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1.
Variation in bumble bee color patterns is well‐documented within and between species. Identifying the genetic mechanisms underlying such variation may be useful in revealing evolutionary forces shaping rapid phenotypic diversification. The widespread North American species Bombus bifarius exhibits regional variation in abdominal color forms, ranging from red‐banded to black‐banded phenotypes and including geographically and phenotypically intermediate forms. Identifying genomic regions linked to this variation has been complicated by strong, near species level, genome‐wide differentiation between red‐ and black‐banded forms. Here, we instead focus on the closely related black‐banded and intermediate forms that both belong to the subspecies B. bifarius nearcticus. We analyze an RNA sequencing (RNAseq) data set and identify a cluster of single nucleotide polymorphisms (SNPs) within one gene, Xanthine dehydrogenase/oxidase‐like, that exhibit highly unusual differentiation compared to the rest of the sequenced genome. Homologs of this gene contribute to pigmentation in other insects, and results thus represent a strong candidate for investigating the genetic basis of pigment variation in B. bifarius and other bumble bee mimicry complexes. 相似文献
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Shane C. Campbell‐Staton Anna Bare Jonathan B. Losos Scott V. Edwards Zachary A. Cheviron 《Molecular ecology》2018,27(9):2243-2255
Understanding the mechanisms that produce variation in thermal performance is a key component to investigating climatic effects on evolution and adaptation. However, disentangling the effects of local adaptation and phenotypic plasticity in shaping patterns of geographic variation in natural populations can prove challenging. Additionally, the physiological mechanisms that cause organismal dysfunction at extreme temperatures are still largely under debate. Using the green anole, Anolis carolinensis, we integrate measures of cold tolerance (CTmin), standard metabolic rate, heart size, blood lactate concentration and RNAseq data from liver tissue to investigate geographic variation in cold tolerance and its underlying mechanisms along a latitudinal cline. We found significant effects of thermal acclimation and latitude of origin on variation in cold tolerance. Increased cold tolerance correlates with decreased rates of oxygen consumption and blood lactate concentration (a proxy for oxygen limitation), suggesting elevated performance is associated with improved oxygen economy during cold exposure. Consistent with these results, co‐expression modules associated with blood lactate concentration are enriched for functions associated with blood circulation, coagulation and clotting. Expression of these modules correlates with thermal acclimation and latitude of origin. Our findings support the oxygen and capacity‐limited thermal tolerance hypothesis as a potential contributor to variation in reptilian cold tolerance. Moreover, differences in gene expression suggest regulation of the blood coagulation cascade may play an important role in reptilian cold tolerance and may be the target of natural selection in populations inhabiting colder environments. 相似文献
3.
Independent or parallel evolution of similar traits is key to understanding the genetics and limitations of adaptation. Adaptation from the same genetic changes in different populations defines parallel evolution. Such genetic changes can derive from standing ancestral variation or de novo mutations and excludes instances of adaptive introgression. In this issue of Molecular Ecology, Walden et al.(2020) investigate the scale of parallel climate adaptation from standing genetic variation between two North American Arabidopsis lyrata lineages, each formed by a distinct evolutionary history during the last glacial cycle. By identifying adaptive variants correlated with three ecologically significant climatic gradients, they show that instead of the same genetic variants or even genes, parallel evolution is only observed at the level of biological processes. The evolution of independent adaptive variants to climate in two genetically close lineages is explained by their different post‐glacial demographic histories. Separate glacial refugia and strong population bottlenecks were probably sufficient to change the landscape of shared allele frequencies, hindering the possibility of parallel evolution. 相似文献
4.
- Mammalian herbivores that consume both aquatic and terrestrial vegetation may have important but little understood effects on freshwater ecosystems. We assessed the effects of North American moose (Alces americanus) and/or beaver (Castor canadensis) on aquatic vegetation and abiotic conditions of three types of waterbodies.
- We established year‐round aquatic exclosures and reference plots in glacial lakes, dammed lakes and riverine ponds (n = 3 in each case). Within plots, we monitored parameters including dissolved oxygen, light, plant diversity and species‐specific plant biomass.
