scholarly journals Darwin’s naturalization hypothesis does not explain the spread of nonnative weed species naturalized in México

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5444
Author(s):  
Judith Sánchez-Blanco ◽  
Ernesto V. Vega-Peña ◽  
Francisco J. Espinosa-García
Keyword(s):  
Residence Time ◽  
Lag Phase ◽  
Herbarium Specimens ◽  
Weed Species ◽  
Species Groups ◽  
Biological Attributes ◽  
Darwin's Naturalization Hypothesis ◽  
Stochastic Events ◽  
Close Relatives ◽  
Darwin’S Naturalization Hypothesis

BackgroundDespite numerous tests of Darwin’s naturalization hypothesis (DNH) evidence for its support or rejection is still contradictory. We tested a DNH derived prediction stating that nonnative species (NNS) without native congeneric relatives (NCR) will spread to a greater number of localities than species with close relatives in the new range. This test controlled the effect of residence time (Rt) on the spread of NNS and used naturalized species beyond their lag phase to avoid the effect of stochastic events in the establishment and the lag phases that could obscure the NCR effects on NNS.MethodsWe compared the number of localities (spread) occupied by NNS with and without NCR using 13,977 herbarium records for 305 NNS of weeds. We regressed the number of localities occupied by NNSversus Rtto determine the effect of time on the spread of NNS. Then, we selected the species withRtgreater than the expected span of the lag phase, whose residuals were above and below the regression confidence limits; these NNS were classified as widespread (those occupying more localities than expected byRt) and limited-spread (those occupying fewer localities than expected). These sets were again subclassified into two groups: NNS with and without NCR at the genus level. The number of NNS with and without NCR was compared usingχ2tests and Spearman correlations between the residuals and the number of relatives. Then, we grouped the NNS using 34 biological attributes and five usages to identify the groups’ possible associations with spread and to test DNH. To identify species groups, we performed a nonmetric multidimensional scaling (NMDS) analysis and evaluated the influences of the number of relatives, localities, herbarium specimens,Rt, and residuals of regression. The Spearman correlation and the Mann–WhitneyUtest were used to determine if the DNH prediction was met. Additionally, we used the clustering objects on subsets of attributes (COSA) method to identify possible syndromes (sets of biological attributes and usages) associated to four groups of NNS useful to test DNH (those with and without NCR and those in more and fewer localities than expected byRt).ResultsResidence time explained 33% of the variation in localities occupied by nonnative trees and shrubs and 46% of the variation for herbs and subshrubs. The residuals of the regression for NNS were not associated with the number or presence of NCR. In each of the NMDS groups, the number of localities occupied by NNS with and without NCR did not significantly differ. The COSA analysis detected that only NNS with NCR in more and fewer localities than expected share biological attributes and usages, but they differ in their relative importance.DiscussionOur results suggest that DNH does not explain the spread of naturalized species in a highly heterogeneous country. Thus, the presence of NCR is not a useful characteristic in risk analyses for naturalized NNS.

Scale dependence in the phylogenetic relatedness of alien and native taxa

2020 ◽  
Vol 13 (5) ◽  
pp. 601-610
Author(s):  
Chris M McGrannachan ◽  
Gillis J Horner ◽  
Melodie A McGeoch
Keyword(s):  
Alien Species ◽  
Spatial Scale ◽  
Native Species ◽  
Spatial Scales ◽  
Pairwise Distance ◽  
Phylogenetic Structure ◽  
Phylogenetic Clustering ◽  
Phylogenetic Relatedness ◽  
Darwin's Naturalization Hypothesis ◽  
Darwin’S Naturalization Hypothesis

