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Diversity ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 29
Author(s):  
Izabela S. Mendes ◽  
Bruno F. Melo ◽  
Júnio S. Damasceno ◽  
Daniel F. Teixeira ◽  
Daniel C. Carvalho

Hypomasticus copelandii is a Neotropical freshwater fish widely distributed across coastal drainages of southeastern Brazil, a highly impacted region of South America. The interspecific phylogenetic relationships within the genus and the taxonomic status of the species remain uncertain. Using two mitochondrial and one nuclear locus, we performed a phylogenetic, species delimitation, and time-calibrated analyses to test the hypothesis that H. copelandii is a species complex currently delimited by different Atlantic coastal systems. Results indicate that H. copelandii presents two well-delimited genetic lineages: one in the northern drainages of the Jucuruçu, Mucuri and Doce rivers, and the other in the southern region represented by the Paraíba do Sul River Basin. The time-calibrated phylogeny indicated a split between the two genetic lineages at around 2.8 million years ago (Ma), which might be related to headwater capture events during the Plio-Pleistocene. The discovery of a distinct genetic lineage for H. copelandii suggests distinct management plans for the northern and southern drainages. Such hidden diversity within the H. copelandii provides useful information for taxonomy and conservation across a severely impacted region of Brazil.


Author(s):  
Lyle T. Wallace ◽  
Michael J. Havey

Cucumber (Cucumis sativus) plants regenerated from cell cultures occasionally possess mosaic (MSC) phenotypes on cotyledons and leaves. Lines MSC3 and MSC16 have distinct MSC phenotypes and originated from plants regenerated from different cell-culture experiments established using a highly inbred wild-type cucumber. Both the mitochondrial (mt) DNA and MSC phenotype of cucumber show paternal transmission, and MSC3 and MSC16 have different mt coding regions at significantly lower copy numbers relative to wild-type plants. A nuclear locus, Paternal sorting of mitochondria (Psm), conditions a high proportion of wild-type progenies, specifically when MSC16 is crossed as the male with wild-type female plants. During this research, we identified plants that produced a high proportion of wild-type progenies in crosses with MSC3 as the male parent. Plants from an F2 family were crossed with MSC3 as the male, progenies were scored for numbers of MSC vs. wild-type plants, and single-nucleotide polymorphisms (SNP) were identified for genetic mapping. A major quantitative trait locus on chromosome 3 was associated with a higher frequency of wild-type progenies from MSC3 as the male parent, and the 1.5-logarithm-of-odds interval for the most significant SNP was located 627 kb from Psm. These results reveal that separate genetic factors control sorting to the wild-type phenotype in progenies from crosses with different MSC parents. The identification of causal genes controlling mitochondrial sorting in cucumber should provide insight regarding nuclear-mitochondrial interactions affecting the prevalence of specific mitochondrial DNA in plants.


2021 ◽  
Vol 9 (5) ◽  
pp. 933
Author(s):  
Ana Cláudia Norte ◽  
Pierre H. Boyer ◽  
Santiago Castillo-Ramirez ◽  
Michal Chvostáč ◽  
Mohand O. Brahami ◽  
...  

Populations of vector-borne pathogens are shaped by the distribution and movement of vector and reservoir hosts. To study what impact host and vector association have on tick-borne pathogens, we investigated the population structure of Borrelia lusitaniae using multilocus sequence typing (MLST). Novel sequences were acquired from questing ticks collected in multiple North African and European locations and were supplemented by publicly available sequences at the Borrelia Pubmlst database (accessed on 11 February 2020). Population structure of B. lusitaniae was inferred using clustering and network analyses. Maximum likelihood phylogenies for two molecular tick markers (the mitochondrial 16S rRNA locus and a nuclear locus, Tick-receptor of outer surface protein A, trospA) were used to confirm the morphological species identification of collected ticks. Our results confirmed that B. lusitaniae does indeed form two distinguishable populations: one containing mostly European samples and the other mostly Portuguese and North African samples. Of interest, Portuguese samples clustered largely based on being from north (European) or south (North African) of the river Targus. As two different Ixodes species (i.e., I. ricinus and I. inopinatus) may vector Borrelia in these regions, reference samples were included for I. inopinatus but did not form monophyletic clades in either tree, suggesting some misidentification. Even so, the trospA phylogeny showed a monophyletic clade containing tick samples from Northern Africa and Portugal south of the river Tagus suggesting a population division in Ixodes on this locus. The pattern mirrored the clustering of B. lusitaniae samples, suggesting a potential co-evolution between tick and Borrelia populations that deserve further investigation.


