Find research datasets worth reusing

Data from: Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists

Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the food web level induced by poleward shifts via topological network analysis of highly resolved boreal and arctic food webs of the Barents Sea. We detected considerable differences in structural properties and link configuration between the boreal and the arctic food webs, the latter being more modular and less connected. We found that a main characteristic of the boreal fish moving poleward into the arctic region of the Barents Sea is high generalism, a property that increases connectance and reduces modularity in the arctic marine food web. Our results reveal that habitats form natural boundaries for food web modules, and that generalists play an important functional role in coupling pelagic and benthic modules. We posit that these habitat couplers have the potential to promote the transfer of energy and matter between habitats, but also the spread of pertubations, thereby changing arctic marine food web structure considerably with implications for ecosystem dynamics and functioning.

opencc-zeroDec 2017View details →

Data from: Interactive effects of climate change and biodiversity loss on ecosystem functioning

Climate change and biodiversity loss are expected to simultaneously affect ecosystems, however research on how each driver mediates the effect of the other has been limited in scope. The multiple stressor framework emphasizes non-additive effects, but biodiversity may also buffer the effects of climate change, and climate change may alter which mechanisms underlie biodiversity-function relationships. Here, we performed an experiment using tank bromeliad ecosystems to test the various ways that rainfall changes and litter diversity may jointly determine ecological processes. Litter diversity and rainfall changes interactively affected multiple functions, but how depended on the process measured. High litter diversity buffered the effects of altered rainfall on detritivore communities, evidence of insurance against impacts of climate change. Altered rainfall affected the mechanisms by which litter diversity influenced decomposition, reducing the importance of complementary attributes of species ("complementarity effects"), and resulting in an increasing dependence on the maintenance of specific species ("dominance effects"). Finally, altered rainfall conditions prevented litter diversity from fuelling methanogenesis, because such changes in rainfall reduced microbial activity by 58%. Together, these results demonstrate that the effects of climate change and biodiversity loss on ecosystems cannot be understood in isolation and interactions between these stressors can be multifaceted.

opencc-zeroDec 2013View details →

Data from: Climate-mediated movement of an avian hybrid zone

The interaction between sibling species that share a zone of contact is a multifaceted relationship affected by climate change. Between sibling species, interactions may occur at whole-organism (direct or indirect competition) or genomic (hybridization and introgression) levels. Tracking hybrid zone movements can provide insights about influences of environmental change on species interactions. Here, we explore the extent and mechanism of movement of the contact zone between black-capped chickadees (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis) at whole-organism and genomic levels. We find strong evidence that winter temperatures limit the northern extent of P. carolinensis by demonstrating a current-day association between the range limit of this species and minimum winter temperatures. We further show that this temperature limitation has been consistent over time because we are able to accurately hindcast the previous northern range limit under earlier climate conditions. Using genomic data, we confirm northward movement of this contact zone over the past decade and highlight temporally consistent differential—but limited—geographic introgression of alleles. Our results provide an informative example of the influence of climate change on a contact zone between sibling species.

Data from: Geological and climatic changes in quaternary shaped the evolutionary history of Calibrachoa heterophylla, an endemic South-Atlantic species of petunia

Background: The glacial and interglacial cycles that characterized the Quaternary greatly affected the distribution and genetic diversity of plants. In the Neotropics, few phylogeographic studies have focused on coastal species outside of the Atlantic Rainforest. Climatic and sea level changes during the Quaternary played an important role in the evolutionary history of many organisms found in coastal regions. To contribute to a better understanding of plant evolution in this environment in Southern South America, we focused on Calibrachoa heterophylla (Solanaceae), an endemic and vulnerable wild petunia species from the South Atlantic Coastal Plain (SACP). Results: We assessed DNA sequences from two cpDNA intergenic spacers and analyzed them using a phylogeographic approach. The present phylogeographic study reveals the influence of complex geologic and climatic events on patterns of genetic diversification. The results indicate that C. heterophylla originated inland and subsequently colonized the SACP; the data show that the inland haplogroup is more ancient than the coastal one and that the inland was not affected by sea level changes in the Quaternary. The major diversification of C. heterophylla that occurred after 0.4 Myr was linked to sea level oscillations in the Quaternary, and any diversification that occurred before this time was obscured by marine transgressions that occurred before the coastal sand barrier's formation. Results of the Bayesian skyline plot showed a recent population expansion detected in C. heterophylla seems to be related to an increase in temperature and humidity that occurred at the beginning of the Holocene. Conclusions: The geographic clades have been formed when the coastal plain was deeply dissected by paleochannels and these correlate very well with the distributional limits of the clades. The four major sea transgressions formed a series of four sand barriers parallel to the coast that progressively increased the availability of coastal areas after the regressions and that may have promoted the geographic structuring of genetic diversity observed today. The recent population expansion for the entire species may be linked with the event of marine regression after the most recent sea transgression at ~5 kya.

