to isolate the phenotypes that promote success in soccer, a complex activity of humans played in nearly every modern society. Using path analysis, we quantified the relationships among morphology, balance, skill, athleticism and performance of soccer players. We focused on performance in two complex motor activities: a simple game of soccer tennis (1 on 1), and a standard soccer match (11 on 11). In both contests, players with greater skill and balance were more likely to perform better. However, maximal athletic ability was not associated with success in a game. A social network analysis revealed that skill also predicted movement. The relationships between phenotypes and success during individual and team sports have potential implications for how selection acts on these phenotypes, in humans and other species, and thus should ultimately interest evolutionary biologists. Hence, we propose a field of evolutionary sports science that lies at the nexus of evolutionary biology and sports science. This would allow biologists to take advantage of the staggering quantity of data on performance in sporting events to answer evolutionary questions that are more difficult to answer for other species. In return, sports scientists could benefit from the theoretical framework developed to study natural selection in non-human species.
      Keywords: behaviour, ecology, evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.0953
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Delayed behavioural shifts undermine the sustainability of
           social-ecological systems
    • Authors: Lafuite, A.- S; de Mazancourt, C, Loreau, M.
      Pages: 20171192 - 20171192
      Abstract: Natural habitat destruction and fragmentation generate a time-delayed loss of species and associated ecosystem services. As social–ecological systems (SESs) depend on a range of ecosystem services, lagged ecological dynamics may affect their long-term sustainability. Here, we investigate the role of consumption changes for sustainability, under a time-delayed ecological feedback on agricultural production. We use a stylized model that couples the dynamics of biodiversity, technology, human demography and compliance with a social norm prescribing sustainable consumption. Compliance with the sustainable norm reduces both the consumption footprint and the vulnerability of SESs to transient overshoot-and-collapse population crises. We show that the timing and interaction between social, demographic and ecological feedbacks govern the transient and long-term dynamics of the system. A sufficient level of social pressure (e.g. disapproval) applied on the unsustainable consumers leads to the stable coexistence of unsustainable and sustainable or mixed equilibria, where both defectors and conformers coexist. Under bistability conditions, increasing extinction debts reduces the resilience of the system, thus favouring abrupt regime shifts towards unsustainable pathways. Given recent evidence of large extinction debts, such results call for farsightedness and a better understanding of time delays when studying the sustainability of coupled SESs.
      Keywords: theoretical biology, ecology, environmental science
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1192
      Issue No: Vol. 284, No. 1868 (2017)
       
  • A novel pathway of nutrient absorption in crustaceans: branchial amino
           acid uptake in the green shore crab (Carcinus maenas)
    • Authors: Blewett, T. A; Goss, G. G.
      Pages: 20171298 - 20171298
      Abstract: Estuaries are environments enriched with dissolved nutrients such as amino acids. To date, marine arthropods are the only invertebrate group that have not been demonstrated to access this potentially important nutrient resource. Using in vitro gill perfusion techniques, we sought to investigate the ability of the green shore crab (Carcinus maenas) to take up the amino acid l-leucine directly from the water. Investigation of the concentration-dependent transport kinetics of radiolabelled l-leucine showed that there are two specific transport pathways across Carcinus gills, one with high affinity and low capacity, and the other with high capacity and low affinity. Using putative competitive substrates and reduced sodium preparations, we were able to identify the putative amino acid transport system associated with high-affinity uptake. This is the first study to demonstrate the absorption of dissolved organic nutrients across the gill epithelium of a marine arthropod.
      Keywords: physiology, cellular biology, environmental science
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1298
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Cooperative breeding influences the number and type of vocalizations in
           avian lineages
    • Authors: Leighton G. M.
