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《African Journal of Range and Forage Science》2013,30(3):211-212
The straight white spines of African Acacia species are conspicuous, rather than being brown and cryptic as in other species. In comparison with species with brown spines, Acacia spines are composed of less dense material. I suggest that by the Acacia spines being readily apparent, browsers can avoid biting them. This avoidance facilitates the trade-off of decreased sturdiness for increased apparency. 相似文献
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Maria V. MAZZAMUTO Andrea GALIMBERTI Giacomo CREMONESI Benoît PISANU Jean‐Louis CHAPUIS Jan STUYCK Giovanni AMORI Haijun SU Gaetano ALOISE Damiano G. PREATONI Lucas A. WAUTERS Maurizio CASIRAGHI Adriano MARTINOLI 《Integrative zoology》2016,11(3):214-228
Integrative taxonomy, a multi‐disciplinary approach adding modern techniques to traditional morphology‐based methods (e.g. molecular and morphological criteria), can play an important role in bioinvasion research to identify introduced taxa, discover pathways of introduction and inform authorities to control and prevent future introductions. The present study is the first on introduced populations of Callosciurus, Asiatic tree squirrels, known as potentially invasive species in Europe (Italy, Belgium and France). We combined molecular (mitochondrial DNA markers: CoxI, D‐loop) and morphometric analysis on skulls, comparing them to the widest morphological and molecular datasets ever assembled for Callosciurus. Squirrels collected in Italy and Belgium share the same haplotypes and skull characteristics, but are conspicuously different from the French population in Antibes. Genetic data revealed close similarity between French squirrels and Pallas's squirrels, Callosciurus erythraeus, from Taiwan, China. Italian and Belgian squirrels formed an independent taxonomic lineage in genetic analyses, whose taxonomic rank needs further investigation. The morphological and morphometric characteristics of these 2 populations are, however, similar to known specimens assigned to Callosciurus erythraeus. These results may indicate a common origin for the populations found in Belgium and Italy. In contrast, French specimens suggest an independent introduction event of squirrels originating from Asia. 相似文献
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Karin Müller Susanne Eder Ulrike Jakop Jürgen Schiller Peter Müller Mohammad Bashawat 《Reproduction in domestic animals》2020,55(Z2):55-60
Cryobanking of gametes in combination with artificial insemination is an essential option to support conservation programmes for endangered and threatened species. About two-thirds of the felid species are classified as ‘near threatened’, ‘vulnerable’ or ‘endangered’ ( www.cites.org ), and mostly, epididymal sperm are collected from euthanized or castrated male felids and cryopreserved. However, epididymal compared with ejaculated and cryopreserved compared with fresh sperm have a limited potential to fertilize if vaginal non-surgical insemination is applied in feline species. Missing or highly diluted seminal fluid in epididymal and cryopreserved sperm, as well as a potential interference of extender ingredients with the natural interactive properties of sperm in the female genital tract is discussed as potential drawback which hampers a proper sperm transit and fertilization besides the limited longevity of cryopreserved feline sperm. Individual components in seminal fluid as well as cryoextenders may adversely alter sperm properties and have a different impact on fertility and preservation success. The identification and investigation of beneficial as well as detrimental components is a precondition to deduce options for improving the process of cryopreservation in felids, particularly, if only epididymal sperm are available. 相似文献
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This review investigates the disordered status of the classification of Medicago genus,both domestically and internationally. Several definitions of a taxonomic species were considered and the names and characteristics of 13 Medicago species in China are reported,together with a detailed summary of the names,life forms,chromosome numbers,pollination methods and natural distribution of about 90 Medicago species worldwide,including the classification of 14 sections and 10 subsections in Medicago. The molecular evolutionary relationships between different species,and the geographical origin of Medicago are discussed,and the genetic relationships between different subspecies in the alfalfa complex are further explained. This study puts forward a method of identifying Medicago species on the basis of deep understanding of the concept of species. A wide collection of global Medicago germplasm resources,aiming to further clarify the evolutionary relationship among different sections and different species by molecular evolution methods is proposed. This review provides a reference framework for future Medicago classification and alfalfa cross breeding. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved. 相似文献
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《African Journal of Range and Forage Science》2013,30(3-4):325-334
Understanding how climate change and land transformation may impact the distribution and diversity of wildlife species requires landscape-level foundational biodiversity surveys. The Karoo BioGaps Project aims to provide such data and to support the scientific assessment for shale gas development projects in the Karoo basin. In this paper we present the findings of the BioGaps mammal survey, which recorded medium and large mammals across twenty-five 1 km × 1 km sampling sites within the proposed fracking footprint using camera trapping techniques. We use sample rarefaction curves, non-parametric species richness estimators and non-metric multidimensional scaling plots to explore both species richness and community structure. We also used a generalised linear model to investigate how species diversity varies with both site-specific and landscape-level predictors. A total of 38 species were recorded at the majority of sites. Longitude (z = 4.018, p = 0.0005) emerged as the best predictor of species diversity across the study area, which we suggest is linked to the clear east–west aridity gradient. Together these results reveal the cosmopolitan distribution of the mammal taxa in the Karoo and could be used to inform decision-making linked to mining activities in the area. 相似文献