Data from: Diversity dynamics of mammals in relation to tectonic and climatic history: comparison of three Neogene records from North America

In modern ecosystems, regions of topographic heterogeneity, when compared with nearby topographically homogeneous regions, support high species densities of mammals and other groups. This biogeographic pattern could be explained by either greater diversification rates or greater accommodation of species in topographically complex regions. In this context, we assess the hypothesis that changes in landscape history have stimulated diversification in mammals. Landscape history includes tectonic and climatic processes that influence topographic complexity at regional scales. We evaluated the influence of changes in topographic complexity and climate on origination and extinction rates of rodents, the most diverse clade of mammals. We compared the Neogene records of rodent diversity for three regions in North America. The Columbia Basin of the Pacific Northwest (Region 1) and the northern Rocky Mountains (Region 2) were tectonically active over much of the Cenozoic and are characterized by high topographic complexity today. The northern Great Plains (Region 3) have been tectonically quiescent, with low relief, throughout the Cenozoic. These three regions have distinctive geologic histories and substantial fossil records. All three regions showed significant changes in diversification and faunal composition over the Neogene. In the montane regions, originations and extinctions peaked at the onset and close, respectively, of the Miocene Climatic Optimum (17–14 Ma), with significant changes in faunal composition accompanying these episodes of diversification. In the Great Plains, rodents showed considerable turnover but infrequent diversification. Peak Neogene diversity in the Great Plains occurred during cooling after the Miocene Climatic Optimum. These histories suggest that climatic changes interacting with increasing topographic complexity intensify macroevolutionary processes. In addition, close tracking of diversity and fossil productivity with the stratigraphic record suggests either large-scale sampling biases or the mutual response of diversity and depositional processes to changes in landscape history.

opencc-zeroAug 2019View details →

Data from: Rapid adaptation to novel climate at the northern range edge of the invasive Asian tiger mosquito Aedes albopictus: a moving target

1. Rapid adaptation in response to novel environments can facilitate species invasions and range expansions. Understanding how invasive disease vectors rapidly evolve to novel conditions—particularly at the edge of its non-native range—has important implications for mitigating the prevalence and spread of disease. 2. Here, we evaluate the role of local adaptation in overwintering capability of the Asian tiger mosquito, Aedes albopictus. This species invaded the Southern US in the 1980s and rapidly spread northward into novel climate compared to its native range. Photoperiodically induced egg diapause is a key trait contributing to the establishment and spread of Ae. albopictus in temperate latitudes, and diapause incidence rapidly developed a cline along a latitudinal gradient in the US shortly after its initial invasion. However, variation in overwintering survival of diapause-induced eggs along this gradient is not known, but is critical to the fitness-related role of diapause evolution in the establishment and spread of Ae. albopictus in its northern US range. 3. Using reciprocal transplants, we detected local adaptation in overwinter survival of diapausing Aedes albopictus eggs. In northern range-edge winters, eggs produced by range-edge individuals survived better than those produced by range-core individuals. Diapause eggs from range-edge and range-core locations survived equally well in range-core winters, and no eggs survived a winter beyond the current northern range limit in the US. 4. Synthesis and applications. These results demonstrate rapid (~ 3 decades) local adaptation of egg diapause, a key trait facilitating overwinter survival and range expansion for the invasive Asian tiger mosquito. In light of these results, control efforts could shift from targeting satellite populations to a focus on preventing dispersal into locally adapted, range-edge locations and to aim removal efforts towards areas surrounding locally adapted populations. Adopting new approaches to target rapidly adapting populations will require large-scale collaboration among control agencies and research institutions, and should begin in the northern US range to better control Ae. albopictus mosquito populations in the face of rapid adaptation.

opencc-zeroDec 2017View details →

Data from: The Rapoport effect and the climatic variability hypothesis in Early Jurassic ammonites