      Pages: 20171508 - 20171508
      Abstract: Although communicative complexity is often predicted to correlate with social complexity in animal societies, few studies have employed large-scale comparative analyses to test whether socially complex species have more complex systems of communication. I tested this social complexity hypothesis in birds (Class: Aves) using the large amount of natural history information that describes both vocal repertoire and social system in these species. To do so, I marshalled data from primary and secondary records of avian vocal repertoires (n = 253), and for each of the species in the dataset I recorded the reported repertoire size and associated species information. Using phylogenetic comparative methods, I found that cooperative breeding was a strong and repeatable predictor of vocal repertoire size, while other social variables, e.g. group size and group stability, had little or no influence on repertoire size. Importantly, repertoire sizes expanded concurrently with the evolution of cooperative breeding, suggesting a direct link between these two traits. Cooperatively breeding species devoted significantly more of their repertoire to contact calls and alarm calls. Overall, these results therefore lend support to the hypothesis that social complexity via behavioural coordination leads to increases in vocal complexity.
      Keywords: behaviour, evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1508
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Co-occurrence of related asexual, but not sexual, lineages suggests that
           reproductive interference limits coexistence
    • Authors: Whitton, J; Sears, C. J, Maddison, W. P.
      Pages: 20171579 - 20171579
      Abstract: We used randomizations to analyse patterns of co-occurrence of sexual and apomictic (asexual) members of the North American Crepis agamic complex (Asteraceae). We expect strong asymmetry in reproductive interactions in Crepis: apomicts produce clonal seeds with no need for pollination and are not subject to reproductive interference from co-occurring relatives. However, because they still produce some viable pollen, apomicts can reduce reproductive success of nearby sexual relatives, potentially leading to eventual local exclusion of sexuals. Consistent with this, randomizations reveal that sexuals are over-represented in isolated sites, while apomicts freely co-occur. Incorporation of taxonomic and phylogenetic evidence indicates that this pattern is not driven by local origins of asexuals. Our evidence that patterns of local co-occurrence are structured by reproductive interference suggests an underappreciated role for these interactions in community assembly, and highlights the need for explicit tests of the relative contributions of ecological and reproductive interactions in generating patterns of limiting similarity.
      Keywords: ecology, evolution
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1579
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Inter-annual variation in seed production has increased over time
           (1900-2014)
    • Authors: Pearse, I. S; LaMontagne, J. M, Koenig, W. D.
      Pages: 20171666 - 20171666
      Abstract: Mast seeding, or masting, is the highly variable and spatially synchronous production of seeds by a population of plants. The production of variable seed crops is typically correlated with weather, so it is of considerable interest whether global climate change has altered the variability of masting or the size of masting events. We compiled 1086 datasets of plant seed production spanning 1900–2014 and from around the world, and then analysed whether the coefficient of variation (CV) in seed set, a measure of masting, increased over time. Over this 115-year period, seed set became more variable for plants as a whole and for the particularly well-studied taxa of conifers and oaks. The increase in CV corresponded with a decrease in the long-term mean of seed set of plant species. Seed set CV increased to a greater degree in plant taxa with a tendency towards masting. Seed set is becoming more variable among years, especially for plant taxa whose masting events are known to affect animal populations. Such subtle change in reproduction can have wide-ranging effects on ecosystems because seed crops provide critical resources for a wide range of taxa and have cascading effects throughout food webs.
      Keywords: plant science, ecology
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1666
      Issue No: Vol. 284, No. 1868 (2017)
       
  • First satellite tracks of South Atlantic sea turtle 'lost years: seasonal
           variation in trans-equatorial movement
    • Authors: Mansfield, K. L; Mendilaharsu, M. L, Putman, N. F, dei Marcovaldi, M. A. G, Sacco, A. E, Lopez, G, Pires, T, Swimmer, Y.
