scholarly journals Congruence between fine-scale genetic breaks and dispersal potential in an estuarine seaweed across multiple transition zones

2019 ◽  
Vol 77 (1) ◽  
pp. 371-378 ◽  
Author(s):  
Katy R Nicastro ◽  
Jorge Assis ◽  
Ester A Serrão ◽  
Gareth A Pearson ◽  
João Neiva ◽  
...  
Keyword(s):  
Glacial Refugia ◽  
Secondary Contact ◽  
Population Fragmentation ◽  
Comprehensive Understanding ◽  
Transition Zones ◽  
Nw Iberia ◽  
Limited Dispersal ◽  
Genetic Clustering ◽  
Glacial Expansion

Abstract Genetic structure in biogeographical transition zones can be shaped by several factors including limited dispersal across barriers, admixture following secondary contact, differential selection, and mating incompatibility. A striking example is found in Northwest France and Northwest Spain, where the estuarine seaweed Fucus ceranoides L. exhibits sharp, regional genetic clustering. This pattern has been related to historical population fragmentation and divergence into distinct glacial refugia, followed by post-glacial expansion and secondary contact. The contemporary persistence of sharp ancient genetic breaks between nearby estuaries has been attributed to prior colonization effects (density barriers) but the effect of oceanographic barriers has not been tested. Here, through a combination of mesoscale sampling (15 consecutive populations) and population genetic data (mtIGS) in NW France, we define regional genetic disjunctions similar to those described in NW Iberia. Most importantly, using high resolution dispersal simulations for Brittany and Iberian populations, we provide evidence for a central role of contemporary hydrodynamics in maintaining genetic breaks across these two major biogeographic transition zones. Our findings further show the importance of a comprehensive understanding of oceanographic regimes in hydrodynamically complex coastal regions to explain the maintenance of sharp genetic breaks along continuously populated coastlines.

Exclusion of the Role of Secondary Contact in an Allele Frequency Cline in the Mussel Mutilus edulis

Evolution ◽  
1985 ◽  
Vol 39 (2) ◽  
pp. 432 ◽  
Author(s):  
Thomas J. Hilbish ◽  
Richard K. Koehn
Keyword(s):  
Allele Frequency ◽  
Secondary Contact

scholarly journals Modeling Uncertainty-Seeking Behavior Mediated by Cholinergic Influence on Dopamine

2019 ◽  
Author(s):  
Marwen Belkaid ◽  
Jeffrey L. Krichmar
Keyword(s):  
Decision Making ◽  
Dopaminergic Neurons ◽  
Cholinergic System ◽  
Dopamine Neurons ◽  
Comprehensive Understanding ◽  
Dopaminergic Activity ◽  
Integrate And Fire ◽  
Major Implication ◽  
Seeking Behavior

AbstractRecent findings suggest that acetylcholine mediates uncertainty-seeking behaviors through its projection to dopamine neurons – another neuromodulatory system known for its major implication in reinforcement learning and decision-making. In this paper, we propose a leaky-integrate-and-fire model of this mechanism. It implements a softmax-like selection with an uncertainty bonus by a cholinergic drive to dopaminergic neurons, which in turn influence synaptic currents of downstream neurons. The model is able to reproduce experimental data in two decision-making tasks. It also predicts that i) in the absence of cholinergic input, dopaminergic activity would not correlate with uncertainty, and that ii) the adaptive advantage brought by the implemented uncertainty-seeking mechanism is most useful when sources of reward are not highly uncertain. Moreover, this modeling work allows us to propose novel experiments which might shed new light on the role of acetylcholine in both random and directed exploration. Overall, this study thus contributes to a more comprehensive understanding of the roles of the cholinergic system and its involvement in decision-making in particular.