- The effects of herbivory by beaver and moose appear to be contingent upon abiotic and plant community characteristics. Exposure to herbivory decreased biomass in riverine ponds and dammed lakes but not in glacial lakes and decreased species richness in riverine ponds and glacial lakes but not in dammed lakes. Changes in macrophyte species diversity correlated with exposure to herbivory only in glacial lakes. Disaggregating the effects of herbivory according to abiotic conditions and plant community characteristics revealed outcomes that are not detectable when results are aggregated.
- In some catchments, the response of the aquatic plant community to beaver and moose herbivory may substantially differ from the response of the surrounding terrestrial plant community. Five of the six waterbodies created by beavers (dammed lakes and riverine ponds) maintained >80% macrophyte cover, despite seasonal reduction in biomass by both moose and beaver. Herbivores appear to cause a short‐term reduction in plant biomass in dammed lakes, resulting in greater light availability, without depleting biomass over a number of years.
5.
K. Aparna T. Nepolean R. K. Srivastsava J. Kholová V. Rajaram S. Kumar B. Rekha S. Senthilvel C.T. Hash V. Vadez 《Plant biology (Stuttgart, Germany)》2015,17(5):1073-1084
There is substantial genetic variation for drought adaption in pearl millet in terms of traits controlling plant water use. It is important to understand genomic regions responsible for these traits. Here, F7 recombinant inbred lines were used to identify quantitative trait loci (QTL) and allelic interactions for traits affecting plant water use, and their relevance is discussed for crop productivity in water‐limited environments. Four QTL contributed to increased transpiration rate under high vapour pressure deficit (VPD) conditions, all with alleles from drought‐sensitive parent ICMB 841. Of these four QTL, a major QTL (35.7%) was mapped on linkage group (LG) 6. The alleles for 863B at this QTL decreased transpiration rate and this QTL co‐mapped to a previously detected LG 6 QTL, with alleles from 863B for grain weight and panicle harvest index across severe terminal drought stress environments. This provided additional support for a link between water saving from a lower transpiration rate under high VPD and drought tolerance. 863B alleles in this same genomic region also increased shoot weight, leaf area and total transpiration under well‐watered conditions. One unexpected outcome was reduced transpiration under high VPD (15%) from the interaction of two alleles for high VPD transpiration (LG 6 (B), 40.7) and specific leaf mass and biomass (LG 7 (A), 35.3), (A, allele from ICMB 841, B, allele from 863B, marker position). The LG 6 QTL appears to combine alleles for growth potential, beneficial for non‐stress conditions, and for saving water under high evaporative demand, beneficial under stressful conditions. Mapping QTL for water‐use traits, and assessing their interactions offers considerable potential for improving pearl millet adaptation to specific stress conditions through physiology‐informed marker‐assisted selection. 相似文献
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Ellen Cheng Karen E. Hodges José Melo‐Ferreira Paulo C. Alves L. Scott Mills 《Molecular ecology》2014,23(12):2929-2942
With climate warming, the ranges of many boreal species are expected to shift northward and to fragment in southern peripheral ranges. To understand the conservation implications of losing southern populations, we examined range‐wide genetic diversity of the snowshoe hare (Lepus americanus), an important prey species that drives boreal ecosystem dynamics. We analysed microsatellite (8 loci) and mitochondrial DNA sequence (cytochrome b and control region) variation in almost 1000 snowshoe hares. A hierarchical structure analysis of the microsatellite data suggests initial subdivision in two groups, Boreal and southwestern. The southwestern group further splits into Greater Pacific Northwest and U.S. Rockies. The genealogical information retrieved from mtDNA is congruent with the three highly differentiated and divergent groups of snowshoe hares. These groups can correspond with evolutionarily significant units that might have evolved in separate refugia south and east of the Pleistocene ice sheets. Genetic diversity was highest at mid‐latitudes of the species' range, and genetic uniqueness was greatest in southern populations, consistent with substructuring inferred from both mtDNA and microsatellite analyses at finer levels of analysis. Surprisingly, snowshoe hares in the Greater Pacific Northwest mtDNA lineage were more closely related to black‐tailed jackrabbits (Lepus californicus) than to other snowshoe hares, which may result from secondary introgression or shared ancestral polymorphism. Given the genetic distinctiveness of southern populations and minimal gene flow with their northern neighbours, fragmentation and loss of southern boreal habitats could mean loss of many unique alleles and reduced evolutionary potential. 相似文献
8.
