Find research datasets worth reusing

Data from: Testing the link between perceived and actual risk of predation: mosquito oviposition site selection and egg predation by native and introduced fish

1. According to the threat-sensitivity hypothesis, prey avoidance behaviour should reflect the magnitude of predation risk. Since predation can strongly affect reproduction success, ovipositing females are expected to adaptively adjust their predator-avoidance response, or local breeding patch selectivity, in accordance with the perceived level of threat posed for their progeny by specific predators. However, association between avoidance and predation can be disrupted when the prey and the predator lack spatio-temporal opportunities to co-evolve, such as in cases of non-native predator introductions. 2. We examined the interactions between mosquitoes (from the genus Culex) and three species of sympatric predaceous freshwater fish, a native cyprinid (Barbus paludinosus), a cichlid (Pseudocrenilabrus philander), and an introduced poeciliid, the Western mosquitofish (Gambusia affinis). 3. In an outdoor mesocosm experiment we quantified patterns of Culex oviposition site selection across fish species using free-roaming, caged, and fish-free treatments. In a complementary laboratory experiment we tested the effectiveness of each fish species as predators of mosquito eggs and larvae. 4. Synthesis and applications. We found evidence for: (i) mosquito egg raft predation by free- roaming fish; (ii) fish-specific avoidance by ovipositing Culex and (iii) a positive association between fish-specific oviposition avoidance and fish-specific efficiency as an egg predator. These results contribute towards a better understanding of predator-prey coevolution, predator-borne cue recognition, and suggest local native fish, the Southern mouthbrooder (Pseudocrenilabrus philander), as an alternative to Gambusia for the biocontrol of Culex mosquitoes.

opencc-zeroDec 2012View details →

Data from: The link between host density and egg production in a parasitoid insect: comparison between agricultural and natural habitats

1. Theory predicts that organisms should invest in overcoming a factor that may limit their reproductive success in direct proportion to their probability of being limited by it. The occurrence of egg limitation (where female insects deplete their eggs while oviposition opportunities are still available) is predicted to impose selection for increased fecundity at the expense of other fitness components. 2. We tested the hypothesis that the fecundity of a proovigenic parasitoid (where females emerge with their full egg load) should be positively correlated with the mean expectation for oviposition opportunities in the environment. More specifically, we tested whether females from agricultural systems, where hosts are often relatively abundant, emerge with more eggs than those from natural habitats. 3. We studied the proovigenic parasitoid wasp Anagrus daanei, which parasitizes eggs of leafhoppers of the genus Erythroneura. Erythroneura spp. leafhoppers feed on Vitis spp. (grapes) and are major pests of commercial vineyards as well as common herbivores of wild Vitis californica, which grows in riparian habitats. We sampled leafhoppers and parasitoids from eight vineyards and eight riparian habitats in central California. 4. We found that leafhopper density was higher at vineyards than in riparian habitats, whereas leafhopper egg size and parasitoid body size did not differ among these habitat types. Parasitoids from vineyards had higher egg loads than parasitoids from wild grapes, and fecundity was positively related to host density across field sites. Parasitoid egg volume was larger in natural sites; however, this variation was not significantly correlated with host density across field sites. Within a single population of parasitoids collected from a vineyard, parasitoid egg load was negatively correlated with longevity, suggesting a trade-off between reproduction and lifespan. 5. The results may be explained by a rapid evolution of reproductive traits in response to oviposition opportunities; or alternatively, by the occurrence of maternal effects on the fecundity of daughters based on the foraging experience of their mothers. 6. The ability of parasitoid fecundity to track mean host availability may strengthen the ability of parasitoids to suppress the population densities of their hosts, and hence may represent an important ecological or eco-evolutionary feedback.

Data from: Cognitive performance is linked to group size and affects fitness in Australian magpies

The Social Intelligence Hypothesis argues that the demands of social life drive cognitive evolution. This idea receives support from comparative studies linking variation in group size or mating systems with cognitive and neuroanatomical differences across species, but findings are contradictory and contentious. To understand the cognitive consequences of sociality it is also important to investigate social variation within species. Here we show that in wild, cooperatively breeding Australian magpies, individuals living in larger groups show elevated cognitive performance, which in turn is linked to increased reproductive success. Individual performance was highly correlated across four cognitive tasks, hinting towards a "general intelligence factor" underlying cognitive performance. Repeated cognitive testing of juveniles at different ages showed that the group size – cognition correlation emerged in early life, suggesting that living in larger groups promotes cognitive development. Furthermore, we found a positive association between female task performance and three indicators of reproductive success, thus identifying a selective benefit of greater cognitive performance. Together, these results provide critical intraspecific evidence that sociality can shape cognitive development and evolution.

