Find research datasets worth reusing

opencc-zeroDec 2020View details →

Age-related reproductive performance of the Adélie Penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy

1. Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. 2. We accounted for within- and among-individuals changes among known-aged Adélie penguins (Pygoscelis adeliae) during 17 years (1997 to 2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. 3. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive lifespan indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive lifespan and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive lifespan, and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in tradeoffs in reproductive lifespan or timing of senescence but not in the overall number of breeding attempts. 4. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. 5. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential tradeoffs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

opencc-zeroDec 2020View details →

Testing which axes of species differentiation underlie covariance of phylogeographic similarity among montane sedge species

Co-distributed species may exhibit similar phylogeographic patterns due to shared environmental factors or discordant patterns attributed to the influence of species-specific traits. Although either concordant or discordant patterns could occur due to chance, stark differences in key traits (e.g., dispersal ability) may readily explain differences between species. Multiple species' attributes may affect genetic patterns, and it is difficult to isolate the contribution of each. Here we compare the relative importance of two attributes, range size and niche breadth, in shaping the spatial structure of genetic variation in four sedge species (genus Carex) from the Rocky Mountains. Within two pairs of co-distributed species, one species exhibits narrow niche breadth, while the other species has broad niche breadth. Furthermore, one pair of co-distributed species has a large geographical distribution, while the other has a small distribution. The four species represent a natural experiment to tease apart how these attributes (i.e., range size and niche breadth) affect phylogeographic patterns. Investigations of genetic variation and structure revealed that range size, but not niche breadth, is related to spatial genetic covariation across species of montane sedges. Our study highlights how isolating key attributes across multiple species can inform their impact on processes driving intraspecific differentiation.

opencc-zeroJan 2021View details →

Reproductive success of the threatened San Clemente Bell's Sparrow in recovering habitats is similar to success in historical habitat

The San Clemente Bell's Sparrow Artemisiospiza belli clementeae is a federally threatened subspecies endemic to San Clemente Island, California. Previous research suggested dependence on boxthorn (Lycium californicum) as breeding habitat and nesting substrate; however, this conclusion was based on data collected when introduced feral ungulates had severely degraded the soil and vegetation cover. Since removal of the ungulates, native vegetation has gradually increased and the San Clemente Bell's Sparrows have expanded into areas where habitat had been unsuitable. To explore how Bell's Sparrows use these areas, we examined reproductive metrics associated with habitat covariates gathered at 214 nest sites used by Bell's Sparrows from 2014 ̶ 2016. We found that nest success in boxthorn habitat, previously considered an essential habitat for Bell's Sparrow nesting, was similar to success in alternative habitat types. Our findings contradict previous conclusions that Bell's Sparrows were boxthorn-dependent. We believe this previously documented relationship was likely due to the lack of available alternative nesting habitat following years of feral ungulate degradation, and Bell's Sparrows now reproduce in multiple habitat types and throughout most of San Clemente Island. Furthermore, our findings illustrate the importance of long-term monitoring and corresponding adaptive management when monitoring species in changing and recovering landscapes.The San Clemente Bell's Sparrow Artemisiospiza belli clementeae is a federally threatened subspecies endemic to San Clemente Island, California. Previous research suggested dependence on boxthorn (Lycium californicum) as breeding habitat and nesting substrate; however, this conclusion was based on data collected when introduced feral ungulates had severely degraded the soil and vegetation cover. Since removal of the ungulates, native vegetation has gradually increased and the San Clemente Bell's Sparrows have expanded into areas where habitat had been unsuitable. To explore how Bell's Sparrows use these areas, we examined reproductive metrics associated with habitat covariates gathered at 214 nest sites used by Bell's Sparrows from 2014 ̶ 2016. We found that nest success in boxthorn habitat, previously considered an essential habitat for Bell's Sparrow nesting, was similar to success in alternative habitat types. Our findings contradict previous conclusions that Bell's Sparrows were boxthorn-dependent. We believe this previously documented relationship was likely due to the lack of available alternative nesting habitat following years of feral ungulate degradation, and Bell's Sparrows now reproduce in multiple habitat types and throughout most of San Clemente Island. Furthermore, our findings illustrate the importance of long-term monitoring and corresponding adaptive management when monitoring species in changing and recovering landscapes.

FIGURE 6 in Revision of the diagnostic characters of two morphologically similar snook species Centropomus viridis and C. nigrescens (Carangiformes: Centropomidae)

FIGURE 6. Difference between the mean shape of Centropomus nigrescens (solid line) and that of C. viridis (dashed line) based on partial Procrustes distances. Arrows indicate the direction of the change.

