51
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Araújo NP, Dias CAR, Stumpp R, Svartman M. Cytogenetic analyses in Trinomys (Echimyidae, Rodentia), with description of new karyotypes. PeerJ 2018; 6:e5316. [PMID: 30083457 PMCID: PMC6074804 DOI: 10.7717/peerj.5316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 07/05/2018] [Indexed: 11/24/2022] Open
Abstract
Trinomys Thomas (1921) is a terrestrial genus of spiny rats endemic to the Brazilian areas of Atlantic Forest and the transitional areas of Cerrado and Caatinga. Although most species have been already karyotyped, the available cytogenetic information is mostly restricted to diploid and fundamental numbers. We analyzed the chromosomes of two Trinomys species: Trinomys moojeni (2n = 56, FN = 106) and Trinomys setosus setosus (2n = 56, FN = 106 and 2n = 56, FN = 108). Our analyses included GTG- and CBG-banding, silver-staining of the nucleolar organizer regions, and chromosome mapping of telomeres and 45S rDNA by fluorescent in situ hybridization (FISH). Comparative GTG- and CBG-banding suggested that the interspecific variation may be due to rearrangements such as pericentric inversions, centromere repositioning, and heterochromatin variation. We report two new karyotypes for T. s. setosus and describe for the first time the banding patterns of the two Trinomys species.
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Affiliation(s)
- Naiara Pereira Araújo
- Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Cayo Augusto Rocha Dias
- Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.,Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas, Belo Horizonte, Minas Gerais, Brazil
| | - Rodolfo Stumpp
- Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marta Svartman
- Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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Evolutionary Mechanisms of Varying Chromosome Numbers in the Radiation of Erebia Butterflies. Genes (Basel) 2018; 9:genes9030166. [PMID: 29547586 PMCID: PMC5867887 DOI: 10.3390/genes9030166] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 03/14/2018] [Accepted: 03/14/2018] [Indexed: 02/03/2023] Open
Abstract
The evolution of intrinsic barriers to gene flow is a crucial step in the process of speciation. Chromosomal changes caused by fusion and fission events are one such barrier and are common in several groups of Lepidoptera. However, it remains unclear if and how chromosomal changes have contributed to speciation in this group. I tested for a phylogenetic signal of varying chromosome numbers in Erebia butterflies by combining existing sequence data with karyological information. I also compared different models of trait evolution in order to infer the underlying evolutionary mechanisms. Overall, I found significant phylogenetic signals that are consistent with non-neutral trait evolution only when parts of the mitochondrial genome were included, suggesting cytonuclear discordances. The adaptive evolutionary model tested in this study consistently outperformed the neutral model of trait evolution. Taken together, these results suggest that, unlike other Lepidoptera groups, changes in chromosome numbers may have played a role in the diversification of Erebia butterflies.
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53
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Deakin JE. Chromosome Evolution in Marsupials. Genes (Basel) 2018; 9:E72. [PMID: 29415454 PMCID: PMC5852568 DOI: 10.3390/genes9020072] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 01/30/2018] [Accepted: 02/01/2018] [Indexed: 12/17/2022] Open
Abstract
Marsupials typically possess very large, distinctive chromosomes that make them excellent subjects for cytogenetic analysis, and the high level of conservation makes it relatively easy to track chromosome evolution. There are two speciose marsupial families with contrasting rates of karyotypic evolution that could provide insight into the mechanisms driving genome reshuffling and speciation. The family Dasyuridae displays exceptional karyotype conservation with all karyotyped species possessing a 2n = 14 karyotype similar to that predicted for the ancestral marsupial. In contrast, the family Macropodidae has experienced a higher rate of genomic rearrangement and one genus of macropods, the rock-wallabies (Petrogale), has experienced extensive reshuffling. For at least some recently diverged Petrogale species, there is still gene flow despite hybrid fertility issues, making this species group an exceptional model for studying speciation. This review highlights the unique chromosome features of marsupial chromosomes, particularly for these two contrasting families, and the value that a combined cytogenetics, genomics, and epigenomics approach will have for testing models of genome evolution and speciation.
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Affiliation(s)
- Janine E Deakin
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2617, Australia.