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Mostegl MM Richter B Nedorost N Lang C Maderner A Dinhopl N Weissenböck H 《Veterinary parasitology》2012,185(2-4):86-90
Three different parasites of the phylum Parabasala (Tritrichomonas foetus, Trichomitus rotunda and Tetratrichomonas buttreyi) have been described in pigs. In a previous study (Mostegl et al., 2011) approximately 47% of 91 paraffin wax-embedded intestinal samples of pigs which were Trichomonas-positive by in situ hybridization using a probe with a broad reactivity spectrum contained other species than T. foetus. Out of these, intestinal trichomonads from three pigs (pigs 1-3) were further analyzed by gene sequencing of a part of the 18S ribosomal RNA (rRNA) gene using primer walking. Subsequently, the partial sequences achieved by the different primer pairs were combined to a sequence of about 1000 bp for each trichomonad. In all three pigs unique sequences were acquired which showed only moderate similarities to sequences available in the GenBank. Alignments and the BLAST analysis showed a high degree of homology between sequences of trichomonads from pig 1 and pig 3 with only 1% difference. These sequences were found to be 92% similar to Hypotrichomonas acosta, a trichomonad isolated from squamate reptiles. The trichomonad sequence detected in the intestine of pig 2 showed about 10% nucleotide differences compared to pigs 1 and 3. This sequence was 97% similar to two Trichomitus batrachorum (a frog symbiont) sequences. A phylogenetic analysis using the neighbor-joining and maximum likelihood methods supported the data of the BLAST analysis. These results suggest the presence of at least two as yet undescribed trichomonad species in the intestinal contents of pigs. 相似文献
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One of the main reasons for the poor acceptance of traditional veld management systems by South African farmers is the inflexibility of these systems. Present recommendations indicate that both research and extension personnel appreciate the advantages of the recently‐developed multicamp approach. Within this framework special attention should now be paid to policy relating to selective grazing, key species and proper use factors. Local studies on nutritive value and the relationship between height of defoliation and percentage utilization, emphasize the importance of the choice of key species. A generalized use factor of 50% removal in the growing season is proposed as an interim guide for grassveld management. The need for simplification of recommendations is emphasized. 相似文献
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《African Zoology》2013,48(1):128-137
The breeding dynamics of three species of rodents, Mastomys natalensis, Aethomys chrysophilus and Gerbilliscus vicina were investigated in a seasonal environment (wet versus dry) in Berega in the eastern parts of central Tanzania. Berega has a distinct unimodal rainfall pattern, with most rainfall from November to April/May. We hypothesized that breeding of rodents in central Tanzania would be confined to the wet season, when unlimited resources would be available for reproduction. We provide evidence of breeding discontinuity in the three species, showing that breeding was seasonally restricted to the wet season and early in the dry season. The observed discontinuity could largely be ascribed to variation in primary productivity between the wet and dry seasons. Reproductively active females were found in the population as early as November, a month into the rainy season, but when early rains occurred, some individuals were already breeding in October. Breeding was more intensive in the latter part of the wet season (March–May) and completely ceased during the dry season. For M. natalensis, survival was highest in the wet period and low in the dry season. The study provides knowledge on the breeding dynamics of rodents in central Tanzania, which can help farmers to take proactive rodent management decisions to prevent high rodent densities and reduce crop damage in the fields. Application of control measures by the community early in the season when populations of reproductive females is lowest will be most rewarding. 相似文献
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Non-pathogenic Actinobacillus isolates antigenically and biochemically similar to Actinobacillus pleuropneumoniae: a novel species? 总被引：3，自引：0，他引：3
Gottschalk M Broes A Mittal KR Kobisch M Kuhnert P Lebrun A Frey J 《Veterinary microbiology》2003,92(1-2):87-101
Two unusual Actinobacillus isolates were recovered from pigs with no clinical signs, no lesions and no history of swine pleuropneumonia. Two representative strains (9953L55 and 0347) analyzed in this study were initially biochemically and antigenically identified as A. pleuropneumoniae serotypes 1 and 9, respectively, by traditional identification methods. Both strains presented, however, negative results with three A. pleuropneumoniae-specific PCR tests and revealed in particular the absence of the apxIV toxin genes. However, both strains produced and secreted ApxII toxin although they only harbored the toxin genes apxIICA, which is an uncommon feature for any of the known A. pleuropneumoniae serotypes. Upon experimental inoculation of pigs, these strains proved to be totally non-pathogenic. Animals infected with one of the strains produced antibodies that cross-react with A. pleuropneumoniae serotypes 1-9-11-specific LC-LPS ELISA. Phylogenetic analysis based on 16S rRNA gene sequence analysis revealed that these strains form a separate phylogenetic group that is distinct from other Actinobacillus species and is particularly different from A. pleuropneumoniae. 相似文献
