Find research datasets worth reusing

Search datasets from major research repositories and use ShareScore to quickly assess how well each record supports discovery, access, and reuse.

206

datasets available to search

ShareScore release 0.9.0

Dataset results

206 results for “clines”

Learn how ShareScore rates datasets ↗

dryad36/100

Body size variation in polyplacophoran mollusks: geographic clines and community structure along the Southeastern Pacific

Aim: To evaluate the latitudinal pattern of body size within and among chiton species employing phylogenetically structured analyses, and to examine the role of geographic variation in temperature, productivity and oxygen availability as potential environmental drivers. Location: Coastal habitats of the Southeastern Pacific along a latitudinal range of nearly 6,000 km, from the Equator to Patagonia (~ 2º to 56º S). Time Period: Present (2011 – 2017). Major taxa: 31 species of polyplacophoran mollusks. Methods: We measured the body length of 6,162 individuals collected in 62 sites, and reconstructed the phylogeny of this group based on two mitochondrial and one nuclear gene regions. We combined this information with data of sea surface temperature, chlorophyll-a concentration –as a proxy of primary productivity– and dissolved oxygen, and assessed which variables best explain the variation in size both within and among species employing phylogenetic generalised least squares (PGLS) and a model comparison approach. Main conclusions: Our analyses show that body size increases consistently with latitude, both within and among species, following Bergmann's rule. Variation in sea surface temperature along the latitudinal gradient provided a substantially better fit than chlorophyll-a and dissolved oxygen. Our results support the temperature-size rule for this lineage and suggest that similar processes could underlie the emergence of intra and interspecific gradients in body size of polyplacophorans. At the community level, chiton species richness was higher at intermediate latitudes and positively correlated with body size variation, suggesting that heterogeneity in size may reduce interspecific competition and contribute to species coexistence in this group. Overall, our study demonstrates that historical events, macroecological adaptive trends and local processes at the community level contribute to the distribution and size variation of polyplacophoran species along the Southeastern Pacific.

opencc-zeroMay 2022View details →

dryad36/100

Data from: Integrating Bayesian genomic cline analyses and association mapping of morphological and ecological traits to dissect reproductive isolation and introgression in a Louisiana Iris hybrid zone

Hybrid zones provide unique opportunities to examine reproductive isolation and introgression in nature. We utilized 45,384 Single Nucleotide Polymorphism (SNP) loci to perform association mapping of 14 floral, vegetative, and ecological traits that differ between Iris hexagona and Iris fulva, and to investigate, using a Bayesian Genomic Cline (BGC) framework, patterns of genomic introgression in a large and phenotypically diverse hybrid zone in southern Louisiana. Many loci of small effect-size were consistently found to be associated with phenotypic variation across all traits, and several individual loci were revealed to influence phenotypic variation across multiple traits. Patterns of genomic introgression were quite heterogeneous throughout the Louisiana Iris genome, with I. hexagona alleles tending to be favored over those of I. fulva. Loci that were found to have exceptional patterns of introgression were also found to be significantly associated with phenotypic variation in a small number of morphological traits. However, this was the exception rather than the rule, as most loci that were associated with morphological trait variation were not significantly associated with excess ancestry. These findings provide insights into the complexity of the genomic architecture of phenotypic differences and are a first step towards identifying loci that are associated with both trait variation and reproductive isolation in nature.

opencc-zeroDec 2016View details →

dryad36/100

Tension zone trapped by exogenous cline: analysis of a narrow hybrid zone between two parapatric Oxytropis species (Fabaceae)