      Pages: 20171730 - 20171730
      Abstract: In the South Atlantic Ocean, few data exist regarding the dispersal of young oceanic sea turtles. We characterized the movements of laboratory-reared yearling loggerhead turtles from Brazilian rookeries using novel telemetry techniques, testing for differences in dispersal during different periods of the sea turtle hatching season that correspond to seasonal changes in ocean currents. Oceanographic drifters deployed alongside satellite-tagged turtles allowed us to explore the mechanisms of dispersal (passive drift or active swimming). Early in the hatching season turtles transited south with strong southward currents. Late in the hatching season, when currents flowed in the opposite direction, turtles uniformly moved northwards across the Equator. However, the movement of individuals differed from what was predicted by surface currents alone. Swimming velocity inferred from track data and an ocean circulation model strongly suggest that turtles' swimming plays a role in maintaining their position within frontal zones seaward of the continental shelf. The long nesting season of adults and behaviour of post-hatchlings exposes young turtles to seasonally varying ocean conditions that lead some individuals further into the South Atlantic and others into the Northern Hemisphere. Such migratory route diversity may ultimately buffer the population against environmental changes or anthropologic threats, fostering population resiliency.
      Keywords: behaviour, ecology
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1730
      Issue No: Vol. 284, No. 1868 (2017)
       
  • The genetic basis and enigmatic origin of melanic polymorphism in pomarine
           skuas (Stercorarius pomarinus)
    • Authors: Janssen, K; Mundy, N. I.
      Pages: 20171735 - 20171735
      Abstract: A key outstanding issue in adaptive evolution is the relationship between the genetics of intraspecific polymorphism and interspecific evolution. Here, we show that the pale/dark ventral plumage polymorphism that occurs in both the pomarine skua (Stercorarius pomarinus) and Arctic skua (S. parasiticus) is the result of convergent evolution at the same locus (MC1R), involving some of the same amino acid sites. The dark melanic MC1R allele in the pomarine skua is strongly divergent from the pale MC1R alleles. Whereas the dark allele is closely related to MC1R alleles in three species of great skua (S. skua, S. maccormicki, S. lonnbergi), the pale pomarine skua MC1R alleles present a star-like pattern in an intermediate position on the haplotype network, closer to alleles of the long-tailed skua (S. longicaudus). Variation at other nuclear loci confirms a close relationship between the pomarine skua and the great skuas. The plumage polymorphism in pomarine skuas might have arisen in the common ancestor of pomarine and great skuas, only being retained in pomarine skuas. Alternatively, the pale and melanic MC1R alleles may have evolved independently in different lineages and been brought together in pomarine skuas by hybridization. In this case, introgression of a pale MC1R allele into the pomarine skua from another skua lineage is most likely. Our current data do not permit us to distinguish between these hypotheses, and assaying genome-wide variation holds much promise in this regard. Nevertheless, we have uncovered an intriguing example of a functionally important allele within one species that is shared across species.
      Keywords: genetics, evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1735
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Testing differential use of payoff-biased social learning strategies in
           children and chimpanzees
    • Authors: Vale, G. L; Flynn, E. G, Kendal, J, Rawlings, B, Hopper, L. M, Schapiro, S. J, Lambeth, S. P, Kendal, R. L.
      Pages: 20171751 - 20171751
      Abstract: Various non-human animal species have been shown to exhibit behavioural traditions. Importantly, this research has been guided by what we know of human culture, and the question of whether animal cultures may be homologous or analogous to our own culture. In this paper, we assess whether models of human cultural transmission are relevant to understanding biological fundamentals by investigating whether accounts of human payoff-biased social learning are relevant to chimpanzees (Pan troglodytes). We submitted 4- and 5-year-old children (N = 90) and captive chimpanzees (N = 69) to a token–reward exchange task. The results revealed different forms of payoff-biased learning across species and contexts. Specifically, following personal and social exposure to different tokens, children's exchange behaviour was consistent with proportional imitation, where choice is affected by both prior personally acquired and socially demonstrated token–reward information. However, when the socially derived information regarding token value was novel, children's behaviour was consistent with proportional observation; paying attention to socially derived information and ignoring their prior personal experience. By contrast, chimpanzees' token choice was governed by their own prior experience only, with no effect of social demonstration on token choice, conforming to proportional reservation. We also find evidence for individual- and group-level differences in behaviour in both species. Despite the difference in payoff strategies used, both chimpanzees and children adopted beneficial traits when available. However, the strategies of the children are expected to be the most beneficial in promoting flexible behaviour by enabling existing behaviours to be updated or replaced with new and often superior ones.
