Distribution of the Main Apis mellifera Mitochondrial DNA Lineages in Italy Assessed Using an Environmental DNA Approach

Growing interest has been emerging on the need to monitor the genetic integrity of the European Apis mellifera subspecies that could be threatened by the human-mediated dispersion of non-native populations and lines. Mitochondrial DNA (mtDNA) lineages can provide useful information for this purpose. In this study, we took advantage of the environmental DNA (eDNA) contained in the honey, which can be analyzed to detect the main groups of mitotypes of the honey bees that produced it. In this study, we applied this eDNA to produce a distribution map all over the Italian peninsula and the two major islands (Sicily and Sardinia) of the following three honey bee mtDNA lineages: A, C and M. A total of 607 georeferenced honey samples, produced in all Italian regions, was analyzed to detect these lineages. The A lineage was widespread in Sicily, as expected, considering that A. m. siciliana carries the African lineage. Surprisingly, this lineage was also reported in about 14% of all other samples produced in almost all continental regions, and in Sardinia. The applied method obtained an updated distribution map of honey bee mtDNA lineages that could be useful to design policies for the conservation of Italian honey bee genetic resources.

Genetic variation of Nigerian cattle inferred from maternal and paternal genetic markers

The African cattle provide unique genetic resources shaped up by both diverse tropical environmental conditions and human activities, the assessment of their genetic diversity will shade light on the mechanism of their remarkable adaptive capacities. We therefore analyzed the genetic diversity of cattle samples from Nigeria using both maternal and paternal DNA markers. Nigerian cattle can be assigned to 80 haplotypes based on the mitochondrial DNA (mtDNA) D-loop sequences and haplotype diversity was 0.985 + 0.005. The network showed two major matrilineal clustering: the dominant cluster constituting the Nigerian cattle together with other African cattle while the other clustered Eurasian cattle. Paternal analysis indicates only zebu haplogroup in Nigerian cattle with high genetic diversity 1.000 ± 0.016 compared to other cattle. There was no signal of maternal genetic structure in Nigerian cattle population, which may suggest an extensive genetic intermixing within the country. The absence of Bos indicus maternal signal in Nigerian cattle is attributable to vulnerability bottleneck of mtDNA lineages and concordance with the view of male zebu genetic introgression in African cattle. Our study shades light on the current genetic diversity in Nigerian cattle and population history in West Africa.

Gene flow in phylogenomics: Sequence capture resolves species limits and biogeography of Afromontane forest endemic frogs from the Cameroon Highlands

ABSTRACTPuddle frogs of the Phrynobatrachus steindachneri species complex are a useful group for investigating speciation and phylogeography in Afromontane forests of the Cameroon Highlands (Cameroon Volcanic Line) in western Central Africa. The species complex is represented by six morphologically relatively cryptic mitochondrial DNA lineages, with only two of them distinguished at the species level – southern P. jimzimkusi and Lake Oku endemic P. njiomock, leaving the remaining four lineages with a pooled identification as ‘P. steindachneri’. In this study, the six mtDNA lineages are subjected to genomic sequence capture analyses to delimit species (together with morphology) and to study biogeography. Nuclear DNA data (387 loci; 571,936 aligned base pairs) distinguished all six mtDNA lineages, but the splitting pattern and depths of divergences supported only four main clades—besides P. jimzimkusi and P. njiomock, only two from the four ‘P. steindachneri’ mtDNA lineages. One is here described as a new species, P. sp. nov. Reticulate evolution (hybridization) was detected within the species complex with morphologically intermediate hybrid individuals placed between the parental species in phylogenomic analyses, forming a phylogenetic artefact – a ladder-like tree pattern. The presence of hybrids is undesirable in standard phylogenetic analyses, but is essential and beneficial in the network multispecies coalescent. This latter approach allowed us an insight into the reticulate evolutionary history of these endemic frogs. Introgressions likely occurred during the Middle and Late Pleistocene climatic oscillations, due to the cyclic connections (likely dominating during cold glacials) and separations (warm interglacials) of montane forests. The genomic phylogeographic pattern supports the earliest division between southern (Mt. Manengouba to Mt. Oku) and northern mountains at the onset of the Pleistocene. Further subdivisions occurred in the Early Pleistocene separating populations from the northernmost (Tchabal Mbabo, Gotel Mts.) and middle mountains (Mt. Mbam, Mt. Oku, Mambilla Plateau), as well as the microendemic lineage restricted to Lake Oku (Mt. Oku). Mount Oku harboring three species is of particular conservation importance. This unique model system is highly threatened as all the species within the complex have exhibited severe population declines in the past decade, placing them on the brink of extinction. We therefore urge for conservation actions in the Cameroon Highlands to preserve their diversity before it is too late.