FIGURE 5 in Revision of the diagnostic characters of two morphologically similar snook species Centropomus viridis and C. nigrescens (Carangiformes: Centropomidae)

FIGURE 5. Scatter plot showing scores on the first two principal components explaining 56.3% of the total variance. Two taxonomic groups are detected, indicating that shape variables obtained by PCA are significant discriminators. Centropomus nigrescens is represented by black circles and C. viridis by gray circles.

FIGURE 3. Phylogenetic relationships among the Centropomus 16S in Revision of the diagnostic characters of two morphologically similar snook species Centropomus viridis and C. nigrescens (Carangiformes: Centropomidae)

FIGURE 3. Phylogenetic relationships among the Centropomus 16S rRNA gene sequences found in the GenBank (March, 2020), only those sequences which overlap with the sequences from this study were selected. Relationships are based on the neighbor-joining method and the Tamura 3-parameter with a gamma distribution (shape parameter = 1). Node value support higher than 60% are shown.

FIGURE 4 in Revision of the diagnostic characters of two morphologically similar snook species Centropomus viridis and C. nigrescens (Carangiformes: Centropomidae)

FIGURE 4. Some morphological variants of the first dorsal fin of genetically identified Centropomus nigrescens (A-C) and C. viridis (D-F) specimens. A and D represent the typical shape accepted for each species (blunt-shaped fin in C. nigrescens and triangular-shaped fin in C. viridis).

FIGURE 1 in Revision of the diagnostic characters of two morphologically similar snook species Centropomus viridis and C. nigrescens (Carangiformes: Centropomidae)

FIGURE 1. The Tropical Eastern Pacific map shows the geographic distribution of Centropomus nigrescens (black line) and C. viridis (gray line). Sampling localities are shown on the insert. The figure was made based on Robertson & Allen (2015).

FIGURE 2 in Revision of the diagnostic characters of two morphologically similar snook species Centropomus viridis and C. nigrescens (Carangiformes: Centropomidae)

FIGURE 2. Representation of the generalized morphology of Centropomus, indicating ten landmarks (black circles) and one semi-landmark (gray circle) on the position of the anatomical structures compared in this study.

opencc-by-4.0Sep 2020View details →

A Comparative Analysis of Temporal Long Text Similarity: Application to Financial Documents

Textual Similarity on MD&A disclosure

opencc-zeroDec 2014View details →

Data from: Lack of genetic isolation by distance, similar genetic structuring but different demographic histories in a fig-pollinating wasp mutualism

Historical abiotic factors such as climatic oscillations and extreme climatic events as well as biotic factors have shaped the structuring of species' genetic diversity. In obligate species-specific mutualisms, the biogeographic histories of the interacting species are tightly linked. This could be particularly true for nuclear genes in the Ficus-pollinating wasp mutualistic association as the insects disperse pollen from their natal tree. In this study we compare spatial genetic structure of plant and pollinator for the Ficus hirta-Valisia javana association throughout South-East China including Hainan Island, for both nuclear and cytoplasmic markers. We show that dispersal of the insect leads to plant and insect presenting similar signatures of lack of genetic isolation by distance for nuclear genes on the continent over a distance of 1000 km. But we also show that the demographic histories of plant and insect are strikingly different. This is in agreement with extreme climatic events leading to transient regional extinctions of the insects, associated with local survival of the plants. We also evidence genetic differentiation for both wasps and fig-tree between the continent and Hainan Island, although the Qiongzhou Strait is only on average 30 km wide suggesting that geographic isolation by itself has not been sufficient to generate this differentiation. Hence, our results suggest that in highly dispersive mutualistic systems, isolation by dispersal limitation across a geographic barrier could be supplemented by isolation by adaptation, and maybe by coevolution, allowing further genetic divergence. In such systems, species may frequently be composed of a single population.

opencc-zeroDec 2018View details →

Data from: Fur seal microbiota are shaped by the social and physical environment, show mother-offspring similarities and are associated with host genetic quality

Despite an increasing appreciation of the importance of host-microbe interactions in ecological and evolutionary processes, the factors shaping microbial communities in wild populations remain poorly understood. We therefore exploited a natural experiment provided by two adjacent Antarctic fur seal (Arctocephalus gazella) colonies of high and low social density and combined 16S rRNA metabarcoding with microsatellite profiling of mother-offspring pairs to investigate environmental and genetic influences on skin microbial communities. Seal-associated bacterial communities differed profoundly between the two colonies, despite the host populations themselves being genetically undifferentiated. Consistent with the hypothesis that social stress depresses bacterial diversity, we found that microbial alpha diversity was significantly lower in the high-density colony. Seals from one of the colonies that contained a stream also carried a subset of freshwater-associated bacteria, indicative of an influence of the physical environment. Furthermore, mothers and their offspring shared similar microbial communities, in support of the notion that microbes may facilitate mother-offspring recognition. Finally, a significant negative association was found between bacterial diversity and heterozygosity, a measure of host genetic quality. Our study thus uncovers a complex interplay between environmental and host genetic effects, while also providing empirical support for the leash model of host control, which posits that bacterial communities are driven not only by bottom-up species interactions, but also by top-down host regulation. Taken together, our findings have broad implications for understanding host-microbe interactions as well as prokaryotic diversity in general.