      Keywords: behaviour, cognition, evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1751
      Issue No: Vol. 284, No. 1868 (2017)
       
  • A load-based mechanism for inter-leg coordination in insects
    • Authors: Dallmann, C. J; Hoinville, T, Dürr, V, Schmitz, J.
      Pages: 20171755 - 20171755
      Abstract: Animals rely on an adaptive coordination of legs during walking. However, which specific mechanisms underlie coordination during natural locomotion remains largely unknown. One hypothesis is that legs can be coordinated mechanically based on a transfer of body load from one leg to another. To test this hypothesis, we simultaneously recorded leg kinematics, ground reaction forces and muscle activity in freely walking stick insects (Carausius morosus). Based on torque calculations, we show that load sensors (campaniform sensilla) at the proximal leg joints are well suited to encode the unloading of the leg in individual steps. The unloading coincides with a switch from stance to swing muscle activity, consistent with a load reflex promoting the stance-to-swing transition. Moreover, a mechanical simulation reveals that the unloading can be ascribed to the loading of a specific neighbouring leg, making it exploitable for inter-leg coordination. We propose that mechanically mediated load-based coordination is used across insects analogously to mammals.
      Keywords: neuroscience, behaviour, biomechanics
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1755
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Intraspecific and interspecific variation in thermotolerance and
           photoacclimation in Symbiodinium dinoflagellates
    • Authors: Diaz-Almeyda, E. M; Prada, C, Ohdera, A. H, Moran, H, Civitello, D. J, Iglesias-Prieto, R, Carlo, T. A, LaJeunesse, T. C, Medina, M.
      Pages: 20171767 - 20171767
      Abstract: Light and temperature are major drivers in the ecology and biogeography of symbiotic dinoflagellates living in corals and other cnidarians. We examined variations in physiology among 11 strains comprising five species of clade A Symbiodinium. We grew cultures at 26°C (control) and 32°C (high temperature) over a duration of 18 days while measuring growth and photochemical efficiency (Fv/Fm). Responses to thermal stress ranged from susceptible to tolerant across species and strains. Most strains exhibited a decrease in cell densities and Fv/Fm when grown at 32°C. Tolerance to high temperature (T32) was calculated for all strains, ranging from 0 (unable to survive at high temperature) to 1 (able survive at high temperature). There was substantial variation in thermotolerance across species and among strains. One strain had a T32 close to 1, indicating that growth was not reduced at 32°C for only this one strain. To evaluate the combined effect of temperature and light on physiological stress, we selected three strains with different levels of thermotolerance (tolerant, intermediate and susceptible) and grew them under five different light intensities (65, 80, 100, 240 and 443 µmol quanta m–2 s–1) at 26 and 32°C. High irradiance exacerbated the effect of high temperature, particularly in strains from thermally sensitive species. This work further supports the recognition that broad physiological differences exist not only among species within Symbiodinium clades, but also among strains within species demonstrating that thermotolerance varies widely between species and among strains within species.
      Keywords: microbiology, plant science, ecology
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1767
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Selective harvest focused on sexual signal traits can lead to extinction
           under directional environmental change
    • Authors: Knell, R. J; Martinez-Ruiz, C.
