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836 results for “species limits”
Data from: Variation in growth and developmental responses to supraoptimal temperatures near latitudinal range limits of gypsy moth Lymantria dispar (L.), an expanding invasive species
Variation in thermal performance within and between populations provides the potential for adaptive responses to increasing temperatures associated with climate change. Organisms experiencing temperatures above their optimum on a thermal performance curve exhibit rapid declines in function and these supraoptimal temperatures can be a critical physiological component of range limits. The gypsy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is one of the best-documented biological invasions and factors driving its spatial spread are of significant ecological and economic interest. The present study examines gypsy moth sourced from different latitudes across its North American range for sensitivity to high temperature in constant temperature growth chamber experiments. Supraoptimal temperatures result in higher mortality in northern populations compared with populations from the southern range extent (West Virginia and coastal plain of Virginia, U.S.A.). Sublethal effects of high temperature on traits associated with fitness, such as smaller pupal mass, are apparent in northern and West Virginia populations. Overall, the results indicate that populations near the southern limits of the range are less sensitive to high temperatures than northern populations from the established range. However, southern populations are lower performing overall, based on pupal mass and development time, relative to northern populations. This suggests that there may be a trade-off associated with decreased heat sensitivity in gypsy moth. Understanding how species adapt to thermal limits and possible fitness trade-offs of heat tolerance represents an important step toward predicting climatically driven changes in species ranges, which is a particularly critical consideration in conservation and invasion ecology.
Data from: Disentangling biotic interactions, environmental filters, and dispersal limitation as drivers of species co-occurrence
A key focus in ecology is to search for community assembly rules. Here we compare two community modelling frameworks that integrate a combination of environmental and spatial data to identify positive and negative species associations from presence-absence matrices, and incorporate an additional comparison using joint species distribution models (JSDM). The frameworks use a dichotomous logic tree that distinguishes dispersal limitation, environmental requirements, and interspecific interactions as causes of segregated or aggregated species pairs. The first framework is based on a classical null model analysis complemented by tests of spatial arrangement and environmental characteristics of the sites occupied by the members of each species pair (Classic framework). The second framework, (SDM framework) implemented here for the first time, builds on the application of environmentally-constrained null models (or JSDMs) to partial out the influence of the environment, and includes an analysis of the geographical configuration of species ranges to account for dispersal effects. We applied these approaches to examine plot-level species co-occurrence in plant communities sampled along a wide elevation gradient in the Swiss Alps. According to the frameworks, the majority of species pairs were randomly associated, and most of the non-random positive and negative species associations could be attributed to environmental filtering and/or dispersal limitation. These patterns were partly detected also with JSDM. Biotic interactions were detected more frequently in the SDM framework, and by JSDM, than in the Classic framework. All approaches detected species aggregation more often than segregation, perhaps reflecting the important role of facilitation in stressful high-elevation environments. Differences between the frameworks may reflect the explicit incorporation of elevational segregation in the SDM framework and the sensitivity of JSDM to the environmental data. Nevertheless, all methods have the potential to reveal general patterns of species co-occurrence for different taxa, spatial scales, and environmental conditions.
Data from: Temperature-dependent oxygen limitation and the rise of Bergmann's Rule in species with aquatic respiration
Bergmann's Rule is the propensity for species-mean body size to decrease with increasing temperature. Temperature-dependent oxygen limitation has been hypothesized to help drive temperature–size relationships among ectotherms, including Bergmann's Rule, where organisms reduce body size under warm oxygen-limited conditions, thereby maintaining aerobic scope. Temperature-dependent oxygen limitation should be most pronounced among aquatic ectotherms that cannot breathe aerially, as oxygen solubility in water decreases with increasing temperature. We use phylogenetically-explicit analyses to show that species-mean adult size of aquatic salamanders with branchial or cutaneous oxygen uptake becomes small in warm environments and large in cool environments, whereas body size of aquatic species with lungs (i.e., that respire aerially), as well as size of semi aquatic and terrestrial species do not decrease with temperature. We argue that oxygen limitation drives the evolution of small size in warm aquatic environments for species with aquatic respiration. More broadly, the stronger decline in size with temperature observed in aquatic vs terrestrial salamander species mirrors the relatively strong plastic declines in size observed previously among aquatic vs terrestrial invertebrates, suggesting that temperature-dependent oxygen availability can help drive patterns of plasticity, micro- and macroevolution.
Data from: Contrasting forms of competition set elevational range limits of species
How abiotic and biotic factors constrain distribution limits at the harsh and benign edges of species ranges is hotly debated, partly because macroecological experiments testing the proximate causes of distribution limits are scarce. It has long been recognized—at least since Darwin's On the Origin of Species—that a harsh climate strengthens competition and thus sets species range limits. Using thorough field manipulations along a large elevation gradient, we show the mechanisms by which temperature determines competition type, resulting in a transition from interference to exploitative competition from the lower to the upper elevation limits in burying beetles (Nicrophorus nepalensis). This transition is an example of Darwin's classic hypothesis that benign climates favor direct competition for highly accessible resources while harsh climates result in competition through resources of high rivalry. We propose that identifying the properties of these key resources will provide a more predictive framework to understand the interplay between biotic and abiotic factors in determining geographic range limits.
