scholarly journals Exploring the morphospace in subterranean spiders

2018 ◽  
Vol 1 ◽  
Author(s):  
Andrea Dejanaz ◽  
Stefano Mammola ◽  
Marco Isaia
Keyword(s):  
Niche Overlap ◽  
Character Displacement ◽  
Morphological Characters ◽  
Similar Degree ◽  
Multidimensional Space ◽  
Italian Alps ◽  
Trophic Specialization ◽  
Direct Competition ◽  
Coexisting Species

In light of the reduced diversity and abundance of species, subterranean habitats represent ideal models systems in which to investigate characters displacement in species sharing the same habitat. In order to minimize direct competition, it is expected that sibling species occupying the same subterranean habitat should differentiate their morphological niche. Conversely, geographically vicariant species occupying similar microhabitats should display a convergent morphology. We tested these hypotheses by studying character displacement in different species of Troglohyphantes Joseph, 1881 spiders (Araneae: Linyphiidae) in the Western Italian Alps. These spiders underwent a remarkable radiations in subterranean habitats, with numerous stenoendemic elements showing different degrees of subterranean adaptation. For each considered species, we examined 10 to 15 females specimens for a number of morphological characters related to body size, degree of subterranean adaptation (eyes development, flattening of the cephalotorax and leg elongation) and trophic specialization (chelicera and fang length). These traits were combined in a multidimensional space in order to describe the geometry of the n-dimensional Hutchinsonian hypervolume representing the morphological niche of each species. Once the hypervolumes were constructed, pairwise similarity among each species niche was calculated using different overlap indexes. We found that the niche hypervolume of all Troglohyphantes species had a comparable size. However, the distance among niche centroids was lower for species with similar subterranean adaptation and significantly higher in coexisting species. Furthermore, when found in the same cave, species with similar degree of adaptation showed a limited niche overlap. Overall, our results highlight the key role of competition in shaping morphology when competing species are present.

scholarly journals Range-wide spatial mapping reveals convergent character displacement of bird song

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190443 ◽  
Author(s):  
Alexander N. G. Kirschel ◽  
Nathalie Seddon ◽  
Joseph A. Tobias
Keyword(s):  
Spatial Patterns ◽  
Evolutionary Biology ◽  
Environmental Gradients ◽  
Empirical Studies ◽  
Remote Sensing Data ◽  
Character Displacement ◽  
Similar Species ◽  
Interspecific Territoriality ◽  
Coexisting Species

A long-held view in evolutionary biology is that character displacement generates divergent phenotypes in closely related coexisting species to avoid the costs of hybridization or ecological competition, whereas an alternative possibility is that signals of dominance or aggression may instead converge to facilitate coexistence among ecological competitors. Although this counterintuitive process—termed convergent agonistic character displacement—is supported by recent theoretical and empirical studies, the extent to which it drives spatial patterns of trait evolution at continental scales remains unclear. By modelling the variation in song structure of two ecologically similar species of Hypocnemis antbird across western Amazonia, we show that their territorial signals converge such that trait similarity peaks in the sympatric zone, where intense interspecific territoriality between these taxa has previously been demonstrated. We also use remote sensing data to show that signal convergence is not explained by environmental gradients and is thus unlikely to evolve by sensory drive (i.e. acoustic adaptation to the sound transmission properties of habitats). Our results suggest that agonistic character displacement driven by interspecific competition can generate spatial patterns opposite to those predicted by classic character displacement theory, and highlight the potential role of social selection in shaping geographical variation in signal phenotypes of ecological competitors.

scholarly journals Range-wide spatial mapping reveals convergent character displacement of bird song

2019 ◽  
Author(s):  
Alexander N. G. Kirschel ◽  
Nathalie Seddon ◽  
Joseph A. Tobias
Keyword(s):  
Spatial Patterns ◽  
Evolutionary Biology ◽  
Environmental Gradients ◽  
Empirical Studies ◽  
Remote Sensing Data ◽  
Character Displacement ◽  
Similar Species ◽  
Interspecific Territoriality ◽  
Coexisting Species

AbstractA long-held view in evolutionary biology is that character displacement generates divergent phenotypes in closely related coexisting species to avoid the costs of hybridisation or ecological competition, whereas an alternative possibility is that signals of dominance or aggression may instead converge to facilitate coexistence among ecological competitors. Although this counter-intuitive process—termed convergent agonistic character displacement—is supported by recent theoretical and empirical studies, the extent to which it drives spatial patterns of trait evolution at continental scales remains unclear. By modeling variation in song structure of two ecologically similar species of Hypocnemis antbird across western Amazonia, we show that their territorial signals converge such that trait similarity peaks in the sympatric zone, where intense interspecific territoriality between these taxa has previously been demonstrated. We also use remote sensing data to show that signal convergence is not explained by environmental gradients and is thus unlikely to evolve by sensory drive (i.e. acoustic adaptation to the sound transmission properties of habitats). Our results suggest that agonistic character displacement driven by interspecific competition can generate spatial patterns opposite to those predicted by classic character displacement theory, and highlight the potential role of social selection in shaping geographical variation in signal phenotypes of ecological competitors.