      Pages: 20171788 - 20171788
      Abstract: Humans commonly harvest animals based on their expression of secondary sexual traits such as horns or antlers. This selective harvest is thought to have little effect on harvested populations because offtake rates are low and usually only the males are targeted. These arguments do not, however, take the relationship between secondary sexual trait expression and animal condition into account: there is increasing evidence that in many cases the degree of expression of such traits is correlated with an animal's overall well-being, which is partly determined by their genetic match to the environment. Using an individual-based model, we find that when there is directional environmental change, selective harvest of males with the largest secondary sexual traits can lead to extinction in otherwise resilient populations. When harvest is not selective, the males best suited to a new environment gain the majority of matings and beneficial alleles spread rapidly. When these best-adapted males are removed, however, their beneficial alleles are lost, leading to extinction. Given the current changes happening globally, these results suggest that trophy hunting and other cases of selective harvest (such as certain types of insect collection) should be managed with extreme care whenever populations are faced with changing conditions.
      Keywords: ecology, evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1788
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Evolutionary history of enigmatic bears in the Tibetan Plateau-Himalaya
           region and the identity of the yeti
    • Authors: Lan, T; Gill, S, Bellemain, E, Bischof, R, Nawaz, M. A, Lindqvist, C.
      Pages: 20171804 - 20171804
      Abstract: Although anecdotally associated with local bears (Ursus arctos and U. thibetanus), the exact identity of ‘hominid’-like creatures important to folklore and mythology in the Tibetan Plateau–Himalaya region is still surrounded by mystery. Recently, two purported yeti samples from the Himalayas showed genetic affinity with an ancient polar bear, suggesting they may be from previously unrecognized, possibly hybrid, bear species, but this preliminary finding has been under question. We conducted a comprehensive genetic survey of field-collected and museum specimens to explore their identity and ultimately infer the evolutionary history of bears in the region. Phylogenetic analyses of mitochondrial DNA sequences determined clade affinities of the purported yeti samples in this study, strongly supporting the biological basis of the yeti legend to be local, extant bears. Complete mitochondrial genomes were assembled for Himalayan brown bear (U. a. isabellinus) and black bear (U. t. laniger) for the first time. Our results demonstrate that the Himalayan brown bear is one of the first-branching clades within the brown bear lineage, while Tibetan brown bears diverged much later. The estimated times of divergence of the Tibetan Plateau and Himalayan bear lineages overlap with Middle to Late Pleistocene glaciation events, suggesting that extant bears in the region are likely descendants of populations that survived in local refugia during the Pleistocene glaciations.
      Keywords: taxonomy and systematics, genetics, evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.1804
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Major histocompatibility complex-linked social signalling affects female
           fertility
    • Authors: Burger, D; Thomas, S, Aepli, H, Dreyer, M, Fabre, G, Marti, E, Sieme, H, Robinson, M. R, Wedekind, C.
      Pages: 20171824 - 20171824
      Abstract: Genes of the major histocompatibility complex (MHC) have been shown to influence social signalling and mate preferences in many species, including humans. First observations suggest that MHC signalling may also affect female fertility. To test this hypothesis, we exposed 191 female horses (Equus caballus) to either an MHC-similar or an MHC-dissimilar stimulus male around the time of ovulation and conception. A within-subject experimental design controlled for non-MHC-linked male characteristics, and instrumental insemination with semen of other males (n = 106) controlled for potential confounding effects of semen or embryo characteristics. We found that females were more likely to become pregnant if exposed to an MHC-dissimilar than to an MHC-similar male, while overall genetic distance to the stimulus males (based on microsatellite markers on 20 chromosomes) had no effect. Our results demonstrate that early pregnancy failures can be due to maternal life-history decisions (cryptic female choice) influenced by MHC-linked social signalling.
      Keywords: behaviour, ecology, evolution
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1824
      Issue No: Vol. 284, No. 1868 (2017)
       
  • The functional syndrome: linking individual trait variability to ecosystem
           functioning
    • Authors: Raffard, A; Lecerf, A, Cote, J, Buoro, M, Lassus, R, Cucherousset, J.