Data from: Linking genetic kinship and demographic analyses to characterize dispersal: methods and application to Blanding's turtle

Characterizing how frequently, and at what life stages and spatial scales, dispersal occurs can be difficult, especially for species with cryptic juvenile periods and long reproductive life spans. Using a combination of mark–recapture information, microsatellite genetic data, and demographic simulations, we characterize natal and breeding dispersal patterns in the long-lived, slow-maturing, and endangered Blanding's turtle (Emydoidea blandingii), focusing on nesting females. We captured and genotyped 310 individual Blanding's turtles (including 220 nesting females) in a central Wisconsin population from 2010 to 2013, with additional information on movements among 3 focal nesting areas within this population available from carapace-marking conducted from 2001 to 2009. Mark–recapture analyses indicated that dispersal among the 3 focal nesting areas was infrequent (<0.03 annual probability). Dyads of females with inferred first-order relationships were more likely to be found within the same nesting area than split between areas, and the proportion of related dyads declined with increasing distance among nesting areas. The observed distribution of related dyads for nesting females was consistent with a probability of natal dispersal at first breeding between nearby nesting areas of approximately 0.1 based on demographic simulations. Our simulation-based estimates of infrequent female dispersal were corroborated by significant spatial genetic autocorrelation among nesting females at scales of <500 m. Nevertheless, a lack of spatial genetic autocorrelation among non-nesting turtles (males and females) suggested extensive local connectivity, possibly mediated by male movements or long-distance movements made by females between terrestrial nesting areas and aquatic habitats. We show here that coupling genetic and demographic information with simulations of individual-based population models can be an effective approach for untangling the contributions of natal and breeding dispersal to spatial ecology.

opencc-zeroNov 2019View details →

Data from: An X-linked meiotic drive allele has strong, recessive fitness costs in female Drosophila pseudoobscura

Selfish 'meiotic drive' alleles are transmitted to >50% of offspring, allowing them to rapidly invade populations even if they reduce the fitness of individuals carrying them. Theory predicts that drivers should either fix or go extinct, yet some drivers defy these predictions by persisting at low, stable frequencies for decades. One possible explanation for this discrepancy is that drivers are especially costly when homozygous, although empirical tests of this idea are rare and equivocal. Here, we measure the fitness of female Drosophila pseudoobscura carrying zero, one, or two copies of the X-linked driver Sex-Ratio (SR). SR had strong negative effects on female offspring production and the probability of reproductive failure, and these effects were largely similar across four genetic backgrounds. SR was especially costly when homozygous. We used our fitness measurements to parameterise a population genetic model, and found that the female fitness costs observed here can explain the puzzlingly low allele frequency of SR in nature. We also use the model to show how spatial variation in female mating behaviour, fitness costs of SR, and the reduced siring success of SR males can jointly explain the North-South cline in SR frequencies across North America.

opencc-zeroOct 2019View details →

Data from: Strong evidence of an Information-Theoretical Conservation Principle linking all discrete systems

Diverse discrete systems share common global properties that lack a unifying theoretical explanation. However, constraining the simplest measure of total information (Hartley-Shannon) in a statistical mechanics framework reveals a principle, the Conservation of Hartley-Shannon Information (CoHSI) that directly predicts both known and unsuspected common properties of discrete systems, as borne out in the diverse systems of computer software, proteins and music. Discrete systems fall into two categories distinguished by their structure: heterogeneous systems in which there is a distinguishable order of assembly of the system's components from an alphabet of unique tokens (e.g. proteins assembled from an alphabet of amino acids), and homogeneous systems in which unique tokens are simply binned, counted and rank ordered. Heterogeneous systems are characterized by an implicit distribution of component lengths, with sharp unimodal peak (containing the majority of components) and a power-law tail, whereas homogeneous systems reduce naturally to Zipf's Law but with a drooping tail in the distribution. We also confirm predictions that very long components are inevitable for heterogeneous systems; that discrete systems can exhibit simultaneously both heterogeneous and homogeneous behavior; and that in systems with more than one consistent token alphabet (e.g. digital music), the alphabets themselves show a power-law relationship.

opencc-zeroDec 2014View details →

Data from: Effective number of breeders provides a link between interannual variation in stream flow and individual reproductive contribution in a stream salmonid

