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S. Vulgaris (s + vulgari)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

An evidence-based approach to equine parasite control: It ain't the 60s anymore

EQUINE VETERINARY EDUCATION, Issue 6 2010
R. M. Kaplan
Summary Most veterinarians continue to recommend anthelmintic treatment programmes for horses that derive from knowledge and concepts more than 40 years old. However, much has changed since these recommendations were first introduced and current approaches routinely fail to provide optimal or even adequate levels of parasite control. There are many reasons for this. Recent studies demonstrate that anthelmintic resistance in equine parasites is highly prevalent and multiple-drug resistance is common in some countries, but few veterinarians take this into account when making treatment decisions or when recommending rotation of anthelmintics. Furthermore, the current approach of treating all horses at frequent intervals was designed specifically to control the highly pathogenic large strongyle, Strongylus vulgaris. But this parasite is now quite uncommon in managed horses in most of the world. Presently, the cyathostomins (small strongyles) are the principal parasitic pathogens of mature horses. The biology and pathogenesis of cyathostomins and S. vulgaris are very different and therefore require an entirely different approach. Furthermore, it is known that parasites are highly over-dispersed in hosts, such that a small percentage of hosts harbour most of the parasites. The common practices of recommending the same treatment programme for all horses despite great differences in parasite burdens, recommending prophylactic treatment of all horses without indication of parasitic disease or knowing what species of parasites are infecting the horses, recommending use of drugs without knowledge of their efficacy and failing to perform diagnostic (faecal egg count) surveillance for estimating parasite burdens and determining treatment efficacy, are all incompatible with current standards of veterinary practice. Consequently, it is necessary that attitudes and approaches to parasite control in horses undergo a complete overhaul. This is best achieved by following an evidence-based approach that takes into account all of these issues and is based on science, not tradition. [source]

Does natural selection promote population divergence?

MOLECULAR ECOLOGY, Issue 12 2002
A comparative analysis of population structure using amplified fragment length polymorphism markers, quantitative traits
Abstract Divergent natural selection is considered an important force in plant evolution leading to phenotypic differentiation between populations exploiting different environments. Extending an earlier greenhouse study of population differentiation in the selfing annual plant Senecio vulgaris, we estimated the degree of population divergence in several quantitative traits related to growth and life history and compared these estimates with those based on presumably neutral molecular markers (amplified fragment length polymorphisms; AFLPs). This approach allowed us to disentangle the effects of divergent selection from that of other evolutionary forces (e.g. genetic drift). Five populations were examined from each of two habitat types (ruderal and agricultural habitats). We found a high proportion of total genetic variance to be among populations, both for AFLP markers (,ST = 0.49) and for quantitative traits (range of QST: 0.26,0.77). There was a strong correlation between molecular and quantitative genetic differentiation between pairs of populations (Mantel's r = 0.59). However, estimates of population differentiation in several quantitative traits exceeded the neutral expectation (estimated from AFLP data), suggesting that divergent selection contributed to phenotypic differentiation, especially between populations from ruderal and agricultural habitats. Estimates of within-population variation in AFLP markers and quantitative genetic were poorly correlated, indicating that molecular marker data may be of limited value to predict the evolutionary potential of populations of S. vulgaris. [source]

Isolation and characterization of microsatellite loci in Senecio

MOLECULAR ECOLOGY RESOURCES, Issue 4 2004
GUOQING LIU
Abstract Interspecific hybridization has resulted in the recent origin of several hybrid Senecio taxa at diploid, tetraploid and hexaploid levels. As part of research aimed at constructing and comparing genomic maps of each of these taxa and their parents, we have isolated microsatellite loci from genomic DNA libraries of S. vulgaris and S. squalidus. Primers of 35 loci amplified microsatellites resolved in agarose gels from one or more of S. vulgaris, S. squalidus, S. aethnensis and S. chrysanthemifolius. Approximately 71% of primers amplified a product in all four species. A survey of microsatellite variation in S. chrysanthemifolius over a subset of 14 loci resolved 2,11 alleles per locus in polyacrylamide gels with expected heterozygosity (HE) ranging from 0.26 to 0.87. [source]

The response of tree squirrels to fragmentation: a review and synthesis

ANIMAL CONSERVATION, Issue 4 2005
John L. Koprowski
Habitat fragmentation is often considered a major threat to biodiversity; however, our understanding of how fragmentation impacts populations is poor. Identifying appropriate models for such studies is difficult. Tree squirrels are dependent on mature forests for food, cover and nests; these are habitats that are being fragmented rapidly and that are easily defined by humans. Squirrels represent excellent models for study of fragmentation. The literature on tree squirrels was reviewed to glean data on density and home-range size in forest fragments. Sufficient data were available on four species (Sciurus carolinensis, S. niger, S. vulgaris, Tamiasciurus hudsonicus). Density was negatively related to fragment size for S. carolinensis and S. niger and marginally so for T. hudsonicus. Sciurus vulgaris did not exhibit this relationship. Home-range size was analysed for three species of Sciurus and was positively related to forest fragment size for S. carolinensis and S. niger. Again, only S. vulgaris did not to show this relationship. Sciurus vulgaris is rarely found in small forest fragments and is believed to be especially sensitive to fragmentation; other tree squirrels appear to be sensitive to fragmentation in more subtle ways. Home range compaction provides a mechanism by which densities may increase in small fragments. The demographic consequences resultant from the high densities of squirrels found in small woodlots are not known but may explain the forest damage, avian nest predation and reduced diversity often cited to occur in woodland fragments. [source]