      Pages: 20171893 - 20171893
      Abstract: Phenotypic variability is increasingly assessed through functional response and effect traits, which provide a mechanistic framework for investigating how an organism responds to varying ecological factors and how these responses affect ecosystem functioning. Covariation between response and effect traits has been poorly examined at the intraspecific level, thus hampering progress in understanding how phenotypic variability alters the role of organisms in ecosystems. Using a multi-trait approach and a nine-month longitudinal monitoring of individual red-swamp crayfish (Procambarus clarkii), we demonstrated that most of the measured response and effect traits were partially stable during the ontogeny of individuals. Suites of response and effect traits were associated with a response syndrome and an effect syndrome, respectively, which were correlated to form a functional syndrome. Using a bioenergetic model, we predicted that differences in the response syndrome composition of hypothetical populations had important ecological effects on a key ecosystem process (i.e. whole-lake litter decomposition) to a level similar to those induced by doubling population size. Demonstrating the existence of a functional syndrome is likely to improve our understanding of the ecological impacts of phenotypic variation among individuals in wild populations across levels of biological organization, and the linkage between ecosystem and evolutionary ecology.
      Keywords: behaviour, ecology
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1893
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Rapid evolution rescues hosts from competition and disease but--despite a
           dilution effect--increases the density of infected hosts
    • Authors: Strauss, A. T; Hite, J. L, Shocket, M. S, Caceres, C. E, Duffy, M. A, Hall, S. R.
      Pages: 20171970 - 20171970
      Abstract: Virulent parasites can depress the densities of their hosts. Taxa that reduce disease via dilution effects might alleviate this burden. However, ‘diluter’ taxa can also depress host densities through competition for shared resources. The combination of disease and interspecific competition could even drive hosts extinct. Then again, genetically variable host populations can evolve in response to both competitors and parasites. Can rapid evolution rescue host density from the harm caused by these ecological enemies' How might such evolution influence dilution effects or the size of epidemics' In a mesocosm experiment with planktonic hosts, we illustrate the joint harm of competition and disease: hosts with constrained evolutionary ability (limited phenotypic variation) suffered greatly from both. However, populations starting with broader phenotypic variation evolved stronger competitive ability during epidemics. In turn, enhanced competitive ability—driven especially by parasites—rescued host densities from the negative impacts of competition, disease, and especially their combination. Interspecific competitors reduced disease (supporting dilution effects) even when hosts rapidly evolved. However, this evolutionary response also elicited a potential problem. Populations that evolved enhanced competitive ability and maintained robust total densities also supported higher densities of infections. Thus, rapid evolution rescued host densities but also unleashed larger epidemics.
      Keywords: ecology, evolution
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.1970
      Issue No: Vol. 284, No. 1868 (2017)
       
  • A signature of dynamic biogeography: enclaves indicate past species
           replacement
    • Authors: Wielstra, B; Burke, T, Butlin, R. K, Arntzen, J. W.
      Pages: 20172014 - 20172014
      Abstract: Understanding how species have replaced each other in the past is important to predicting future species turnover. While past species replacement is difficult to detect after the fact, the process may be inferred from present-day distribution patterns. Species with abutting ranges sometimes show a characteristic distribution pattern, where a section of one species range is enveloped by that of the other. Such an enclave could indicate past species replacement: when a species is partly supplanted by a competitor, but a population endures locally while the invading species moves around and past it, an enclave forms. If the two species hybridize and backcross, the receding species is predicted to leave genetic traces within the expanding one under a scenario of species replacement. By screening dozens of genes in hybridizing crested newts, we uncover genetic remnants of the ancestral species, now inhabiting an enclave, in the range of the surrounding invading species. This independent genetic evidence supports the past distribution dynamics we predicted from the enclave. We suggest that enclaves provide a valuable tool in understanding historical species replacement, which is important because a major conservation concern arising from anthropogenic climate change is increased species replacement in the future.