Understanding the processes that control deep soil carbon (C) dynamics and accumulation is of key importance, given the relevance of soil organic matter (SOM) as a vast C pool and climate change buffer. Methodological constraints of measuring SOM decomposition in the field prevent the addressing of real‐time rhizosphere effects that regulate nutrient cycling and SOM decomposition. An invasive lineage of Phragmites australis roots deeper than native vegetation (Schoenoplectus americanus and Spartina patens) in coastal marshes of North America and has potential to dramatically alter C cycling and accumulation in these ecosystems. To evaluate the effect of deep rooting on SOM decomposition we designed a mesocosm experiment that differentiates between plant‐derived, surface SOM‐derived (0–40 cm, active root zone of native marsh vegetation), and deep SOM‐derived mineralization (40–80 cm, below active root zone of native vegetation). We found invasive P. australis allocated the highest proportion of roots in deeper soils, differing significantly from the native vegetation in root : shoot ratio and belowground biomass allocation. About half of the CO2 produced came from plant tissue mineralization in invasive and native communities; the rest of the CO2 was produced from SOM mineralization (priming). Under P. australis, 35% of the CO2 was produced from deep SOM priming and 9% from surface SOM. In the native community, 9% was produced from deep SOM priming and 44% from surface SOM. SOM priming in the native community was proportional to belowground biomass, while P. australis showed much higher priming with less belowground biomass. If P. australis deep rooting favors the decomposition of deep‐buried SOM accumulated under native vegetation, P. australis invasion into a wetland could fundamentally change SOM dynamics and lead to the loss of the C pool that was previously sequestered at depth under the native vegetation, thereby altering the function of a wetland as a long‐term C sink. 相似文献
9.
Lisa M. Schile John C. Callaway Katharine N. Suding N. Maggi Kelly 《Ecology and evolution》2017,7(4):1276-1285
Climate change impacts, such as accelerated sea‐level rise, will affect stress gradients, yet impacts on competition/stress tolerance trade‐offs and shifts in distributions are unclear. Ecosystems with strong stress gradients, such as estuaries, allow for space‐for‐time substitutions of stress factors and can give insight into future climate‐related shifts in both resource and nonresource stresses. We tested the stress gradient hypothesis and examined the effect of increased inundation stress and biotic interactions on growth and survival of two congeneric wetland sedges, Schoenoplectus acutus and Schoenoplectus americanus. We simulated sea‐level rise across existing marsh elevations and those not currently found to reflect potential future sea‐level rise conditions in two tidal wetlands differing in salinity. Plants were grown individually and together at five tidal elevations, the lowest simulating an 80‐cm increase in sea level, and harvested to assess differences in biomass after one growing season. Inundation time, salinity, sulfides, and redox potential were measured concurrently. As predicted, increasing inundation reduced biomass of the species commonly found at higher marsh elevations, with little effect on the species found along channel margins. The presence of neighbors reduced total biomass of both species, particularly at the highest elevation; facilitation did not occur at any elevation. Contrary to predictions, we documented the competitive superiority of the stress tolerator under increased inundation, which was not predicted by the stress gradient hypothesis. Multifactor manipulation experiments addressing plant response to accelerated climate change are integral to creating a more realistic, valuable, and needed assessment of potential ecosystem response. Our results point to the important and unpredicted synergies between physical stressors, which are predicted to increase in intensity with climate change, and competitive forces on biomass as stresses increase. 相似文献
10.
