Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Mais filtros

Base de dados
País como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Zootaxa ; 3981(3): 367-84, 2015 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-26250000

RESUMO

The Magpie Fiddler ray, Trygonorrhina melaleuca Scott 1954, is presently South Australia's (SA) rarest fish, represented by only three museum specimens collected near Adelaide over the past 60 years and listed as Endangered in the IUCN Red List of Threatened Species. However, there is some doubt as to whether the Magpie Fiddler Ray is a different species from the widespread and common Southern Fiddler Ray, Trygonorrhina dumerilii (Castelnau 1873), resulting in two very contrasting scenarios for marine conservation. If the Magpie Fiddler Ray is a black and white patterned variant of the Southern Fiddler Ray then it will be removed from the Red List and appear as a synonym of T. dumerilii. Conversely, if it proves to be a different species then it remains SA's rarest fish species and highly data deficient. We analysed mtDNA and the largest ever nuclear gene dataset (>4,000 loci) applied to chondrichthyan species level systematics from the most recently collected Magpie Fiddler Ray specimens and a geographically representative selection of Southern Fiddler Rays to determine the species status of this enigmatic ray. We found that the Magpie Fiddler Rays share a mitochondrial haplotype with 23 Southern Fiddler Rays and are not differentiated from 35 Southern Fiddler Rays at more than 4000 SNPs derived from DArTseq data. The morphological trait values that are putatively diagnostic for the Magpie Fiddler Ray fall within the range of variation observed among Southern Fiddler Rays. Our analyses are consistent with the notion that the Magpie Fiddler Ray is a rare colour and pattern variant of the widespread and abundant Southern Fiddler Ray. We also identified two hybrids between the Eastern and Southern Fiddler Rays, only the third time that hybrids have been identified in nature in chondrichthyans. Our results provide critical guidance in the assessment of its conservation status and an ending to a 60 year old conundrum for marine conservation.


Assuntos
Besouros/classificação , Rajidae/classificação , Distribuição Animal , Estruturas Animais/anatomia & histologia , Estruturas Animais/crescimento & desenvolvimento , Animais , Austrália , Tamanho Corporal , Besouros/anatomia & histologia , Besouros/crescimento & desenvolvimento , Cor , Ecossistema , Feminino , Masculino , Tamanho do Órgão , Filogenia , Rajidae/anatomia & histologia , Rajidae/genética , Rajidae/crescimento & desenvolvimento
2.
Zootaxa ; 3616: 135-50, 2013 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-24758799

RESUMO

A new species of the eyeless eleotrid genus Milyeringa is described from wells sunk on Barrow Island, Western Australia. Milyeringa justitia n. sp. is the third species of the genus to be named. Morphological data and cytochrome c oxidase subunit I (COI) DNA sequence data from a wide sample of localities at which the genus occurs was used to evaluate relationships and species limits. Milyeringa veritas is redescribed, and M. brooksi is synonymised with M. veritas. The unique form and ecology of these fishes, plus the threats to their survival, warrants immediate and continuing attention in management.


Assuntos
Peixes/classificação , Estruturas Animais/anatomia & histologia , Estruturas Animais/crescimento & desenvolvimento , Animais , Cavernas , Proteínas de Peixes/genética , Peixes/anatomia & histologia , Peixes/genética , Peixes/crescimento & desenvolvimento , Dados de Sequência Molecular , Filogenia , Austrália Ocidental
3.
Evolution ; 57(11): 2619-27, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14686536

RESUMO

Molecular data derived from allozymes and mitochondrial nucleotide sequences, in combination with karyotypes, sex ratios, and inheritance data, have revealed the widespread Australian lizard Menetia greyii to be a complex of sexual and triploid unisexual taxa. Three sexual species, three presumed parthenogenetic lineages, and one animal of uncertain status were detected amongst 145 animals examined from south-central Australia, an area representing less than one-seventh of the total distribution of the complex. Parthenogenesis appears to have originated via interspecific hybridization, although presumed sexual ancestors could only be identified in two cases. The allozyme and mtDNA data reveal the presence of many distinct clones within the presumed parthenogenetic lineages. This new instance of vertebrate parthenogenesis is a first for the Scincidae and only the second definitive case of unisexuality in an indigenous Australian vertebrate.


Assuntos
Lagartos/genética , Lagartos/fisiologia , Partenogênese/fisiologia , Filogenia , Animais , Austrália , Sequência de Bases , Análise por Conglomerados , Primers do DNA , Geografia , Isoenzimas , Cariotipagem , Dados de Sequência Molecular , Análise de Componente Principal , Análise de Sequência de DNA
4.
Syst Biol ; 56(4): 543-63, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17654361

RESUMO

A phylogeny of tetrapods is inferred from nearly complete sequences of the nuclear RAG-1 gene sampled across 88 taxa encompassing all major clades, analyzed via parsimony and Bayesian methods. The phylogeny provides support for Lissamphibia, Theria, Lepidosauria, a turtle-archosaur clade, as well as most traditionally accepted groupings. This tree allows simultaneous molecular clock dating for all tetrapod groups using a set of well-corroborated calibrations. Relaxed clock (PLRS) methods, using the amniote = 315 Mya (million years ago) calibration or a set of consistent calibrations, recovers reasonable divergence dates for most groups. However, the analysis systematically underestimates divergence dates within archosaurs. The bird-crocodile split, robustly documented in the fossil record as being around approximately 245 Mya, is estimated at only approximately 190 Mya, and dates for other divergences within archosaurs are similarly underestimated. Archosaurs, and particulary turtles have slow apparent rates possibly confounding rate modeling, and inclusion of calibrations within archosaurs (despite their high deviances) not only improves divergence estimates within archosaurs, but also across other groups. Notably, the monotreme-therian split ( approximately 210 Mya) matches the fossil record; the squamate radiation ( approximately 190 Mya) is younger than suggested by some recent molecular studies and inconsistent with identification of approximately 220 and approximately 165 Myo (million-year-old) fossils as acrodont iguanians and approximately 95 Myo fossils colubroid snakes; the bird-lizard (reptile) split is considerably older than fossil estimates (< or = 285 Mya); and Sphenodon is a remarkable phylogenetic relic, being the sole survivor of a lineage more than a quarter of a billion years old. Comparison with other molecular clock studies of tetrapod divergences suggests that the common practice of enforcing most calibrations as minima, with a single liberal maximal constraint, will systematically overestimate divergence dates. Similarly, saturation of mitochondrial DNA sequences, and the resultant greater compression of basal branches means that using only external deep calibrations will also lead to inflated age estimates within the focal ingroup.


Assuntos
Anfíbios/genética , Biodiversidade , Aves/genética , Proteínas de Homeodomínio/genética , Mamíferos/genética , Filogenia , Répteis/genética , Animais , Calibragem , Fósseis , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa