1
|
Brookwell R, Finlayson K, van de Merwe JP. A comparative analysis of the karyotypes of three dolphins - Tursiops truncatus Montagu, 1821, Tursiops australis Charlton-Robb et al., 2011, and Grampus griseus Cuvier, 1812. COMPARATIVE CYTOGENETICS 2021; 15:53-63. [PMID: 33628396 PMCID: PMC7892529 DOI: 10.3897/compcytogen.v15.i1.60398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/16/2021] [Indexed: 06/12/2023]
Abstract
The aim of this study is to produce G-banded karyotypes of three dolphin species, Tursiops truncatus Montagu, 1821, Tursiops australisCharlton-Robb et al., 2011, and Grampus griseus Cuvier, 1812, and to determine if any differences between the species can be observed. Monolayer skin cultures were established and processed for chromosome study by trypsin banding. The results indicate that the three species here investigated have the same diploid number (2n = 44) and very similar gross chromosome morphology, however G-banding allows distinction between each species. Chromosome 1 in G. griseus is significantly different from the other 2 species, and chromosome 2 in T. australis is subtly different from the other 2 species. This result is of potential significance in taxonomic studies, and can provide an unequivocal answer in the assessment of suspected hybrids between these species.
Collapse
Affiliation(s)
- Ross Brookwell
- Cytogenetics Department, Sullivan Nicolaides Pathology, 24 Hurworth street, Bowen Hills, Queensland, 4006, AustraliaCytogenetics Department, Sullivan Nicolaides PathologyBowen HillsAustralia
| | - Kimberly Finlayson
- Australian Rivers Institute, Griffith University Gold Coast, Edmund Rice drive, Southport, Queensland, 4215, AustraliaGriffith University Gold CoastSouthportAustralia
| | - Jason P. van de Merwe
- Australian Rivers Institute, Griffith University Gold Coast, Edmund Rice drive, Southport, Queensland, 4215, AustraliaGriffith University Gold CoastSouthportAustralia
| |
Collapse
|
2
|
Antoniou A, Frantzis A, Alexiadou P, Paschou N, Poulakakis N. Evidence of introgressive hybridization between Stenella coeruleoalba and Delphinus delphis in the Greek Seas. Mol Phylogenet Evol 2018; 129:325-337. [PMID: 30218775 DOI: 10.1016/j.ympev.2018.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 05/29/2018] [Accepted: 09/08/2018] [Indexed: 10/28/2022]
Abstract
Natural interspecific hybridization might be more important for the evolutionary history and speciation of animals than previously thought, considering several demographic and life history traits as well as habitat disturbance as factors that promote it. In this aspect, cetaceans comprise an interesting case in which the occurrence of sympatric species in mixed associations provides excellent opportunities for interspecific sexual interaction and the potential for hybridization. Here, we present evidence of natural hybridization for two cetacean species commonly occurring in the Greek Seas (Stenella coeruleoalba and Delphinus delphis), which naturally overlap in the Gulf of Corinth by analyzing highly resolving microsatellite DNA markers and mitochondrial DNA sequences in skin samples from 45 individuals of S. coeruleoalba, 12 D. delphis and three intermediate morphs. Employing several phylogenetic and population genetic approaches, we found 15 individuals that are potential hybrids including the three intermediate morphs, verifying the occurrence of natural hybridization between species of different genera. Their hybrids are fertile and able to reproduce not only with the other hybrids but also with each of the two-parental species. However, current evidence does not allow firm conclusions whether hybridization might constitute a step towards the generation of a new species and/or the swan song of an already existing species (i.e., D. delphis). Given that the focal species form mixed pods in several areas of Mediterranean, this study is an excellent opportunity to understand the mechanisms leading to hybridization in the context of gene flow and urges for the evaluation of the genetic status of common dolphins in the Mediterranean.
Collapse
Affiliation(s)
- Aglaia Antoniou
- Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), Hellenic Centre for Marine Research, Gournes Pediados, P.O. Box 2214, 71003 Irakleio, Crete, Greece.
| | - Alexandros Frantzis
- Pelagos Cetacean Research Institute, Terpsichoris 21, 16671 Vouliagmeni, Greece
| | - Paraskevi Alexiadou
- Pelagos Cetacean Research Institute, Terpsichoris 21, 16671 Vouliagmeni, Greece
| | - Nefeli Paschou
- Department of Biology, School of Sciences and Engineering, University of Crete, Vasilika Vouton, Gr-71300 Heraklion, Crete, Greece; Natural History Museum of Crete, School of Sciences and Engineering, University of Crete, Knossos Av., GR-71409 Heraklion, Crete, Greece
| | - Nikos Poulakakis
- Department of Biology, School of Sciences and Engineering, University of Crete, Vasilika Vouton, Gr-71300 Heraklion, Crete, Greece; Natural History Museum of Crete, School of Sciences and Engineering, University of Crete, Knossos Av., GR-71409 Heraklion, Crete, Greece
| |
Collapse
|
3
|
Kurihara N, Tajima Y, Yamada TK, Matsuda A, Matsuishi T. Description of the karyotypes of Stejneger's beaked whale (Mesoplodon stejnegeri) and Hubbs' beaked whale (M. carlhubbsi). Genet Mol Biol 2017; 40:803-807. [PMID: 28981559 PMCID: PMC5738608 DOI: 10.1590/1678-4685-gmb-2016-0284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 02/06/2017] [Indexed: 11/21/2022] Open
Abstract
The genus Mesoplodon (Cetacea: Odontoceti: Ziphiidae) is one of
the few cetacean genera with the karyotype 2n = 42. The 2n = 42 karyotype of
M. europaeus and M. carlhubbsi is largely
consistent with the general cetacean karyotype 2n = 44, although other 2n = 42
karyotypes do not exhibit clear homologies with the general cetacean karyotype.