The European green crab (Carcinus maenas) is a newly invasive species in Newfoundland, where it has likely been present for ≤15 years. The green crab has been found in stomach contents of American lobster (Homarus americanus) in New England and Nova Scotia, Canada, but predation on this species has not yet been quantified in Newfoundland. We conducted feeding experiments to determine whether lobsters from Newfoundland were as likely as those from Nova Scotia (which have coexisted with green crabs for >60 years) to recognize and prey upon this new species. We also performed experiments to determine whether green crabs reach a size refuge from predation and whether factors including starvation, availability of alternate food sources, or habitat complexity would influence the probability of lobster attacking or feeding on green crabs. In our trials, lobster origin had no significant effect on crab predation; lobsters, irrespective of origin, were more likely to consume small (<40 mm carapace width [CW]) and medium (40–65 mm CW) crabs than larger (>65 mm CW) ones. Nevertheless, even small lobsters (73–76 mm carapace length, 300 g) were able to kill and consume the largest green crabs (78 mm CW, 100 g). Green crabs were less likely to be attacked or eaten when an alternative food source was present, suggesting that the lobsters were preying on the crabs, rather than simply killing them in a dispute over territory. The addition of a shelter provided a refuge for the green crabs; however, the crabs were only able to avoid being injured or eaten if this shelter was structurally complex. The green crab is slowly spreading westward around the island of Newfoundland, and so its long‐term effects, interactions with other organisms, and contribution to the diet of Newfoundland lobsters remain to be seen. 相似文献
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Emily J. Howells Andrew G. Bauman Grace O. Vaughan Benjamin C. C. Hume Christian R. Voolstra John A. Burt 《Molecular ecology》2020,29(5):899-911
Reef‐building corals are at risk of extinction from ocean warming. While some corals can enhance their thermal limits by associating with dinoflagellate photosymbionts of superior stress tolerance, the extent to which symbiont communities will reorganize under increased warming pressure remains unclear. Here we show that corals in the hottest reefs in the world in the Persian Gulf maintain associations with the same symbionts across 1.5 years despite extreme seasonal warming and acute heat stress (≥35°C). Persian Gulf corals predominantly associated with Cladocopium (clade C) and most also hosted Symbiodinium (clade A) and/or Durusdinium (clade D). This is in contrast to the neighbouring and milder Oman Sea, where corals associated with Durusdinium and only a minority hosted background levels of Cladocopium. During acute heat stress, the higher prevalence of Symbiodinium and Durusdinium in bleached versus nonbleached Persian Gulf corals indicates that genotypes of these background genera did not confer bleaching resistance. Within symbiont genera, the majority of ITS2 rDNA type profiles were unique to their respective coral species, confirming the existence of host‐specific symbiont lineages. Notably, further differentiation among Persian Gulf sites demonstrates that symbiont populations are either isolated or specialized over tens to hundreds of kilometres. Thermal tolerance across coral species was associated with the prevalence of a single ITS2 intragenomic sequence variant (C3gulf), definitive of the Cladocopium thermophilum group. The abundance of C3gulf was highest in bleaching‐resistant corals and at warmer sites, potentially indicating a specific symbiont genotype (or set of genotypes) that may play a role in thermal tolerance that warrants further investigation. Together, our findings indicate that co‐evolution of host–Symbiodiniaceae partnerships favours fidelity rather than flexibility in extreme environments and under future warming. 相似文献
13.
Matthew A. Mumma Chris Zieminski Todd K. Fuller Shane P. Mahoney Lisette P. Waits 《Molecular ecology resources》2015,15(5):1133-1144
Monitoring large carnivores is difficult because of intrinsically low densities and can be dangerous if physical capture is required. Noninvasive genetic sampling (NGS) is a safe and cost‐effective alternative to physical capture. We evaluated the utility of two NGS methods (scat detection dogs and hair sampling) to obtain genetic samples for abundance estimation of coyotes, black bears and Canada lynx in three areas of Newfoundland, Canada. We calculated abundance estimates using program capwire , compared sampling costs, and the cost/sample for each method relative to species and study site, and performed simulations to determine the sampling intensity necessary to achieve abundance estimates with coefficients of variation (CV) of <10%. Scat sampling was effective for both coyotes and bears and hair snags effectively sampled bears in two of three study sites. Rub pads were ineffective in sampling coyotes and lynx. The precision of abundance estimates was dependent upon the number of captures/individual. Our simulations suggested that ~3.4 captures/individual will result in a < 10% CV for abundance estimates when populations are small (23–39), but fewer captures/individual may be sufficient for larger populations. We found scat sampling was more cost‐effective for sampling multiple species, but suggest that hair sampling may be less expensive at study sites with limited road access for bears. Given the dependence of sampling scheme on species and study site, the optimal sampling scheme is likely to be study‐specific warranting pilot studies in most circumstances. 相似文献
14.
