1,791 research outputs found

    Mitochondrial Intergenic Spacer in Fairy Basslets (Serranidae: Anthiinae) and the Simultaneous Analysis of Nucleotide and Rearrangement Data

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    We present the results of a study that implements a recently developed phylogenetic algorithm that combines fixed-states nucleotide optimization with breakpoint analysis to identify and examine the evolution of a mitochondrial intergenic spacer between the tRNAVal and 16S rRNA loci in a clade of fairy basslets (Serranidae: Anthiinae). The results of the analysis indicate that this spacer evolved once and that it may be increasing in size through evolutionary time. The resulting molecular hypothesis corroborates much of the previous morphological phylogenetic work.We would like to thank J. Smith (Los Alamos National Laboratory) and J. Faivovich, T. Grant, K. Pickett, J. Sparks, M. Stiassny, and K. Tang (all at or formerly at the American Museum of Natural History [AMNH]) for discussing aspects of this project with us. We are grateful to H. Endo (Kochi University), the Gahan Family, J. Leis and M. McGrouther (Australian Museum), Reef and Fin (Stamford, CT), and H. Walker (Scripps Institution of Oceanography) for providing specimens used in this study. This project was supported by funding from the AMNH Lerner-Gray Program for Marine Research, the NASA–Ames Fundamental Space Biology Program, the Field Museum of Natural History, and the National Science Foundation (DEB-0405246 and DEB-0732642)

    Temporal Patterns of Diversification across Global Cichlid Biodiversity (Acanthomorpha: Cichlidae)

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    The contrasting distribution of species diversity across the major lineages of cichlids makes them an ideal group for investigating macroevolutionary processes. In this study, we investigate whether different rates of diversification may explain the disparity in species richness across cichlid lineages globally. We present the most taxonomically robust time-calibrated hypothesis of cichlid evolutionary relationships to date. We then utilize this temporal framework to investigate whether both species-rich and depauperate lineages are associated with rapid shifts in diversification rates and if exceptional species richness can be explained by clade age alone. A single significant rapid rate shift increase is detected within the evolutionary history of the African subfamily Pseudocrenilabrinae, which includes the haplochromins of the East African Great Lakes. Several lineages from the subfamilies Pseudocrenilabrinae (Australotilapiini, Oreochromini) and Cichlinae (Heroini) exhibit exceptional species richness given their clade age, a net rate of diversification, and relative rates of extinction, indicating that clade age alone is not a sufficient explanation for their increased diversity. Our results indicate that the Neotropical Cichlinae includes lineages that have not experienced a significant rapid burst in diversification when compared to certain African lineages (rift lake). Neotropical cichlids have remained comparatively understudied with regard to macroevolutionary patterns relative to African lineages, and our results indicate that of Neotropical lineages, the tribe Heroini may have an elevated rate of diversification in contrast to other Neotropical cichlids. These findings provide insight into our understanding of the diversification patterns across taxonomically disparate lineages in this diverse clade of freshwater fishes and one of the most species-rich families of vertebrates.This work was supported by NSF grants DEB 0716155, DEB 0732642, and DEB 1060869 to WLS, DEB 0910081 to MPD, DEB 0916695 to PC, DEB 1258141 to MPD and WLS, DEB 1311408 to CDM, and IOS 0749943 to JSS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    A Response to Mooi, Williams and Gill

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    This is the publisher's version, which the author has permission to share. The original version may be found at the following link: http://www.mapress.com/zootaxa/list/2011/2946.htm

    Will the Real Phylogeneticists Please Stand Up?

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    This is the publisher's version, also availalble electronically from http://www.mapress.com/zootaxa/list/2011/2946.html.In a recently published commentary, Mooi & Gill asserted that there is a crisis brewing in systematic ichthyology caused by a failure of investigators to apply the basic tenets of outgroup comparison to recover clades based solely on shared apomorphic characters. The result, they claim, is that many recent analyses disregard real synapomorphies and discover clades by phenetic rather than phylogenetic principles. We take the opportunity to refute this claim and assert that matrix-based analyses, whether parametric or nonparametric, satisfy the basic tenets of Hennig’s methods, resulting in monophyletic groups confirmed by synapomorphies

    Two waves of colonization straddling the K–Pg boundary formed the modern reef fish fauna

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    Living reef fishes are one of the most diverse vertebrate assemblages on Earth. Despite its prominence and ecological importance, the origins and assembly of the reef fish fauna is poorly described. A patchy fossil record suggests that the major colonization of reef habitats must have occurred in the Late Cretaceous and early Palaeogene, with the earliest known modern fossil coral reef fish assemblage dated to 50 Ma. Using a phylogenetic approach, we analysed the early evolutionary dynamics of modern reef fishes. We find that reef lineages successively colonized reef habitats throughout the Late Cretaceous and early Palaeogene. Two waves of invasion were accompanied by increasing morphological convergence: one in the Late Cretaceous from 90 to 72 Ma and the other immediately following the end-Cretaceous mass extinction. The surge in reef invasions after the Cretaceous–Palaeogene boundary continued for 10 Myr, after which the pace of transitions to reef habitats slowed. Combined, these patterns match a classic niche-filling scenario: early transitions to reefs were made rapidly by morphologically distinct lineages and were followed by a decrease in the rate of invasions and eventual saturation of morphospace. Major alterations in reef composition, distribution and abundance, along with shifts in climate and oceanic currents, occurred during the Late Cretaceous and early Palaeogene interval. A causal mechanism between these changes and concurrent episodes of reef invasion remains obscure, but what is clear is that the broad framework of the modern reef fish fauna was in place within 10 Myr of the end-Cretaceous extinction.Work was supported by NSF grant nos. DEB-1061981 and DEB-0717009 to P.C.W., DEB-1061806 and DEB-1110552 to T.J.N. and DEB-1060869 and EF-0732642 to W.L.S., and NERC grant no. NE/I005536/1 to M.F

    Australian songbird body size tracks climate variation: 82 species over 50 years.

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    The observed variation in the body size responses of endotherms to climate change may be explained by two hypotheses: the size increases with climate variability (the starvation resistance hypothesis) and the size shrinks as mean temperatures rise (the heat exchange hypothesis). Across 82 Australian passerine species over 50 years, shrinking was associated with annual mean temperature rise exceeding 0.012°C driven by rising winter temperatures for arid and temperate zone species. We propose the warming winters hypothesis to explain this response. However, where average summer temperatures exceeded 34°C, species experiencing annual rise over 0.0116°C tended towards increasing size. Results suggest a broad-scale physiological response to changing climate, with size trends probably reflecting the relative strength of selection pressures across a climatic regime. Critically, a given amount of temperature change will have varying effects on phenotype depending on the season in which it occurs, masking the generality of size patterns associated with temperature change. Rather than phenotypic plasticity, and assuming body size is heritable, results suggest selective loss or gain of particular phenotypes could generate evolutionary change but may be difficult to detect with current warming rates.The work was partly supported by the Australian Research Council (DP120102651); JLG was partly supported by an Australian Research Council Future Fellowship (FT150100139); TA is funded by an Australian Research Council Future Fellowship (FT180100354); WJS is funded by Arcadia
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