Therefore, the chromosomes of Mesoplodon species may be the key
to understanding cetacean karyological evolution. In the present study, the male
karyotypes of M. stejnegeri and M. carlhubbsi
were examined. In both species, the diploid number of the male karyotype was 42.
Both species had the following characteristics: 1) a huge subtelocentric X
chromosome with a large C-block; 2) a small metacentric Y chromosome; 3)
nucleolus organizer regions (NORs) in the terminal regions of a large autosome
and one or two small metacentric autosomes; 4) small metacentric autosomes; 5)
large submetacentric and subtelocentric autosomes; 6) less accumulated
C-heterochromatin in the centromeric region; and 7) heteromorphism in
C-heterochromatin accumulation between homologues. Characteristics 1 and 3 are
peculiar to only the karyotypes of Mesoplodon species, whereas
characteristics 4, 5, 6, and 7 are also found in the species with the general
cetacean karyotype 2n = 44.
Collapse
Affiliation(s)
- Nozomi Kurihara
- Faculty of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi prefecture, Japan
| | - Yuko Tajima
- Department of Zoology, National Museum of Nature and Science, Tsukuba-shi, Ibaraki prefecture, Japan
| | - Tadasu K Yamada
- Department of Zoology, National Museum of Nature and Science, Tsukuba-shi, Ibaraki prefecture, Japan
| | - Ayaka Matsuda
- Graduate School of Fisheries Sciences, Hokkaido University, Hakodate-shi, Hokkaido, Japan
| | - Takashi Matsuishi
- Faculty of Fisheries Science, Hokkaido University, Hakodate-shi, Hokkaido, Japan
| |
Collapse
|
4
|
Hybrid speciation in a marine mammal: the clymene dolphin (Stenella clymene). PLoS One 2014; 9:e83645. [PMID: 24421898 PMCID: PMC3885441 DOI: 10.1371/journal.pone.0083645] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/05/2013] [Indexed: 11/19/2022] Open
Abstract
Natural hybridization may result in the exchange of genetic material between divergent lineages and even the formation of new taxa. Many of the Neo-Darwinian architects argued that, particularly for animal clades, natural hybridization was maladaptive. Recent evidence, however, has falsified this hypothesis, instead indicating that this process may lead to increased biodiversity through the formation of new species. Although such cases of hybrid speciation have been described in plants, fish and insects, they are considered exceptionally rare in mammals. Here we present evidence for a marine mammal, Stenella clymene, arising through natural hybridization. We found phylogenetic discordance between mitochondrial and nuclear markers, which, coupled with a pattern of transgressive segregation seen in the morphometric variation of some characters, support a case of hybrid speciation. S. clymene is currently genetically differentiated from its putative parental species, Stenella coerueloalba and Stenella longisrostris, although low levels of introgressive hybridization may be occurring. Although non-reticulate forms of evolution, such as incomplete lineage sorting, could explain our genetic results, we consider that the genetic and morphological evidence taken together argue more convincingly towards a case of hybrid speciation. We anticipate that our study will bring attention to this important aspect of reticulate evolution in non-model mammal species. The study of speciation through hybridization is an excellent opportunity to understand the mechanisms leading to speciation in the context of gene flow.
Collapse
|
5
|
Molecular cytogenetic characterization of the Amazon River dolphin Inia geoffrensis. Genetica 2012; 140:307-15. [PMID: 23010983 DOI: 10.1007/s10709-012-9680-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 09/08/2012] [Indexed: 10/27/2022]
Abstract
Classical and molecular cytogenetic (18S rDNA, telomeric sequence, and LINE-1 retrotransposon probes) studies were carried out to contribute to an understanding of the organization of repeated DNA elements in the Amazon River dolphin (boto, Inia geoffrensis). Twenty-seven specimens were examined, each presenting 2n = 44 chromosomes, the karyotype formula 12m + 14sm + 6st + 10t + XX/XY, and fundamental number (FN) = 74. C-positive heterochromatin was observed in terminal and interstitial positions, with the occurrence of polymorphism. Interstitial telomeric sequences were not observed. The nucleolar organizer region (NOR) was located at a single site on a smallest autosomal pair. LINE-1 was preferentially distributed in the euchromatin regions, with the greatest accumulation on the X chromosome. Although the karyotype structure in cetaceans is considered to be conserved, the boto karyotype demonstrated significant variations in its formula, heterochromatin distribution, and the location of the NOR compared to other cetacean species. These results contribute to knowledge of the chromosome organization in boto and to a better understanding of karyoevolution in cetaceans.
Collapse
|
6
|
|
7
|
|
8
|
|
9
|
|
10
|
|
11
|
A contrasted pattern of chromosome evolution in two genera of lemmings, Lemmus and Dicrostonyx (Mammalia, Rodentia). Genetica 1983. [DOI: 10.1007/bf00122372] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|