Extensive hybridization between two Andean warbler species with shallow divergence in mtDNA

The Auk ◽  
2021 ◽  
Vol 138 (1) ◽  
Author(s):  
Laura N Céspedes-Arias ◽  
Andrés M Cuervo ◽  
Elisa Bonaccorso ◽  
Marialejandra Castro-Farias ◽  
Alejandro Mendoza-Santacruz ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Contact Zone ◽  
Hybrid Zone ◽  
Secondary Contact ◽  
Tropical Andes ◽  
Phenotypic Data ◽  
Geographic Ranges ◽  
Intermediate Phenotypes ◽  
Ecological Barriers

Abstract Studying processes acting on differentiated populations upon secondary contact, such as hybridization, is important to comprehensively understand how species are formed and maintained over time. However, avian speciation studies in the tropical Andes have largely focused on the role of topographic and ecological barriers promoting divergence in allopatry, seldom examining hybridization and introgression. We describe a hybrid zone involving 2 closely related Andean warblers (Parulidae), the Golden-fronted Redstart (Myioborus ornatus), and the Spectacled Redstart (Myioborus melanocephalus). Geographic ranges of these species abut near the Colombia-Ecuador border and many specimens from the region exhibit intermediate phenotypes, but a formal description of phenotypic variation in the contact zone was heretofore lacking. We collected specimens across a transect encompassing the area where ranges abut and areas where only “pure” parental phenotypes of M. ornatus chrysops and M. melanocephalus ruficoronatus occur. We described variation in plumage traits including patterns of head and ventral coloration and tail markings based on 321 specimens. To describe genetic variation in the contact zone and over a broader phylogeographic context, we used sequences of the mitochondrial ND2 gene for 219 individuals across the transect and the entire range of both species, including all subspecies, from Venezuela to Bolivia. We documented a hybrid zone ~200 km wide based on head coloration, where intermediate plumage phenotypes are most common and “pure” forms do not overlap geographically, consistent with extensive hybridization. Across the range of the M. ornatus–M. melanocephalus complex, mitochondrial genetic structure was shallow, with genetic breaks only coinciding clearly with one topographic feature. Such a low genetic structure is striking given the high diversity in plumage phenotypes and the current taxonomy of the group. Our phenotypic data suggest that barriers to hybridization are not strong, and allow us to postulate hypotheses to be tested using forthcoming genomic data.

Shared Life and Politics

2020 ◽  
pp. 86-128
Author(s):  
Sara Brill
Keyword(s):  
Political Life ◽  
The Political ◽  
Human Beings ◽  
Comprehensive Understanding

This chapter tracks the role of shared life in Aristotle’s account of the political bond, including its formation, maintenance, and the factors that bring about its dissolution. Here suzēn forms a spectrum, from the familial bond of those who cannot live without one another to the reciprocal affection of chosen friends, and includes both the impulse to live together that exists by merit of the kind of animal the human is (a political animal) and the exercise of the capacity for choice when it is directed to other human beings. Its inclusion of both human impulse and choice indicates that a comprehensive understanding of the phenomenon of shared life requires one to locate human political life within the context of Aristotle’s broader study of political animality.

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.

scholarly journals Two-electron transfer stabilized by excited-state aromatization

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jinseok Kim ◽  
Juwon Oh ◽  
Seongchul Park ◽  
Jose L. Zafra ◽  
Justin R. DeFrancisco ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Excited States ◽  
Transfer Process ◽  
Comprehensive Understanding ◽  
Electron Transfer Process ◽  
Photoactive Materials ◽  
Donor Acceptor ◽  
Scientific Significance

Abstract The scientific significance of excited-state aromaticity concerns with the elucidation of processes and properties in the excited states. Here, we focus on TMTQ, an oligomer composed of a central 1,6-methano[10]annulene and 5-dicyanomethyl-thiophene peripheries (acceptor-donor-acceptor system), and investigate a two-electron transfer process dominantly stabilized by an aromatization in the low-energy lying excited state. Our spectroscopic measurements quantitatively observe the shift of two π-electrons between donor and acceptors. It is revealed that this two-electron transfer process accompanies the excited-state aromatization, producing a Baird aromatic 8π core annulene in TMTQ. Biradical character on each terminal dicyanomethylene group of TMTQ allows a pseudo triplet-like configuration on the 8π core annulene with multiexcitonic nature, which stabilizes the energetically unfavorable two-charge separated state by the formation of Baird aromatic core annulene. This finding provides a comprehensive understanding of the role of excited-state aromaticity and insight to designing functional photoactive materials.

