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1.
- Ecological niche modelling is a technique used to estimate potential distributions of invasive species based on available occurrence data and associated environmental conditions. Maximum entropy (Maxent) is a powerful method for ecological niche modelling and yet has only rarely been applied to aquatic species.
- Here we applied Maxent to estimate the potential distribution of the invasive Chinese mystery snail (Cipangopaludina chinesis) in Wisconsin and analysed several methodological issues associated with using Maxent for lentic species.
- To generate Maxent estimates of the potential distribution of C. chinesis, we used presence records from 292 lakes, five spatially explicit climatic variables, and two lake‐specific environmental data sets (area, conductivity) from 7995 lakes. Our investigations included three aspects that could affect model prediction accuracy and transferability: (i) combining climate and lake variables into a single data set in two different ways, using each lake as a single observation and as a grid of 1 ha cells; (ii) varying the size of the background data set (locations without presences); and (iii) contrasting environmental conditions between locations with and without C. chinesis.
- The lake‐based model had higher accuracy than the grid‐based model, although both models had accuracy values indicative of good performance. Conductivity and lake area were important predictor variables for both models, but had higher contribution to the lake‐based model accuracy. Decreasing the background sample size minimally affected model accuracy and thus Maxent can be used even when background sampling does not meet the algorithm's default settings. Lastly, lakes that were environmentally dissimilar from lakes with known C. chinesis records were more likely to be predicted unsuitable by both grid‐based and lake‐based models.
- Overall, the models predicted high potential suitability across Wisconsin lakes for C. chinesis, especially in lakes ≥60 ha. Our study provides evidence that small or environmentally biased presence data sets may underestimate the number of environmentally suitable locations of invasive species.
2.
Lertluk Ngernsiri Wichian Piyajaraprasert Wijit Wisoram David John Merritt 《Acta zoologica》2015,96(3):312-318
The ovaries of female lac insects, Kerria chinensis Mahd (Sternorrhyncha: Coccoidea: Kerridae), at the last nymphal stage are composed of several balloon‐like clusters of cystocytes with different sizes. Each cluster consists of several clusters of cystocytes arranging in rosette forms. At the adult stage, the pair of ovaries consists of about 600 ovarioles of the telotrophic‐meroistic type. An unusual feature when considering most scale insects is that the lateral oviducts are highly branched, each with a number of short ovarioles. Each ovariole is subdivided into an anterior trophic chamber (tropharium) containing six or seven large trophocytes and a posterior vitellarium harbouring one oocyte which is connected with the trophic chamber via a nutritive cord. No terminal filament is present. Late‐stage adult females show synchronized development of the ovarioles, while in undernourished females, a small proportion of ovarioles proceed to maturity. 相似文献
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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
5.
Interspecific competition for shared resources should select for evolutionary divergence in resource use between competing species, termed character displacement. Many purported examples of character displacement exist, but few completely rule out alternative explanations. We reared genetically diverse populations of two species of bean beetles, Callosobruchus maculatus and Callosobruchus chinensis, in allopatry and sympatry on a mixture of adzuki beans and lentils, and assayed oviposition preference and other phenotypic traits after four, eight, and twelve generations of (co)evolution. C. maculatus specializes on adzuki beans; the generalist C. chinensis uses both beans. C. chinensis growing in allopatry emerged equally from both bean species. In sympatry, the two species competing strongly and coexisted via strong realized resource partitioning, with C. chinensis emerging almost exclusively from lentils and C. maculatus emerging almost exclusively from adzuki beans. However, oviposition preferences, larval survival traits, and larval development rates in both beetle species did not vary consistently between allopatric versus sympatric treatments. Rather, traits evolved in treatment‐independent fashion, with several traits exhibiting reversals in their evolutionary trajectories. For example, C. chinensis initially evolved a slower egg‐to‐adult development rate on adzuki beans in both allopatry and sympatry, then subsequently evolved back toward the faster ancestral development rate. Lack of character displacement is consistent with a previous similar experiment in bean beetles and may reflect lack of evolutionary trade‐offs in resource use. However, evolutionary reversals were unexpected and remain unexplained. Together with other empirical and theoretical work, our results illustrate the stringency of the conditions for character displacement. 相似文献
6.
