skip to main content

Explore Research Products in the NSF-PAR

  • Home
  • Search Results
  • Page 1 of 1

Search for: All records

Creators/Authors contains: "Dittmann, Donna L."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. ; ; ; ( , Biological Journal of the Linnean Society)
    Abstract

    Pelagic seabirds are highly mobile, reducing opportunities for population isolation that might promote differentiation and speciation. At the same time, many seabirds are philopatric, and their tendency to return to their natal islands to breed might reduce gene flow sufficiently to permit local adaptation and differentiation. To test the net impact of these competing processes, estimates of differentiation and gene flow based on comprehensive geographical sampling are required. We leveraged diverse source material to achieve comprehensive geographical sampling in a widespread seabird, the Wedge-tailed Shearwater (Ardenna pacifica). Using data from sequence capture and high-throughput sequencing of 2402 loci containing 20 780 single nucleotide polymorphisms, we tested for population differentiation and gene flow among breeding areas. We found little evidence of deep divergences within A. pacifica but were able to resolve fine-scale differentiation across island groups. This differentiation was sufficient to assign individuals sampled away from breeding areas to their likely source populations. Estimated effective migration surfaces revealed reduced migration between the Indian Ocean and Pacific Ocean, presumably owing to land barriers, and across the equatorial Pacific Ocean, perhaps associated with differences in breeding schedule. Our results reveal that, despite their mobility, pelagic seabirds can exhibit fine-scale population differentiation and reduced gene flow among ocean basins.

     
    more » « less
  2. ; ; ; ; ; ; ( , BMC Ecology and Evolution)
    Abstract Background

    Divergence time estimation is fundamental to understanding many aspects of the evolution of organisms, such as character evolution, diversification, and biogeography. With the development of sequence technology, improved analytical methods, and knowledge of fossils for calibration, it is possible to obtain robust molecular dating results. However, while phylogenomic datasets show great promise in phylogenetic estimation, the best ways to leverage the large amounts of data for divergence time estimation has not been well explored. A potential solution is to focus on a subset of data for divergence time estimation, which can significantly reduce the computational burdens and avoid problems with data heterogeneity that may bias results.

     Results

    In this study, we obtained thousands of ultraconserved elements (UCEs) from 130 extant galliform taxa, including representatives of all genera, to determine the divergence times throughout galliform history. We tested the effects of different “gene shopping” schemes on divergence time estimation using a carefully, and previously validated, set of fossils. Our results found commonly used clock-like schemes may not be suitable for UCE dating (or other data types) where some loci have little information. We suggest use of partitioning (e.g., PartitionFinder) and selection of tree-like partitions may be good strategies to select a subset of data for divergence time estimation from UCEs. Our galliform time tree is largely consistent with other molecular clock studies of mitochondrial and nuclear loci. With our increased taxon sampling, a well-resolved topology, carefully vetted fossil calibrations, and suitable molecular dating methods, we obtained a high quality galliform time tree.

     Conclusions

    We provide a robust galliform backbone time tree that can be combined with more fossil records to further facilitate our understanding of the evolution of Galliformes and can be used as a resource for comparative and biogeographic studies in this group.

     
    more » « less
  3. ; ( , Evolution)