The Willingness of Social Work Students to Engage in Policy Practice: The Role of Personality Traits and Political Participation Predictors

2020 ◽  
Author(s):  
Talia Meital Schwartz-Tayri
Keyword(s):  
Social Work ◽  
Personality Traits ◽  
Big Five ◽  
Social Work Students ◽  
Political Knowledge ◽  
Big Five Personality ◽  
Comprehensive Understanding ◽  
Political Skills ◽  
Policy Practice

Abstract The current study aimed to expand our knowledge regarding social work students’ willingness to engage in policy practice (EPP). A theoretical model integrating the Big Five personality framework with the ‘Civic Voluntarism Model’ (CVM) was examined, using a sample of 160 social work students in Israel. Findings revealed a moderate level of EPP willingness. Among the CVM predictors, political skills, political knowledge and political interest were significantly positively associated with social work students’ EPP willingness. Among the Big Five traits, extroversion, conscientiousness and openness to experience were significantly associated with EPP willingness. Path analysis showed that political skills were the strongest predictor of EPP willingness and that political skills and extroversion had a direct effect on EPP willingness. The significant mediation paths demonstrated the dynamics by which the study predictors interacted in explaining 49 per cent of the variance in EPP willingness. The study concluded that the examination of a model incorporating the Big Five personality traits and modified CVM predictors provided a comprehensive understanding of EPP willingness and, therefore, should be adopted to explain social workers’ actual engagement in policy practice.

scholarly journals A developed understanding of the beneficiary’s interest in commercial trusts through a comparative study of Chinese law

2020 ◽  
Vol 27 (3) ◽  
pp. 343-357
Author(s):  
Ruiqiao Zhang
Keyword(s):  
Comparative Study ◽  
Theoretical Basis ◽  
Comprehensive Understanding ◽  
Main Claim ◽  
Chinese Law ◽  
Judicial Interpretations

Trusts have existed for centuries, while societies and economies have developed in the intervening years. This requires renovations, or new judicial interpretations, of what a trust is in order to adapt it to modern circumstances. Based on a discussion about the theoretical basis for the research – the new role of trusts in a commercial context and the essence of the trust – the author provides a developed understanding of the beneficiary’s interest to adjust the traditional trust notions to meet the demands of commercial practices. She argues that, based on a case study of Chinese law, a beneficiary’s right can be explained as a special personal claim consisting of three parts: the main claim (personal claims), appurtenant rights (rights of supervision) and security rights (rights of revocation). The theory of beneficiary’s special personal claim provides a more unified and comprehensive understanding of the nature of the beneficiary’s interest, particularly in newly developed commercial trusts.

Intraoperative Neurophysiological Monitoring of the Laryngeal Nerves During Anterior Neck Surgery

2016 ◽  
Vol 126 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Anurag Tewari ◽  
Ravi N. Samy ◽  
Joshua Castle ◽  
Tiffany M. Frye ◽  
Miguel E. Habeych ◽  
...  
Keyword(s):  
Organizational Support ◽  
Neck Surgery ◽  
Neurophysiological Monitoring ◽  
Nerve Injuries ◽  
Comprehensive Understanding ◽  
Anterior Neck ◽  
Anterior Compartment ◽  
Neural Monitoring ◽  
Nerve Identification

Contributions to the literature on intraoperative neuro monitoring (IONM) during endocrine and head and neck surgery have increased over recent years. Organizational support for neural monitoring during surgery is becoming evident and is increasingly recognized as an adjunct to visual nerve identification. A comprehensive understanding of the role of IONM for prevention of nerve injuries is critical to maximize safety during surgery of the anterior compartment of the neck. This review will explore the potential advantages of IONM to improve the outcomes among patients undergoing anterior neck surgery.

Sign in / Sign up

Export Citation Format

Share Document