The effective number of breeders that give rise to a cohort (Nb) is a promising metric for genetic monitoring of species with overlapping generations; however, more work is needed to understand factors that contribute to variation in this measure in natural populations. We tested hypotheses related to interannual variation in Nb in two long-term studies of brook trout populations. We found no supporting evidence for our initial hypothesis that inline image reflects inline image (defined as the number of adults in a population at the time of reproduction). inline image was stable relative to inline image and did not follow trends in abundance (one stream negative, the other positive). We used stream flow estimates to test the alternative hypothesis that environmental factors constrain Nb. We observed an intermediate optimum autumn stream flow for both inline image (R2 = 0.73, P = 0.02) and full-sibling family evenness (R2 = 0.77, P = 0.01) in one population and a negative correlation between autumn stream flow and full-sib family evenness in the other population (r = −0.95, P = 0.02). Evidence for greater reproductive skew at the lowest and highest autumn flow was consistent with suboptimal conditions at flow extremes. A series of additional tests provided no supporting evidence for a related hypothesis that density-dependent reproductive success was responsible for the lack of relationship between Nb and NC (so-called genetic compensation). This work provides evidence that Nb is a useful metric of population-specific individual reproductive contribution for genetic monitoring across populations and the link we provide between stream flow and Nb could be used to help predict population resilience to environmental change.

Data from: Genetic profiling links changing sea-ice to shifting beluga whale migration patterns

There is increasing concern over how Arctic fauna will adapt to climate related changes in sea-ice. We used long-term sighting and genetic data on beluga whales (Delphinapterus leucas) in conjunction with multi-decadal patterns of sea-ice in the Pacific Arctic to investigate the influence of sea-ice on spring migration and summer residency patterns. Substantial variations in sea-ice conditions were detected across seasons, years and sub-regions, revealing ice–ocean dynamics more complex than Arctic-wide trends suggest. This variation contrasted with a highly consistent pattern of migration and residency by several populations, indicating that belugas can accommodate widely varying sea-ice conditions to perpetuate philopatry to coastal migration destinations. However, a number of anomalous migration and residency events were detected and coincided with anomalous ice years, and in one case with an increase in killer whale (Orcinus orca) sightings and reported predation on beluga whales. The behavioural shifts were likely driven by changing sea-ice and associated changes in resource dispersion and predation risk. Continued reductions in sea-ice may result in increased predation at key aggregation areas and shifts in beluga whale behaviour with implications for population viability, ecosystem structure and the subsistence cultures that rely on them.

Data from: Linking vital rates of landbirds on a tropical island to rainfall and vegetation greenness

Remote tropical oceanic islands are of high conservation priority, and they are exemplified by range-restricted species with small global populations. Spatial and temporal patterns in rainfall and plant productivity may be important in driving dynamics of these species. Yet, little is known about environmental influences on population dynamics for most islands and species. Here we leveraged avian capture-recapture, rainfall, and remote-sensed habitat data (enhanced vegetation index [EVI]) to assess relationships between rainfall, vegetation greenness, and demographic rates (productivity, adult apparent survival) of three native bird species on Saipan, Northern Mariana Islands: rufous fantail (Rhipidura rufifrons), bridled white-eye (Zosterops conspicillatus), and golden white-eye (Cleptornis marchei). Rainfall was positively related to vegetation greenness at all but the highest rainfall levels. Temporal variation in greenness affected the productivity of each bird species in unique ways. Predicted productivity of rufous fantail was highest when dry and wet season greenness values were high relative to site-specific 5-year seasonal mean values (i.e., relative greenness); while the white-eye species had highest predicted productivity when relative greenness contrasted between wet and dry seasons. Survival of rufous fantail and bridled white eye was positively related to relative dry-season greenness and negatively related to relative wet-season greenness. Bridled white-eye survival also showed evidence of a positive response to overall greenness. Our results highlight the potentially important role of rainfall regimes in affecting population dynamics of species on oceanic tropical islands. Understanding linkages between rainfall, vegetation, and animal population dynamics will be critical for developing effective conservation strategies in this and other regions where the seasonal timing, extent, and variability of rainfall is expected to change in the coming decades.

opencc-zeroDec 2014View details →

Data from: Toward a mechanistic understanding of human-induced rapid environmental change: a case study linking energy development, nest predation, and predators