      Keywords: evolution
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.2014
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Selection bias in studies of human reproduction-longevity trade-offs
    • Authors: Helle S.
      Pages: 20172104 - 20172104
      Abstract: A shorter lifespan as a potential cost of high reproductive effort in humans has intrigued researchers for more than a century. However, the results have been inconclusive so far and despite strong theoretical expectations we do not currently have compelling evidence for the longevity costs of reproduction. Using Monte Carlo simulation, it is shown here that a common practice in human reproduction-longevity studies using historical data (the most relevant data sources for this question), the omission of women who died prior to menopausal age from the analysis, results in severe underestimation of the potential underlying trade-off between reproduction and lifespan. In other words, assuming that such a trade-off is expressed also during reproductive years, the strength of the trade-off between reproduction and lifespan is progressively weakened when women dying during reproductive ages are sequentially and non-randomly excluded from the analysis. In cases of small sample sizes (e.g. few hundreds of observations), this selection bias by reducing statistical power may even partly explain the null results commonly found in this field. Future studies in this field should thus apply statistical approaches that account for or avoid selection bias in order to recover reliable effect size estimates between reproduction and longevity.
      Keywords: evolution, health and disease and epidemiology
      PubDate: 2017-11-29T00:39:48-08:00
      DOI: 10.1098/rspb.2017.2104
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Deep pelagic food web structure as revealed by in situ feeding
           observations
    • Authors: Choy, C. A; Haddock, S. H. D, Robison, B. H.
      Pages: 20172116 - 20172116
      Abstract: Food web linkages, or the feeding relationships between species inhabiting a shared ecosystem, are an ecological lens through which ecosystem structure and function can be assessed, and thus are fundamental to informing sustainable resource management. Empirical feeding datasets have traditionally been painstakingly generated from stomach content analysis, direct observations and from biochemical trophic markers (stable isotopes, fatty acids, molecular tools). Each approach carries inherent biases and limitations, as well as advantages. Here, using 27 years (1991–2016) of in situ feeding observations collected by remotely operated vehicles (ROVs), we quantitatively characterize the deep pelagic food web of central California within the California Current, complementing existing studies of diet and trophic interactions with a unique perspective. Seven hundred and forty-three independent feeding events were observed with ROVs from near-surface waters down to depths approaching 4000 m, involving an assemblage of 84 different predators and 82 different prey types, for a total of 242 unique feeding relationships. The greatest diversity of prey was consumed by narcomedusae, followed by physonect siphonophores, ctenophores and cephalopods. We highlight key interactions within the poorly understood ‘jelly web’, showing the importance of medusae, ctenophores and siphonophores as key predators, whose ecological significance is comparable to large fish and squid species within the central California deep pelagic food web. Gelatinous predators are often thought to comprise relatively inefficient trophic pathways within marine communities, but we build upon previous findings to document their substantial and integral roles in deep pelagic food webs.
      Keywords: behaviour, ecology, environmental science
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.2116
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Coral calcification mechanisms facilitate adaptive responses to ocean
           acidification
    • Authors: Schoepf, V; Jury, C. P, Toonen, R. J, McCulloch, M. T.
      Pages: 20172117 - 20172117
      Abstract: Ocean acidification (OA) is a pressing threat to reef-building corals, but it remains poorly understood how coral calcification is inhibited by OA and whether corals could acclimatize and/or adapt to OA. Using a novel geochemical approach, we reconstructed the carbonate chemistry of the calcifying fluid in two coral species using both a pH and dissolved inorganic carbon (DIC) proxy (11B and B/Ca, respectively). To address the potential for adaptive responses, both species were collected from two sites spanning a natural gradient in seawater pH and temperature, and then subjected to three pHT levels (8.04, 7.88, 7.71) crossed by two temperatures (control, +1.5°C) for 14 weeks. Corals from the site with naturally lower seawater pH calcified faster and maintained growth better under simulated OA than corals from the higher-pH site. This ability was consistently linked to higher pH yet lower DIC values in the calcifying fluid, suggesting that these differences are the result of long-term acclimatization and/or local adaptation to naturally lower seawater pH. Nevertheless, all corals elevated both pH and DIC significantly over seawater values, even under OA. This implies that high pH upregulation combined with moderate levels of DIC upregulation promote resistance and adaptive responses of coral calcification to OA.
