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Article Reference Woodland in a f luvio-lacustrine environment on the dry Mongolian Plateau during the late Paleocene: Evidence from the mammal bearing Subeng section (Inner Mongolia, P.R. China)
Located in Library / RBINS Staff Publications
Article Reference High-resolution carbon isotope stratigraphy and mammalian faunal change at the Paleocene-Eocene boundary in the Honeycombs area of the Southern Bighorn Basin, Wyoming.
Located in Library / RBINS Staff Publications
Article Reference Oldest fossil avian remains from the Indian subcontinental plate
Located in Library / RBINS Staff Publications
Article Reference A land snail's view of a fragmented landscape
Habitat fragmentation may influence the genetic structure of populations, especially of species with low mobility. So far, these effects have been mainly studied by surveying neutral markers, and much less by looking at ecologically relevant characters. Therefore, we aimed to explore eventual patterns of covariation between population structuring in neutral markers and variation in shell morphometrics in the forest-associated snail Discus rotundatus in relation to habitat fragment characteristics. To this end, we screened shell morphometric variability and sequence variation in a fragment of the mitochondrial 16S rDNA gene in D. rotundatus from the fragmented landscape of the Lower Rhine Embayment, Germany. The 16S rDNA of D. rotundatus was highly variable, with a total of 118 haplotypes (384 individuals) forming four clades and one unresolved group. There was a geographic pattern in the distribution of the clades with the river Rhine apparently separating two groups. Yet, at the geographic scale considered, there was no obvious effect of fragmentation on shell morphometrics and 16S rDNA variation because G(ST) often was as high within, as between forests. Instead, the age of the habitat and (re-)afforestation events appeared to affect shell shape and 16S rDNA in terms of the number of clades per site. The ecologically relevant characters thus supported the presumably neutral mitochondrial DNA markers by indicating that populations of not strictly stenecious species may be (relatively) stable in fragments. However, afforestation after large clearcuts and habitat gain after the amendment of deforestation are accompanied by several, seemingly persistent peculiarities, such as altered genetic composition and shell characters (e.g. aperture size). (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 839-850.
Located in Library / RBINS Staff Publications
Article Reference Absence of cadmium excretion and high assimilation result in cadmium biomagnification in a wolf spider
Cd biomagnification in the terrestrial food chain appears to be dependent on the physiological properties of the organisms rather than on their trophic level. Although high Cd body burdens in spiders from the field have been reported many times, experimental verification of the key factors that determine the rate of cadmium accumulation is lacking. We investigated the cadmium assimilation rate in the common wolf spider Pirata piraticus fed with contaminated fruit flies. Spiders were fed for 42 days with contaminated flies, followed by a detoxicification period of 28 days. Every 14 days, a subsample of spiders and flies was taken for Cd determination. It was demonstrated that a high cadmium assimilation (69.5\%) and an excretion rate approaching zero resulted in high Cd concentration factors. The results indicate the importance of spiders in cadmium biomagnification along critical pathways. (C) 2003 Elsevier Science (USA). All rights reserved.
Located in Library / RBINS Staff Publications
Article Reference Can multiple mating compensate for slower development and shorter adult life in a male dimorphic dwarf spider?