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Cooper SJB, Ottewell K, MacDonald AJ, Adams M, Byrne M, Carthew SM, Eldridge MDB, Li Y, Pope LC, Saint KM, Westerman M. Phylogeography of southern brown and golden bandicoots: implications for the taxonomy and distribution of endangered subspecies and species. AUST J ZOOL 2018. [DOI: 10.1071/zo19052] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Southern brown (Isoodon obesulus) and golden (Isoodon auratus) bandicoots are iconic Australian marsupials that have experienced dramatic declines since European settlement. Conservation management programs seek to protect the remaining populations; however, these programs are impeded by major taxonomic uncertainties. We investigated the history of population connectivity to inform subspecies and species boundaries through a broad-scale phylogeographic and population genetic analysis of Isoodon taxa. Our analyses reveal a major east–west phylogeographic split within I. obesulus/I. auratus, supported by both mtDNA and nuclear gene analyses, which is not coincident with the current species or subspecies taxonomy. In the eastern lineage, all Tasmanian samples formed a distinct monophyletic haplotype group to the exclusion of all mainland samples, indicative of long-term isolation of this population from mainland Australia and providing support for retention of the subspecific status of the Tasmanian population (I. o. affinis). Analyses further suggest that I. o. obesulus is limited to south-eastern mainland Australia, representing a significant reduction in known range. However, the analyses provide no clear consensus on the taxonomic status of bandicoot populations within the western lineage, with further analyses required, ideally incorporating data from historical museum specimens to fill distributional gaps.
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Matveevsky S, Kolomiets O, Bogdanov A, Hakhverdyan M, Bakloushinskaya I. Chromosomal Evolution in Mole Voles Ellobius (Cricetidae, Rodentia): Bizarre Sex Chromosomes, Variable Autosomes and Meiosis. Genes (Basel) 2017; 8:E306. [PMID: 29099806 PMCID: PMC5704219 DOI: 10.3390/genes8110306] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 11/16/2022] Open
Abstract
This study reports on extensive experimental material covering more than 30 years of studying the genetics of mole voles. Sex chromosomes of Ellobius demonstrate an extraordinary case of mammalian sex chromosomes evolution. Five species of mole voles own three types of sex chromosomes; typical for placentals: XY♂/XX♀; and atypical X0♂/X0♀; or XX♂/XX♀. Mechanisms of sex determination in all Ellobius species remain enigmatic. It was supposed that the Y chromosome was lost twice and independently in subgenera Bramus and Ellobius. Previous to the Y being lost, the X chromosome in distinct species obtained some parts of the Y chromosome, with or without Sry, and accumulated one or several copies of the Eif2s3y gene. Along with enormous variations of sex chromosomes, genes of sex determination pathway and autosomes, and five mole vole species demonstrate ability to establish different meiotic mechanisms, which stabilize their genetic systems and make it possible to overcome the evolutionary deadlocks.
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Affiliation(s)
- Sergey Matveevsky
- Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia.
| | - Oxana Kolomiets
- Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia.
| | - Alexey Bogdanov
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia.
| | | | - Irina Bakloushinskaya
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334, Russia.
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Duchêne DA, Bragg JG, Duchêne S, Neaves LE, Potter S, Moritz C, Johnson RN, Ho SYW, Eldridge MDB. Analysis of Phylogenomic Tree Space Resolves Relationships Among Marsupial Families. Syst Biol 2017; 67:400-412. [DOI: 10.1093/sysbio/syx076] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 09/08/2017] [Indexed: 02/02/2023] Open
Affiliation(s)
- David A Duchêne
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Jason G Bragg
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
- National Herbarium of NSW, The Royal Botanic Gardens and Domain Trust, Sydney, NSW 2000, Australia
| | - Sebastián Duchêne
- Centre for Systems Genomics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Linda E Neaves
- Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney, NSW 2000, Australia
| | - Sally Potter
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
- Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney, NSW 2000, Australia
| | - Craig Moritz
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Rebecca N Johnson
- Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney, NSW 2000, Australia
| | - Simon Y W Ho
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Mark D B Eldridge
- Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney, NSW 2000, Australia
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