Abstract Aims Darwin’s naturalization hypothesis proposes that successfully established alien species are less closely related to native species due to differences in their ecological niches. Studies have provided support both for and against this hypothesis. One reason for this is the tendency for phylogenetic clustering between aliens and natives at broad spatial scales with overdispersion at fine scales. However, little is known about how the phylogenetic relatedness of alien species alters the phylogenetic structure of the communities they invade, and at which spatial scales effects may manifest. Here, we examine if invaded understorey plant communities, i.e. containing both native and alien taxa, are phylogenetically clustered or overdispersed, how relatedness changes with spatial scale and how aliens affect phylogenetic patterns in understorey communities. Methods Field surveys were conducted in dry forest understorey communities in south-east Australia at five spatial scales (1, 20, 500, 1500 and 4500 m2). Standardized effect sizes of two metrics were used to quantify phylogenetic relatedness between communities and their alien and native subcommunities, and to examine how phylogenetic patterns change with spatial scale: (i) mean pairwise distance and (ii) mean nearest taxon distance (MNTD). Important Findings Aliens were closely related to each other, and this relatedness tended to increase with scale. Native species and the full community exhibited either no clear pattern of relatedness with increasing spatial scale or were no different from random. At intermediate spatial scales (20–500 m2), the whole community tended towards random whereas the natives were strongly overdispersed and the alien subcommunity strongly clustered. This suggests that invasion by closely related aliens shifts community phylogenetic structure from overdispersed towards random. Aliens and natives were distantly related across spatial scales, supporting Darwin’s naturalization hypothesis, but only when phylogenetic distance was quantified as MNTD. Phylogenetic dissimilarity between aliens and natives increased with spatial scale, counter to expected patterns. Our findings suggest that the strong phylogenetic clustering of aliens is driven by human-mediated introductions involving closely related taxa that can establish and spread successfully. Unexpected scale-dependent patterns of phylogenetic relatedness may result from stochastic processes such as fire and dispersal events and suggest that competition and habitat filtering do not exclusively dominate phylogenetic relationships at fine and coarse spatial scales, respectively. Distinguishing between metrics that focus on different evolutionary depths is important, as different metrics can exhibit different scale-dependent patterns.

Effect of Ensiling and Rumen Digestion by Cattle on Weed Seed Viability

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 104-108 ◽  
Author(s):  
Robert E. Blackshaw ◽  
Lyle M. Rode
Keyword(s):  
Time Course ◽  
Seed Viability ◽  
Grass Species ◽  
Lag Phase ◽  
Rapid Decline ◽  
Weed Species ◽  
Embryo Viability ◽  
Seed Survival ◽  
Gradual Process ◽  
Broadleaf Species

Studies were conducted to determine the effect of ensiling and/or rumen digestion by cattle on the germination and viability of several common weed species. Seed survival of grass species subjected to ensiling and/or rumen digestion tended to be less than that of broadleaf species. Downy brome, foxtail barley, and barnyardgrass were nonviable after either ensiling for 8 weeks or rumen digestion for 24 h. Some green foxtail (17%) and wild oats (0 to 88%) seeds survived digestion in the rumen but were killed by the ensiling process. Varying percentages of seeds of kochia, redroot pigweed, common lambsquarters, wild buckwheat, round-leaved mallow, and field pennycress remained viable after ensiling (3 to 30%), rumen digestion (15 to 98%), and ensiling plus rumen digestion (2 to 19%). A time course study of rumen digestion indicated that loss of seed viability often was not a gradual process. With some species, there was an initial lag phase while degradation of the protective seed coat likely occurred, followed by a rapid decline in embryo viability. The diet fed to livestock appeared to affect viability losses caused by rumen digestion. Estimates of seed survival with varying rates of passage through the rumen due to differing ratios of grain to forage in the diet are presented.

Relating initial paraquat injury to final efficacy in selected weed species influenced by environmental conditions

2020 ◽  
pp. 1-10
Author(s):  
Nick T. Harre ◽  
Garth W. Duncan ◽  
Julie M. Young ◽  
Bryan G. Young
Keyword(s):  
Environmental Factors ◽  
Negative Relationship ◽  
Injury Rate ◽  
Time Of Day ◽  
Palmer Amaranth ◽  
Shoot Biomass ◽  
Lag Phase ◽  
Progression Rate ◽  
Weed Species ◽  
Time Of Application

