scholarly journals Diversity of resident plant communities could weaken their allelopathic resistance against alien and native invaders

2021 ◽  
Author(s):  
Ling Yuan ◽  
Junmin Li ◽  
Mark van Kleunen
Keyword(s):  
Plant Communities ◽  
Single Species ◽  
Resident Species ◽  
Test Species ◽  
Diverse Communities ◽  
Allelopathic Effects ◽  
Almost All ◽  
Germination Experiment ◽  
Germinated Seeds

AbstractElton’s classic diversity-invasibility hypothesis posits that diversity of resident communities increases resistance against invaders. We tested whether the diversity-invasibility relationsip might be mediated by allelopathic effects of the resident species. In a large germination experiment, we exposed seeds of six alien and six native test species to leachates of one, three, six or twelve species. The leachates tended to slightly delay germination, and almost all single-species leachates reduced the proportion of germinated seeds. Nevertheless, the overall effect of the plant leachate mixtures on the proportion of germinated seeds was not significant. This was because a higher diversity of the leachates increased the proportion of germinated seeds, particularly for native test species. Among the six alien test species, it was only the most invasive one that benefited from increased diversity of the leachates, just like the natives did. Overall, our findings suggest that allelopathy of diverse communities does not provide resistance but could actually facilitate the germination of invaders.

Cranial morphology and systematics of an extraordinary sample of the Late Neogene dwarf tapir, Tapirus polkensis (Olsen)

2009 ◽  
Vol 83 (2) ◽  
pp. 238-262 ◽  
Author(s):  
Richard C. Hulbert ◽  
Steven C. Wallace ◽  
Walter E. Klippel ◽  
Paul W. Parmalee
Keyword(s):  
Single Species ◽  
Relative Strength ◽  
Cranial Morphology ◽  
Linear Measurements ◽  
Average Mass ◽  
Gray Fossil Site ◽  
Extant Species ◽  
Late Neogene ◽  
Fossil Site ◽  
Almost All

The previously poorly known “Tapiravus” polkensis Olsen, 1960 (Mammalia, Perissodactyla, Tapiridae) is now known from abundant, well preserved specimens from both the type area in central Florida and from the Gray Fossil Site (GFS) in eastern Tennessee. The latter has produced over 75 individuals, the greatest number of tapirids from a single fossil site, including many articulated skeletons. Almost all linear measurements taken on skulls, mandibles, and cheek teeth from GFS have coefficients of variation less than 10 (most between 3 and 7), indicating the presence of a single species. However, the sample reveals considerable intraspecific variation for a few key morphologic features, including development of the sagittal crest, outline shape of the nasals, and number and relative strength of lingual cusps on the P1. The Florida sample of T. polkensis is more limited, but has the same state as the GFS sample for all preserved characters of systematic significance, and while the Florida teeth are on average smaller (especially narrower lower cheek teeth), they fall either within or just below the observed range of the Gray Fossil Site population. The new material supports a reassignment of “Tapiravus” polkensis to the genus Tapirus, and demonstrates that the geologic age of the species is significantly younger than previously thought, Hemphillian rather than Barstovian. Tapirus polkensis is the smallest known North American Tapirus, and smaller than any of the extant species in the genus, with an estimated average mass of 125 kg.

scholarly journals Airborne environmental DNA metabarcoding detects more diversity, with less sampling effort, than a traditional plant community survey

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mark D. Johnson ◽  
Mohamed Fokar ◽  
Robert D. Cox ◽  
Matthew A. Barnes
Keyword(s):  
Plant Community ◽  
Plant Communities ◽  
Traditional Method ◽  
Environmental Dna ◽  
Single Species ◽  
Community Survey ◽  
Sampling Effort ◽  
Sampling Campaign ◽  
Dna Metabarcoding ◽  
Human Health Impacts

Abstract Background Airborne environmental DNA (eDNA) research is an emerging field that focuses on the detection of species from their genetic remnants in the air. The majority of studies into airborne eDNA of plants has until now either focused on single species detection, specifically only pollen, or human health impacts, with no previous studies surveying an entire plant community through metabarcoding. We therefore conducted an airborne eDNA metabarcoding survey and compared the results to a traditional plant community survey. Results Over the course of a year, we conducted two traditional transect-based visual plant surveys alongside an airborne eDNA sampling campaign on a short-grass rangeland. We found that airborne eDNA detected more species than the traditional surveying method, although the types of species detected varied based on the method used. Airborne eDNA detected more grasses and forbs with less showy flowers, while the traditional method detected fewer grasses but also detected rarer forbs with large showy flowers. Additionally, we found the airborne eDNA metabarcoding survey required less sampling effort in terms of the time needed to conduct a survey and was able to detect more invasive species than the traditional method. Conclusions Overall, we have demonstrated that airborne eDNA can act as a sensitive and efficient plant community surveying method. Airborne eDNA surveillance has the potential to revolutionize the way plant communities are monitored in general, track changes in plant communities due to climate change and disturbances, and assist with the monitoring of invasive and endangered species.

