The complete mitochondrial genome of the Bechstein's bat, Myotis bechsteinii (Chiroptera, Vespertilionidae)

Cryptic hybridization between the ancient lineages of Natterer's bat (Myotis nattereri)

Studying hybrid zones that form between morphologically cryptic taxa offers valuable insights into the mechanisms of cryptic speciation and the evolution of reproductive barriers. Although hybrid zones have long been the focus of evolutionary studies, the awareness of cryptic hybrid zones increased recently due to rapidly growing evidence of biological diversity lacking obvious phenotypic differentiation. The characterization of cryptic hybrid zones with genome-wide analysis is in its early stages and offers new perspectives for studying population admixture and thus the impact of gene flow. In this study, we investigate the population genomics of the Myotis nattereri complex in one of its secondary contact zones, where a putative hybrid zone is formed between two of its cryptic lineages. By utilizing a whole-genome shotgun sequencing approach, we aim to characterize this cryptic hybrid zone in detail. Demographic analysis suggests that the cryptic lineages diverged during the Pliocene, c. 3.6 million years ago. Despite this ancient separation, the populations in the contact zone exhibit mitochondrial introgression and a considerable amount of mixing in nuclear genomes. The genomic structure of the populations corresponds to geographic locations and the genomic admixture changes along a geographic gradient. These findings suggest that there is no effective hybridization barrier between both lineages, nevertheless, their population structure is shaped by dispersal barriers. Our findings highlight how such deeply diverged cryptic lineages can still readily hybridize in secondary contact.

Presumptive First Record of Myotis aurascens (Chiroptera, Vespertilionidae) from China with a Phylogenetic Analysis

Bat groups have a high degree of species diversity, and the taxonomic status and phylogenetic relationships among bat species have always been research hotspots. Due to the fact that morphological characteristics do not always reflect the evolutionary relationships among species, mitochondrial DNA has been widely used in the study of species relationships due to its maternal inheritance pattern. Myotis aurascens has been suggested as a possible synonym for M. davidii. However, the status of this classification has been controversial. In this study, the morphological and molecular characteristics of a M. aurascens captured from Inner Mongolia, China, were analyzed to determine its taxonomic status. In terms of morphological features, the body weight was 6.33 g, the head and body length were 45.10 mm, the forearm length was 35.87 mm, and the tragus length was 7.51 mm. These values all fell within the species signature data range. Nucleotide skew analysis of the protein-coding genes (PCGs) suggested that only five PCGs (ND1, ND2, COX2, ATP8, and ND4) showed AT-skew value within the mitogenome of M. aurascens. Except for ND6, the GC-skew values of the other PCGs were negative, reflecting the preference for C and T bases compared to G and A bases. Molecular phylogenetic analyses based on mitochondrial PCGs indicated that M. aurascens was a distinct species from M. davidii and phylogenetically closer to M. ikonnikovi, M. alcathoe, and M. mystacinus. Genetic distance analysis also showed that M. aurascens and M. davidii were distantly related. Therefore, the integrated analysis demonstrated that M. aurascens should be considered a distinct species rather than a synonym of M. davidii. Our study could provide a reference for enriching species diversity and research on conservation in China.

First record of disk-footed bat Eudiscopus denticulus (Chiroptera, Vespertilionidae) from China and resolution of phylogenetic position of the genus

The disk-footed bat Eudiscopus denticulus(Osgood, 1932) is a rare species in Southeast Asia. During two chiropteran surveys in the summer of 1981 and 2019, eight and three small Myotis-like bats with distinct disk-like hindfeet were collected from Yunnan Province, China, respectively. External, craniodental, and phylogenetic evidence confirmed these specimens as E. denticulus, representing a new genus in China. The complete mitochondrial genome consistently showed robust support for E. denticulus as a basal lineage within Myotinae. The coding patterns and characteristics of its mitochondrial genome were similar to that of other published genomes fromMyotis. The echolocation signals of the newly collected individuals were analyzed. The potential distribution range of Eudiscopus in Southeast Asia inferred using the MaxEnt model indicated its potential occurrence along the southern border region of Yunnan, China.

The published complete mitochondrial genome of Eptesicus serotinus is a chimera of Vespertilio sinensis and Hypsugo alaschanicus (Mammalia: Chiroptera)

The mitogenome of Eptesicus serotinus (Serotine bat) was published in 2013 with GenBank accession number KF111725 and NCBI Reference Sequence number NC_022474. This sequence was placed with Vespertilio sinensis (Asian parti-colored bat) in a COI gene tree but with Hypsugo alashanicus (Alashanian pipistrelle) in a cytochrome b gene tree. Direct comparison of mitogenomes showed that 92.4% of this mitogenome is similar to Vespertilio sinensis, 5.9% to Hypsugo alaschanicus, and that 1.6% of the mitogenome could not be attributed to either species, or any other species. This mitogenome has been re-used in at least 17 phylogenies. Our findings suggest that mitogenomes are best verified with multiple gene trees, followed by direct comparison of sequences. We conclude that greater vigilance is warranted to ensure that problematic sequences do not enter the scientific record, and are not re-used in subsequent studies.