scholarly journals Dietary niche overlap of free-roaming dingoes and domestic dogs: the role of human-provided food

2014 ◽  
Vol 95 (2) ◽  
pp. 392-403 ◽  
Author(s):  
Thomas M. Newsome ◽  
Guy-Anthony Ballard ◽  
Mathew S. Crowther ◽  
Peter J. S. Fleming ◽  
Christopher R. Dickman
Keyword(s):  
Niche Overlap ◽  
Domestic Dogs ◽  
Dietary Niche

NEST SITE SELECTION BY BUMBLE BEES (HYMENOPTERA: APIDAE) IN SOUTHERN ALBERTA

1978 ◽  
Vol 110 (3) ◽  
pp. 301-318 ◽  
Author(s):  
K. W. Richards
Keyword(s):  
Site Selection ◽  
Nest Site ◽  
Niche Overlap ◽  
Nest Site Selection ◽  
Bumble Bees ◽  
Social Parasites ◽  
Southern Alberta ◽  
Nesting Sites ◽  
Coexisting Species ◽  
Nesting Preferences

AbstractThe niche breadth and overlap in nesting preferences of 15 species of bumble bees were investigated in Alberta. Some of the factors that influence the distribution of nesting sites and abundance of species and permit the species to coexist in sympatry are discussed. Artificial domiciles were used as potential nesting sites. Some species were specialists in terms of nest site selection while others were generalists. The few natural nests found, the long periods spent by queens searching for nests, the high frequency of usurpation or direct interference and death of intruders, and the frequency of high niche overlap values between species are evidence that nesting sites are limited and are incompletely partitioned among the coexisting species. Usurpation also demonstrates the competition among individuals and species. Phenological differences in nest establishment influence the competition among the species. Camouflaging of tunnels presumably reduces the intensity of usurpation and protects queens and the brood from inclement weather and from social parasites (e.g., Psithyrus) and predators.

scholarly journals The Valine Anticodon and Valylatability of Peanut Clump Virus RNAs Are Not Essential but Provide a Modest Competitive Advantage in Plants

2000 ◽  
Vol 74 (18) ◽  
pp. 8720-8725 ◽  
Author(s):  
Daiki Matsuda ◽  
Patrice Dunoyer ◽  
Odile Hemmer ◽  
Christiane Fritsch ◽  
Theo W. Dreher
Keyword(s):  
Sequence Analysis ◽  
Nicotiana Benthamiana ◽  
General Characteristic ◽  
Wild Type ◽  
Genomic Rnas ◽  
Viral Rnas ◽  
Fold Reduction ◽  
Direct Competition

ABSTRACT The role of valine aminoacylation of the two genomic RNAs ofPeanut clump virus (PCV) was studied by comparing the amplification in vivo of RNAs with GAC, GΔC, or CCA anticodons in the tRNA-like structure (TLS) present at the 3′ end of each viral RNA. The PCV RNA1 TLS of isolate PCV2 possesses a GAC anticodon and is capable of highly efficient valylation, whereas the RNA2 TLS has a GΔC anticodon that does not support valylation. The presence in RNA1 of GΔC or CCA anticodons that conferred nonvalylatability resulted in about 2- to 4-fold and a 14- to 24-fold reduction, respectively, in RNA accumulations in tobacco BY-2 protoplasts inoculated with the RNA1 variants together with wild-type RNA2(GΔC). No differences in RNA levels were observed among protoplasts inoculated with the three variant RNA2s in the presence of wild-type RNA1(GAC). All combinations of valylatable and nonvalylatable RNAs 1 and 2 were similarly infectious in Nicotiana benthamiana plants, and viral RNAs accumulated to similar levels; all input TLS sequences were present unchanged in apical leaves. In direct competition experiments in N. benthamiana plants, however, both RNA1 and RNA2 with GAC valylatable anticodons outcompeted the nonvalylatable variants. We conclude that valylation provides a small but significant replicational advantage to both PCV RNAs. Sequence analysis of the TLS from RNA2 of a second PCV isolate, PO2A, revealed the presence of an intact GAC valine anticodon, suggesting that the differential valylation of the genomic RNAs of isolate PCV2 is not a general characteristic of PCV.