Abstract Weed control of paraquat can be erratic and may be attributable to differing species sensitivity and/or environmental factors for which minor guidance is available on commercial labels. Therefore, the objectives of this research were to quantify selectivity of paraquat across select weed species and the influence of environmental factors. Experiments were performed under controlled conditions in the greenhouse and growth chamber. Compared with purple deadnettle (dose necessary to reduce shoot biomass by 50% = 39 g ai ha−1), waterhemp, Palmer amaranth, giant ragweed, and horseweed were 4.9, 3.3, 1.9, and 1.3 times more sensitive to paraquat, respectively. The injury progression rate over 3 d after treatment (DAT) was a more accurate predictor of final efficacy at 14 DAT than the lag phase until symptoms first appeared. For example, at the 17.5 g ha−1 dose, the injury rate of waterhemp and Palmer amaranth was, on average, 3.6 times greater than that of horseweed and purple deadnettle. The influence of various environmental factors on paraquat efficacy was weed specific. Applications made at sunrise improved control of purple deadnettle over applications at solar noon or sunset. Lower light intensities (200 or 600 μmol m−2 s−1) surrounding the time of application improved control of waterhemp and horseweed more than 1,000 μmol m−2 s−1. Day/night temperatures of 27/16 C improved horseweed and purple deadnettle control compared with day/night temperatures of 18/13 C. Though control was positively associated with injury rates in the application time of day and temperature experiments, a negative relationship was observed for waterhemp in the light-intensity experiment. Thus, although there are conditions that enhance paraquat efficacy, the specific target species must also be considered. These results advocate paraquat dose recommendations, currently based on weed height, be expanded to address sensitivity differences among weeds. Moreover, these findings contrast with paraquat labels stating temperatures of 13 C or lower do not reduce paraquat efficacy.

A revision of Centaurea sect. Cynaroides (Asteraceae, Cardueae—Centaureinae)

Phytotaxa ◽  
2018 ◽  
Vol 363 (1) ◽  
pp. 1 ◽  
Author(s):  
KAZEM NEGARESH ◽  
MOHAMMAD REZA RAHIMINEJAD
Keyword(s):  
Natural Habitat ◽  
Taxonomic Status ◽  
Herbarium Specimens ◽  
Chromosome Counts ◽  
Type Specimens ◽  
Distribution Maps ◽  
Biogeographical Distribution ◽  
Distribution And Ecology ◽  
Three New Species ◽  
Close Relatives

The taxonomic status of the taxa known to belong to Centaurea sect. Cynaroides and its close relatives was revised on the basis of herbarium specimens from the authors’ expeditions and other collections. It is established that Boissier is the correct author for C. sect. Cynaroides, and C. regia is designated as a lectotype of this section. Thirty seven species are recognised in the section. Three new species (C. kamalnejadii, C. mozaffarianii, and C. zarrei), four new subspecies (C. amadanensis subsp. ranjbarii, C. cataonica subsp. syriaca, C. gigantea subsp. rechingeri, and C. kurdica subsp. ciliata) and two varieties (C. regia var. longispinosa and C. regia var. purpurea) are described. Two subspecies are reduced to the variety rank, and two varieties are elevated to the subspecies rank. Centaurea sect. Paraphysis is reduced as a synonym of C. sect. Cynaroides. Centaurea onopordifolia is transferred from C. sect. Cynaroides to a new section, i.e. C. sect. Cardueae. Three lectotypes are designated, six lectotypes from previous lectotypifications are rejected and the author names for six species are corrected. The recognized taxa, the relevant synonyms, type details, examined specimen lists, full descriptions and a taxonomic key are provided for this section. Distribution maps are provided for each sections, species, subspecies and varieties. Images of the type specimens of all taxa and also photos of the species in its natural habitat and related fields are provided. Five chromosome counts (2n = 18) are reported for C. amadanensis subsp. amadanensis, C. amadanensis subsp. gymnoclada, C. nemecii, C. regia var. regia, and C. regia var. purpurea. Biogeographical distribution and ecology of taxa of C. sect. Cynaroides are presented and discussed. In addition, cytotaxonomy, homoploidy and evolution of C. sect. Cynaroides are illustrated and discussed. Finally, the pollination of C. sect. Cynaroides is illustrated, and also images of the pollinators of some species of the section are provided.

scholarly journals Different effects of invader–native phylogenetic relatedness on invasion success and impact: a meta-analysis of Darwin's naturalization hypothesis

