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61.
The Atlantic molly Poecilia mexicana inhabits a variety of habitats. In previous studies, small males from clear-water populations showed considerably more sexual behaviours than large males. Males from a sulphur creek, the El Azufre, or from a sulphur cave (cave molly) showed comparatively low sexual activity, and typical size-dependent mating behaviour was either absent or large males showed even more sexual behaviour than smaller ones. Sexually deprived cave molly males increased their sexual activity, but small males still did not show more sexual behaviour than large ones, suggesting that the genetic basis for typical size-dependent mating behaviour has been lost. Likely, the extreme abiotic conditions (hypoxia and toxic hydrogen sulphide) have selected against energetically costly behaviours. In this paper, we examined how El Azufre males would respond to sexual deprivation. We found these males to also increase their sexual activity after sexual deprivation but, unlike cave mollies, small males now showed more sexual behaviour than large ones, suggesting that the genetic basis for this behaviour is not lost in this population. Differences between populations may be due to the less harsh characteristics of El Azufre (e.g. less H2S), resulting in weaker selection against energy-consuming behaviours. Furthermore, we tested for potential costs of male sexual harassment for females in terms of reduced feeding efficiency in the presence of a male, as was shown for P. mexicana from a clear-water population, but was not found in cave mollies or the El Azufre fish. Test females were either starved for 1 week to increase hunger levels or male sexual deprivation and female starvation were combined; however, we found no evidence for male sexual harassment even after these treatments. Our results parallel previous findings in the cave molly and suggest that El Azufre males have lost specific behavioural traits that cause sexual harassment. 相似文献
62.
ANDREA FERREIRA DA COSTA PABLO JOSÉ FRANCISCO PENA RODRIGUES MARIA DAS GRAÇAS LAPA WANDERLEY 《Botanical journal of the Linnean Society. Linnean Society of London》2009,159(1):163-181
The species related to Vriesea paraibica (Bromeliaceae, Tillandsioideae) have controversial taxonomic limits. For several decades, this group has been identified in herbarium collections as V. × morreniana, an artificial hybrid that does not grow in natural habitats. The aim of this study was to assess the morphological variation in the V. paraibica complex through morphometric analyses of natural populations. Two sets of analyses were performed: the first involved six natural populations (G1) and the second was carried out on taxa that emerged from the first analysis, but using material from herbarium collections (G2). Univariate ANOVA was used, as well as discriminant analysis of 16 morphometric variables in G1 and 18 in G2. The results of the analyses of the two groups were similar and led to the selection of diagnostic traits of four species. Lengths of the lower and median floral bracts were significant for the separation of red and yellow floral bracts. Vriesea paraibica and V. interrogatoria have red bracts; these two species are differentiated by the widths of the lower and median portions of the inflorescence and by scape length. These structures are larger in the former and smaller in the latter. Of the species with yellow floral bracts, V. eltoniana is distinguished by longer leaf blades and scapes and V. flava is characterized by its shorter sepal lengths. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 163–181. 相似文献
63.
Rüdiger Riesch Michael Tobler Martin Plath Ingo Schlupp 《Environmental Biology of Fishes》2009,84(1):89-94
Life history traits within species often vary among different habitats. We measured female fecundity in mollies (Poecilia mexicana) from a H2S-rich cave and from a neighbouring surface habitat, as well as in laboratory-reared individuals of both populations raised
in either light or continuous darkness. Compared to conspecifics from surface habitats, cave-dwelling P. mexicana had reduced fecundity (adjusted for size) in the field. In the laboratory, the fecundity of surface mollies was higher in
light than in darkness, whereas fecundity in the cave mollies was almost unaffected by the ambient light conditions. Our results
suggest a heritable component to the reduction in fecundity in female cave mollies. Moreover, the reduced plasticity in fecundity
of cave mollies in response to light conditions might be an example of genetic assimilation or channelling of a life history
trait in a population invading a new environment. 相似文献
64.
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66.
YIT ARN TEH OLIVIER MAZÉAS ALYSSA R. ATWOOD TRIFFID ABEL ROBERT C. RHEW 《Global Change Biology》2009,15(2):330-345
The Arctic tundra has been shown to be a potentially significant regional sink for methyl chloride (CH3Cl) and methyl bromide (CH3Br), although prior field studies were spatially and temporally limited, and did not include gross flux measurements. Here we compare net and gross CH3Cl and CH3Br fluxes in the northern coastal plain and continental interior. As expected, both regions were net sinks for CH3Cl and CH3Br. Gross uptake rates (−793 nmol CH3Cl m−2 day−1 and −20.3 nmol CH3Br m−2 day−1) were 20–240% greater than net fluxes, suggesting that the Arctic is an even greater sink than previously believed. Hydrology was the principal regulator of methyl halide flux, with an overall trend towards increasing methyl halide uptake with decreasing soil moisture. Water table depth was one of the best predictors of net and gross uptake, with uptake increasing proportionately with water table depth. In drier areas, gross uptake was very high, averaging −1201 nmol CH3Cl m−2 day−1 and −34.9 nmol CH3Br m−2 day−1; in flooded areas, gross uptake was significantly lower, averaging −61 nmol CH3Cl m−2 day−1 and −2.3 nmol CH3Br m−2 day−1. Net and gross uptake was greater in the continental interior than in the northern coastal plain, presumably due to drier inland conditions. Within certain microtopographic features (low‐ and high‐centered polygons), uptake rates were positively correlated with soil temperature, indicating that temperature played a secondary role in methyl halide uptake. Incubations suggested that the inverse relationship between water content and methyl halide uptake was the result of mass transfer limitation in saturated soils, rather than because of reduced microbial activity under anaerobic conditions. These findings have potential regional significance, as the Arctic is expected to become warmer and drier due to anthropogenic climate forcing, potentially enhancing the Arctic sink for CH3Cl and CH3Br. 相似文献
67.