《化学与生物多样性》2018,15(2)
Phytochmical investigation of roots of Actinidia chinensisPlanch . led to the isolation triterpenoids 1 – 16 , including a new compound 2α,3α,23,24‐tetrahydroxyursa‐12,20(30)‐dien‐28‐oic acid ( 1 ). Their structures were identified on the basis of spectroscopic analysis, including 1D‐ and 2D‐NMR, HR‐ESI mass spectrometry, and by comparison with the literatures. The cytotoxicities of triterpenoids 1 – 16 against a panel of cultured human cancer cell lines (HepG2, A549, MCF‐7, SK‐OV‐3, and HeLa) were evaluated. The new compound 1 exhibited moderate antitumor activities with IC50 values of 19.62 ± 0.81, 18.86 ± 1.56, 45.94 ± 3.62, 62.41 ± 2.29, and 28.74 ± 1.07 μm , respectively. The experiment data might be available to explain the use of roots of A. chinensis to treat various cancers in traditional Chinese medicine. 相似文献
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Frugivores with disparate foraging behavior are considered to vary in their seed dispersal effectiveness (SDE). Measured SDEs for gibbons and macaques for a ‘primate‐fruit’ were comparable despite the different foraging and movement behavior of the primates. This could help facilitate fruit trait convergence in diverse fruit–frugivore networks. 相似文献
9.
Robert R. Fitak Elmira Mohandesan Jukka Corander Pamela A. Burger 《Molecular ecology resources》2016,16(1):314-324
The single‐humped dromedary (Camelus dromedarius) is the most numerous and widespread of domestic camel species and is a significant source of meat, milk, wool, transportation and sport for millions of people. Dromedaries are particularly well adapted to hot, desert conditions and harbour a variety of biological and physiological characteristics with evolutionary, economic and medical importance. To understand the genetic basis of these traits, an extensive resource of genomic variation is required. In this study, we assembled at 65× coverage, a 2.06 Gb draft genome of a female dromedary whose ancestry can be traced to an isolated population from the Canary Islands. We annotated 21 167 protein‐coding genes and estimated ~33.7% of the genome to be repetitive. A comparison with the recently published draft genome of an Arabian dromedary resulted in 1.91 Gb of aligned sequence with a divergence of 0.095%. An evaluation of our genome with the reference revealed that our assembly contains more error‐free bases (91.2%) and fewer scaffolding errors. We identified ~1.4 million single‐nucleotide polymorphisms with a mean density of 0.71 × 10?3 per base. An analysis of demographic history indicated that changes in effective population size corresponded with recent glacial epochs. Our de novo assembly provides a useful resource of genomic variation for future studies of the camel's adaptations to arid environments and economically important traits. Furthermore, these results suggest that draft genome assemblies constructed with only two differently sized sequencing libraries can be comparable to those sequenced using additional library sizes, highlighting that additional resources might be better placed in technologies alternative to short‐read sequencing to physically anchor scaffolds to genome maps. 相似文献
10.
Volodymyr Radchuk Rajiv Sharma Elena Potokina Ruslana Radchuk Diana Weier Eberhard Munz Miriam Schreiber Martin Mascher Nils Stein Thomas Wicker Benjamin Kilian Ljudmilla Borisjuk 《The Plant journal : for cell and molecular biology》2019,98(6):961-974
Phylogenetically related groups of species contain lineage‐specific genes that exhibit no sequence similarity to any genes outside the lineage. We describe here that the Jekyll gene, required for sexual reproduction, exists in two much diverged allelic variants, Jek1 and Jek3. Despite low similarity, the Jek1 and Jek3 proteins share identical signal peptides, conserved cysteine positions and direct repeats. The Jek1/Jek3 sequences are located at the same chromosomal locus and inherited in a monogenic Mendelian fashion. Jek3 has a similar expression as Jek1 and complements the Jek1 function in Jek1‐deficient plants. Jek1 and Jek3 allelic variants were almost equally distributed in a collection of 485 wild and domesticated barley accessions. All domesticated barleys harboring the Jek1 allele belong to single haplotype J1‐H1 indicating a genetic bottleneck during domestication. Domesticated barleys harboring the Jek3 allele consisted of three haplotypes. Jekyll‐like sequences were found only in species of the closely related tribes Bromeae and Triticeae but not in other Poaceae. Non‐invasive magnetic resonance imaging revealed intrinsic grain structure in Triticeae and Bromeae, associated with the Jekyll function. The emergence of Jekyll suggests its role in the separation of the Bromeae and Triticeae lineages within the Poaceae and identifies the Jekyll genes as lineage‐specific. 相似文献