The increase of species range size towards high latitudes, known as the Rapoport's rule, remains one of the most debated and poorly understood macroecological patterns. Numerous studies have challenged both its universality and the main mechanism originally proposed to explain it, i.e. the climatic variability hypothesis. Here we study this pattern on a group of fossil marine organisms: the early Pliensbachian ammonites of the western Tethys. We further take into account the influence of the marked provincialism prevailing at that time, with a Mediterranean province (MED) and a Northwest European province (NWE) located on each side of a latitudinally-oriented palaeobiogeographic barrier. We find that only species from the NWE province display a Rapoport effect, whereas species from the more tropical MED province show a boundary effect and have larger range sizes in average. This dual pattern can be explained by an alternative climatic variability hypothesis that better captures latitudinal seasonal variations and outlines the influence of the intertropical zone, characterized by stable and homogeneous climate that allows species to disperse over very large areas, regardless of their thermal tolerance. Accordingly, the NWE province probably displayed a gradient of seasonal climatic variations which caused the emergence of a Rapoport effect, whereas the MED province was probably located in the intertropical zone where no gradient in species range size is expected. Our multi-scale approach further shows that the Rapoport effect is scale dependent and may be labile through time. This probably explains the conflicting results of previous studies carried out at various spatio-temporal scales.

opencc-zeroDec 2018View details →

Data from: Recent decadal drought reverts warming–triggered growth enhancement in contrasting climates in the southern Andes treeline

Aims: Rising temperature and declining summer precipitation due to the 1970s-climate shift in southern South America have reduced forest productivity at dry sites. Here, we worked with the most widespread Southern Hemisphere treeline species, Nothofagus pumilio, across contrasting climatic conditions and determined whether rising atmospheric CO2 concentrations as well as warmer and drier climatic conditions provoked by the 70s-climatic shift have been causing systematic changes in treeline growth rates and intrinsic water-use efficiency (iWUE).Location: 36–54° S, southern Andes. Time period: 1950–2010. Major taxa studied: Nothofagus pumilio. Methods: We worked at five disparate climatic treeline locations, spanning 18 degrees of latitude; at each location, we sampled trees at four different elevations, including treeline elevation. We quantified the variation of annual tree-ring width (TRW) as a function of climate, elevation, tree age, size, annual CO2 concentrations, and location, using linear mixed-effects models and interpreted TRW trends in relation to iWUE and isotope (δ13C and δ18O) signalling. Results: Across locations, the patterns of treeline growth occurring in the 1980–2010 period exhibited a clear and significant negative trend, in contrast to the previous 1950–1980 period. We found an increase of iWUE and δ18O across time and locations. Given that an increase in δ18O indicates a decrease in stomatal conductance, we assert that drought-induced stomatal closure appears to be causing the reduction in growth. Main conclusions: We show unequivocal evidence that warmer and drier summer conditions translated into a decrease of growth rates along the elevational treeline of the southern Andes, reverting previous growth improvements linked to climate warming. An improvement in iWUE at all locations is most likely explained by decreased stomatal conductance given the rising δ18O signal. An iWUE–growth decoupling may act as an ecological strategy to respond to drought.

opencc-zeroJun 2021View details →

Data from: Testing macroecological abundance patterns: the relationship between local abundance and range size, range position and climatic suitability among European vascular plants

Aim: A fundamental question in macroecology centres around understanding the relationship between species' local abundance and their distribution in geographic and climatic space (i.e. the multi-dimensional climatic space or climatic niche). Here, we tested three macroecological hypotheses that link local abundance to the following range properties: (1) the abundance-range size relationship, (2) the abundance-range centre relationship, and (3) the abundance-suitability relationship. Location: Europe Taxon: Vascular plants Methods: Distribution range maps were extracted from the Chorological Database to derive information on the range and niche sizes of 517 European vascular plant species. To estimate local abundance, we assessed samples from 744,513 vegetation plots in the European Vegetation Archive, where local species' abundance is available as plant cover per plot. We then calculated the 'centrality', i.e. the distance between the location of the abundance observation and each species' range centre in geographic and climatic space. The climatic suitability of plot locations was estimated using coarse-grain species distribution models (SDMs). The relationships between centrality or climatic suitability with abundance were tested using linear models and quantile regression. We summarized the overall trend across species' regression slopes from linear models and quantile regression using a meta-analytical approach. Results: We did not detect any positive relationships between a species' mean local abundance and the size of its geographic range or climatic niche. Contrasting yet significant correlations were detected between abundance and centrality or climatic suitability among species. Main conclusions: Our results do not provide unequivocal support for any of the relationships tested, demonstrating that determining properties of species' distributions at large grains and extents might be of limited use for predicting local abundance, including current SDM approaches. We conclude that environmental factors influencing individual performance and local abundance are likely to differ from those factors driving plant species' distribution at coarse resolution and broad geographic extents.