scholarly journals Comparison of Prediction Equations for Estimating Inside Bark Diameters for Yellow-Poplar, Red Maple, and Red Pine in West Virginia

2009 ◽  
Vol 26 (1) ◽  
pp. 5-8 ◽  
Author(s):  
John R. Brooks ◽  
Lichun Jiang
Keyword(s):  
West Virginia ◽  
Single Species ◽  
Prediction Equation ◽  
Red Pine ◽  
Red Maple ◽  
Nonlinear Prediction ◽  
Prediction Equations ◽  
Yellow Poplar ◽  
Taper Function ◽  
Almost All

Abstract The ability to predict inside bark diameters was investigated using taper data for red maple, red pine and yellow-poplar from several stands in West Virginia. Inside bark estimates were based on Grosenbaugh's STX prediction equations, a segmented polynomial taper function fitted to inside bark diameter data, an existing polynomial prediction equation published for several hardwood species in this region and a nonlinear prediction equation fitted to the taper data. Grosenbaugh's STX is a computer program for processing tree measurements and includes three equations to allow flexibility and greater accuracy in predicting inside bark upper stem diameters. The nonlinear equation had the smallest overall prediction error in almost all cases investigated. The taper function had the largest error but does not require knowledge of the specific upper stem outside bark diameter. No single STX bark option was found to be optimal for all species or for a single species from two different geographic regions.

scholarly journals Community-level reorganizations following migratory pollinator dynamics along a latitudinal gradient

2020 ◽  
Vol 287 (1930) ◽  
pp. 20200649 ◽  
Author(s):  
Ainhoa Magrach ◽  
Carlos Lara ◽  
Ubaldo Márquez Luna ◽  
Sergio Díaz-Infante ◽  
Ingrid Parker
Keyword(s):  
Fruit Set ◽  
Niche Overlap ◽  
Biodiversity Loss ◽  
Latitudinal Gradients ◽  
Migratory Species ◽  
Resident Species ◽  
Pollination Services ◽  
Community Persistence ◽  
Diversity Gradient ◽  
Diverse Communities

Predicting how communities re-arrange in response to changes in species composition remains a key challenge in ecology. Migratory species, which enter and leave communities across latitudinal gradients, offer us a unique opportunity to evaluate community- and species-level responses to a shift in community composition. We focused on a migratory hummingbird and the communities that host it along a latitudinal and species diversity gradient. Our results show higher niche overlap in more diverse communities, allowing resident species to compensate for the loss of the migrant in providing pollination services. Contrastingly, in less diverse communities, the migrant behaves as a specialist, monopolizing abundant resources. In its absence, its role is not fully covered by resident species, resulting in a decrease in the fruit set of the migrant's preferred plant species. These results help us understand the potential impacts of biodiversity loss and have important implications for community persistence given expected changes in the migratory behaviours of some species.

A monograph of the Bradoriid arthropods from the Lower Cambrian of SW China

2001 ◽  
Vol 92 (3) ◽  
pp. 347-409 ◽  
Author(s):  
Hou Xian-guang ◽  
David J. Siveter ◽  
Mark Williams ◽  
Feng Xiang-hong
Keyword(s):  
Lower Cambrian ◽  
Yunnan Province ◽  
Single Species ◽  
Taxonomic Diversity ◽  
Zoological Nomenclature ◽  
Yangtze Platform ◽  
Animal Group ◽  
Sw China ◽  
Almost All ◽  
High Diversity