Franziska Günter Michaël Beaulieu Kasimir F. Freiberg Ines Welzel Nia Toshkova Anamarija
agar Tatjana Sim
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Klaus Fischer 《Journal of evolutionary biology》2020,33(7):920-929
Understanding how organisms adapt to complex environments is a central goal of evolutionary biology and ecology. This issue is of special interest in the current era of rapidly changing climatic conditions. Here, we investigate clinal variation and plastic responses in life history, morphology and physiology in the butterfly Pieris napi along a pan‐European gradient by exposing butterflies raised in captivity to different temperatures. We found clinal variation in body size, growth rates and concomitant development time, wing aspect ratio, wing melanization and heat tolerance. Individuals from warmer environments were more heat‐tolerant and had less melanised wings and a shorter development, but still they were larger than individuals from cooler environments. These findings suggest selection for rapid growth in the warmth and for wing melanization in the cold, and thus fine‐tuned genetic adaptation to local climates. Irrespective of the origin of butterflies, the effects of higher developmental temperature were largely as expected, speeding up development; reducing body size, potential metabolic activity and wing melanization; while increasing heat tolerance. At least in part, these patterns likely reflect adaptive phenotypic plasticity. In summary, our study revealed pronounced plastic and genetic responses, which may indicate high adaptive capacities in our study organism. Whether this may help such species, though, to deal with current climate change needs further investigation, as clinal patterns have typically evolved over long periods. 相似文献
15.
Sara Marin Anaïs Gibert Juliette Archambeau Vincent Bonhomme Mylne Lascoste Benoit Pujol 《Molecular ecology》2020,29(16):3010-3021
Phenotypic divergence among natural populations can be explained by natural selection or by neutral processes such as drift. Many examples in the literature compare putatively neutral (FST) and quantitative genetic (QST) differentiation in multiple populations to assess their evolutionary signature and identify candidate traits involved with local adaptation. Investigating these signatures in closely related or recently diversified species has the potential to shed light on the divergence processes acting at the interspecific level. Here, we conducted this comparison in two subspecies of snapdragon plants (eight populations of Antirrhinum majus pseudomajus and five populations of A. m. striatum) in a common garden experiment. We also tested whether altitude was involved with population phenotypic divergence. Our results identified candidate phenological and morphological traits involved with local adaptation. Most of these traits were identified in one subspecies but not the other. Phenotypic divergence increased with altitude for a few biomass‐related traits, but only in A. m. striatum. These traits therefore potentially reflect A. m. striatum adaptation to altitude. Our findings imply that adaptive processes potentially differ at the scale of A. majus subspecies. 相似文献
16.
