Nuclear Recombination-activating Gene Research Articles

A new Mexican endemic species of yellow-eared bat in the genus Vampyressa (Phyllostomidae, Stenodermatinae)

Abstract Bats from the genus Vampyressa Thomas, 1900 are known from a relatively small number of individuals in Mexico. Through recent collecting efforts in southwestern Mexico, we detected several previously unknown populations of Vampyressa, which appeared to represent a lineage independent from but closely related to V. thyone. Here, we describe this lineage as a new species of the genus Vampyressa from the Mexican states of Guerrero and Oaxaca. The new species is currently known from at least 8 collected specimens and 3 released individuals from 8 localities, and can be differentiated from V. pusilla and V. thyone based on pelage and skull characters, size, mitochondrial Cytochrome b, and nuclear Recombination-activating gene 2 sequence data. The new species has been captured mainly in the lowlands but occurs along a wide altitudinal range from 150 to 2,200 m above sea level. Most of the records of the new species are from west of the Isthmus of Tehuantepec, which evidences a new case of a phylogenetic break at this biogeographic barrier. The genus Vampyressa now includes 6 species, and Mexico expands its position as the country with the largest number of endemic bats in the Neotropics, totaling 20 endemics.

Cryptic biodiversity in the freshwater fishes of the Kimberley endemism hotspot, northwestern Australia

The prevalence of unrecognised cryptic species impairs biodiversity estimates, clouds biological research and hinders conservation planning. As the rate of cryptic species detection increases globally, research is needed to determine how frequent cryptic species are, whether they are more common in given management regions, and whether these patterns are consistent across taxonomic groups. The Kimberley region in remote northwestern Australia harbours some of the most speciose, and morphologically and functionally diverse, endemic animal and plant communities on the continent. The rugged and changeable landscape also appears to contain a large proportion of cryptic terrestrial species, raising the question of whether similar patterns are also found among aquatic taxa, which have yet to be studied using integrative systematic approaches. If true, then the actual levels of aquatic biodiversity are yet to be fully realised. Here we conducted a molecular assessment of where species boundaries may exist in the Kimberley regions’ most speciose freshwater fish family, the Terapontidae (grunters), with a combined morphological assessment of the regions’ most speciose terapontid genus, Syncomistes. Assessment of nuclear markers (54 allozyme loci), sequence data (mitochondrial cytochrome b (cytb); nuclear recombination activation gene one (RAG1)) and 31 meristic and 36 morphometric characters provides evidence for 13 new candidate species across three different genera. Many of these candidate species are narrow range endemics. Our findings raise several questions about the evolutionary origin of the Kimberley’s endemic fish fauna and highlight the likelihood that freshwater fish species diversity in the Kimberley is severely under-represented by current systematic frameworks, with significant implications for ecological research, conservation and management.

Testing for Genetic Divergence within and among Isolated Populations of a Threatened Species in Georgia and Alabama,Percina aurolineata(Percidae; Goldline Darter)

Percina aurolineata (Percidae: subgenus Hadropterus) (Goldline Darter) is a federally threatened species that currently exists in disjunct populations in the Coosawattee River, GA, and Cahaba River, AL. These 2 Mobile Basin drainages are home to considerable endemism, and these disjunctions may actually represent cryptic diversity within Goldline Darter. We examined sequence data from the mitochondrial cytochrome b gene (cyt b) and nuclear recombination-activation gene exon 1 (RAG1) from specimens (n = 34) collected from 4 streams in the Coosawattee River drainage and 4 streams in the Cahaba River drainage for the purpose of assessing phylogenetic structure and genetic divergence to test the hypothesis that the disjunct populations of Goldline Darter represent a single species. Specimens from each of the rivers sampled were not resolved as a clade in any analysis. For cyt b, divergence within the Coosawattee was 0.8%, divergence within the Cahaba was 0.3%, and net divergence between populations was 0.4%. For RAG1, divergence within the Coosawattee was 0.0%, divergence within the Cahaba was 0.1%, and net divergence between populations was 0.0%. We detected a unique allele for RAG1 with a frequency of 0.559 in the Cahaba specimens. No clades were resolved that contained specimens representative of only one locality and the difference between mean divergence among and within rivers was low; thus, these results support the hypothesis that the disjunct populations of Goldline Darter represent a single species and an evolutionarily significant unit. The divergence of allele frequencies among Cahaba and Coosawattee for RAG1 qualifies them as separate management units, and future conservation efforts should manage them as such.

