Environmental features influencing Carabid beetle (Coleoptera) assemblages along a recently deglaciated area in the Alpine region

Abstract.  1. The spatio-temporal approach was used to evaluate the environmental features influencing carabid beetle assemblages along a chronosequence of an Italian Alpine glacier foreland. The influence of environmental variables on species richness, morphology (wing and body length), and distribution along the chronosequence was tested.
2. Species richness was found to be a poor indicator of habitat due to weak influences by environmental variables. It seems that the neighbouring habitats of a glacier foreland are not able to determine significant changes in carabid species richness.
3. Instead it appears that history (age since deglaciation) and habitat architecture of a glacier foreland are strongly correlated to species adaptive morphological traits, such as wing morphology and body length. Assemblages characterised by species with reduced wing size are linked to the older stages of the chronosequence, where habitat is more structured. Assemblages characterised by the largest species are linked to the younger sites near the glacier. These morphological differentiations are explained in detail.
4. Habitat age can therefore be considered the main force determining assemblage composition. On the basis of the relationship between morphological traits and environmental variables, it seems likely that age since deglaciation is the main variable influencing habitat structure (primary effect) on the Forni foreland. The strong relationship between carabid assemblages and habitat type indicates that site age has but a secondary effect on carabid assemblages. This may be utilised to interpret potential changes in assemblages linked to future glacier retreat.     

StemBell therapy stabilizes atherosclerotic plaques after myocardial infarction

Background aims. After a myocardial infarction (MI) atherosclerosis is accelerated leading to destabilization of the atherosclerotic plaque. mesenchymal stromal cells are a promising therapeutic option for atherosclerosis. Previously, we demonstrated a novel stem cell delivery technique, with adipose stem cells coupled to microbubbles (i.e., StemBells) as therapy after MI. In this study, we aim to investigate the effect of StemBell therapy on atherosclerotic plaques in an atherosclerotic mouse model after MI. Methods. MI was induced in atherosclerotic Apolipoprotein E–deficient mice that were fed a high-fat Western diet. Six days post-MI, the mice received either 5?×?10⁵/100 µL StemBells or vehicle intravenously. The effects of StemBell treatment on the size and stability of aortic root atherosclerotic plaques and the infarcted heart were determined 28 days post-MI via (immuno)histological analyses. Moreover, monocyte subtypes and lipids in the blood were studied. Results. StemBell treatment resulted in significantly increased cap thickness, decreased intra-plaque macrophage density and increased percentage of intra-plaque anti-inflammatory macrophages and chemokines, without affecting plaque size and serum cholesterol/triglycerides. Furthermore, StemBell treatment significantly increased the percentage of anti-inflammatory macrophages within the infarcted myocardium but did not affect cardiac function nor infarct size. Finally, also the average percentage of anti-inflammatory monocytes in the circulation was increased after StemBell therapy. Discussion. StemBell therapy increased cap thickness and decreased intra-plaque inflammation after MI, indicative of stabilized atherosclerotic plaque. It also induced a shift of circulating monocytes and intra-plaque and intra-cardiac macrophages towards anti-inflammatory phenotypes. Hence, StemBell therapy may be a therapeutic option to prevent atherosclerosis acceleration after MI.     

Behavioural and life‐history regulation in a unisexual/bisexual mating system: does male mate choice affect female reproductive life histories?

In theory, unisexual taxa have an advantage over ecologically similar bisexual species because unisexuals produce twice as many daughters and, thus, should quickly outcompete coexisting bisexuals in any given population. For sperm‐dependent unisexual (gynogenetic) species, stable coexistence with their bisexual sperm donors can be postulated if male mate choice puts unisexual females at a disadvantage through sperm limitation, thus halving their reproductive output compared to bisexuals (‘behavioural regulation hypothesis’). We tested for a potential life‐history signature of male mate choice in a system of coexisting bisexual sailfin mollies (Poecilia latipinna) and gynogenetic Amazon mollies (Poecilia formosa). Specifically, we gave P. latipinna males an opportunity to freely interact (and mate) with both types of females and, after 25 days, quantified the proportion of (1) females with sperm in their genital tract and (2) pregnant females. A higher proportion of P. latipinna females (53.7%) had sperm in their genital tract (compared to only 25.9% in P. formosa), corroborating a previous study on wild‐caught fish. This translated into a higher frequency (42.6%) of P. latipinna females being pregnant (compared to 29.6% in P. formosa); however, among pregnant females, no significant differences between species in reproductive life‐history traits (such as offspring number or size) were uncovered. Hence, although the findings of the present study confirm that male discrimination against unisexual females leads to reduced reproductive output in unisexuals, the observed magnitude of differences in targeted life histories between the two types of females is unlikely to be the sole factor regulating stable coexistence in this system. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 598–606.     

Effects of feeding frequency on nestling begging and digestion

Nestling begging has the potential to provide parents with honest information about both short- and long-term nutritional needs, yet the importance of previous feeding experience remains largely untested in empirical studies. We examined the effect of two experimental feeding rates on nestling begging in Southern Grey Shrikes Lanius meridionalis using differences in load size to equalize the total volume of food received. There was variation in the pattern of begging behaviour between six pairs of siblings during a hand-feeding trial, although individuals maintained a similar begging intensity throughout a 9-h feeding period. Both treatment groups showed elevated begging responses during a terminal deprivation period, but nestlings fed small food items at frequent intervals demonstrated higher begging responses after a period of deprivation than did siblings fed large food items infrequently. As nestlings fed frequently with small food items had greater levels of undigested protein present in their faeces than birds fed large items infrequently, we suggest experimentally induced variation in digestive efficiency may account for the observed differences in begging behaviour. The possible role of learning, the adaptive significance of trade-offs between feeding rate and digestive efficiency, and a possible conflict of interests between parents and offspring are discussed.     

