21
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Did sex chromosome turnover promote divergence of the major mammal groups? : De novo sex chromosomes and drastic rearrangements may have posed reproductive barriers between monotremes, marsupials and placental mammals

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Comparative mapping and sequencing show that turnover of sex determining genes and chromosomes, and sex chromosome rearrangements, accompany speciation in many vertebrates. Here I review the evidence and propose that the evolution of therian mammals was precipitated by evolution of the male‐determining SRY gene, defining a novel XY sex chromosome pair, and interposing a reproductive barrier with the ancestral population of synapsid reptiles 190 million years ago (MYA). Divergence was reinforced by multiple translocations in monotreme sex chromosomes, the first of which supplied a novel sex determining gene. A sex chromosome‐autosome fusion may have separated eutherians (placental mammals) from marsupials 160 MYA. Another burst of sex chromosome change and speciation is occurring in rodents, precipitated by the degradation of the Y. And although primates have a more stable Y chromosome, it may be just a matter of time before the same fate overtakes our own lineage.

          Also watch the video abstract.

          Related collections

          Most cited references81

          • Record: found
          • Abstract: found
          • Article: not found

          Chromosome inversions, local adaptation and speciation.

          We study the evolution of inversions that capture locally adapted alleles when two populations are exchanging migrants or hybridizing. By suppressing recombination between the loci, a new inversion can spread. Neither drift nor coadaptation between the alleles (epistasis) is needed, so this local adaptation mechanism may apply to a broader range of genetic and demographic situations than alternative hypotheses that have been widely discussed. The mechanism can explain many features observed in inversion systems. It will drive an inversion to high frequency if there is no countervailing force, which could explain fixed differences observed between populations and species. An inversion can be stabilized at an intermediate frequency if it also happens to capture one or more deleterious recessive mutations, which could explain polymorphisms that are common in some species. This polymorphism can cycle in frequency with the changing selective advantage of the locally favored alleles. The mechanism can establish underdominant inversions that decrease heterokaryotype fitness by several percent if the cause of fitness loss is structural, while if the cause is genic there is no limit to the strength of underdominance that can result. The mechanism is expected to cause loci responsible for adaptive species-specific differences to map to inversions, as seen in recent QTL studies. We discuss data that support the hypothesis, review other mechanisms for inversion evolution, and suggest possible tests.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Paleontological evidence to date the tree of life.

            The role of fossils in dating the tree of life has been misunderstood. Fossils can provide good "minimum" age estimates for branches in the tree, but "maximum" constraints on those ages are poorer. Current debates about which are the "best" fossil dates for calibration move to consideration of the most appropriate constraints on the ages of tree nodes. Because fossil-based dates are constraints, and because molecular evolution is not perfectly clock-like, analysts should use more rather than fewer dates, but there has to be a balance between many genes and few dates versus many dates and few genes. We provide "hard" minimum and "soft" maximum age constraints for 30 divergences among key genome model organisms; these should contribute to better understanding of the dating of the animal tree of life.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Whole-genome sequence of a flatfish provides insights into ZW sex chromosome evolution and adaptation to a benthic lifestyle.

              Genetic sex determination by W and Z chromosomes has developed independently in different groups of organisms. To better understand the evolution of sex chromosomes and the plasticity of sex-determination mechanisms, we sequenced the whole genomes of a male (ZZ) and a female (ZW) half-smooth tongue sole (Cynoglossus semilaevis). In addition to insights into adaptation to a benthic lifestyle, we find that the sex chromosomes of these fish are derived from the same ancestral vertebrate protochromosome as the avian W and Z chromosomes. Notably, the same gene on the Z chromosome, dmrt1, which is the male-determining gene in birds, showed convergent evolution of features that are compatible with a similar function in tongue sole. Comparison of the relatively young tongue sole sex chromosomes with those of mammals and birds identified events that occurred during the early phase of sex-chromosome evolution. Pertinent to the current debate about heterogametic sex-chromosome decay, we find that massive gene loss occurred in the wake of sex-chromosome 'birth'.
                Bookmark

                Author and article information

                Journal
                Bioessays
                Bioessays
                10.1002/(ISSN)1521-1878
                BIES
                Bioessays
                John Wiley and Sons Inc. (Hoboken )
                0265-9247
                1521-1878
                23 June 2016
                August 2016
                : 38
                : 8 ( doiID: 10.1002/bies.v38.8 )
                : 734-743
                Affiliations
                [ 1 ] School of Life ScienceLa Trobe University MelbourneAustralia
                [ 2 ] Institute of Applied EcologyUniversity of Canberra Australia
                [ 3 ] Research School of BiologyAustralian National University CanberraAustralia
                Author notes
                [*] [* ] Corresponding author:

                Jennifer A. M. Graves

                E‐mail: j.graves@ 123456latrobe.edu.au

                Article
                BIES201600019
                10.1002/bies.201600019
                5094562
                27334831
                5b3b3ba1-3fc0-4cd6-ad5a-4c127a9e5c26
                © 2016 The Authors. BioEssays Published by WILEY Periodicals, Inc.

                This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

                History
                Page count
                Pages: 10
                Categories
                Insights & Perspectives
                Insights & Perspectives
                Hypotheses
                Custom metadata
                2.0
                bies201600019
                August 2016
                Converter:WILEY_ML3GV2_TO_NLMPMC version:4.9.6 mode:remove_FC converted:03.11.2016

                Cell biology
                animal genomics,de novo sex‐determining genes,hybrid incompatibility,mammal evolution,sex chromosome differentiation and degradation,sex chromosome rearrangement

                Comments

                Comment on this article