opencc-zeroDec 2016View details →

Data from: The effects of climate warming and disturbance on the colonization potential of ornamental alien plant species

1. A large number of alien plant species have been introduced as ornamental garden plants to Europe, but relatively few have become invasive. Low climatic suitability may be limiting the current invasion potential of many alien ornamental species. However, with ongoing disturbance and climate change, this barrier may be reduced for some species. 2. Here we tested how colonization ability (a prerequisite for invasion) of frequently planted alien ornamentals depends on disturbance and heating, and on their species characteristics. We sowed seeds of 37 non-naturalized alien herbaceous garden-plant species into native grassland plots with and without disturbance, and with and without infrared heating lamps. To assess whether their responses differ from those within the regional wild flora, we also sowed 14 native species and 12 naturalized alien species. During two years, we assessed the likelihoods of germination, first-year survival, second-year survival and flowering of these 63 study species. 3. The heating treatment, which also reduced soil moisture, decreased all measures of colonization success, but more so for sown native species than for the non-naturalized and naturalized alien ones. The disturbance treatment increased colonization success, and because heating decreased productivity of the undisturbed grassland plots, it also increased invasibility of these plots. Average colonization success of non-naturalized aliens was reduced by heating, but some species were not affected or performed even better with heating, particularly those with an annual life span and a high seed mass. Winter hardiness improved colonization ability of non-naturalized aliens, but this advantage was reduced in the heated plots. 4. Synthesis. Disturbance increased and heating decreased the absolute colonization success of most of the 63 species sown. However, heating had stronger adverse effects on the resident grassland and sown native species than either type of sown alien species. Together, these results suggest that some alien plants may have greater colonization success relative to native plants under a warmer climate.

Data from: Biotic and climatic velocity identify contrasting areas of vulnerability to climate change

Metrics that synthesize the complex effects of climate change are essential tools for mapping future threats to biodiversity and predicting which species are likely to adapt in place to new climatic conditions, disperse and establish in areas with newly suitable climate, or face the prospect of extirpation. The most commonly used of such metrics is the velocity of climate change, which estimates the speed at which species must migrate over the earth's surface to maintain constant climatic conditions. However, "analog-based" velocities, which represent the actual distance to where analogous climates will be found in the future, may provide contrasting results to the more common form of velocity based on local climate gradients. Additionally, whereas climatic velocity reflects the exposure of organisms to climate change, resultant biotic effects are dependent on the sensitivity of individual species as reflected in part by their climatic niche width. This has motivated development of biotic velocity, a metric which uses data on projected species range shifts to estimate the velocity at which species must move to track their climatic niche. We calculated climatic and biotic velocity for the Western Hemisphere for 1961–2100, and applied the results to example ecological and conservation planning questions, to demonstrate the potential of such analog-based metrics to provide information on broad-scale patterns of exposure and sensitivity. Geographic patterns of biotic velocity for 2954 species of birds, mammals, and amphibians differed from climatic velocity in north temperate and boreal regions. However, both biotic and climatic velocities were greatest at low latitudes, implying that threats to equatorial species arise from both the future magnitude of climatic velocities and the narrow climatic tolerances of species in these regions, which currently experience low seasonal and interannual climatic variability. Biotic and climatic velocity, by approximating lower and upper bounds on migration rates, can inform conservation of species and locally-adapted populations, respectively, and in combination with backward velocity, a function of distance to a source of colonizers adapted to a site's future climate, can facilitate conservation of diversity at multiple scales in the face of climate change.

opencc-zeroDec 2013View details →

Data from: Evolution in the sabertooth cat, Smilodon fatalis, in response to Pleistocene climate change