Macroinvertebrate diversity in headwater streams: a review

1. Headwater streams are ubiquitous in the landscape and are important sources of water, sediments and biota for downstream reaches. They are critical sites for organic matter processing and nutrient cycling, and may be vital for maintaining the 'health' of whole river networks.
2. Macroinvertebrates are an important component of biodiversity in stream ecosystems and studies of macroinvertebrate diversity in headwater streams have mostly viewed stream systems as linear reaches rather than as networks, although the latter may be more appropriate to the study of diversity patterns in headwater systems.
3. Studies of macroinvertebrate diversity in headwater streams from around the world illustrated that taxonomic richness is highly variable among continents and regions, and studies addressing longitudinal changes in taxonomic richness of macroinvertebrates generally found highest richness in mid-order streams.
4. When stream systems are viewed as networks at the landscape-scale, α-diversity may be low in individual headwater streams but high β-diversity among headwater streams within catchments and among catchments may generate high γ-diversity.
5. Differing ability and opportunity for dispersal of macroinvertebrates, great physical habitat heterogeneity in headwater streams, and a wide range in local environmental conditions may all contribute to high β-diversity among headwater streams both within and among catchments.
6. Moving beyond linear conceptual models of stream ecosystems to consider the role that spatial structure of river networks might play in determining diversity patterns at the landscape scale is a promising avenue for future research.     

Microhabitat preferences drive phylogeographic disparities in two Australian funnel web spiders

Comparative phylogeography is underpinned by the assumption that sympatrically‐distributed taxa will have experienced similar environmental histories, resulting in broadly congruent spatial structuring of phylogenetic lineages, particularly if they inhabit similar niches. However, divergent local conditions, specifically those related to microhabitat, may produce significantly divergent systematic signatures of demographic histories. In the present study, we compare the phylogenetic and population genetic spatial patterns displayed by two species of niche‐separated (but sympatrically distributed) Australian funnel web spiders (Mygalomorphae: Hexathelidae). We demonstrate that an apparently minor disparity in habitat niche has led to divergent experiences of a common environmental history in the saproxylic Hadronyche cerberea and the ground‐burrowing Atrax sutherlandi. Furthermore, we take a crucial first step in documenting the molecular systematics of a group that has traditionally suffered from a dearth of research interest. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 805–819.     

A tale of two haplotype groups: evaluating the New World Junonia ring species hypothesis using the distribution of divergent COI haplotypes

The New World Junonia butterflies are a possible ring species with a circum‐Caribbean distribution. Previous reports suggest a steady transition between North and South American forms in Mesoamerica, but in Cuba the forms were thought to co‐exist without interbreeding representing the overlapping ends of the ring. Three criteria establish the existence of a ring species: a ring‐shaped geographic distribution, gene flow among intervening forms and genetic isolation in the region of range overlap. We evaluated mitochondrial cytochrome oxidase I haplotypes in Junonia from nine species in the Western Hemisphere to test the Junonia ring species hypothesis. Junonia species are generally not monophyletic with respect to COI haplotypes, which are shared across species. However, two major COI haplotype groups exist. Group A predominates in South America, and Group B predominates in North and Central America. Therefore, COI haplotypes can be used to assess the degree of genetic influence a population receives from each continent. Junonia shows a ring‐shaped distribution around the Caribbean, and evidence is consistent with gene flow among forms of Junonia, including those from Mesoamerica. However, we detected no discontinuity in gene flow in Cuba or elsewhere in the Caribbean consistent with genetic isolation in the region of overlap. Although sampling is still very limited in the critical region, the only remaining possibility for a circum‐Caribbean discontinuity in gene flow is at the Isthmus of Panama, where there may be a transition from 98% Group B haplotypes in Costa Rica to 85–100% Group A haplotypes in South America.     

Conserved flanking microsatellite sequences (ReFS) differentiate between Lepidoptera species,and provide insight into microsatellite evolution

High rates of mutation and homoplasy mean that microsatellites generally are not considered to be useful molecular markers for inferring systematic relationships between species. However, an earlier pilot study suggested that conserved flanking microsatellite sequences, also known as repetitive flanking sequences (ReFS), may form a basis for a dominant marker that can differentiate between species of Lepidoptera. We present data that demonstrate that ReFS are quick and easy to use, and generate highly repeatable banding patterns from a range of Lepidoptera species. Sequence data from a subset of ReFS‐amplified bands revealed microsatellite families with flanking sequences that are more conserved within than among species: this is probably attributable to recombination‐mediated events, transposition of mobile elements or a combination of the two. Our data support the use of ReFS as dominant interspecific molecular markers, and add to the growing literature on the evolution of microsatellites in Lepidoptera.     

Western Snowy Plovers Charadrius alexandrinus nivosus select nesting substrates that enhance egg crypsis and improve nest survival

Predation is an important cause of nest failure for many birds and has shaped the life‐history characteristics of many species, especially ground‐nesting shorebirds. We examined nesting success, causes of clutch failure and nest survival in relation to variation in substrate characteristics in a colour‐marked population of Western Snowy Plovers Charadrius alexandrinus nivosus breeding on riverine gravel bars in coastal northern California. Plovers experienced higher nesting success on gravel bars than on nearby beaches, which were characterized by more homogeneous, sandy substrates. On gravel bars, Plovers nested in habitats characterized by large, heterogeneous substrates, with more egg‐sized stones, compared with random sites. Egg crypsis, as indexed by time required of a naïve observer to detect a nest, increased with number of egg‐sized substrates. Nest survival correlated negatively with heterogeneity of substrates and positively with the number of egg‐sized stones. Consistently high nesting success of Plovers on gravel bars indicates that this high‐quality habitat deserves special management considerations given the species’ threatened status.