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The two independent domestication events in the genus Oryza that led to African and Asian rice offer an extremely useful system for studying the genetic basis of parallel evolution. This system is also characterized by parallel de‐domestication events, with two genetically distinct weedy rice biotypes in the US derived from the Asian domesticate. One important trait that has been altered by rice domestication and de‐domestication is hull colour. The wild progenitors of the two cultivated rice species have predominantly black‐coloured hulls, as does one of the two U.S. weed biotypes; both cultivated species and one of the US weedy biotypes are characterized by straw‐coloured hulls. Using Black hull 4 (Bh4) as a hull colour candidate gene, we examined DNA sequence variation at this locus to study the parallel evolution of hull colour variation in the domesticated and weedy rice system. We find that independent Bh4‐coding mutations have arisen in African and Asian rice that are correlated with the straw hull phenotype, suggesting that the same gene is responsible for parallel trait evolution. For the U.S. weeds, Bh4 haplotype sequences support current hypotheses on the phylogenetic relationship between the two biotypes and domesticated Asian rice; straw hull weeds are most similar to indica crops, and black hull weeds are most similar to aus crops. Tests for selection indicate that Asian crops and straw hull weeds deviate from neutrality at this gene, suggesting possible selection on Bh4 during both rice domestication and de‐domestication. 相似文献
12.
Tengfei Liu Chao Fang Yanming Ma Yanting Shen Congcong Li Qing Li Min Wang Shulin Liu Jixiang Zhang Zhengkui Zhou Rui Yang Zheng Wang Zhixi Tian 《The Plant journal : for cell and molecular biology》2016,85(3):396-409
Although the selection of coding genes during plant domestication has been well studied, the evolution of MIRNA genes (MIRs) and the interaction between microRNAs (miRNAs) and their targets in this process are poorly understood. Here, we present a genome‐wide survey of the selection of MIRs and miRNA targets during soybean domestication and improvement. Our results suggest that, overall, MIRs have higher evolutionary rates than miRNA targets. Nonetheless, they do demonstrate certain similar evolutionary patterns during soybean domestication: MIRs and miRNA targets with high expression and duplication status, and with greater numbers of partners, exhibit lower nucleotide divergence than their counterparts without these characteristics, suggesting that expression level, duplication status, and miRNA–target interaction are essential for evolution of MIRs and miRNA targets. Further investigation revealed that miRNA–target pairs that are subjected to strong purifying selection have greater similarities than those that exhibited genetic diversity. Moreover, mediated by domestication and improvement, the similarities of a large number of miRNA–target pairs in cultivated soybean populations were increased compared to those in wild soybeans, whereas a small number of miRNA–target pairs exhibited decreased similarity, which may be associated with the adoption of particular domestication traits. Taken together, our results shed light on the co‐evolution of MIRs and miRNA targets during soybean domestication. 相似文献
13.
Interspecific resource competition is expected to select for divergence in resource use, weakening interspecific relative to intraspecific competition, thus promoting stable coexistence. More broadly, because interspecific competition reduces fitness, any mechanism of interspecific competition should generate selection favoring traits that weaken interspecific competition. However, species also can adapt to competition by increasing their competitive ability, potentially destabilizing coexistence. We reared two species of bean beetles, the specialist Callosobruchus maculatus and the generalist C. chinensis, in allopatry and sympatry on a mixture of adzuki beans and lentils, and assayed mutual invasibility after four, eight, and twelve generations of evolution. Contrary to the expectation that coevolution of competitors will weaken interspecific competition, the rate of mutual invasibility did not differ between sympatry and allopatry. Rather, the invasion rate of C. chinensis, but not C. maculatus, increased with duration of evolution, as C. chinensis adapted to lentils without experiencing reduced adaptation to adzuki beans, and regardless of the presence or absence of C. maculatus. Our results highlight that evolutionary responses to interspecific competition promote stable coexistence only under specific conditions that can be difficult to produce in practice. 相似文献
14.
Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected for increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity for plasticity in crop plants like barley (Hordeum vulgare). However, the effects of domestication on the evolution of root plasticity are essentially unknown. Using a split container approach, we examined the differences in root plasticity among three domestication levels of barley germplasm (wild, landrace, and cultivar) grown under different concentrations and distribution patterns of soil nutrients. Domestication level, nutrient concentration, and nutrient distribution interactively affected average root diameter; differential root allocation (within‐plant plasticity) was greatest in wild barley (Hordeum spontaneum), especially under low nutrient levels. Correlations of within‐plant root plasticity and plant size were most pronounced in modern cultivars under low‐nutrient conditions. Barley plants invested more resources to root systems when grown in low‐nutrient soils and allocated more roots to higher‐nutrient locations. Root plasticity in barley is scale dependent and varies with domestication level. Although wild barley harbors a greater capacity for within‐plant root plasticity than domesticated barley, cultivars exhibited the greatest capacity to translate within‐plant plasticity into increased plant size. 相似文献
15.
Plants depend upon both genetic differences and phenotypic plasticity to cope with environmental variation over different timescales. The spatial variation in foliar δ13C levels along a moisture gradient represents an overlay of genetic and plastic responses. We hypothesized that such a spatial variation would be more obvious than the variation arising purely from a plastic response to moisture change. Leymus chinensis and Stipa spp. were sampled from Inner Mongolia along a dry‐wet transect, and some of these species were transplanted to an area with a moisture gradient. For Stipa spp., the slope of foliar δ13C and mean annual precipitation along the transect was significantly steeper than that of foliar δ13C and mean annual precipitation after the watering treatment. For L. chinensis, there was a general decreasing trend in foliar δ13C under the different (increasing) watering levels; however, its populations showed an irregular relationship between foliar δ13C and moisture origin. Therefore, support for our hypothesis was obtained from Stipa spp., but not from L. chinensis. 相似文献
16.
Pavel Flegontov Vyacheslav Yurchenko Julius Lukeš 《The Journal of eukaryotic microbiology》2016,63(5):657-678
Comparison of the genomes of free‐living Bodo saltans and those of parasitic trypanosomatids reveals that the transition from a free‐living to a parasitic life style has resulted in the loss of approximately 50% of protein‐coding genes. Despite this dramatic reduction in genome size, B. saltans and trypanosomatids still share a significant number of common metabolic traits: glycosomes; a unique set of the pyrimidine biosynthetic pathway genes; an ATP‐PFK which is homologous to the bacterial PPi‐PFKs rather than to the canonical eukaryotic ATP‐PFKs; an alternative oxidase; three phosphoglycerate kinases and two GAPDH isoenzymes; a pyruvate kinase regulated by fructose‐2,6‐bisphosphate; trypanothione as a substitute for glutathione; synthesis of fatty acids via a unique set of elongase enzymes; and a mitochondrial acetate:succinate coenzyme A transferase. B. saltans has lost the capacity to synthesize ubiquinone. Among genes that are present in B. saltans and lost in all trypanosomatids are those involved in the degradation of mureine, tryptophan and lysine. Novel acquisitions of trypanosomatids are components of pentose sugar metabolism, pteridine reductase and bromodomain‐factor proteins. In addition, only the subfamily Leishmaniinae has acquired a gene for catalase and the capacity to convert diaminopimelic acid to lysine. 相似文献
17.
The taxonomy of the humpback dolphin genus Sousa has been controversial and unsettled for centuries, but recent work indicates that there are several valid species. A review of multiple lines of evidence from skeletal morphology, external morphology, coloration, molecular genetics, and biogeography, in combination provides strong support for the recognition of four species of Sousa. These include S. teuszii (Kükenthal, 1892), a species with uniform gray coloration and a prominent dorsal hump, which is found in the Atlantic Ocean off West Africa. The species S. plumbea (G. Cuvier, 1829) has similar external appearance to S. teuszii, but has a more pointed dorsal fin. It occurs in the Indian Ocean from South Africa to Myanmar (Burma). The original taxon, S. chinensis (Osbeck, 1765), is reserved for the species that has a larger dorsal fin with no prominent hump, and largely white adult coloration. It ranges from eastern India to central China and throughout Southeast Asia. Finally, we describe a new species of Sousa, the Australian humpback dolphin, which occurs in the waters of the Sahul Shelf from northern Australia to southern New Guinea. It has a lower dorsal fin, more extensive dark color on the body, and a dorsal “cape.” It is separated from the Indo‐Pacific humpback dolphin by a wide distributional gap that coincides with Wallace's Line. 相似文献
18.