Epiphytic lichen conservation in the Italian Alps: the role of forest type

2014 ◽  
Vol 11 ◽  
pp. 164-172 ◽  
Author(s):  
Juri Nascimbene ◽  
Pier Luigi Nimis ◽  
Matteo Dainese
Keyword(s):  
Forest Type ◽  
Italian Alps ◽  
Epiphytic Lichen ◽  
Lichen Conservation

scholarly journals Understanding the evolution of phenotypical characters in the Micarea prasina group (Pilocarpaceae) and descriptions of six new species within the group

MycoKeys ◽  
2019 ◽  
Vol 57 ◽  
pp. 1-30
Author(s):  
Beata Guzow-Krzemińska ◽  
Emmanuël Sérusiaux ◽  
Pieter P. G. van den Boom ◽  
A. Maarten Brand ◽  
Annina Launis ◽  
...  
Keyword(s):  
New Species ◽  
Secondary Metabolites ◽  
Phylogenetic Analyses ◽  
Morphological Characters ◽  
Its Rdna ◽  
Ancestral State ◽  
Secondary Substances ◽  
Gyrophoric Acid

Six new Micarea species are described from Europe. Phylogenetic analyses, based on three loci, i.e. mtSSU rDNA, Mcm7 and ITS rDNA and ancestral state reconstructions, were used to evaluate infra-group divisions and the role of secondary metabolites and selected morphological characters on the taxonomy in the M.prasina group. Two main lineages were found within the group. The Micareamicrococca clade consists of twelve species, including the long-known M.micrococca and the newly described M.microsorediata, M.nigra and M.pauli. Within this clade, most species produce methoxymicareic acid, with the exceptions of M.levicula and M.viridileprosa producing gyrophoric acid. The M.prasina clade includes the newly described M.azorica closely related to M.prasina s.str., M.aeruginoprasina sp. nov. and M.isidioprasina sp. nov. The species within this clade are characterised by the production of micareic acid, with the exception of M.herbarum which lacks any detectable substances and M.subviridescens that produces prasinic acid. Based on our reconstructions, it was concluded that the ancestor of the M.prasina group probably had a thallus consisting of goniocysts, which were lost several times during evolution, while isidia and soredia evolved independently at multiple times. Our research supported the view that the ancestor of M.prasina group did not produce any secondary substances, but they were gained independently in different lineages, such as methoxymicareic acid which is restricted to M.micrococca and allied species or micareic acid present in the M.prasina clade.

scholarly journals Considering the role of ecology on individual differentiation

2016 ◽  
Vol 39 ◽  
Author(s):  
Tomás Cabeza de Baca ◽  
Rafael Antonio Garcia ◽  
Michael Anthony Woodley of Menie ◽  
Aurelio José Figueredo
Keyword(s):  
Social Roles ◽  
Social Systems ◽  
Character Displacement ◽  
Complex Societies ◽  
Levels Of Organization ◽  
Multiple Levels ◽  
Individual Differentiation ◽  
Strategic Differentiation ◽  
Integration Effort

AbstractOur commentary articulates some of the commonalities between Baumeister et al.'s theory of socially differentiated roles and Strategic Differentiation-Integration Effort. We expand upon the target article's position by arguing that differentiating social roles is contextual and driven by varying ecological pressures, producing character displacement not only among individuals within complex societies, but also across social systems and multiple levels of organization.

Cryptic Diversity and Sexual Selection

2020 ◽  
pp. 447-471
Author(s):  
Matthias Galipaud ◽  
Loïc Bollache ◽  
Clément Lagrue
Keyword(s):  
Sexual Selection ◽  
Morphological Traits ◽  
Character Displacement ◽  
Secondary Contact ◽  
Cryptic Diversity ◽  
Reproductive Character Displacement ◽  
Behavioral Traits ◽  
Genetic Techniques ◽  
Existing Data

Recent advances in molecular and genetic techniques have revealed tremendous hidden genetic diversity in plants and animals. Crustaceans are no exception and, in fact, present one of the highest levels of cryptic diversity among the metazoans. Beyond the importance of such discovery and its multiple implications for taxonomy and ecology, it is now timely to investigate the potential causes of cryptic diversity. This chapter reviews the theoretical and experimental literature, seeking evidences for a relationship between sexual selection and cryptic diversity in crustaceans. It proposes three scenarios for the role of sexual selection on the origin and maintenance of pre-mating isolation and genetic divergence among crustacean populations, and suggests ways to discriminate among them experimentally or using existing data. Assuming that taxonomic identification is largely based on differences in sexually selected morphological traits, it also reviews evidence for a cryptic action of sexual selection on crustacean phenotypes. Specifically, if sexual selection acts primarily on chemical, visual, or behavioral traits, it is likely that allopatric crustacean populations remain morphologically similar even when they are reproductively isolated. This review shows that the strength of sexual selection likely differs among allopatric populations but does not seem to consistently induce pre-mating isolation (e.g. as in copepods and amphipods). Research is now needed to try to identify general patterns and determine the role of sexual selection on pre-mating isolation after secondary contact between populations, through reinforcement and reproductive character displacement.

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