Naomi Itonaga Ulrich Köppen Martin Plath Dieter Wallschläger 《Journal of Ethology》2010,28(2):393-397
We examined breeding dispersal directions in the white stork (Ciconia ciconia), a migratory bird breeding in large parts of Europe. We asked whether and how the direction of the major spring/autumn migration
route (from south-east to north-west and vice versa) affects breeding dispersal directions. Breeding dispersal directions
were clearly nonrandomly distributed and were influenced by the major spring migration direction, leading to a bias toward
south-eastward and north-westward breeding dispersal. 相似文献
68.
Valerio Ketmaier Heiko Stuckas Julien Hempel Ingmar Landeck Michael Tobler Martin Plath Ralph Tiedemann 《Organisms Diversity & Evolution》2010,10(5):381-395
Gravel Bank Grasshopper (Chorthippus pullus) populations inhabit two contrasting environments, pebbly gravel banks with scarce vegetation cover in mountainous areas
along the Alps and lowland grasslands dominated by Common Heather (Calluna vulgaris). Heath populations of C. pullus have been rediscovered only recently, and show a distribution scattered across Central Europe. The wings are reduced in this
species; thus, it has low potential for long-distance dispersal. We used sequence data on a newly developed non-coding nuclear
marker from three gravel-bank and four heath populations to test whether grasshoppers from the two environments represent
distinct lineages. Gravel-bank populations were studied in southern Germany (Bavaria), heath populations in eastern Germany
(Brandenburg and Saxony) and Ukraine. We compared those genetic data with an analysis of variation in a suite of morphometric
traits. Finally, we combined genetic and morphometric data to reconstruct a plausible scenario for the ecological shift observed
in C. pullus. Our newly developed marker did not sort populations from contrasting environments in two monophyletic lineages. Nevertheless,
we found a general lack of gene flow between the gravel-bank and heath populations. There was pronounced variation among populations
in morphometric traits. That variation was partially partitioned by habitat type, and populations from the same habitat tended
to be more similar than those from different habitats. Our data suggest that heath populations originated through northward
expansion from multiple southern European refugia, and that the gravel-bank populations represent one of these sources. Patterns
of genetic and morphometric divergence suggest that gravel-bank and heath populations may be in the process of incipient speciation. 相似文献
69.
Research laboratories studying the genetics of companion animals have no database tools specifically designed to aid in the
management of the many kinds of data that are generated, stored and analyzed. We have developed a relational database, "DOG-SPOT,"
to provide such a tool. Implemented in MS-Access, the database is easy to extend or customize to suit a lab's particular needs.
With DOG-SPOT a lab can manage data relating to dogs, breeds, samples, biomaterials, phenotypes, owners, communications, amplicons,
sequences, markers, genotypes and personnel. Such an integrated data structure helps ensure high quality data entry and makes
it easy to track physical stocks of biomaterials and oligonucleotides. 相似文献
70.
Life on the edge: hydrogen sulfide and the fish communities of a Mexican cave and surrounding waters 总被引:9,自引:0,他引:9
Tobler M Schlupp I Heubel KU Riesch R de León FJ Giere O Plath M 《Extremophiles : life under extreme conditions》2006,10(6):577-585
Most eucaryotic organisms classified as living in an extreme habitat are invertebrates. Here we report of a fish living in a Mexican cave (Cueva del Azufre) that is rich in highly toxic H2S. We compared the water chemistry and fish communities of the cave and several nearby surface streams. Our study revealed high concentrations of H2S in the cave and its outflow (El Azufre). The concentrations of H2S reach more than 300 μM inside the cave, which are acutely toxic for most fishes. In both sulfidic habitats, the diversity of fishes was heavily reduced, and Poecilia mexicana was the dominant species indicating that the presence of H2S has an all-or-none effect, permitting only few species to survive in sulfidic habitats. Compared to habitats without H2S, P. mexicana from the cave and the outflow have a significantly lower body condition. Although there are microhabitats with varying concentrations of H2S within the cave, we could not find a higher fish density in areas with lower concentrations of H2S. We discuss that P. mexicana is one of the few extremophile vertebrates. Our study supports the idea that extreme habitats lead to an impoverished species diversity. 相似文献