2016 ◽  
Vol 283 (1838) ◽  
pp. 20160663 ◽  
Author(s):  
Chao Ma ◽  
Shao-peng Li ◽  
Zhichao Pu ◽  
Jiaqi Tan ◽  
Manqiang Liu ◽  
...  
Keyword(s):  
Alien Species ◽  
Meta Analysis ◽  
Regional Scale ◽  
Local Scale ◽  
Invasion Success ◽  
Native Communities ◽  
Invasion Stage ◽  
Investigation Methods ◽  
Darwin's Naturalization Hypothesis ◽  
Darwin’S Naturalization Hypothesis

Darwin's naturalization hypothesis (DNH), which predicts that alien species more distantly related to native communities are more likely to naturalize, has received much recent attention. The mixed findings from empirical studies that have tested DNH, however, seem to defy generalizations. Using meta-analysis to synthesize results of existing studies, we show that the predictive power of DNH depends on both the invasion stage and the spatial scale of the studies. Alien species more closely related to natives tended to be less successful at the local scale, supporting DNH; invasion success, however, was unaffected by alien–native relatedness at the regional scale. On the other hand, alien species with stronger impacts on native communities tended to be more closely related to natives at the local scale, but less closely related to natives at the regional scale. These patterns are generally consistent across different ecosystems, taxa and investigation methods. Our results revealed the different effects of invader–native relatedness on invader success and impact, suggesting the operation of different mechanisms across invasion stages and spatial scales.

scholarly journals Microbial Risks in Household UF Purifiers and Disinfection Strategy with Electrolysis

2020 ◽  
Vol 143 ◽  
pp. 02028
Author(s):  
Yucheng Chen ◽  
Jian-nan Fu ◽  
Yi Wang ◽  
Jian Ding ◽  
Xiaoying Lian ◽  
...  
Keyword(s):  
Drinking Water ◽  
Residence Time ◽  
Bacterial Growth ◽  
Microbial Contamination ◽  
Tap Water ◽  
Lag Phase ◽  
Pilot Test ◽  
Acceptable Range ◽  
Hygienic Standard ◽  
Microbial Risks

The research studied microbial deterioration in household ultrafiltration membrane (UF) purifiers with residence time and anti-bacterial strategy with electrolysis. The pilot test was conducted on a household drinking water purifier. A 72-h stagnation test and a 60-min anti-bacterial test with electrolysis were subsequently done. There were some findings in this study: (1) The level of HPC exceeded the hygienic standard when the stagnation time was more than 3 h. (2) The lag phase of bacterial growth was no more than 12 h in filters. (3) With the method of electrolysis, microbial contamination induced by water stagnation can be controlled in the acceptable range, which was more efficient than the method of flushing with tap water.

A cladistic and biogeographic analysis of Chinese Neopsylla Wagner (Siphonaptera : Ctenophthalmidae)

2003 ◽  
Vol 17 (5) ◽  
pp. 607 ◽  
Author(s):  
Liang Lu ◽  
Houyong Wu
Keyword(s):  
Host Preference ◽  
Cladistic Analysis ◽  
Primary Host ◽  
Host Preferences ◽  
History Of ◽  
Paraphyletic Group ◽  
Species Groups ◽  
Close Relatives ◽  
Independent Species ◽  
Biogeographic Analysis

A cladistic analysis of 29 Chinese species of Neopsylla Wagner, 1903 is carried out based on morphology. Rothschildiana Smit, 1952 and Tamiophila Jordan, 1938, two close relatives of Neopsylla, are also included in the analysis. The results support four species-groups among the Neopsylla: the anoma-group, the stevensi-group, the specialis-group and the setosa-group, and an independent species, N. angustimanubra Wu, Wu�& Liu, 1966. Species of Rothschildiana are included in the stevensi-group and Tamiophila grandis is a member of the setosa-group. Therefore Neopsylla is a paraphyletic group and Rothschildiana and Tamiophila are junior synonyms. The four species-groups show different distributions and host preferences. Rattus is the primary host of the anoma- and stevensi-groups, although some species of the anoma-group have shifted to Myospalax. The specialis-group predominantly infects Apodemus. The setosa-group shifted host preference from the Murinae to genera of Cricetinae and Sciurinae. The reasons for the changes in host and distributions of the species-groups are discussed in relation to the zoogeographic history of China.

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