Jenni Kesniemi Toni Jernfors Anton Lavrinienko Kati Kivisaari Mikko Kiljunen Tapio Mappes Phillip C. Watts 《Molecular ecology》2019,28(20):4620-4635
Wildlife inhabiting environments contaminated by radionuclides face putative detrimental effects of exposure to ionizing radiation, with biomarkers such as an increase in DNA damage and/or oxidative stress commonly associated with radiation exposure. To examine the effects of exposure to radiation on gene expression in wildlife, we conducted a de novo RNA sequencing study of liver and spleen tissues from a rodent, the bank vole Myodes glareolus. Bank voles were collected from the Chernobyl Exclusion Zone (CEZ), where animals were exposed to elevated levels of radionuclides, and from uncontaminated areas near Kyiv, Ukraine. Counter to expectations, we did not observe a strong DNA damage response in animals exposed to radionuclides, although some signs of oxidative stress were identified. Rather, exposure to environmental radionuclides was associated with upregulation of genes involved in lipid metabolism and fatty acid oxidation in the livers – an apparent shift in energy metabolism. Moreover, using stable isotope analysis, we identified that fur from bank voles inhabiting the CEZ had enriched isotope values of nitrogen: such an increase is consistent with increased fatty acid metabolism, but also could arise from a difference in diet or habitat between the CEZ and elsewhere. In livers and spleens, voles inhabiting the CEZ were characterized by immunosuppression, such as impaired antigen processing, and activation of leucocytes involved in inflammatory responses. In conclusion, exposure to low dose environmental radiation impacts pathways associated with immunity and lipid metabolism, potentially as a stress‐induced coping mechanism. 相似文献
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Jacqueline Jerney Sanna Suikkanen Elin Lindehoff Anke Kremp 《Ecology and evolution》2019,9(8):4443-4451
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Chuan Yan Nils Chr. Stenseth Charles J. Krebs Zhibin Zhang 《Global Change Biology》2013,19(11):3263-3271
The classic 10‐year population cycle of snowshoe hares (Lepus americanus, Erxleben 1777) and Canada lynx (Lynx canadensis, Kerr 1792) in the boreal forests of North America has drawn much attention from both population and community ecologists worldwide; however, the ecological mechanisms driving the 10‐year cyclic dynamic pattern are not fully revealed yet. In this study, by the use of historic fur harvest data, we constructed a series of generalized additive models to study the effects of density dependence, predation, and climate (both global climate indices of North Atlantic Oscillation index (NAO), Southern Oscillation index (SOI) and northern hemispheric temperature (NHT) and local weather data including temperature, rainfall, and snow). We identified several key pathways from global and local climate to lynx with various time lags: rainfall shows a negative, and snow shows a positive effect on lynx; NHT and NAO negatively affect lynx through their positive effect on rainfall and negative effect on snow; SOI positively affects lynx through its negative effect on rainfall. Direct or delayed density dependency effects, the prey effect of hare on lynx and a 2‐year delayed negative effect of lynx on hare (defined as asymmetric predation) were found. The simulated population dynamics is well fitted to the observed long‐term fluctuations of hare and lynx populations. Through simulation, we find density dependency and asymmetric predation, only producing damped oscillation, are necessary but not sufficient factors in causing the observed 10‐year cycles; while extrinsic climate factors are important in producing and modifying the sustained cycles. Two recent population declines of lynx (1940–1955 and after 1980) were likely caused by ongoing climate warming indirectly. Our results provide an alternative explanation to the mechanism of the 10‐year cycles, and there is a need for further investigation on links between disappearance of population cycles and global warming in hare–lynx system. 相似文献
20.
J. Adam Langley Thomas J. Mozdzer Katherine A. Shepard Shannon B. Hagerty J. Patrick Megonigal 《Global Change Biology》2013,19(5):1495-1503
Elevated CO2 and nitrogen (N) addition directly affect plant productivity and the mechanisms that allow tidal marshes to maintain a constant elevation relative to sea level, but it remains unknown how these global change drivers modify marsh plant response to sea level rise. Here we manipulated factorial combinations of CO2 concentration (two levels), N availability (two levels) and relative sea level (six levels) using in situ mesocosms containing a tidal marsh community composed of a sedge, Schoenoplectus americanus, and a grass, Spartina patens. Our objective is to determine, if elevated CO2 and N alter the growth and persistence of these plants in coastal ecosystems facing rising sea levels. After two growing seasons, we found that N addition enhanced plant growth particularly at sea levels where plants were most stressed by flooding (114% stimulation in the + 10 cm treatment), and N effects were generally larger in combination with elevated CO2 (288% stimulation). N fertilization shifted the optimal productivity of S. patens to a higher sea level, but did not confer S. patens an enhanced ability to tolerate sea level rise. S. americanus responded strongly to N only in the higher sea level treatments that excluded S. patens. Interestingly, addition of N, which has been suggested to accelerate marsh loss, may afford some marsh plants, such as the widespread sedge, S. americanus, the enhanced ability to tolerate inundation. However, if chronic N pollution reduces the availability of propagules of S. americanus or other flood‐tolerant species on the landscape scale, this shift in species dominance could render tidal marshes more susceptible to marsh collapse. 相似文献