Development of a multiplex system to assess DNA persistence in taphonomic studies

In this study, we have developed a PCR multiplex that can be used to assess DNA degradation and at the same time monitor for inhibition: primers have been designed to amplify human, pig, and rabbit DNA, allowing pig and rabbit to be used as experimental models for taphonomic research, but also enabling studies on human DNA persistence in forensic evidence. Internal amplified controls have been added to monitor for inhibition, allowing the effects of degradation and inhibition to be differentiated. Sequence data for single-copy nuclear recombination activation gene (RAG-1) from human, pig, and rabbit were aligned to identify conserved regions and primers were designed that targeted amplicons of 70, 194, 305, and 384 bp. Robust amplification in all three species was possible using as little as 0.3 ng of template DNA. These have been combined with primers that will amplify a bacterial DNA template within the PCR. The multiplex has been evaluated in a series of experiments to gain more knowledge of DNA persistence in soft tissues, which can be important when assessing what material to collect following events such as mass disasters or conflict, when muscle or bone material can be used to aid with the identification of human remains. The experiments used pigs as a model species. When whole pig bodies were exposed to the environment in Northwest England, DNA in muscle tissue persisted for over 24 days in the summer and over 77 days in the winter, with full profiles generated from these samples. In addition to time, accumulated degree days (ADD) were also used as a measure that combines both time and temperature-24 days was in summer equivalent to 295 ADD whereas 77 days in winter was equivalent to 494 ADD.

Diversification and reproductive isolation: cryptic species in the only New World high-duty cycle bat, Pteronotus parnellii

BackgroundMolecular techniques are increasingly employed to recognize the presence of cryptic species, even among commonly observed taxa. Previous studies have demonstrated that bats using high-duty cycle echolocation may be more likely to speciate quickly. Pteronotus parnellii is a widespread Neotropical bat and the only New World species to use high-duty cycle echolocation, a trait otherwise restricted to Old World taxa. Here we analyze morphological and acoustic variation and genetic divergence at the mitochondrial COI gene, the 7th intron region of the y-linked Dby gene and the nuclear recombination-activating gene 2, and provide extensive evidence that P. parnellii is actually a cryptic species complex.ResultsCentral American populations form a single species while three additional species exist in northern South America: one in Venezuela, Trinidad and western Guyana and two occupying sympatric ranges in Guyana and Suriname. Reproductive isolation appears nearly complete (only one potential hybrid individual found). The complex likely arose within the last ~6 million years with all taxa diverging quickly within the last ~1-2 million years, following a pattern consistent with the geological history of Central and northern South America. Significant variation in cranial measures and forearm length exists between three of the four groups, although no individual morphological character can discriminate these in the field. Acoustic analysis reveals small differences (5–10 kHz) in echolocation calls between allopatric cryptic taxa that are unlikely to provide access to different prey resources but are consistent with divergence by drift in allopatric species or through selection for social recognition.ConclusionsThis unique approach, considering morphological, acoustic and multi-locus genetic information inherited maternally, paternally and bi-parentally, provides strong support to conclusions about the cessation of gene flow and degree of reproductive isolation of these cryptic species.

Phylogenetic Relationships of the Genus Homatula (Cypriniformes: Nemacheilidae), with Special Reference to the Biogeographic History around the Yunnan-Guizhou Plateau

Species of the nemacheilid genus Homatula are endemic to the Yunnan-Guizhou Plateau of China. Herein we provide phy-logenetic inferences of species relationships based on complete sequences of the mitochondrial cytochrome b gene (cyt b)and partial sequences of the nuclear recombination activation gene (RAG 1). Both gene trees (and the concatenated dataset) support the recognition of five clades in the genus. These analyses also support the hypothesis that two of the lineagesresolved represent undescribed species awaiting formal description, and, further, that two previously recognized speciesare junior synonyms; both are genetically indistinguishable from other previously recognized species. Divergence timesof the major clades in Homatula are inferred to be Late Pliocene and the Early Pleistocene, and are correlated with themassive geological events associated with the uplift of the Qinghai-Tibetan Plateau occurring at these times. The recon-struction of drainage histories suggests that the fish faunas of the Nu and Lancang rivers are basal relative to other riverinefaunas in the region, and that the Nanpan and the Jinsha rivers share a more recent history than with any other river systems included in our study.