ABSTRACTThis paper evaluates the taxonomy, biostratigraphy, and palaeogeographical significance of the Cambrian bradoriid arthropods of China, the majority of which occur in the lower Cambrian of SW China. Of bradoriid faunas world-wide, Chinese occurrences yield the greatest number of specimens and a comparatively high diversity at all taxonomic levels. Nevertheless, taxonomic diversity is much less than previously supposed. Some 80 bradoriid genera and nearly 300 species have been proposed on the basis of Chinese material. By contrast, in our study, which encompasses all of the important Chinese bradoriid faunas, we recognise only 16 genera and 21 species, including those treated under open nomenclature. Interpretation of deformed specimens as discrete species and lack of application of the rules of the International Code of Zoological Nomenclature resulted in taxonomic splitting and a proliferation of names. There are an additional 12 poorly known monotypic genera of uncertain systematic status that are listed but not treated further herein. One phosphatocopid species, a group originally thought closely related to the Bradoriida, is also described.Most Chinese bradoriid material is known from Yunnan Province; the group also occurs in Guizhou, Henan, Hubei, Hunan, Liaoning, Qinghai, Shaanxi, Sichuan, Xinjiang and Zhejiang provinces. The first bradoriids occur just below the Abadiella trilobite Biozone. They are most prolific and diverse in the Qiongzhusian Stage, constituting the most abundant animal group; the succeeding Canglangpuian Stage contains fewer individuals and species. A previously proposed bradoriid biozonal scheme lacks rigour and is of little practical value: of the five supposed biozones, two correspond to trilobite zones and three are based on taxa that herein are considered to belong to a single species.Palaeogeographically the bradoriids occur in the Middle and especially the Western subprovinces of the Cambrian of the SW China (Yangtze) Platform. Almost all of the bradoriid genera and species are endemic to that region. The palaeogeographical links with other bradoriid faunas are mostly within the Redlichiid trilobite Realm, with areas such as N China, Australia and parts of central Asia.

scholarly journals Systematics and geographical distribution ofGalbaspecies, a group of cryptic and worldwide freshwater snails

2019 ◽  
Author(s):  
Pilar Alda ◽  
Manon Lounnas ◽  
Antonio A. Vázquez ◽  
Rolando Ayaqui ◽  
Manuel Calvopiña ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Cryptic Species ◽  
Single Species ◽  
Integrative Approach ◽  
Freshwater Snails ◽  
Stabilizing Selection ◽  
Species Complexes ◽  
The Status ◽  
Liver Flukes ◽  
Almost All

AbstractCryptic species can present a significant challenge to the application of systematic and biogeographic principles, especially if they are invasive or transmit parasites or pathogens. Detecting cryptic species requires a pluralistic approach in which molecular markers facilitate the detection of coherent taxonomic units that can then be analyzed using various traits (e.g., internal morphology) and crosses. In asexual or self-fertilizing species, the latter criteria are of limited use. We studied a group of cryptic freshwater snails (genusGalba)from the family Lymnaeidae that have invaded almost all continents, reproducing mainly by self-fertilization and transmitting liver flukes to humans and livestock. We aim to clarify the systematics, distribution and phylogenetic relationships of these species with an integrative approach that includes morphology (shell and reproductive anatomy), molecular markers, wide-scale sampling across America, and data retrieved from GenBank (to include Old World samples). Our phylogenetic analysis suggests that the genusGalbaoriginated ca. 22 Myr ago and today comprises six clusters of species. Four of these clusters (G.truncatula,G.cubensis/viator,G.humilisandG.schirazensis) are morphologically cryptic and constitute species or species complexes with wide variation in their genetic diversity, geographic distribution and invasiveness. The other two clusters constitute a single species or a species complex (Galba cousini/meridensis) that demonstrate more geographically restricted distributions and exhibit an alternative morphology more phylogenetically derived than the cryptic one. Further genetic studies are required to clarify the status of bothG. cousini/meridensisandG.cubensis/viator. We emphasize that noGalbaspecies should be identified without molecular markers and that additional sampling is required, especially in North America, Eurasia and Africa to clarify remaining questions in systematics and biogeography. We also discuss several hypotheses that can explain crypsis inGalba, such as convergence and morphological stasis, and hypothesize a role for stabilizing selection in amphibious (rather than strictly freshwater) habitats.

scholarly journals Shape and size of the arenas affect amphipod behaviours: implications for ecotoxicology

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5271 ◽  
Author(s):  
Shanelle A. Kohler ◽  
Matthew O. Parker ◽  
Alex T. Ford
Keyword(s):  
False Negative ◽  
Careful Consideration ◽  
Negative Effects ◽  
Mean Velocity ◽  
Major Drawback ◽  
Test Species ◽  
Amphipod Crustacean ◽  
Almost All ◽  
Invertebrate Models ◽  
A Current