opencc-zeroDec 2012View details →

Data from: Convergence and divergence during the adaptation to similar environments by an Australian groundsel

Adaptation to replicate environments is often achieved through similar phenotypic solutions. Whether selection also produces convergent genomic changes in these situations remains largely unknown. The variable groundsel, Senecio lautus, is an excellent system to investigate the genetic underpinnings of convergent evolution, since morphologically similar forms of these plants have adapted to the same environments along the coast of Australia. We compared range-wide patterns of genomic divergence in natural populations of this plant and searched for regions putatively affected by natural selection. Our results indicate that environmental adaptation followed complex genetic trajectories, affecting multiple loci, implying both the parallel recruitment of the same alleles and the divergence of completely different genomic regions across geography. An analysis of the biological functions of candidate genes suggests that adaptation to coastal environments may have occurred through the recruitment of different genes participating in similar processes. The relatively low genetic convergence that characterizes the parallel evolution of S. lautus forms suggests that evolution is more constrained at higher levels of biological organization.

Data from: Egg mimicry by the pacific koel: mimicry of one host facilitates exploitation of other hosts with similar egg types

When brood parasites exploit multiple host species, egg rejection by hosts may select for the evolution of host-specific races, where each race mimics a particular host's egg type. However, some brood parasites that exploit multiple hosts with the ability to reject foreign eggs appear to have only a single egg type. In these cases, it is unclear how the parasite egg escapes detection by its hosts. Three possible explanations are: (i) host-specific races are present, but differences in egg morphology are difficult for the human eye to detect; (ii) the brood parasite evolves a single egg type that is intermediate in appearance between the eggs of its hosts; (iii) or the parasite evolves mimicry of one of its hosts, which subsequently allows it to exploit other species with similar egg morphology. Here we test these possibilities by quantifying parameters of egg appearance of the brood-parasitic Pacific Koel (Eudynamys orientalis) and seven of its hosts. Koel eggs laid in the nests of different hosts did not show significant differences in colour or pattern, suggesting that koels have not evolved host-specific races. Koel eggs were similar in colour, luminance and pattern to the majority of hosts, but were significantly more similar in colour and luminance to one of the major hosts than to two other major hosts, supporting hypothesis (iii). Our findings suggest that mimicry of one host can allow a brood parasite to exploit new hosts with similar egg morphologies, which could inhibit the evolution of host defences in naïve hosts.

Data from: Population genetic and field ecological analyses return similar estimates of dispersal over space and time in an endangered amphibian

The explosive growth of empirical population genetics has seen a proliferation of analytical methods leading to a steady increase in our ability to accurately measure key population parameters, including genetic isolation, effective population size, and gene flow in natural systems. Assuming they yield similar results, population genetic methods offer an attractive complement to, or replacement of, traditional field ecological studies. However, empirical assessments of the concordance between direct field ecological and indirect population genetic studies of the same populations are uncommon in the literature. In this study, we investigate genetic isolation, rates of dispersal, and population sizes for the endangered California tiger salamander, Ambystoma californiense, across multiple breeding seasons in an intact vernal pool network. We then compare our molecular results to a previously published study based on multi-year, mark-recapture data from the same breeding sites. We found that field and genetic estimates of population size were only weakly correlated, but dispersal rates were remarkably congruent across studies and methods. In fact, dispersal probability functions derived from genetic data and traditional field ecological data were a significant match, suggesting that either method can be used effectively to assess population connectivity. These results provide one of the first explicit tests of the correspondence between landscape genetic and field ecological approaches to measuring functional population connectivity and suggest that even single-year genetic samples can return biologically meaningful estimates of natural dispersal and gene flow.

Data from: Naturally occurring hybrids of coral reef butterflyfishes have similar fitness compared to parental species

Hybridisation can produce evolutionary novelty by increasing fitness and adaptive capacity. Heterosis, or hybrid vigour, has been documented in many plant and animal taxa, and is a notable consequence of hybridisation that has been exploited for decades in agriculture and aquaculture. On the contrary, loss of fitness in naturally occurring hybrid taxa has been observed in many cases. This can have negative consequences for the parental species involved (wasted reproductive effort), and has raised concerns for species conservation. This study evaluates the relative fitness of previously documented butterflyfish hybrids of the genus Chaetodon from the Indo-Pacific suture zone at Christmas Island. Histological examination confirmed the reproductive viability of Chaetodon hybrids. Examination of liver lipid content showed that hybrid body condition was not significantly different from parent species body condition. Lastly, size at age data revealed no difference in growth rates and asymptotic length between hybrids and parent species. Based on the traits measured in this study, naturally occurring hybrids of Chaetodon butterflyfishes have similar fitness to their parental species, and are unlikely to supplant parental species under current environmental conditions at the suture zone. However, given sufficient fitness and on going genetic exchange between the respective parental species, hybrids are likely to persist within the suture zone.