Oedothorax gibbosus (Blackwall, 1841) is a dwarf spider characterized by the occurrence of a male dimorphism: the tuberosus male does not show any remarkable differentiation at the dorsal side of the carapace; the gibbosus morph on the contrary has a hunch behind the eye region, with a transversal groove densely clothed with hairs. These structures play an important function in the gustatorial courtship, being the uptake of secretions by the female from a body part of the male during courtship. Based on standardized survival experiments we show that tuberosus has a greater overall survival strength for different humidity levels than gibbosus. The two male morphs of O. gibbosus also have a different mating strategy: tuberosus as well as gibbosus copulate with virgin females, but gibbosus copulates significantly more with already inseminated females. Because of this strategy gibbosus secures its offspring notwithstanding the faster development, the longer adult life and the greater overall survival strength of tuberosus. (C) 2004 The Linnean Society of London
Located in Library / RBINS Staff Publications
Article Reference Complementarity effects drive positive diversity effects on biomass production in experimental benthic diatom biofilms
P1. Positive effects of species diversity on ecosystem functioning have often been demonstrated in 'macrobial' communities. This relation and the responsible mechanisms are far less clear for microbial communities. Most experimental studies on microorganisms have used randomly assembled communities that do not resemble natural communities. It is therefore difficult to predict the consequences of realistic, non-random diversity loss. 2. In this study, we used naturally co-occurring diatom species from intertidal mudflats to assemble communities with realistically decreasing diversity and analysed the effect of non-random species loss on biomass production. 3. Our results demonstrate a highly positive biodiversity effect on production, with mixtures outperforming the most productive component species in more than half of the combinations. These strong positive diversity effects could largely be attributed to positive complementarity effects (including both niche complementarity and facilitation), despite the occurrence of negative selection effects which partly counteracted the positive complementarity effects at higher diversities. 4. Facilitative interactions were, at least in part, responsible for the higher biomass production. For one of the species, Cylindrotheca closterium, we show its ability to significantly increase its biomass production in response to substances leaked into the culture medium by other diatom species. In these conditions, the species drastically reduced its pigment concentration, which is typical for mixotrophic growth. 5. Synthesis. We show that both species richness and identity have strong effects on the biomass production of benthic diatom biofilms and that transgressive overyielding is common in these communities. In addition, we show mechanistic evidence for facilitation which is partly responsible for enhanced production. Understanding the mechanisms by which diversity enhances the performance of ecosystems is crucial for predicting the consequences of species loss for ecosystem functioning.
Located in Library / RBINS Staff Publications
Article Reference Condition-dependent mate choice and its implications for population differentiation in the wolf spider Pirata piraticus
When populations face different environmental conditions, both local adaptation and phenotypic plasticity may cause interpopulation divergence of behavioral or phenotypic properties on which mate choice is based. If sustained, this may result in genetic differentiation even in the presence of extant gene flow. Condition dependence of mate choice is one of the main mechanisms explaining these environmental effects. We tested whether experimental food stress affects mate choice in male and female Pirata piraticus spiders from one heavily polluted and one unpolluted reference population. Compared with control females, food-stressed females from the reference population showed a decreased probability of copulation and preferred smaller mates. Females from the polluted population, in contrast, did not show a significant response to food stress and showed size-assortative mating, most strongly under food stress. We explain these results in 2 complementary ways. First, spiders from populations that are not adapted to cope with stress may be less willing to mate when eggs are not fully matured. Second, food-deprived females may show a larger responsiveness toward smaller males because the latter resemble prey more and hungry females tend to attack moving objects more often. Results from this study support the prediction that variation in body condition, driven by local ecological factors, may affect mating behavior and may ultimately lead to population divergence in important life-history traits such as body size.
Located in Library / RBINS Staff Publications
Article Reference Differences in geographic distribution and habitat of some cryptic species in the Pardosa lugubris group (Lycosidae, Araneae) in Belgium
The habitat and distribution of some closely related species of the P. lugubris s.l. group in Belgium are described to contribute to our understanding of the coexistence and speciation of these 'cryptic' species. With a few exceptions, P. lugubris has its main distribution in the lower part of Belgium where it occurs on sandy, nutrient poor soils. P. saltans occurs widely in Belgium except for in the Campine region where the species is totally absent. P. alacris was only found at three localities where limestone outcrops are present. The habitat of P. lugubris is pine and birch forests while in Fagus woodlands, only P. saltans was found. In Quercus forests, both species were found, often in mixed populations. A combination of micro- and macroclimatological features and habitat characteristics cause the differences in distribution of these species.
Located in Library / RBINS Staff Publications
Article Reference Differentiation between two salt marsh beetle ecotypes: Evidence for ongoing speciation
The plausibility of trait divergence under divergent natural selection in the presence of gene flow in natural populations is a contentious issue in evolutionary research. Its importance lies in the fact that this process is thought to be one of the key triggers in ecological speciation in which a species splits into ecologically distinct forms when separate niches are occupied. in this study we demonstrate strong genetic divergence at the IDH1 locus between pond- and canal-inhabiting individuals of the salt marsh beetle Pogonus chalceus from the Guerande salt fields. Moreover, wing size, a trait that has a heritable basis in this species, was significantly larger in the pond populations, which is in concordance with the unstable nature of this habitat. The relationship between IDH1 allele frequencies and wing size variation was consistent with patterns seen across western European populations. By means of neutral allozymes and microsatellites we detected a small but significant degree of sexual isolation between ecotypes. We conclude that speciation is ongoing and that divergence reflects a balance between selection and gene flow.
Located in Library / RBINS Staff Publications