2021 ◽  
pp. 1-9
Author(s):  
John H. Chau ◽  
Michelle Greve ◽  
Bettine Jansen van Vuuren

Abstract DNA sequence data have become a crucial tool in assessing the relationship between morphological variation and genetic and taxonomic groups, including in the Antarctic biota. Morphologically distinct populations of submersed aquatic vascular plants were observed on sub-Antarctic Marion Island, potentially representing the two species of such plants listed in the island's flora, Limosella australis R.Br. (Scrophulariaceae) and Ranunculus moseleyi Hook.f. (Ranunculaceae). To confirm their taxonomic identity, we sequenced a nuclear locus (internal transcribed spacer; ITS) and two plastid loci (trnL-trnF, rps16) from three specimens collected on Marion Island and compared the sequences with those in public sequence databases. For all three loci, sequences from the Marion Island specimens were nearly identical despite morphological dissimilarity, and phylogenetic analyses resolved them to a position in Limosella. In phylogenetic trees and comparisons of species-specific sequence polymorphisms, the Marion Island specimens were closest to a clade comprising Limosella aquatica L., L. curdieana F.Muell. and L. major Diels for ITS and closest to L. australis for the plastid loci. Cytonuclear discordance suggests a history of hybridization or introgression, which may have consequences for morphological variability and ecological adaptation.


2021 ◽  
Author(s):  
Lyle T. Wallace ◽  
Michael J. Havey

Abstract Passage of the highly inbred line ‘B’ of cucumber through cell cultures has produced regenerated plants with a mosaic (MSC) phenotype on cotyledons and leaves, as well as rearrangements in the mitochondrial DNA. Both of these characteristics show paternal transmission. MSC3 and MSC16 were derived from independent cell-culture experiments and have distinct mosaic phenotypes and different under-represented regions in their mitochondrial DNAs. A nuclear locus, Psm for paternal transmission of mitochondria, conditions a high proportion of wild type progenies when MSC16 is crossed as the male with female plants carrying the Psm- allele. Plants with homozygous genotypes at Psm were crossed with both MSC3 and MSC16, and segregation of wild-type versus mosaic progenies in these families were not consistent suggesting that sorting of wild-type progenies from crosses with MSC3 and MSC16 have different genetic bases. We identified cucumber plants that produced a high proportion of wild-type progenies in crosses with MSC3 as the male parent. Plants from a segregating F2 family were crossed with MSC3 as the male and progenies scored for numbers of mosaic versus wild-type progenies. The same F2 plants were genotyped-by-sequencing and single nucleotide polymorphisms identified for genetic mapping. Quantitative analysis of the proportion of wild-type testcross progenies identified a major quantitative trait locus (QTL) in the same genomic region as the Psm locus; however the most significant SNP associated with this QTL was located approximately 856 kilobases from Psm. Eventual identification of a candidate gene controlling this unique mitochondrial sorting in cucumber should reveal important aspects of mitochondrial-nuclear interactions affecting the prevalence of specific mitochondrial DNAs.


2020 ◽  
Vol 96 (1) ◽  
pp. 205-216
Author(s):  
Jessica Colavite ◽  
Amanda M. Windsor ◽  
William Santana

A new genus of majoid spider crab, Pohleusgen. nov. is established for Pericera septemspinosa Stimpson, 1871 and Pericera heptacantha Bell, 1836, based on morphology and molecular data from the partial sequences of the 12S and 16S mitochondrial genes and the 18S small subunit rRNA nuclear locus. The species are re-described and illustrated, based on material from several localities of the western Atlantic and eastern Pacific oceans. The carapace, antennal and pterygostomial spines, male thoracic sternum and first gonopods are distinctive characters, distinguishing Pohleusgen. nov. from species assigned to Macrocoeloma Miers, 1879, where P. septemspinosus and P. heptacanthus are currently included.


