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 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 Generalizing clusters of similar species as a signature of coexistence under competition

2018 ◽  
Author(s):  
Rafael D’Andrea ◽  
Maria Riolo ◽  
Annette Ostling
Keyword(s):  
Environmental Gradients ◽  
Species Traits ◽  
Life History Strategies ◽  
Recent Theory ◽  
Similar Species ◽  
Demographic Stochasticity ◽  
Competing Species ◽  
Environmental Preferences ◽  
Self Organized ◽  
Coexisting Species

AbstractPatterns of trait distribution among competing species can potentially reveal the processes that allow them to coexist. It has been recently proposed that competition may drive the spontaneous emergence of niches comprising clusters of similar species, in contrast with the dominant paradigm of greater-than-chance species differences. However, current clustering theory relies largely on heuristic rather than mechanistic models. Furthermore, studies of models incorporating demographic stochasticity and immigration, two key players in community assembly, did not observe clusters. Here we demonstrate clustering under partitioning of resources, partitioning of environmental gradients, and a competition-colonization tradeoff. We show that clusters are robust to demographic stochasticity, and can persist under immigration. While immigration may sustain clusters that are otherwise transient, too much dilutes the pattern. In order to detect and quantify clusters in nature, we introduce and validate metrics which have no free parameters nor require arbitrary trait binning, and weigh species by their abundances rather than relying on a presence-absence count. By generalizing beyond the circumstances where clusters have been observed, our study contributes to establishing them as an update to classical trait patterning theory.Author SummarySpecies traits determine how they compete with each other. As such, patterns in the distributions of traits in a community of competing species may reveal the processes responsible for coexistence. One central idea in theoretical ecology is that the strength of competition relates to similarity in species needs and strategies, and therefore if competition plays out at short timescales, coexisting species should be more different than expected by chance. However, recent theory suggests that competition may lead species to temporarily self-organize into groups with similar traits. Here we show that this clustering is a generic feature of competitive dynamics, which is robust to demographic stochasticity and can be indefinitely maintained by immigration. We show that clustering arises whether species coexist by partitioning resources, environmental preferences, or through tradeoffs in life-history strategies. We introduce and validate metrics that, given species traits and abundances, determine whether they are clustered, and if so, how many clusters occur. By showing the generality of self-organized species clusters and providing a tools for their detection, our study contributes to updating classical ideas about how competition shapes communities, and motivates searches for them in nature.

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 Sex in the wild: how and why field-based studies contribute to solving the problem of sex

2017 ◽  
Author(s):  
Maurine Neiman ◽  
Patrick G. Meirmans ◽  
Tanja Schwander ◽  
Stephanie Meirmans
Keyword(s):  
Adaptive Evolution ◽  
Evolutionary Biology ◽  
Empirical Studies ◽  
Empirical Evaluation ◽  
Natural Populations ◽  
Strong Support ◽  
Niche Differentiation ◽  
In The Wild ◽  
Supplementary Material

AbstractWhy and how sexual reproduction is maintained in natural populations, the so-called “queen of problems”, is a key unanswered question in evolutionary biology. Recent efforts to solve the problem of sex have often emphasized results generated from laboratory settings. Here, we use a survey of representative “sex in the wild” literature to review and synthesize the outcomes of empirical studies focused on natural populations. Especially notable results included relatively strong support for mechanisms involving niche differentiation and a near absence of attention to adaptive evolution. Support for a major role of parasites is largely confined to a single study system, and only three systems contribute most of the support for mutation accumulation hypotheses. This evidence for taxon specificity suggests that outcomes of particular studies should not be more broadly extrapolated without extreme caution. We conclude by suggesting steps forward, highlighting tests of niche differentiation mechanisms in both lab and nature and empirical evaluation of adaptive evolution-focused hypotheses in the wild. We also emphasize the value of leveraging the growing body of genomic resources for non-model taxa to address whether the clearance of harmful mutations and spread of beneficial variants in natural populations proceeds as expected under various hypotheses for sex.Author contributionsSM and MN conceived the paper idea, SM, PM, MN, and TS designed the review strategy, reviewed and analysed the literature, and wrote the manuscript. All authors gave final approval for publication.Data archival locationThe results of our literature survey are provided as electronic supplementary material.

scholarly journals Multiple adaptive solutions to face climatic constraints: novel insights in the debate over the role of convergence in local adaptation

2021 ◽  
Author(s):  
Badr Benjelloun ◽  
Kevin Leempoel ◽  
Frederic Boyer ◽  
Sylvie Stucki ◽  
Ian Streeter ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Evolutionary Biology ◽  
Environmental Gradients ◽  
Relative Role ◽  
Mammal Species ◽  
Environmental Pressures ◽  
Adaptive Mechanisms ◽  
Rainfall Seasonality ◽  
Set Up

The extent to which genomic convergence shapes locally adapted phenotypes in different species remains a fundamental question in evolutionary biology. It would help assessing the relative role of historical contingencies versus determinism in evolution. To bring new insights to this debate we set up a framework which aimed to compare the adaptive trajectories of two domesticated mammal species co-distributed in diversified landscapes. We sequenced the genomes of 160 sheep and 161 goats extensively managed along environmental gradients, including temperature, rainfall, seasonality and altitude, to identify genes and biological processes shaping local adaptation. Allele frequencies at adaptive loci were rarely found to vary gradually along environmental gradients, but rather displayed a discontinuous shift at the extremities of environmental clines. Of the more than 430 adaptive genes identified, only 6 were orthologous between sheep and goats and those responded differently to environmental pressures, suggesting different adaptive mechanisms in these two closely related species. Such diversity of adaptive pathways may result from a high number of biological functions involved in adaptation to multiple eco-climatic gradients, and provides more arguments for the role of contingency and stochasticity in adaptation rather than repeatability and determinism.

Mathematics Textbook as an Object of Research/Matematički udžbenik kao predmet istraživanja

2014 ◽  
Vol 16 ◽  
Author(s):  
Dubravka Glasnović Gracin
Keyword(s):  
Mathematics Education ◽  
Mathematical Knowledge ◽  
Empirical Studies ◽  
Mathematics Textbooks ◽  
Mathematics Textbook ◽  
Mathematics Book

AbstractA mathematics textbook can be described as an officially authorized and pedagogically designed mathematics book written to provide mathematical knowledge to students. This description suggests the authority of the textbook - because it has been authorized by an administrative source and because it deals with authorized knowledge. This paper provides an overview of research on mathematics textbooks. The emphasis is on questions concerning the extent to which and how textbooks are used in mathematics education in Croatia and in the world.Research results show that mathematics textbooks are widely used in mathematics education worldwide. This finding points to the need for research on the content and structure of textbooks. Such studies are combined with the associated results on how textbooks are used in the classroom and which methods teachers apply in using textbooks in mathematics education. The results of the empirical studies show that teachers use textbooks for lesson preparation and pupils use mathematics textbooks for exercises to a great extent. These results imply that such an important role of textbooks in mathematics education deserves additional attention, with the goal of understanding and improving mathematics education.Key words: mathematics education; overview; research on textbook---SažetakMatematički udžbenik može se opisati kao službeno autorizirana i pedagoki osmiljena matematička knjiga napisana s ciljem da učenicima ponudi matematičke sadržaje. Taj opis sugerira autoritet udžbenika jer ga je autorizirao administrativni izvor i jer sadrži autorizirano znanje. Ovaj članak daje pregled istraživanja matematičkih udžbenika, a naglasak je na pitanjima u kojoj mjeri i kako se udžbenici koriste u nastavi matematike u Hrvatskoj i u svijetu.Rezultati raznih istraživanja pokazuju da se udžbenici u velikoj mjeri koriste u nastavi matematike irom svijeta. Taj nalaz ukazuje na potrebu za istraživanjem sadržaja i strukture matematičkih udžbenika. Uz to, prikazani su rezultati istraživanja o tome na koji se način udžbenici koriste u razredu i koje metode nastavnici prakticiraju prilikom upotrebe udžbenika na nastavi. Rezultati empirijskih studija pokazuju da nastavnici udžbenike većinom koriste za pripremu nastavnog sata, a učenici udžbenike koriste u najvećoj mjeri za vježbanje. Ti rezultati ukazuju na to da tako važna uloga udžbenika u matematičkom obrazovanju zaslužuje dodatnu pažnju s ciljem razumijevanja i poboljanja nastave matematike.Ključne riječi: istraživanje udžbenika; nastava matematike; pregled.

