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Madagascar's mouse lemurs and more

PLOS

Delimiting Species without Nuclear Monophyly in Madagascar's Mouse Lemurs.

Background: Speciation begins when populations become genetically separated through a substantial reduction in gene flow, and it is at this point that a genetically cohesive set of populations attain the sole property of species: the independent evolution of a population-level lineage. The comprehensive delimitation of species within biodiversity hotspots, regardless of their level of divergence, is important for understanding the factors that drive the diversification of biota and for identifying them as targets for conservation. However, delimiting recently diverged species is challenging due to insufficient time for the differential evolution of characters--including morphological differences, reproductive isolation, and gene tree monophyly--that are typically used as evidence for separately evolving lineages.

Methodology: In this study, we assembled multiple lines of evidence from the analysis of mtDNA and nDNA sequence data for the delimitation of a high diversity of cryptically diverged population-level mouse lemur lineages across the island of Madagascar. Our study uses a multi-faceted approach that applies phylogenetic, population genetic, and genealogical analysis for recognizing lineage diversity and presents the most thoroughly sampled species delimitation of mouse lemur ever performed.

Conclusions: The resolution of a large number of geographically defined clades in the mtDNA gene tree provides strong initial evidence for recognizing a high diversity of population-level lineages in mouse lemurs. We find additional support for lineage recognition in the striking concordance between mtDNA clades and patterns of nuclear population structure. Lineages identified using these two sources of evidence also exhibit patterns of population divergence according to genealogical exclusivity estimates. Mouse lemur lineage diversity is reflected in both a geographically fine-scaled pattern of population divergence within established and geographically widespread taxa, as well as newly resolved patterns of microendemism revealed through expanded field sampling into previously poorly and well-sampled regions.

Competing Interests: The authors have declared that no competing interests exist.

Funding: This project was supported by grant DEB 0516276 from the National Science Foundation, and by funding from the John D. and Catherine T. MacArthur Foundation, the German Primate Center (DPZ), the Deutsche Forschungsgemeinschaft (grant Ka 1082-8), and the Volkswagen Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Contacts:

David W. Weisrock
University of Kentucky
dweis2@uky.edu

Jen Laloup
Public Library of Science
jlaloup@plos.org
415-624-1220

Citation: Weisrock DW, Rasoloarison RM, Fiorentino I, Ralison JM, Goodman SM, et al. (2010) Delimiting Species without Nuclear Monophyly in Madagascar's Mouse Lemurs. PLoS ONE 5(3): e9883. doi:10.1371/journal.pone.0009883

PLEASE LINK TO THE SCIENTIFIC ARTICLE IN ONLINE VERSIONS OF YOUR REPORT (URL goes live after the embargo ends): http://dx.plos.org/10.1371/journal.pone.0009883

FOR A PRESS-ONLY PREVIEW OF THE FULL ARTICLE, VISIT THE FOLLOWING URL:: http://www.plos.org/press/pone-05-03-weisrock.pdf


Words and Melody Are Intertwined in Perception of Sung Words: EEG and Behavioral Evidence.

Background: Language and music, two of the most unique human cognitive abilities, are combined in song, rendering it an ecological model for comparing speech and music cognition. The present study was designed to determine whether words and melodies in song are processed interactively or independently, and to examine the influence of attention on the processing of words and melodies in song.

Methods: Event-Related brain Potentials (ERPs) and behavioral data were recorded while non-musicians listened to pairs of sung words (prime and target) presented in four experimental conditions: same word, same melody; same word, different melody; different word, same melody; different word, different melody. Participants were asked to attend to either the words or the melody, and to perform a same/different task. In both attentional tasks, different word targets elicited an N400 component, as predicted based on previous results. Most interestingly, different melodies (sung with the same word) elicited an N400 component followed by a late positive component. Finally, ERP and behavioral data converged in showing interactions between the linguistic and melodic dimensions of sung words.

Conclusion: The finding that the N400 effect, a well-established marker of semantic processing, was modulated by musical melody in song suggests that variations in musical features affect word processing in sung language. Implications of the interactions between words and melody are discussed in light of evidence for shared neural processing resources between the phonological/semantic aspects of language and the melodic/harmonic aspects of music.

Competing Interests: The authors have declared that no competing interests exist

Funding: This research was supported by a grant from the Human Frontier Science Program ''An interdisciplinary approach to the problem of language and music specificity'' (HFSP#RGP0053) to M. Besson and was conducted at the Institut de Neurosciences Cognitives de la Me´diterrane´ e, while R.L. Gordon was a graduate student. D. Scho¨n and C. Aste´sano were supported by the HFSP grant; C. Magne benefitted from a ''Cognitive Science'' Fellowship from the French Ministry of Research; and R.L. Gordon benefited from a Fellowship from the American Academy of University Women. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Contacts:

Reyna L. Gordon
University of Barcelona, Spain
E-mail: reyna.gordon@alumni.usc.edu

Jen Laloup
Public Library of Science
jlaloup@plos.org
415-624-1220

Citation: Gordon RL, Scho¨n D, Magne C, Aste´sano C, Besson M (2010) Words and Melody Are Intertwined in Perception of Sung Words: EEG and Behavioral Evidence. PLoS ONE 5(3): e9889. doi:10.1371/journal.pone.0009889

PLEASE LINK TO THE SCIENTIFIC ARTICLE IN ONLINE VERSIONS OF YOUR REPORT (URL goes live after the embargo ends): http://dx.plos.org/10.1371/journal.pone.0009889

FOR A PRESS-ONLY PREVIEW OF THE FULL ARTICLE, VISIT THE FOLLOWING URL: http://www.plos.org/press/pone-05-03-gordon.pdf

[Related images/movies for press use: http://www.plos.org/press/pone-05-03-gordonfigure1.jpg

Caption: Examples of stimuli in the four experimental conditions: same word, same melody (a); same word, different melody (b); different word, same melody (c); different word, different melody (d). Credit: Figure 1 from Gordon et al. PLoS ONE: e9889]

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