The late Pleistocene was a time of environmental change, culminating in an extinction event. Few fossil localities record a temporal series of carnivore fossil populations from this interesting interval as well as Rancho La Brea (RLB). We analyzed mandibles of Smilodon fatalis from RLB using 2D geometric morphometrics to examine if, and how, mandibular shape changes through time. S. fatalis shows mandibular evolution with oscillations between a small, ancestral-type morph in pits 77 (≈37 Kybp) and 2051 (≈26 Kybp), a larger, more derived morph in pits 91 (≈28 Kybp) and 61-67 (≈13.6 Kybp), and an intermediate morph from pit 13 (≈17.7 Kybp). These oscillations end in pit 61-67, where Smilodon exhibits its greatest body size, widest gape, and lowest bite forces. Additionally, variation is lowest in pit 61-67, which was deposited concurrent with the Bølling-Allerød warming event, which may have important implications for the timing or conditions during the extinction event. Contra to a temporal Bergmann's rule, such rapid warming events appear to be correlated with larger, derived, morphologies while static, cooler, climates correlate with gracile, ancestral morphologies.

opencc-zeroDec 2016View details →

Data from: Heterogeneous distributional responses to climate warming: evidence from rodents along a subtropical elevational gradient

Background: Understanding whether species' elevational range is shifting in response to directional changes in climate and whether there is a predictable pattern in that response is one of the major challenges in ecology. However, so far very little is known about the distributional responses of subtropical species to climate change, especially for small mammals. In this study, we examined the elevational range shifts at three range points (upper and lower range limits and abundance-weighted range centre) of rodents over a 30-year period (1986 to 2014-2015), in a subtropical forest of Southwest China. We also examined the influences of four ecological traits (body mass, habitat breadth, diet and daily activity pattern) on the upslope shifts in species' abundance-weighted range centres. Results: Despite the warming trend between 1986 and 2015, the eleven rodent species in analysis displayed heterogeneous dynamics at each of the three range points. Species which have larger body sizes and narrower habitat breadths, show both diurnal and nocturnal activities and more specialized dietary requirements, are more likely to exhibit upslope shifts in abundance-weighted range centres. Conclusions: Species' distributional responses can be heterogeneous even though there are directional changes in climate. Our study indicates that climate-induced alleviation of competition and lag in response may potentially drive species' range shift, which may not conform to the expectation from climate change. Difference in traits can lead to different range dynamics. Our study also illustrates the merit of multi-faceted assessment in studying elevational range shifts.

Data from: Influence of late Quaternary climate change on present patterns of genetic variation in valley oak, Quercus lobata Née

Phylogeography and ecological niche models (ENMs) suggest that late Quaternary glacial cycles have played a prominent role in shaping present population genetic structure and diversity, but have not applied quantitative methods to dissect the relative contribution of past and present climate vs. other forces. We integrate multilocus phylogeography, climate-based ENMs and multivariate statistical approaches to infer the effects of late Quaternary climate change on contemporary genetic variation of valley oak (Quercus lobata Née). ENMs indicated that valley oak maintained a stable distribution with local migration from the last interglacial period (~120 ka) to the Last Glacial Maximum (~21 ka, LGM) to the present compared with large-scale range shifts for an eastern North American white oak (Quercus alba L.). Coast Range and Sierra Nevada foothill populations diverged in the late Pleistocene before the LGM [104 ka (28–1622)] and have occupied somewhat distinct climate niches, according to ENMs and coalescent analyses of divergence time. In accordance with neutral expectations for stable populations, nuclear microsatellite diversity positively correlated with niche stability from the LGM to present. Most strikingly, nuclear and chloroplast microsatellite variation significantly correlated with LGM climate, even after controlling for associations with geographic location and present climate using partial redundancy analyses. Variance partitioning showed that LGM climate uniquely explains a similar proportion of genetic variance as present climate (16% vs. 11–18%), and together, past and present climate explains more than geography (19%). Climate can influence local expansion–contraction dynamics, flowering phenology and thus gene flow, and/or impose selective pressures. These results highlight the lingering effect of past climate on genetic variation in species with stable distributions.

Data from: Postglacial climate and fire-mediated vegetation change on the western Olympic Peninsula, Washington

