Search results for "differentiation"

Divergent parasite infections in sympatric cichlid species in Lake Victoria

2018

Parasitism has been proposed as a factor in host speciation, as an agent affecting coexistence of host species in species-rich communities and as a driver of post-speciation diversification. Young adaptive radiations of closely related host species of varying ecological and genomic differentiation provide interesting opportunities to explore interactions between patterns of parasitism, divergence and coexistence of sympatric host species. Here, we explored patterns in ectoparasitism in a community of 16 fully sympatric cichlid species at Makobe Island in Lake Victoria, a model system of vertebrate adaptive radiation. We asked whether host niche, host abundance or host genetic differentiatio…

Speciation in the Brachionus plicatilis Species Complex

2017

The Brachionus plicatilis species complex is the best-studied example among rotifers where the use of integrative taxonomy, coupling morphology, ecology, physiology, cross-mating experiments, and DNA taxonomy helps disentangling the biological reality of the different species in the complex. Here we review the theoretical and empirical approaches in species definition applied to the B. plicatilis complex, we outline the history of the discovery of the complex, and we explore the evidence in support of the currently accepted presence of 15 species. We review the evidence for long-distance dispersal and for co-occurrence of the species in the complex, including the processes favoring the co-o…

Dendritic cell metabolism: moving beyond in vitro-culture-generated paradigms

2021

Dendritic cells (DCs) are key orchestrators of immunity and tolerance. It has become evident that DC function can be influenced by cellular metabolic programs. However, conclusions from early metabolic studies using in vitro GM-CSF DC cultures fail to correlate with bona fide DC populations. Here, we discuss the existing paradigms in the DC metabolism field, focusing on the limitations of the models utilized. Furthermore, we introduce alternative models to generate DCs in vitro that better emulate DCs found in vivo. Finally, we highlight new techniques to evaluate DC metabolism at the single-cell level. The combination of these two strategies could help advance the DC metabolism field towar…

2019

A central prediction of niche theory is that biotic communities are structured by niche differentiation arising from competition. To date, there have been numerous studies of niche differentiation in local ant communities, but little attention has been given to the macroecology of niche differentiation, including the extent to which particular biomes show distinctive patterns of niche structure across their global ranges. We investigated patterns of niche differentiation and competition in ant communities in tropical rainforests, using different baits reflecting the natural food spectrum. We examined the extent of temporal and dietary niche differentiation and spatial segregation of ant com…

Tooth tales told by dental diet proxies: An alpine community of sympatric ruminants as a model to decipher the ecology of fossil fauna

2021

Abstract Paleobiologists tend to use dietary information as an ecological indicator because diet is a fundamental link between an organism and its environment. However, the ecological information from fossilized hard tissues is often difficult to interpret, because links between environment, diet, and hard tissue biology are insufficiently studied in modern communities. To address this dilemma, we investigated dietary proxies commonly used by paleobiologists in a 4-ruminant community from the French Alps. Dental microwear texture analyses are applied to 82 specimens of roe deer, red deer, chamois, and mouflons. Intra-tooth serial enamel stable carbon and oxygen isotope analyses of the struc…

Consumer perspectives on coastal fisheries and product labelling in France and Italy

2022

Abstract The term ‘coastal fisheries’ designates a form of fishing which is under heavy pressure due to competition by large-scale high sea fishing. Setting up markets for seafood from coastal fisheries might offer possibilities of product differentiation when appreciated by consumers. The aim of this research is to analyse the potential of marketing seafood from coastal fisheries by investigating consumers’ perception of coastal fisheries and their attitudes towards a label for coastal fishery products in France and Italy. This research combined qualitative (focus groups) and quantitative methods (online survey) in two different steps. ‘Coastal fisheries’ were mainly perceived positively, …

Analysis of spatial patterns informs community assembly and sampling requirements for Collembola in forest soils

2018

Abstract The relative importance of niche separation, non-equilibrial and neutral models of community assembly has been a theme in community ecology for many decades with none appearing to be applicable under all circumstances. In this study, Collembola species abundances were recorded over eleven consecutive years in a spatially explicit grid and used to examine (i) whether observed beta diversity differed from that expected under conditions of neutrality, (ii) whether sampling points differed in their relative contributions to overall beta diversity, and (iii) the number of samples required to provide comparable estimates of species richness across three forest sites. Neutrality could not…

Fine‐grain beta diversity of Palaearctic grassland vegetation

2021

QUESTIONS: Which environmental factors influence fine-grain beta diversity of vegetation and do they vary among taxonomic groups? LOCATION: Palaearctic biogeographic realm. METHODS: We extracted 4,654 nested-plot series with at least four different grain sizes between 0.0001 m² and 1,024 m² from the GrassPlot database, covering a wide range of different grassland and other open habitat types. We derived extensive environmental and structural information for these series. For each series and four taxonomic groups (vascular plants, bryophytes, lichens, all), we calculated the slope parameter (z-value) of the power law species–area relationship (SAR), as a beta diversity measure. We tested whe…

Maternal effects in quail and zebra finches: behavior and hormones.

2013

8 pages; International audience; Maternal effects are influences of parents on offspring phenotype occurring through pathways other than inherited DNA. In birds, two important routes for such transmission are parental behavior and non-DNA egg constituents such as yolk hormones. Offspring traits subject to parental effects include behavior and endocrine function. Research from the Adkins-Regan lab has used three avian species to investigate maternal effects related to hormones and behavior. Experiments with chickens and Japanese quail have shown that maternal sex steroids can influence sex determination to produce biased offspring sex ratios. Because all birds have a ZZ/ZW chromosomal sex de…

Molecular and morphological data suggest weak phylogeographic structure in the fairy shrimp Streptocephalus torvicornis (Branchiopoda, Anostraca)

2017

Inland aquatic organisms almost ubiquitously display a pattern of marked provincialism characterized by substantial population differentiation and genealogical discontinuities. This is the result of strong priority effects and local adaptation following dispersal and colonization of new habitats. We present a case that defies this biogeographic paradigm. We have investigated the phylogeography of the fairy shrimp Streptocephalus torvicornis across its circum-Mediterranean and Eurasian distribution. Based on three independent datasets, namely sequence variation at 12S and 16S rRNA, cyst morphology and male second antenna characters, we discern a pattern of extensive genetic and morphological…