1. Demographic consequences of human-induced rapid environmental change (HIREC) have been widely documented for many populations. The mechanisms underlying such patterns, however, are rarely investigated and yet are critical to understand for effective conservation and management. 2. We investigated the mechanisms underlying reduced avian nest survival with intensification of natural gas development, an increasing source of HIREC globally. We tested the hypothesis that energy development increased the local activity of important nest predator species thereby elevating nest predation rates. During 2011–2012, we surveyed predators and monitored 668 nests of Brewer's sparrows Spizella breweri, sagebrush sparrows Artemisiospiza nevadensis and sage thrashers Oreoscoptes montanus breeding at twelve sites spanning a gradient of habitat loss from energy development in western Wyoming, USA. 3. Nine species, representing four mammalian and three avian families, were video-recorded depredating eggs and nestlings. Important nest predator species differed across songbird species, despite similar nesting habitats. Approximately 75% of depredation events were by rodents. 4. Consistent with our predictions, detections of most rodent nest predators increased with surrounding habitat loss due to natural gas development, which was associated with increased probability of nest predation for our three focal bird species. 5. An altered nest predator assemblage was therefore at least partly responsible for elevated avian nest predation risk in areas with more surrounding energy development. 6. Synthesis and applications. We demonstrate one mechanism, i.e. the local augmentation of predators, by which human-induced rapid environmental change (HIREC) can influence the demography of local populations. Given the accelerating trajectory of global energy demands, an important next step will be to understand why the activity and/or abundance of rodent predators increased with surrounding habitat loss from energy development activities.

opencc-zeroDec 2016View details →

Data from: Major histocompatibility complex-linked social signalling affects female fertility

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 a MHC-similar or a 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 a MHC-dissimilar than to a 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.

opencc-zeroDec 2016View details →

Data from: Linking songbird nest predation to seedling density: sugar maple masting as a resource pulse in a forest food web

The ecological literature presents considerable evidence for top-down forcing on the maintenance of species diversity. Yet, in temperate forests, bottom-up forces often exert a strong influence on ecosystem functioning. Here, we report on the indirect influence of a pulsed resource, sugar maple (Acer saccharum) seed production, on nest survival in a migratory songbird. We hypothesized that seed production in year t would determine daily nest survival rate in year t + 1 through its effects on seed-eating rodents. We used the density of sugar maple seedlings (with cotyledons) in year t + 1 as a proxy for seed production in year t and predicted that it would be inversely related to songbird nest survival the same year. We estimated the density of sugar maple seedlings, eastern chipmunk (Tamias striatus) activity, and daily nest survival rate in the ovenbird (Seiurus aurocapilla) over four successive years in a northern hardwood forest of New Brunswick, Canada. Seedling density varied by two orders of magnitude between years, whereas an index of chipmunk activity changed by an order of magnitude. Both variables were positively correlated and negatively correlated to daily nest survival rate. A logistic-exposure model including only seedling density received the greatest level of support (lowest AICc). Previous studies have reported the effect of sugar maple masting on seed-eating rodent populations, but the strong link we report between seedling density and songbird nest survival is novel. A nocturnal seed-eating nest predator, deer mouse (Peromyscus maniculatus), was not considered in our models, which may explain why chipmunk was not the best predictor of daily nest survival rate. The trophic linkages we observed are remarkably strong for a temperate forest ecosystem and might become more prevalent in northeastern North America, at least on calcium-rich soils, with the loss of large-diameter beech trees as a result of beech bark disease.

Data from: Linking oceanographic conditions, migratory schedules and foraging behaviour during the non‐breeding season to reproductive performance in a long‐lived seabird

1. Studies of the mechanisms underlying climate-induced population changes are critically needed to better understand and accurately predict population responses to climate change. Long-lived migratory species might be particularly vulnerable to climate change as they are constrained by different climate conditions and energetic requirements during the breeding and non-breeding seasons. Yet, most studies primarily focus on the breeding season of these species lifecycle. Environmental conditions experienced in the non-breeding season may have downstream effects on the other stages of the annual lifecycle. Not investigating such effects may potentially lead to erroneous inferences about population dynamics. 2. Combining demographic and tracking data collected between 2006 and 2013 at Kerguelen Island on a long-lived migratory seabird, the Black-Browed Albatross (Thalassarche melanophris), we investigated the links between sea surface temperature during the non-breeding season and behavioural and phenological traits (at-sea behaviour and migratory schedules) while accounting for different responses between birds of different sex and reproductive status (previously failed or successful breeders). We then explored if variation in the foraging behaviour and timing of spring migration influenced subsequent reproductive performance. 3. Our results showed that foraging activity and migratory schedules varied by both sex and reproductive status suggesting different energetic requirements and constraints among individuals. Higher sea surface temperatures during late winter, assumed to reflect poor winter conditions, were associated with an earlier departure from the wintering grounds and an extended pre-breeding period. However, an earlier spring migration and an earlier return to Kerguelen grounds were associated with a lower breeding success. 4. Our results highlighted that behaviour during some periods of the non-breeding season, particularly towards the end of the wintering period and the pre-breeding period had a significant effect on the subsequent reproductive success. Therefore, caution needs to be given to all stages of the annual cycle when predicting the influence of climate on population dynamics.