The mode and tempo of forest compositional change during periods of rapid climate change, including the potential for the fire regime to produce non-linear relationships between climate and vegetation, is a long-standing theme of forest ecological research. In the old conifer forests of the coastal Pacific Northwest, fire disturbances are sufficiently rare that their relation to climate and their ecological effects are poorly understood. We used a 14,700-year high-resolution sediment record from Yahoo Lake on the Olympic Peninsula to examine vegetation (landscape vegetation from pollen and local vegetation from macrofossils) and fire (landscape fire from total charcoal and local fire from charcoal peaks) in conjunction with independent records of climate. We hypothesized that the successional stage of the local forest will exhibit alternate stable states over a range of fire activity, that species turnover will increase abruptly above a certain level of fire activity and that both responses would be more gradual at the landscape scale than the local scale. Supporting these hypotheses, at the local scale we found strong evidence for alternate stable states of late vs. early successional communities and inertia of species turnover to changing fire activity. At the landscape scale, vegetation responded more gradually to changing fire activity. From 14,700 to 7000 years ago, high landscape vegetation turnover occurred along with high landscape fire activity, especially during the warm summers of the early Holocene. In several instances local species turned over completely following fire events but several centuries after climate change. In contrast, during the last 7000 years the local forest composition was dominated by late-successional species with little species turnover despite periods of moderate fire activity. We suggest that the relatively minor climate fluctuations of the past 7000 years were not sufficient to cause large-scale species turnover after fire. The Yahoo Lake fire and vegetation record of the early Holocene provides a model for dramatic ecosystem change following an anticipated shift to warmer summer temperatures.

opencc-zeroDec 2018View details →

Data from: Impacts of growing-season climate on tree growth and post-fire regeneration in ponderosa pine and Douglas-fir forests

We studied the impacts of climate variability on low-elevation forests in the U.S. northern Rocky Mountains by quantifying how post-fire tree regeneration and radial growth varied with growing-season climate. We reconstructed post-fire regeneration and radial growth rates of Pinus ponderosa and Pseudotsuga menziesii at 33 sites that burned between 1992 and 2007, by aging seedlings at the root-shoot boundary. We also measured radial growth in adult trees from 12 additional sites that burned between 1900 and 1990. To quantify the relationship between climate and regeneration, we characterized seasonal climate before, during, and after recruitment pulses using superposed epoch analysis. To quantify growth sensitivity to climate, we performed moving regression analysis for each species and for juvenile and adult life stages. Climatic conditions favoring regeneration and tree growth differed between species. Water deficit and temperature were significantly lower than average during recruitment pulses of ponderosa pine, suggesting that germination-year climate limits regeneration. Growing degree days were significantly higher than average during years with Douglas-fir recruitment pulses, but water deficit was significantly lower one year following pulses, suggesting moisture sensitivity in two-year-old seedlings. Growth was also sensitive to water deficit, but effects varied between life stages, species, and through time, with juvenile ponderosa pine growth more sensitive to climate than adult growth and juvenile Douglas-fir growth. Increasing water deficit corresponded with reduced adult growth of both species. Increases in maximum temperature and water deficit corresponded with increases in juvenile growth of both species in the early 20th century but strong reductions in growth for juvenile ponderosa pine in recent decades. Changing sensitivity of growth to climate suggests that increased temperature and water deficit may be pushing these species towards the edge of their climatic tolerances. Our study demonstrates increased vulnerability of dry mixed-conifer forests to post-fire regeneration failures and decreased growth as temperatures and drought increase. Shifts towards unfavorable conditions for regeneration and juvenile growth may alter the composition and resilience of low-elevation forests to future climate and fire activity.

Data from: Reconstructing changes in the genotype, phenotype, and climatic niche of an introduced species

An introduced species must contend with enormous environmental variation in its introduced range. In this study, we use niche models and ordination analyses to reconstruct changes in genotype, phenotype, and climatic niche of Johnsongrass (Sorghum halepense), which is regarded as one of the world's most threatening invasive plants. In the United States, Johnsongrass has rapidly evolved within- and among-population genetic diversity; our results show that genetic differentiation in expanding Johnsongrass populations has resulted in phenotypic variation that is consistent with habitat and climatic variation encountered during its expansion. Moreover, Johnsongrass expanded from agricultural to non-agricultural habitat, and now, despite occupying overlapping ranges, extant agricultural and non-agricultural populations are genetically and phenotypically distinct and manifest different plastic responses when encountering environmental variation. Non-agricultural accessions are broadly distributed in climatic and geographic space and their fitness traits demonstrate plastic responses to common garden conditions that are consistent with local specialization. In contrast, agricultural accessions demonstrate "general purpose" plastic responses and have more restricted climatic niches and geographic distributions. They also grow much larger than non-agricultural accessions. If these differences are adaptive, our results suggest that adaptation to local habitat variation plays a crucial role in the ecology of this invader. Further, its success relates to its ability to succeed on dual fronts, by responding simultaneously to habitat and climate variability and by capitalizing on differential responses to these factors during its range expansion.