Amanda A. Pierce Jacobus C. de Roode Leiling Tao 《Biological journal of the Linnean Society. Linnean Society of London》2016,119(1):194-200
Herbivores have evolved numerous behavioural and physiological adaptations to host plants; however, molecular adaptations are still poorly understood. One well‐studied case comprises the specialist insects that feed on cardenolide‐containing plants. Here, convergent molecular evolution in the Na+/K+‐ATPase results in a reduced sensitivity to cardenolides across four insect orders. Because different plant species and genotypes differ in toxicity, Na+/K+‐ATPase may be under differential selection from geographically varying host plants. We examined the α subunit of Na+/K+‐ATPase in monarch butterflies (Danaus plexippus) from six worldwide populations to test whether differences in their host plant chemistry result in local adaptation at the molecular level. Although our study revealed multiple synonymous changes, we did not find these to be population‐specific, nor did we identify nonsynonymous changes. Additionally, we compared the amino acid sequence of this subunit across 19 species. We identified two novel changes at sites 836 (K836N) and 840 (E840R) in the αM7‐αM8 regions in the genus Danaus. Although previous studies focused on the first two trans‐membrane domains, C‐terminal domains may also interact with cardenolides. These results reveal a lack of molecular evolution of Na+/K+‐ATPase at the population level, and call for additional attention regarding the C‐terminal regions of this important enzyme. 相似文献
19.
Xianjun Lai Lang Yan Yanli Lu James C. Schnable 《The Plant journal : for cell and molecular biology》2018,93(5):843-855
The domestication of diverse grain crops from wild grasses was a result of artificial selection for a suite of overlapping traits producing changes referred to in aggregate as ‘domestication syndrome’. Parallel phenotypic change can be accomplished by either selection on orthologous genes or selection on non‐orthologous genes with parallel phenotypic effects. To determine how often artificial selection for domestication traits in the grasses targeted orthologous genes, we employed resequencing data from wild and domesticated accessions of Zea (maize) and Sorghum (sorghum). Many ‘classic’ domestication genes identified through quantitative trait locus mapping in populations resulting from wild/domesticated crosses indeed show signatures of parallel selection in both maize and sorghum. However, the overall number of genes showing signatures of parallel selection in both species is not significantly different from that expected by chance. This suggests that while a small number of genes will extremely large phenotypic effects have been targeted repeatedly by artificial selection during domestication, the optimization part of domestication targeted small and largely non‐overlapping subsets of all possible genes which could produce equivalent phenotypic alterations. 相似文献
20.
Mohamed Ghalayini Melanie Magnan Sara Dion Ouassila Zatout Lucie Bourguignon Olivier Tenaillon Mathilde Lescat 《Molecular ecology》2019,28(19):4470-4485
In vitro experimental evolution has taught us many lessons on the molecular bases of adaptation. To move towards more natural settings, evolution in the mice gut has been successfully performed. Yet, these experiments suffered from the use of laboratory strains as well as the use of axenic or streptomycin‐treated mice to maintain the inoculated strains. To circumvent these limitations, we conducted a one‐year experimental evolution in vivo using a natural isolate of E. coli, strain 536, in conditions mimicking as much as possible natural environment with mother‐to‐offspring microbiota transmission. Mice were then distributed in 24 independent cages and separated into two different diets: a regular one (chow diet, CD) and high‐fat and high‐sugar one (Western Diet, WD). Genome sequences revealed an early and rapid selection during the breastfeeding period that selected the constitutive expression of the well‐characterized lactose operon. E. coli was lost significantly more in CD than WD; however, we could not detect any genomic signature of selection, nor any diet specificities during the later part of the experiments. The apparently neutral evolution presumably due to low population size maintained nevertheless at high frequency the early selected mutations affecting lactose regulation. The rapid loss of lactose operon regulation challenges the idea that plastic gene expression is both optimal and stable in the wild. 相似文献