Hybrid zones have been widely highlighted for their interest in understanding evolutionary processes. It is generally accepted that hybrid zones can be maintained in a balance between dispersal and selection. However, the selective forces can either be endogenous (i.e., genetic incompatibilities between parental taxa) or exogenous (i.e., parental taxa are adapted to different environments). In this study, we evaluated these alternatives and determined the maintenance of a narrow hybrid zone between parapatric distributed Oxytropis diversifolia and O. leptophylla in Nei Mongol, China. For 507 individuals sampled from two populations in the hybrid zone, 12 O. diversifolia populations and five O. leptophylla populations, we measured leaf-morphological characteristics, quantified genetic structure using 11 nuclear microsatellite loci and five chloroplast DNA intergenic regions, collected micro- and macrohabitat data, and conducted geographical cline analysis. We found that the two species differed in leaf morphology, and putative hybrids showed either intermediacy or a bias to O. diversifolia. Parental taxa formed two genetically distinct clusters, while populations in the hybrid zone consisted of both parental forms and various admixed individuals, exhibiting a bimodal pattern. The hybrid zone was coupled to ecological transitions of both microhabitat (i.e., the slope) and macroclimatic conditions. However, the genetic clines were significantly narrower than the environmental cline. Our results indicate that endogenous selection can be primarily responsible for maintaining the hybrid zone, while local adaptation accounts for the position of the zone. We further suggest the probable outcome of hybridization could be introgression.

opencc-zeroNov 2022View details →

dryad36/100

Hybrid cline or hybrid lineage: A genomic reevaluation of Sibley's classic species conundrum in Pipilo towhees

Hybrid zones are often described as clines of genetic and phenotypic traits moving across species barriers through introgression. Yet, hybrid zones can also be spatially complex and shift over time, and dispersal and vicariance can isolate portions of a cline, potentially leading to hybrid lineage formation. We reassessed Sibley's (1950) gradient between Collared Towhee (Pipilo ocai) and Spotted Towhee (P. maculatus) in Central Mexico to test whether it conformed to a typical tension-zone cline model. By comparing historical and modern data, we found that cline centers for genetic and phenotypic traits have not shifted over the course of 70 years. This equilibrium suggests that secondary contact between these species, which originally diverged over 2 million years ago, likely dates to the Pleistocene. Given the amount of mtDNA divergence, parental ends of the cline have very low autosomal nuclear differentiation (FST = 0.12). Dramatic and coincident cline shifts in mtDNA and throat color suggest the possibility of sexual selection as a factor in differential introgression, while a contrasting cline shift in green back color hints at a role for natural selection. Supporting the idea of a continuum between hybrid clines and hybrid lineage formation, the towhee gradient can be analyzed as one population under isolation-by-distance, as a two-population cline, and as three lineages experiencing divergence with gene flow. In the middle of the gradient, a hybrid lineage has become partly isolated, likely due both to forested habitat shrinking and fragmenting as it moved upslope after the last glacial maximum and a stark environmental transition. The towhee system offers a window into the potential outcomes of hybridization across a dynamic landscape including the creation of novel genomic and phenotypic combinations and incipient hybrid lineages.

opencc-zeroDec 2022View details →

dryad36/100

Parasite infection and the movement of the aquatic snail Potamopyrgus antipodarum along a depth cline

<ol> <li>Parasite species that use two or more host species during their life cycle depend on successful transmission between these species. These successive host species may have different habitat requirements; for example, one host species can be aquatic while the other is terrestrial. To overcome this complicating factor in transmission, a wide diversity of parasite species have adaptations that alter habitat preference in one host species in order to facilitate transmission to the next host species.</li> <li>Two common trematode parasites from New Zealand, Atriophallophorus winterbourni and Notocotylus spp., both have a two-host life‑cycle. The aquatic snail Potamopyrgus antipodarum is the intermediate host, from which the parasites require transmission to dabbling ducks or other waterfowl. Of these parasites, A. winterbourni is most frequently found in snails from the shallow-water margin, which may indicate parasite-induced movement of infected snails to the foraging habitat of dabbling ducks.</li> <li>To test if the parasites manipulate the snails to move to shallow water, we stretched tubular mesh cages across depth-specific ecological habitat zones in a lake. Both infected and healthy snails were released into the cages. After eleven days, significantly higher infection frequencies of A. winterbourni were retrieved from the shallowest end of the cages, while Notocotylus spp. frequencies did not vary with depth.</li> <li>The hypothesis that A. winterbourni induces its snail host to move toward the shallow-water habitat cannot be rejected based on the results from the experiment. Although additional research will be needed to address alternative explanations, the depth preference of infected snails may be a parasite adaptation that facilitates trophic transmission of parasites to dabbling ducks.</li> </ol>

opencc-zeroMay 2023View details →

dryad36/100

Data from: Phenotypic clines in herbivore resistance and reproductive traits in wild plants along an agricultural gradient