      Keywords: physiology, ecology, environmental science
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.2117
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Condition-dependent female preference for male genitalia length is based
           on male reproductive tactics
    • Authors: Hernandez-Jimenez, A; Rios-Cardenas, O.
      Pages: 20172223 - 20172223
      Abstract: There is extensive morphological variation of male genitalia across animals with internal fertilization, even among closely related species. Most studies attempting to explain this extraordinary diversity have focused on processes that occur post-copula (e.g. sperm competition, cryptic female choice). Only a few studies have focused on the pre-copula process of female preference. In addition, the extent to which this variation could be associated with the use of different reproductive tactics has yet to be explored. Here, we show that female preference for male genitalia length in two livebearing fishes depends on the type of reproductive tactic of the males being evaluated as well as the body condition of the female. In a species where all males coax females to acquire matings (courters), females preferred males with short genitalia. In a species with genetically influenced alternative reproductive tactics (courter males that only court and produce courter sons, sneaker males that use the coercive tactic of sneak chase and produce sneaker sons), female preference depended on an interaction between male tactic and female condition: females in good condition preferred courter males with short genitalia, and sneaker males with long genitalia. Our results suggest that female preference for male traits favourable to their sons may be an important factor contributing to the diversification of male genitalia. Despite the contrasting selection for genitalia length that our female preference tests suggest, we found no significant differences in genitalia length between coaxing (courters) and coercive (sneakers) males. Our study represents a starting point to more clearly understand the role of alternative reproductive tactics and variation in female mate preference in the evolution of male genitalia.
      Keywords: behaviour, ecology, evolution
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.2223
      Issue No: Vol. 284, No. 1868 (2017)
       
  • Hierarchical social networks shape gut microbial composition in wild
           Verreaux's sifaka
    • Authors: Perofsky, A. C; Lewis, R. J, Abondano, L. A, Di Fiore, A, Meyers, L. A.
      Pages: 20172274 - 20172274
      Abstract: In wild primates, social behaviour influences exposure to environmentally acquired and directly transmitted microorganisms. Prior studies indicate that gut microbiota reflect pairwise social interactions among chimpanzee and baboon hosts. Here, we demonstrate that higher-order social network structure—beyond just pairwise interactions—drives gut bacterial composition in wild lemurs, which live in smaller and more cohesive groups than previously studied anthropoid species. Using 16S rRNA gene sequencing and social network analysis of grooming contacts, we estimate the relative impacts of hierarchical (i.e. multilevel) social structure, individual demographic traits, diet, scent-marking, and habitat overlap on bacteria acquisition in a wild population of Verreaux's sifaka (Propithecus verreauxi) consisting of seven social groups. We show that social group membership is clearly reflected in the microbiomes of individual sifaka, and that social groups with denser grooming networks have more homogeneous gut microbial compositions. Within social groups, adults, more gregarious individuals, and individuals that scent-mark frequently harbour the greatest microbial diversity. Thus, the community structure of wild lemurs governs symbiotic relationships by constraining transmission between hosts and partitioning environmental exposure to microorganisms. This social cultivation of mutualistic gut flora may be an evolutionary benefit of tight-knit group living.
      Keywords: behaviour, microbiology, ecology
      PubDate: 2017-12-06T00:05:20-08:00
      DOI: 10.1098/rspb.2017.2274
      Issue No: Vol. 284, No. 1868 (2017)
       
 
 
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