2019 ◽  
Author(s):  
Shadi Adineh ◽  
Joseph A. Ross

ABSTRACTMitochondria are typically maternally inherited. In many species, this transmission pattern is produced by sperm-borne mitochondria being eliminated either from sperm before fertilization or from the embryo after fertilization. In the nematode Caenorhabditis briggsae, repeatedly backcrossing hybrids to genetically diverse males can elicit paternal mitochondrial transmission. Studies of other taxa also suggest that hybridization increases paternal mitochondrial transmission. Thus, hybrid genotypes might disrupt the systems that normally prevent paternal mitochondrial transmission. Given the reliance of a number of genetic analyses on the assumption of purely maternal mitochondrial inheritance, it would be broadly valuable to learn more about the processes embryos employ to prevent sperm-borne mitochondria from persisting in offspring, as well as the circumstances under which paternal transmission might be expected to occur. To quantify the tempo of paternal mitochondrial transmission in hybrids, we assessed the presence of paternal mitotypes in replicate lines at three timepoints spanning fifteen generations. All lines exhibited paternal mitochondrial transmission. However, this heteroplasmy always then resolved to homoplasmy for the maternal mitotype. Additionally, one nuclear locus exhibited allele transmission ratio distortion that might reflect mito-nuclear co-evolution. This study frames the genetic architecture of a hybrid genetic incompatibility that leads to paternal mitochondrial transmission and to a reduction in hybrid fitness.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5160 ◽  
Author(s):  
Jinming Lu ◽  
Yuan Zhang ◽  
Hongwei Chen

The genus Pseudostegana (Okada, 1978) currently contains thirty-nine described species. A number of Pseudostegana were collected from the fieldwork in southwestern China from 2010 to 2017. Eleven new species were discovered and are described from southwestern China: Pseudostegana alpina Zhang & Chen, sp. nov.; Pseudostegana amnicola Zhang & Chen, sp. nov.; Pseudostegana amoena Zhang & Chen, sp. nov.; Pseudostegana mailangang Zhang & Chen, sp. nov.; Pseudostegana meiduo Zhang & Chen, sp. nov.; Pseudostegana meiji Zhang & Chen, sp. nov.; Pseudostegana mystica Zhang & Chen, sp. nov.; Pseudostegana stictiptrata Zhang & Chen, sp. nov.; Pseudostegana stigmatptera Zhang & Chen, sp. nov.; Pseudostegana ximalaya Zhang & Chen, sp. nov. and Pseudostegana zhuoma Zhang & Chen, sp. nov. A key to all Chinese Pseudostegana species based on morphological characters is provided. Two mitochondrial loci (COI and ND2) and one nuclear locus (28S rRNA) were sequenced for the Pseudostegana specimens, and Bayesian and RAxML concatenated analyses were run. Molecular species delimitation is performed using the distance-based automatic barcode gap discovery (ABGD) method. Molecular data support the morphological characteristics observed among these Chinese species and confirm the new species as being distinctly different.


Zootaxa ◽  
2018 ◽  
Vol 4378 (4) ◽  
pp. 451 ◽  
Author(s):  
MAXWELL J. BERNT ◽  
WILLIAM G. R. CRAMPTON ◽  
ALEXANDER B. ORFINGER ◽  
JAMES S. ALBERT

We describe Melanosternarchus amaru as a new genus and species of Apteronotidae from the deep channels of blackwater and clearwater tributaries of the Amazon River in Brazil and Peru. The new species superficially resembles members of the widespread “Apteronotus” bonapartii species group, from which it can be readily distinguished by expanded bones of the infraorbital laterosensory canal. It can further be distinguished from all other apteronotids by a unique combination of characters: reduced premaxillary dentition, a large gape, and an absence of scales from the entire dorsum. A molecular phylogenetic analysis using three mitochondrial loci and one nuclear locus (~3000 bp) places this genus as sister to Compsaraia, and these two genera together as a clade sister to Pariosternarchus; all nodes with strong statistical support. The clade formed by these three genera includes five species, four of which are restricted to the Amazon basin. The apparent habitat preference of the new species for low-conductivity blackwater and clearwater rivers has not been reported in other apteronotid species. 


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