1,721,110 research outputs found
Is the taxonomy of Brachycephalus (Anura: Brachycephalidae) in need of rescue? A reply to Condez et al. (2017)
No full textPie, Marcio R., Ribeiro, Luiz F., Bornschein, Marcos R. (2017): Is the taxonomy of Brachycephalus (Anura: Brachycephalidae) in need of rescue? A reply to Condez et al. (2017). Zootaxa 4350 (3): 587-589, DOI: 10.11646/zootaxa.4350.3.1
Phylogenetic diversity and the structure of host-epiphyte interactions across the Neotropics
No full textUnderstanding the mechanisms driving community assembly has been a major focus of ecological research for nearly a century, yet little is known about these mechanisms in commensal communities, particularly with respect to their historical/evolutionary components. Here, we use a large-scale dataset of 4,440 vascular plant species to explore the relationship between the evolutionary distinctiveness (ED) (as measured by the ’species evolutionary history’ (SEH)) of host species and the phylogenetic diversity (PD) of their associated epiphyte species. Although there was considerable variation across hosts and their associated epiphyte species, they were largely unrelated to host SEH. Our results mostly support the idea that the determinants of epiphyte colonization success might involve host characteristics that are unrelated to host SEH (e.g., architectural differences between hosts). While determinants of PD of epiphyte assemblages are poorly known, they do not appear to be related to the evolutionary history of host species. Instead, they might be better explained by neutral processes of colonization and extinction. However, the high level of phylogenetic signal in epiphyte PD (independent of SEH) suggests it might still be influenced by yet unrecognized evolutionary determinants. This study highlights how little is still known about the phylogenetic determinants of epiphyte communities
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A null model of morphospace occupation.
No full textProgress in understanding the relationship between lineage diversity, morphological diversity, and morphospace dynamics has been hampered by the lack of an appropriate null model of morphospace occupation. In this article, we introduce a simple class of models based on branching random walks (BRWs) for continuous traits. We show that many of the observed patterns of morphospace occupation might be simply a consequence of the dynamics of BRWs and therefore might not require special explanations. We also provide expected patterns of morphospace occupation according to a number of different conditions. In particular, we model BRWs on neutral landscapes and demonstrate that clumping in morphospace is possible even in the absence of adaptive landscapes with well-defined peaks and valleys. The quantitative definition of the BRW provides a means to analyze, both computationally and analytically, patterns of morphospace occupation according to different hypotheses.</p
Lek behavior as the mating strategy of Setellia sp. (Diptera:Richardiidae)
No full textA field study revealed that the mating system of the richardiid Setellia sp. meets even the most stringent definition of lek behavior. Males remain on the upper surface of the leaves of Saranthe aff. klotzchiana (Maranthaceae), where they perform ritualized displays related to courtship and territorial behavior. Correlational data support the existence of reproductive dominance hierarchies, which are based on both male vs. male and female vs. female agonistic interactions. Curiously, the behavioral acts performed by Setellia sp. show remarkable similarities to other nonrelated dipteran lekkers. Aspects of evolution and convergence of these behaviors in the Acalyptratae are considered.</p
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The influence of phylogenetic uncertainty on the detection of positive darwinian selection
No full textThe power of maximum likelihood tests of positive selection on protein-coding genes depends heavily on detecting and accounting for potential biases in the studied data set. Although the influence of transition: transversion and codon biases have been investigated in detail, little is known about how inaccuracy in the phylogeny used during the calculations affects the performance of these tests. In this study, 3 empirical data sets are analyzed using sets of simulated topologies corresponding to low, intermediate, and high levels of phylogenetic uncertainty. The detection of positive selection was largely unaffected by errors in the underlying phylogeny. However, the number of sites identified as being under positive selection tended to be overestimated.</p
Behavioral repertoire, age polyethism and adult transport in Ectatomma opaciventre (Formicidae:Ponerinae)
No full textThis study describes the behavioral repertoire of a mature colony of Ectatomma opaciventre Roger. Twenty-eight different behavioral acts were recorded from 4538 individual observations. There was evidence of age polyethism, with young workers performing significantly more brood care and allogrooming than older workers. Experiments were also performed to investigate the behavioral organization of nest relocation in E. opaciventre. This complex social behavior was regulated by a few workers which specialized in transporting nestmates, including other workers, winged gynes, males, and the queen. Winged gynes were also observed performing adult transport. The carrying posture utilized in E. opaciventre is similar to that in other ponerines, although some idiosyncratic features were detected.</p
Signal evolution in prey recognition systems
No full textIn this paper a graphical model first developed in the context of kin recognition is adapted to the study of signalling in predator-prey systems. Antipredation strategies are envisioned as points along a signal-to-noise (S/N) axis, with concealing (low S/N) and conspicuous (high S/N) strategies being placed at opposite sides of this axis. Optimal prey recognition systems should find a trade-off between acceptance errors (going after a background cue as if it were a prey) and rejection errors (not going after a prey as if it were background noise). The model also predicts the types of cues the predator should use in opposite sides of the S/N axis.</p
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