The Role of Theories of Embodied Cognition in Research and Modeling of Emotions

2019 ◽  
Vol 62 (5) ◽  
pp. 124-138
Author(s):  
Alexandra V. Shiller
Keyword(s):  
Artificial Intelligence ◽  
Embodied Cognition ◽  
Mirror Neurons ◽  
Empirical Studies ◽  
Unknown Quantity ◽  
Emotional Processes ◽  
Strong Artificial Intelligence ◽  
European Philosophy ◽  
Postmodern Philosophy

The article analyzes the role of theories of embodied cognition for the development of emotion research. The role and position of emotions changed as philosophy developed. In classical and modern European philosophy, the idea of the “primacy of reason” prevailed over emotions and physicality, emotions and affective life were described as low-ranking phenomena regarding cognitive processes or were completely eliminated as an unknown quantity. In postmodern philosophy, attention focuses on physicality and sensuality, which are rated higher than rational principle, mind and intelligence. Within the framework of this approach, there is a recently emerged theory of embodied cognition, which allows to take a fresh look at the place of emotions in the architecture of mental processes – thinking, perception, memory, imagination, speech. The article describes and analyzes a number of empirical studies showing the impossibility of excluding emotional processes and the significance of their research for understanding the architecture of embodied cognition. However, the features of the architecture of embodied cognition remain unclear, and some of the discoveries of recent years (mirror neurons or neurons of simulation) rather raise new questions and require further research. The rigorously described and clear architecture of the embodied cognition can grow the theoretical basis that will allow to advance the studies of learning processes, language understanding, psychotherapy techniques, social attitudes and stereotypes, highlight the riddle of consciousness and create new theories of consciousness or even create an anthropomorphic artificial intelligence that is close to “strong artificial intelligence.”

Expectations from Chinese Muslim Converts for Islamization of Society in Malaysia: Lessons from Life of the Companions (Angkaan Pengubahsuaian Cina Islam untuk Pengislaman Soci-ety di Malaysia: Pelajaran dari Kehidupan Para Sahabat)

2019 ◽  
Vol 16 (1) ◽  
pp. 278-296
Author(s):  
Mek Wok Mahmud ◽  
Sayed Sikandar Shah Haneef
Keyword(s):  
Economic Development ◽  
Empirical Studies ◽  
The Self ◽  
Way Of Life ◽  
Socio Economic Development ◽  
Chinese Muslims ◽  
Process Studies ◽  
Divine Guidance

Reversion to Islam while opening golden opportunities for a revert in terms of divine guidance and spiritual salvation is coming with somewhat insurmountable challenges in terms of Islamization of the self, family and contributions to the overall development of Malaysia as a multi-religious country. This is especially so when Islam as an official religion has made the issue of Islamization of the Malaysian society and its systems amongst the pivotal national agendas in the country.  As to what is the role of Chinese Muslims (reverts) in the process, studies, among others, have purported to present the statistics about their share in socio-economic development. Similarly, empirical studies point to the odds faced by this community at personal, family and community levels in their path for transition to the full Islamic way of life. To the presenters of this paper, however, the macro dimension of what it means to become a Muslim which is essential for adjustment to the Islamic requirements has not been sufficiently highlighted in discourses in the area. Accordingly, this paper presents the position statements on Islamic expectations from Chinese reverts with the purpose of motivating them to achieve greater things in the area of Islamization of their community and the nation to the effect. Keywords: Chinese converts, Islamization, expectations and challenges. Abstrak kembalinya seseorang kepada agama Islam selain dari membuka peluang keemasan dalam mendapat  petunjuk Ilahi dan pengisian rohani turut disertai dengan cabaran yang amat sukar untuk diatasi termasuklah cabaran Islamisasi diri, keluarga serta sumbangan kepada pembangunan keseluruhan Malaysia sebagai negara berbilang agama. Hal ini menjadi satu keutamaan terutamanya apabila Islam memegang status sebagai agama rasmi persekutuan yang menjadikan isu Islamisasi masyarakat Malaysia sebagai satu agenda nasional. Bagi menjayakan agenda ini, peranan umat Islam dari kalangan masyarakat Cina (cina muslim) juga perlu diambil kira. Statistik menunjukkan cina muslim turut mempunyai bahagian dalam menyumbang terhadap pembangunan sosio-ekonomi negara. Dalam pada masa yang sama, kajian empirikal membuktikan adanya bentuk bentuk cabaran yang dihadapi oleh komuniti ini di peringkat peribadi, keluarga dan komuniti dalam perjalanan mereka untuk kembali kepada cara hidup Islam yang sepenuhnya. Bagi kami pengkaji kertas ini, dimensi makro dalam menjadikan dan mengertikan  seseorang itu Muslim terutamanya dalam menyesuaikan diri dengan ajaran  Islam masih belum cukup diberi  penjelasan dan penerangan yang sewajarnya. Oleh itu, makalah ini cuba menerangkan idea dan cadangan yang berguna kepada cina muslim dengan tujuan memotivasikan  mereka bagi  mencapai kejayaan  yang lebih besar dari aspek Islamisasi di kalangan komuniti mereka seterusnya memberi sumbangan kepada negara. Kata kunci:  Cina Muslim, Islamisasi, harapan dan cabaran.

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