opencc-zeroDec 2010View details →

Data from: Similarity and specialization of the larval versus adult diet of European butterflies and moths

Many herbivorous insects feed on plant tissues as larvae but use other resources as adults. Adult nectaring is an important component of the diet of many adult herbivores, but few studies compare adult and larval feeding for broad groups of insects. We compiled a dataset of larval host use and adult nectar sources for 995 butterfly and moth species (Lepidoptera) in Central Europe. Using a phylogenetic generalized least squares approach, we found that Lepidoptera that fed on more plant species as larvae were also nectar-feeding on more plant species as adults. Lepidoptera that lack functional mouthparts as adults on average used more plant species as larval hosts than Lepidoptera with adult mouthparts. We found that 54% of Lepidoptera include their larval host as a nectar source. By creating null models describing similarity between larval and adult nectar sources, we furthermore show that Lepidoptera nectar on their larval host more than would be expected if they fed at random on available nectar sources. Despite nutritional differences of plant tissue and nectar, we show that there are similarities between adult and larval feeding in Lepidoptera. This suggests that either behavioral or digestive constraints are retained throughout the lifecycle of holometabolous herbivores, affecting host breadth and identity.

Data from: Ecological interactions and coexistence are predicted by gene expression similarity in freshwater green algae

Phenotypic variation controls the species interactions which determine whether or not species coexist. Long-standing hypotheses in ecology and evolution posit that phenotypic differentiation enables coexistence by increasing the size of niche differentiation. This hypothesis has only been tested using macroscopic traits to date, but niche differentiation, particularly of microscopic organisms, also occurs at the molecular and metabolic level. We examined how phenotypic variation that arises at the level of gene expression over evolutionary time affects phytoplankton species interactions and coexistence. We predicted that similarity in gene expression among species would decline with phylogenetic distance, and that reduced similarity in gene expression would weaken competition, increase facilitation and promote coexistence. To test this, we grew eight species of freshwater green algae in monocultures and bicultures for 46 days in a laboratory microcosm experiment. We quantified the strength of species interactions by: (i) fitting Lotka–Volterra models to time-series densities and estimating interaction coefficients, and (ii) calculating relative densities that compare species' steady-state densities in biculture to those in monoculture. We used Illumina high throughput sequencing to quantify the expression of 1253 families of homologous genes, including a set of 17 candidate genes that we hypothesized a priori to be involved in competition or facilitation. Synthesis. We found that closely related species had greater similarity in gene expression than did distantly related species, but as gene expression became more similar, species experienced weaker competition or greater facilitation, and were more likely to coexist. We identified gene functional categories that were uniquely differentially regulated in association with particular species interaction types. Contrary to common thinking in ecology and evolution, similarity in gene expression, and not differentiation, was associated with weaker competition, facilitation and coexistence.

opencc-zeroDec 2015View details →

Data from: Introduced Drosophila subobscura populations perform better than native populations during an oviposition choice task due to increased fecundity but similar learning ability

The success of invasive species is tightly linked to their fitness in a putatively novel environment. While quantitative components of fitness have been studied extensively in the context of invasive species, fewer studies have looked at qualitative components of fitness, such as behavioral plasticity, and their interaction with quantitative components, despite intuitive benefits over the course of an invasion. In particular, learning is a form of behavioral plasticity that makes it possible to finely tune behavior according to environmental conditions. Learning can be crucial for survival and reproduction of introduced organisms in novel areas, for example, for detecting new predators, or finding mates or oviposition sites. Here we explored how oviposition performance evolved in relation to both fecundity and learning during an invasion, using native and introduced Drosophila subobscura populations performing an ecologically relevant task. Our results indicated that, under comparable conditions, invasive populations performed better during our oviposition task than did native populations. This was because invasive populations had higher fecundity, together with similar cognitive performance when compared to native populations, and that there was no interaction between learning and fecundity. Unexpectedly, our study did not reveal an allocation trade-off (i.e., a negative relationship) between learning and fecundity. On the contrary, the pattern we observed was more consistent with an acquisition trade-off, meaning that fecundity could be limited by availability of resources, unlike cognitive ability. This pattern might be the consequence of escaping natural enemies and/or competitors during the introduction. The apparent lack of evolution of learning may indicate that the introduced population did not face novel cognitive challenges in the new environment (i.e., cognitive "pre-adaptation"). Alternatively, the evolution of learning may have been transient and therefore not detected.