Data from: When should species richness be energy limited, and how would we know?
Energetic constraints are fundamental to ecology and evolution, and empirical relationships between species richness and estimates of available energy (i.e. resources) have led some to suggest that richness is energetically constrained. However, the mechanism linking energy with richness is rarely specified and predictions of secondary patterns consistent with energy-constrained richness are lacking. Here, we lay out the necessary and sufficient assumptions of a causal relationship linking energy gradients to richness gradients. We then describe an eco-evolutionary simulation model that combines spatially explicit diversification with trait evolution, resource availability and assemblage-level carrying capacities. Our model identified patterns in richness and phylogenetic structure expected when a spatial gradient in energy availability determines the number of individuals supported in a given area. A comparison to patterns under alternative scenarios, in which fundamental assumptions behind energetic explanations were violated, revealed patterns that are useful for evaluating the importance of energetic constraints in empirical systems. We use a data set on rockfish (genus Sebastes) from the northeastern Pacific to show how empirical data can be coupled with model predictions to evaluate the role of energetic constraints in generating observed richness gradients.
Data from: Limits to speciation inferred from times to secondary sympatry and ages of hybridizing species along a latitudinal gradient
Range expansions are critical to renewed bouts of allopatric or parapatric speciation. Limits on range expansions—and, by implication, speciation—include dispersal ability and permeability of geographical barriers. In addition, recently diverged taxa may interfere with each other, preventing mutual expansion of each other's range into sympatry, because reproductive isolation is incomplete and/or ecological competition particularly strong. On the basis of geographical distributions and mitochondrial DNA phylogenetic information for 418 recently diverged species of New World birds, we estimate that secondary sympatry takes on the order of millions of years following population splitting and hence could impose an important limit on the rate of range expansion, thereby limiting further rounds of species formation. Average rates of achievement of sympatry have been faster in the temperate region (we estimate 1.7 million years to sympatry at 60°) than in the tropics (3.2 million years to sympatry at the equator). Evidence from the ages of species with hybrid zones implies that one factor associated with the slowed sympatry in the tropics is the rate of accumulation of reproductive isolation.
Data from: Tracking climate change in a dispersal-limited species: reduced spatial and genetic connectivity in a montane salamander
Tropical montane taxa are often locally adapted to very specific climatic conditions, contributing to their lower dispersal potential across complex landscapes. Climate and landscape features in montane regions affect population genetic structure in predictable ways, yet few empirical studies quantify the effects of both factors in shaping genetic structure of montane-adapted taxa. Here, we considered temporal and spatial variability in climate to explain contemporary genetic differentiation between populations of the montane salamander, Pseudoeurycea leprosa. Specifically, we used ecological niche modelling (ENM) and measured spatial connectivity and gene flow (using both mtDNA and microsatellite markers) across extant populations of P. leprosa in the Trans-Mexican Volcanic Belt (TVB). Our results indicate significant spatial and genetic isolation among populations, but we cannot distinguish between isolation by distance over time or current landscape barriers as mechanisms shaping population genetic divergences. Combining ecological niche modelling, spatial connectivity analyses, and historical and contemporary genetic signatures from different classes of genetic markers allows for inference of historical evolutionary processes and predictions of the impacts future climate change will have on the genetic diversity of montane taxa with low dispersal rates. Pseudoeurycea leprosa is one montane species among many endemic to this region and thus is a case study for the continued persistence of spatially and genetically isolated populations in the highly biodiverse TVB of central Mexico.
FIGURE 14 in The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae)
FIGURE 14. Single most parsimonious cladogram produced by analysis of data matrix in Table 1. Character distributions shown by black hash marks for uniquely derived states and gray hash marks for homoplasious states.
FIGURE 9 in The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae)
FIGURE 9. Tachytrechus transversus (Van Duzee) male abdomen and hypopygium: (A) apical portion of abdomen (hypopygium removed); (B) apex of eversible pregenitalic structure (ventral view); (C) hypopygium (left lateral view); (D) hypopygium ventral view (postgonite, surstylus and cerci not shown). Abbreviations: apv lobe: apicoventral epandrial lobe; bv lobe: basiventral epandrial lobe; cerc: cercus; dsur: dorsal lobe of surstylus; hypd: hypandrium; pgt: postgonite; ph: phallus; S: sternite; T: tergite; vsur: ventral lobe of surstylus.
FIGURE 13 in The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae)
FIGURE 13. Known distribution of Tachytrechus alatus (Becker), T. analis (Parent), T. dios Brooks sp. nov., T. giganteus (Brooks) and T. peruicus Yang & Zhang.