The conversion of natural landscapes to agriculture is a leading cause of biodiversity loss worldwide. While many studies examine how landscape modification affects species diversity, a trait-based approach can provide new insights into species responses to environmental change. Wild plants persisting in heavily modified landscapes provide a unique opportunity to examine species' responses to land use change. Trait expression within a community plays an important role in structuring species interactions, highlighting the potential implications of landscape mediated trait changes on ecosystem functioning. Here we test the effect of increasing agricultural landscape modification on defensive and reproductive traits in three commonly occurring Brassicaceae species to evaluate plant responses to landscape change. We collected seeds from populations at spatially separated sites with variation in surrounding agricultural land cover and grew them in a greenhouse common garden, measuring defensive traits through an herbivore no-choice bioassay as well as reproductive traits such as flower size and seed set. In two of the three species, plants originating from agriculturally dominant landscapes expressed a consistent reduction in flower size and herbivore leaf consumption. One species also showed reduced fitness associated with increasingly agricultural landscapes. These findings suggest that wild plants are responding to landscape modification, highlighting that species diversity alone does not fully capture the effects of land use change.

opencc-zeroMay 2023View details →

dryad36/100

Data for: Latitudinal cline of death-feigning behaviour in a beetle (Tribolium castaneum)

Death-feigning behaviour is a phenomenon in which a prey is rendered motionless due to stimulation or threat from a predator. This anti-predator defense mechanism has been observed across numerous animal taxa and is considered adaptive in nature. However, longer durations of death feigning can result in decreased opportunities for feeding and reproduction, and therefore is often associated with higher fitness costs as compared to environments without predators. Differences have also been observed in the frequencies and durations of death-feigning behaviours within animal populations, and these differences are thought to be influenced by the balance between survival and other fitness costs. Furthermore, this balance is predicted to vary in response to changes in environmental conditions. In this study, we examined the frequency and duration of death-feigning behaviours in 38 populations of the red flour beetle (Tribolium castaneum). Our results demonstrate that frequencies and durations of the death-feigning behaviours in Tribolium castaneum show geographical variations and a latitude cline, indicating that this behaviour is influenced by location as well as latitude. This study is the first to demonstrate the existence of a latitudinal cline in death-feigning behaviour and suggests that this behavior might have evolved in response to environmental factors that vary with latitude.

opencc-zeroJun 2023View details →

dryad36/100

Data from: Rural selection drives the evolution of an urban-rural cline in coat color in gray squirrels

<div> Phenotypic differences between urban and rural populations are well-documented, but the evolutionary processes driving trait variation along urbanization gradients are often unclear. We combined spatial data on abundance, trait variation, and measurements of fitness to understand cline structure and test for natural selection on heritable coat color morphs (melanic, gray) of eastern gray squirrels (Sciurus carolinensis) along an urbanization gradient. Population surveys using remote cameras and visual counts at 76 sites along the urbanization gradient revealed a significant cline in melanism, decreasing from 48% in the city center to <5% in rural woodlands. Among 76 squirrels translocated to test for phenotypic selection, survival was lower for the melanic than gray morph in rural woodlands, whereas there was no difference in survival between color morphs in the city. These results suggest the urban-rural cline in melanism is explained by natural selection favoring the gray morph in rural woodlands combined with relaxed selection in the city. Our study illustrates how trait variation between urban and rural populations can emerge from selection primarily in rural populations rather than adaptation to novel features of the urban environment. This reposotory contains a) occupancy data, point count data, and R code used to estimate the urban-rural cline in melanism, and b) radiotelemetry data and R code used to estimate differential survival between color morphs in urban and rural environments. </div>

opencc-zeroSep 2023View details →

dryad36/100