Data from: Recombination changes at the boundaries of fully and partially sex-linked regions between closely related Silene species pairs

The establishment of a region of suppressed recombination is a critical change during sex chromosome evolution, leading to such properties as Y (and W) chromosome genetic degeneration, accumulation of repetitive sequences and heteromorphism. Although chromosome inversions can cause large regions to have suppressed recombination, and inversions are sometimes involved in sex chromosome evolution, gradual expansion of the non-recombining region could potentially sometimes occur. We here test whether closer linkage has recently evolved between the sex-determining region and several genes that are partially sex-linked in Silene latifolia, using Silene dioica, a closely related dioecious plants whose XY sex chromosome system is inherited from a common ancestor. The S. latifolia pseudoautosomal region (PAR) includes several genes extremely closely linked to the fully Y-linked region. These genes were added to an ancestral PAR of the sex chromosome pair in two distinct events probably involving translocations of autosomal genome regions causing multiple genes to become partially sex-linked. Close linkage with the PAR boundary must have evolved since these additions, because some genes added in both events now show almost complete sex linkage in S. latifolia. We compared diversity patterns of five such S. latifolia PAR boundary genes with their orthologues in S. dioica, including all three regions of the PAR (one gene that was in the ancestral PAR and two from each of the added regions). The results suggest recent recombination suppression in S. latifolia, since its split from S. dioica.

Data from: Insect wing loss is tightly linked to the treeline: evidence from a diverse stonefly assemblage

The secondary loss of flight in previously winged insect lineages has long fascinated biologists. Habitat stability and isolation are thought to play important roles in driving wing reduction (Roff 1990, 1994), with exposure to high winds suggested to accelerate this process (Darwin 1859), although the role exposure plays in insect wing loss has never been empirically demonstrated. Here we assess fine-scale distributional records from a diverse regional stonefly assemblage, to demonstrate a widespread association between wing loss and the treeline in New Zealand. The observed pattern suggests that exposure plays a crucial role driving wing loss in alpine insects.

opencc-zeroDec 2013View details →

Data from: Impact on offspring methylation patterns of maternal gestational diabetes mellitus and intrauterine growth restraint suggest common genes and pathways linked to subsequent type 2 diabetes risk

Size at birth, postnatal weight gain, and adult risk for type 2 diabetes may reflect environmental exposures during developmental plasticity and may be mediated by epigenetics. Both low birth weight (BW), as a marker of fetal growth restraint, and high birth weight (BW), especially after gestational diabetes mellitus (GDM), have been linked to increased risk of adult type 2 diabetes. We assessed DNA methylation patterns using a bead chip in cord blood samples from infants of mothers with GDM (group 1) and infants with prenatal growth restraint indicated by rapid postnatal catch-up growth (group 2), compared with infants with normal postnatal growth (group 3). Seventy-five CpG loci were differentially methylated in groups 1 and 2 compared with the controls (group 3), representing 72 genes, many relevant to growth and diabetes. In replication studies using similar methodology, many of these differentially methylated regions were associated with levels of maternal glucose exposure below that defined by GDM [the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study] or were identified as changes observed after randomized periconceptional nutritional supplementation in a Gambian cohort characterized by maternal deprivation. These studies provide support for the concept that similar epigenetic modifications may underpin different prenatal exposures and potentially increase long-term risk for diseases such as type 2 diabetes.

Data from: Multiple mating is linked to social setting, and benefits the males in a communally rearing mammal

Individuals in social species may mate with multiple opposite sex individuals, including members of the same or different social groups. This variation may be linked to genetic benefits, where multiple mating decreases risk of inbreeding. Multiple mating also may be constrained by the socio-spatial setting through its effect on availability of mates. Since multiple mating with individuals from same or different groups may determine sex-specific fitness effects, we also examined how multiple mating modulates social benefits of females and males. We used 7 years of data on demography, social organization, and genetics of a natural population of the group-living and colonial rodent, Octodon degus, to determine how kin and sex composition within social groups, and spatial relations between these groups (i.e., colonial habits) influence multiple mating and its fitness consequences. 81.3% of males and 64.9% of females produced offspring with multiple opposite sex individuals within groups and with individuals of neighboring groups. Thus, polygynandry was the dominant mating system in the degu population examined. Multiple mating in degus was high when compared with estimates reported in other social mammals. Variation in female and male multiple mating was better explained by social setting through its effect on availability of potential mates rather than by benefits derived from decreasing risk of inbreeding. Finally, our study revealed how multiple mating enhances male, but not female reproductive success.