Molecular phylogenetic relationships of pangasiid and schilbid catfishes in Thailand

In this study, the phylogenetic relationships among 13 pangasiids and six schilbids of Thailand were reconstructed based on the almost complete mitochondrial cytochrome b (cyt b), 12S rRNA, tRNA-Val and 16S rRNA, as well as the partial nuclear recombination-activating gene 1 (rag1) sequences by using the maximum likelihood and the Bayesian inference methods of phylogenetic reconstruction. The reconstructed phylogeny based on the concatenated sequence data set recovered Pangasiidae and Schilbidae as reciprocally monophyletic groups. Within Pangasiidae, four major clades were recovered, which according to the cyt b genetic distances can be categorized into four genera: Pangasius, Pseudolais, Helicophagus and Pangasianodon. The genus Pangasianodon was strongly supported as the most basal taxon within pangasiids, whereas Pseudolais + Helicophagus were recovered as a sister group of Pangasius. Within the latter, the giant pangasius Pangasius sanitwongsei was recovered as a sister group of the spot pangasius Pangasius larnaudii, Pangasius krempfi as a sister group of Pangasius nasutus + Pangasius conchophilus and Pangasius polyuranodon as a sister species of Pangasius macronema. Other internal phylogenetic relationships, however, were unresolved. Within Schilbidae, Pseudeutropius was supported as the most basal lineage. Eutropiichthys was recovered as a sister group of Clupisoma. The enigmatic Clupisoma sinense was recognized as more closely related to Laides longibarbis than to Clupisoma prateri. Thus, based on the cyt b genetic distances, a recategorization of C. sinense to the genus Laides is suggested. On the basis of a relaxed clock fossil calibration, the divergence of pangasiids and schilbids was estimated to have occurred 14·93 million years before present (b.p.) during the Miocene epoch. The separation between Pangasiidae and Schilbidae took place c. 13·12 Mb.p. during the early middle Miocene. The estimated divergence time of pangasiids is similar to the age of the calibrated fossil, Cetopangasius chaetobranchus, which was discovered in north-central Thailand. This suggests that the oldest pangasiid ancestor diverged into diverse genera in the area.

Systematics of the Etheostoma cinereum (Teleostei: Percidae) species complex (subgenus Allohistium)

We examined geographic variation within the Ashy Darter, Etheostoma cinereum, of the mitochondrially enconded cyto-chrome b gene (cyt b) and nuclear recombination activation gene 1 (RAG1) as well as pigmentation, 6 meristic variables,and 20 morphometric variables for patterns indicative of speciation within the complex. Four geographically disjunct en-tities were identified by at least one of the datasets corresponding to the Cumberland, Duck, Elk, and upper Tennesseeriver systems. Monophyly of cyt b and RAG1 sequences, modal meristic differences, moderate morphometric divergence,and unique pigmentation in specimens from the Cumberland River suggest this entity represents an evolutionary speciesunder many different species concepts and is described herein as Etheostoma maydeni. Other populations exhibit varyingdegrees of divergence in the different datasets and have conflicting relationships in phylogenetic analyses using cyt b andRAG1 sequences, leaving the evolutionary history and taxonomic status of the Duck, Elk and upper Tennessee populations unclear.

Phylogeny of the Southeast Asian freshwater fish genus Pangio (Cypriniformes; Cobitidae)

The genus Pangio is one of the most species-rich of the loach family Cobitidae and widespread across South and Southeast Asia. Its species diversity has never been studied under a clear phylogenetic approach, but four ‘species-groups’ were proposed according to the most obvious morphological characters. We present here phylogenetic analyses of the genus Pangio based on sequence data of the mitochondrial cytochrome b gene, the nuclear recombination-activating gene 1 (RAG 1) and a combined dataset of 109 specimens from 18 morphologically identified species across the whole distribution area of the genus. Our data reveal the existence of three major lineages within Pangio. Two of our major lineages were congruent with formerly proposed species-groups, the remaining two species-groups together formed the third major lineage; herein we refer to the lineages as to anguillaris-group, kuhlii-oblonga group and shelfordii-group. The application of a molecular clock dated the age of the three lineages to 33–29 million years. At the species level, our data suggest about 30 distinct lineages, indicating that there is a high number of undescribed species within Pangio. The use of Pangio to address biogeographic questions is demonstrated with the example of the shelfordii-group, which is distributed across Sundaland.

The phylogenetic relationships among Noturus catfishes (Siluriformes: Ictaluridae) as inferred from mitochondrial gene cytochrome b and nuclear recombination activating gene 2

Madtom catfishes of the genus Noturus are a well-known component of the North American ichthyofauna. Original nucleotide sequence data were collected from mitochondrial (cytochrome b) and nuclear (recombination activating gene 2) genes and used to estimate genetic variation and infer phylogenetic relationships among and within species of Noturus. Mitochondrial sequences were variable among species and several species were found to contain considerable genetic diversity. Relationships among members of the subgenus Rabida were resolved and in many cases well supported. Relationships among members of the subgenus Schilbeodes were poorly resolved. Previous phylogenetic hypotheses and the traditional classification (except the furiosus species group) were rejected in their explicit form according to the Kishino–Hasegawa and Shimodaira–Hasegawa tests of tree score difference.