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Different models are available to estimate species’ niche and distribution. Mechanistic and correlative models have different underlying conceptual bases, thus generating different estimates of a species’ niche and geographic extent. Hybrid models, which combining correlative and mechanistic approaches, are considered a promising strategy; however, no synthesis in the literature assessed their applicability for terrestrial vertebrates to allow best-choice model considering their strengths and trade-offs. Here, we provide a systematic review of studies that compared or integrated correlative and mechanistic models to estimate species’ niche for terrestrial vertebrates under climate change. Our goal was to understand their conceptual, methodological, and performance differences, and the applicability of each approach. The studies we reviewed directly compared mechanistic and correlative predictions in terms of accuracy or estimated suitable area, however, without any quantitative analysis to support comparisons. Contrastingly, many studies suggest that instead of comparing approaches, mechanistic and correlative methods should be integrated (hybrid models). However, we stress that the best approach is highly context-dependent. Indeed, the quality and effectiveness of the prediction depends on the study's objective, methodological design, and which type of species’ niche and geographic distribution estimated are more appropriate to answer the study's issue. 相似文献
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Botelho NS de Paula SB Panagio LA Pinge-Filho P Yamauchi LM Yamada-Ogatta SF 《Zoonoses and public health》2012,59(1):16-22
The aim of this study was to isolate yeasts from the faeces of urban bats inhabiting the city of Londrina, Paraná, Brazil and to determine their potential virulence attributes. Seven (12.3%) of 57 bats screened in this study showed yeasts in their faeces. Five species of the genus Candida were isolated: C. guilliermondii, C. krusei, C. lusitaniae, C. parapsilosis, and C. pelliculosa. No phospholipase activity was detected in the egg yolk plate assay; however, all isolates demonstrated protease secretion in skim milk agar. Yeasts isolated from bats produced biofilm on the surface of polystyrene plates and all were classified as intermediate biofilm producers. Minimal inhibitory concentration (MIC) values for fluconazole in the yeasts varied according to the species. Only one isolate (M34 - C. lusitaniae) was considered susceptible dose-dependent to fluconazole. The yeasts were injected intravenously into Swiss mice, and at 15 days post-infection, the animals were killed and portions of their kidneys cultured on Sabouraud dextrose agar medium. All tissues analysed showed positive cultures of Candida spp. This is the first study evaluating the presence of fungi in the faeces of bats in an urban region, where the yeast species found were shown to be potentially pathogenic. As bats are commonly found in cities, these findings indicate the need for continuous surveillance concerning environmental contamination by their excreta. 相似文献
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Several arthropods that live as ectoparasites on domestic dogs can cause severe dermatitis or act as vectors of pathogenic agents, resulting in serious diseases not only in dogs, but also in humans. We studied ectoparasites found on Canis familiaris sampled in five areas in Buenos Aires province, Argentina. The prevalence of fleas, ticks and lice was analyzed, as well as their seasonal variations through the different sites studied. The kind of infestation found in each host was determined and the intensity of natural infestation was estimated. The study was carried out from October 2001 to July 2002, with 116 dogs that lived in rural areas and did not receive control treatments. In order to remove the ectoparasites, the dogs' skin was rubbed with a piece of cotton soaked in ether. All dogs had at least one species of ectoparasites. A total number of 5193 ectoparasites were found corresponding to four species, 15.7% Ctenocephalides canis, 73% Rhipicephalus sanguineus, 1.8 Linognathus setosus and 9.4% Heterodoxus spiniger. R. sanguineus was the most abundant species, and C. canis was the only flea species found. This may be due to the dogs being exclusively rural animals. Within the zones sampled, Magdalena showed the greatest prevalence, maybe as a consequence of having the highest relative humidity in relation to the other areas. Triple infestation (ticks-fleas-lice) was observed in 56.9% of the dogs; 39.6% presented double infestation, most being ticks-fleas, and only 3.4% showed simple infestation (lice). Female hosts were the most affected. Even though there were records of ectoparasites throughout all the year, a higher intensity was observed during the spring months, most likely as a result of the increase in temperature after the winter months. 相似文献
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Herbaceous species preference was studied during autumn and winter periods of occupation, on rotationally‐grazed Dohne Sourveld, at four different stocking rates. Only the most abundant grass species in the sward were monitored. Animals (cattle and sheep) grazed selectively (for plant species) during both autumn and winter, but the degree of selectivity increased in winter. Although animals could be forced to graze less selectively by increasing the stocking rate in autumn, stocking rate did not affect the sequence of species selection, but merely accelerated the process. Regrazing of tillers during grazing periods was a common occurrence in all but the heavy stocking rate treatment. Although Tristachya leucothrix was the most preferred species, the amount (mass) of this species that was grazed per unit basal tuft area was less than that of Themeda triandra. 相似文献
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Three major grass species of the Nylsvley study site were studied: Eragrostis pallens. Digitaria eriantha and Panicum maximum. Growth analysis for the peak growth season was carried out with respect to phytomass, biomass and necromass. The results of this analysis were correlated to photosynthetic activity, measured using infra‐red gas analysis and labelled carbon dioxide leaf exposures. Detailed studies of driving force variables, such as light, temperature, soil moisture and leaf water potential were carried out in order to determine their effects on stomatal resistance. From this it is anticipated that it will be possible to estimate the increase in biomass and the factors determining it, throughout the growing season. 相似文献