The use of behaviour in ecotoxicology is expanding, however the lack of standardisation and validation of these assays currently presents a major drawback in moving forward in the development of behavioural assays. Furthermore, there is a current paucity of control data on test species, particularly invertebrate models. In this study we assessed a range of behaviours associated with spatial distribution and locomotion in relation to arena size and shape in two species of amphipod crustacean (Echinogammarus marinus and Gammarus pulex). Arena shape had significant effects on almost all behavioural parameters analysed. Increasing arena size resulted in an increased mean velocity and activity plus increased proportional use of the central zones. These results indicate that ‘ceiling effects’ may occur in some ecotoxicological studies resulting in potentially ‘false’ negative effects if careful consideration is not paid to experimental design. Differences in behaviours were observed between the two species of amphipod. For example, G. pulex spend approximately five times (∼20%) more of the available time crossing the central zones of the arenas compared to E. marinus (∼4%) which could have implications on assessing anxiolytic behaviours. The results of this study highlight several behaviours with potential for use in behavioural ecotoxicology with crustaceans but also underscore the need for careful consideration when designing these behavioural assays.

scholarly journals Wildfires in the Campanian of James Ross Island: a new macro-charcoal record for the Antarctic Peninsula

2021 ◽  
Author(s):  
Flaviana Jorge de Lima ◽  
Juliana Manso Sayão ◽  
Luiza C. M. de Oliveira Ponciano ◽  
Luiz C. Weinschütz ◽  
Rodrigo Figueiredo ◽  
...  
Keyword(s):  
Plant Communities ◽  
Antarctic Peninsula ◽  
Taxonomic Affinity ◽  
Global Event ◽  
New Information ◽  
Affected Plant ◽  
First Occurrence ◽  
James Ross Island ◽  
Almost All ◽  
The Antarctic

The Cretaceous “high-fire” period was a global event that reached almost all continental masses during that period in Earth’s history. The extensive wildfires directly affected plant communities. Significant palaeobotanical records in the Antarctic Peninsula have been studied from the James Ross Sub-Basin, especially from the Santa Marta Formation. However, there is no described evidence for palaeo-wildfires in the area so far. Here, we present the first occurrence of fossilized macro-charcoal coming from James Ross Island, confirming that palaeo-wildfires occurred in the Campanian vegetation preserved in the Santa Marta Formation. The new charcoal material has a gymnospermous taxonomic affinity, more specifically with the Araucariaceae, which is in accordance with previous palaeobotanical records from James Ross Island. This occurrence adds new information to the construction of the palaeo-wildfire scenario for Gondwana.

scholarly journals Species delimitation within the Glaucidium brodiei owlet complex using bioacoustic tools

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Chyi Yin Gwee ◽  
James A. Eaton ◽  
Elize Y. X. Ng ◽  
Frank E. Rheindt
Keyword(s):  
Natural History ◽  
Species Delimitation ◽  
Species Complex ◽  
Principal Component ◽  
Single Species ◽  
Natural History Museum ◽  
Species Boundaries ◽  
Test Species ◽  
History Museum ◽  
Plumage Colouration

Abstract Background The taxonomy of the Collared Owlet (Glaucidium brodiei) species complex is confused owing to great individual variation in plumage colouration seemingly unrelated to their distribution. Although generally recognised as a single species, vocal differences among the subspecies have been noted by field recordists. However, there is no study assessing the vocal differences among these four subspecies. Methods We obtained 76 sound recordings of the G. brodiei species complex comprising all four subspecies. We conducted bioacoustic examinations using principal component analysis and the Isler criterion to quantitatively test species boundaries within the G. brodiei complex. In addition, we compared plumage colouration among 13 specimens of the G. brodiei complex deposited at the Natural History Museum at Tring, UK and the Lee Kong Chian Natural History Museum, Singapore to ascertain the presence of plumage differences across taxa. Results We found the Bornean and Sumatran populations vocally similar to each other, but distinctly different from the mainland and Taiwan populations. The vocal pattern seems to corroborate plumage distinctions in the colouration of neck collars: the Bornean and Sumatran taxa share a white neck collar, whereas the continental and Taiwan taxa share a rufous neck collar. Conclusions We propose the taxonomic elevation of the Sumatran and Bornean populations to species level as Sunda Owlet G. sylvaticum, with one subspecies on Sumatra (G. s. sylvaticum) and Borneo (G. s. borneense) each. Our study corroborates the importance of bioacoustics in ascertaining species boundaries in non-passerines, and emphasises the significance of incorporating multiple species delimitation approaches when making taxonomic decisions.

Sign in / Sign up

Export Citation Format

Share Document