FIGURE 12 in The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae)
FIGURE 12. Known distribution of Tachytrechus costaricensis Brooks sp. nov., T. transversus (Van Duzee) and T. zumbadoi Brooks sp. nov.
FIGURE 11 in The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae)
FIGURE 11. Tachytrechus zumbadoi Brooks sp. nov. hypopygium: (A) left lateral view; (B) ventral view (postgonite, surstylus and cerci not shown); (C) cercus (dorsal view). Abbreviations: acc proc: accessory epandrial process; apv lobe: apicoventral epandrial lobe; bv lobe: basiventral epandrial lobe; cerc: cercus; epand: epandrium; hypd: hypandrium; pgt: postgonite; ph: phallus; vsur: ventral lobe of surstylus.
FIGURE 4 in The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae)
FIGURE 4. Tachytrechus costaricensis Brooks sp. nov. hypopygium: (A) left lateral view; (B) ventral view (postgonite, surstylus and cerci not shown); (C) surstylus, postgonite and apical margin of epandrium (left lateral view); (D) postgonite (dorsal view). Abbreviations: acc proc: accessory epandrial process; apv lobe: apicoventral epandrial lobe; bv lobe: basiventral epandrial lobe; cerc: cercus; dsur: dorsal lobe of surstylus; epand: epandrium; hypd: hypandrium; pgt: postgonite; ph: phallus; vsur: ventral lobe of surstylus.
FIGURE 5 in The limits of polymorphism in Liolaemus rothi: Molecular and phenotypic evidence for a new species of the Liolaemus boulengeri clade (Iguanidae, Liolaemini) from boreal Patagonia of Chile
FIGURE 5. Map of the North-Western Patagonia of Argentina and Chile, showing the distribution of Liolaemus hermannunezi (black circle), L. rothi (empty circles), L. sagei (cross), and L. loboi (black triangle). Details on the wide Patagonian geographical distribution of L. rothi can be found in Cei (1986)
FIGURE 4 in The limits of polymorphism in Liolaemus rothi: Molecular and phenotypic evidence for a new species of the Liolaemus boulengeri clade (Iguanidae, Liolaemini) from boreal Patagonia of Chile
FIGURE 4. Holotype of Liolaemus hermannunezi, male, MNHNC 3785, from 10 km E of Los Barros, near Pichachén Pass, Eighth Region, Chile. Photo D. Pincheira-Donoso.
FIGURE 3. Phylogenetic relationships among 67 in The limits of polymorphism in Liolaemus rothi: Molecular and phenotypic evidence for a new species of the Liolaemus boulengeri clade (Iguanidae, Liolaemini) from boreal Patagonia of Chile
FIGURE 3. Phylogenetic relationships among 67 Liolaemini taxa based on maximum parsimony analysis of 1710 aligned positions of DNA sequence data (length = 5810 steps). Strict consensus of five equally most parsimonious trees. Bootstrap values are presented above branches and decay indices are shown in bold below branches on the cladogram.
FIGURE 2 in The limits of polymorphism in Liolaemus rothi: Molecular and phenotypic evidence for a new species of the Liolaemus boulengeri clade (Iguanidae, Liolaemini) from boreal Patagonia of Chile
FIGURE 2. (a) Adult male of L. hermannunezi in life. Specimen collected approximately 8 km E of Los Barros, Laguna del Laja, Chile; (b) adult female from the same locality. Photos J. A. Schulte.
FIGURE 4 in Species limits in Pteruthius (Aves: Corvida) shrike-babblers: a comparison between the Biological and Phylogenetic Species Concepts
FIGURE 4. Sonogram excerpts of ten recordings from three localities across the range of the P. xanthochlorus complex, accompanied by sampling locality and name of recordist; x-axis depicts time in seconds, y-axis depicts frequency in kHz; Roman numerals refer to homologous song types; XC numbers refer to catalogue numbers in the xeno-canto sound collection and are given where applicable.
FIGURE 1 in Species limits in Pteruthius (Aves: Corvida) shrike-babblers: a comparison between the Biological and Phylogenetic Species Concepts
FIGURE 1. Sonogram excerpts of the vocalizations of 19 out of 30 sampled individuals of the P. flaviscapis complex accompanied by sampling locality and name of recordist or source; x-axis depicts time in seconds, y-axis depicts frequency in kHz; XC numbers refer to catalogue numbers in the xeno-canto sound collection and are given where applicable.
FIGURE 2 in Species limits in Pteruthius (Aves: Corvida) shrike-babblers: a comparison between the Biological and Phylogenetic Species Concepts
FIGURE 2. Sonogram excerpts of song type A (shared between Java and mainland) and song type B (Java only) of the P. aenobarbus complex, accompanied by sampling locality and name of recordist; x-axis depicts time in seconds, y-axis depicts frequency in kHz; XC number refers to catalogue number in the xeno-canto sound collection and is given where applicable.
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.