opencc-zeroDec 2016View details →

Data from: Shifts in hatch dates do not provide pied flycatchers with a rapid ontogenetic route to adjust offspring time schedules to climate change

1. Environments change rapidly, and it is unclear whether organisms with complex life-styles, such as avian migrants, are able to adjust sufficiently. For understanding human impacts on ecosystem functioning, it is crucial to understand how well, and by which mechanisms species are able to adapt. 2. To improve the understanding of migrants' ability to adjust their annual timing to climate change, we investigated ontogenetic hatch date effects on adult spring migration timing and female egg laying dates. We experimentally delayed hatch dates of pied flycatchers Ficedula hypoleuca by one week in three breeding seasons by delaying incubation onset. We investigate if natural and experimental (shifts in) hatch date affected timing of recruiting individuals up to at least three years after the manipulation. 3. Spring arrival dates were positively correlated to natural variation in hatch dates in three of the five years considered, but no such effects were found in egg laying. Experiments showed that delayed hatching resulted in delayed arrival and laying only in one-year old and not in older birds. These effects were mostly observed during one of the study years. 4. The discrepancy between experimental and natural hatch date effects indicate that a causal hatch date effect is not generally responsible for the correlation between hatch date and timing during adulthood. Instead, we propose that natural hatch date effects on spring arrival arise from genetic variation in migration schedules, while delays in hatching induced carry-over effects on arrival and laying dates in offspring (e.g. the experimental effect in 2010). Strong support for year-specific expression of hatch date and delay effects on time schedules imply that trait-variation can be easily obscured. The latter may explain the lack of hatch date effects on female egg laying. 5. Our results imply that plasticity in breeding phenology does not provide pied flycatchers with a non-genetic inheritance route to rapidly advance annual cycles. Instead, plasticity may rather masks (genetic) trait-variation for selection to act on, and thereby slow down micro-evolutionary adaptation to changing environments.

opencc-zeroJun 2019View details →

Data from: Seasonality in spatial distribution: climate and land use have contrasting effects on the species richness of breeding and wintering birds

Aim: Many studies have examined large-scale distributions of various taxa and their drivers, emphasizing the importance of climate, topography, and land-use. Most studies have dealt with distributions over a single season or annually without considering seasonality. However, animal distributions and their drivers can differ among seasons because many animals migrate to suitable climates and areas with abundant prey resources. We aim to clarify seasonality in bird distributions and their drivers. Location: Japan. Methods: We examined the effects of climate (annual mean temperature, snow depth), topography (elevation), and land use (extent of surrounding habitat) on bird species richness, in the breeding and wintering seasons separately, using nationwide data (254 forest and 43 grassland sites, respectively). We separately analyzed the species richness of all species, residents, short-, and long-distance migrants in forests and grasslands. Results: In the breeding season, the annual mean temperature negatively affected all groups (except for forest and grassland residents), and the extent of surrounding habitat positively affected many groups. By contrast, in the wintering season, temperature positively affected all groups (except for forest residents), and the extent of surrounding habitat positively affected only grassland long-distance migrants. In both seasons, the species richness of forest and grassland residents was high in regions of moderate and high temperature, respectively. Moreover, snow depth negatively affected all forest groups in the wintering season. Mapping expected species richness suggested that regions with different climates served as habitats for different groups during different seasons. Main conclusions: All regions were important bird habitats depending on the season, reflecting the contrasting effects of temperature across seasons. In the breeding season, surrounding land-use was also an important driver. To understand the seasonal role that each region and environment plays in maintaining species/communities, a large-scale study considering both environmental seasonality and species distribution is needed.

Data from: Functional mismatch in a bumble bee pollination mutualism under climate change

Ecological partnerships, or mutualisms, are globally widespread, sustaining agriculture and biodiversity. Mutualisms evolve through the matching of functional traits between partners, such as tongue length of pollinators and flower tube depth of plants. Long-tongued pollinators specialize on flowers with deep corolla tubes, whereas shorter-tongued pollinators generalize across tube lengths. Losses of functional guilds because of shifts in global climate may disrupt mutualisms and threaten partner species. We found that in two alpine bumble bee species, decreases in tongue length have evolved over 40 years. Co-occurring flowers have not become shallower, nor are small-flowered plants more prolific. We argue that declining floral resources because of warmer summers have favored generalist foraging, leading to a mismatch between shorter-tongued bees and the longer-tubed plants they once pollinated.