Coexistence of Three Divergent mtDNA Lineages in Northeast Asia Provides New Insights into Phylogeography of Goldfish (Carssius auratus)

Goldfish (Carassius aurautus), which is a middle size cyprinid, widely distribute throughout Eurasia. Phylogeographic studies using mtDNA markers have revealed several divergent lineages within goldfish. In this study, mtDNA variations were determined to elucidate the phylogeographical pattern and genetic structure of goldfish in Northeast Asia. A total of 1054 individuals from Amur river basin were analyzed, which including five newly collected populations and four previously reported populations. Three distinct mtDNA lineages were identified in those samples, two of which corresponded to two known lineages C2 and C6, respectively. The third lineage referred to as C7, following six known lineages of goldfish in mainland Eurasia. AMOVA results suggested that most of the genetic variations were among lineages, rather than among populations or twice samplings. We noted that the control region (CR) and cytochrome b (cytb) sequences of lineage C7 have been reported in previous studies, respectively. However, the evolutionary position and distribution pattern of this lineage was not discussed in the context of the species. Our results showed that “odd” CR and “hidden” cytb sequences from Central Asia represent the same mtDNA lineage of goldfish. The known samples of C7 lineage were collected from Central Asia (Eastern Kazakhstan and Western Mongolia) to East Asia (Northeast China and Far East Russia), which suggested that it had a wider distribution, rather than limit in Central Asia.

Cultural variation impacts paternal and maternal genetic lineages of the Hmong-Mien and Sino-Tibetan groups from Thailand

The Hmong-Mien (HM) and Sino-Tibetan (ST) speaking groups are known as hill tribes in Thailand; they were the subject of the first studies to show an impact of patrilocality vs. matrilocality on patterns of mitochondrial (mt) DNA vs. male-specific portion of the Y chromosome (MSY) variation. However, HM and ST groups have not been studied in as much detail as other Thai groups; here we report and analyze 234 partial MSY sequences (∼2.3 mB) and 416 complete mtDNA sequences from 14 populations that, when combined with our previous published data, provides the largest dataset yet for the hill tribes. We find a striking difference between Hmong and IuMien (Mien-speaking) groups: the Hmong are genetically different from both the IuMien and all other Thai groups, whereas the IuMien are genetically more similar to other linguistic groups than to the Hmong. In general, we find less of an impact of patrilocality vs. matrilocality on patterns of mtDNA vs. MSY variation than previous studies. However, there is a dramatic difference in the frequency of MSY and mtDNA lineages of Northeast Asian (NEA) origin vs. Southeast Asian (SEA) origin in HM vs. ST groups: HM groups have high frequencies of NEA MSY lineages but lower frequencies of NEA mtDNA lineages, while ST groups show the opposite. A potential explanation is that the ancestors of Thai HM groups were patrilocal, while the ancestors of Thai ST groups were matrilocal. Overall, these results attest to the impact of cultural practices on patterns of mtDNA vs. MSY variation.

Mitochondrial lineages or discrete species? Assessing diversity within Timon tangitanus (Lacertidae) using mitochondrial and nuclear DNA sequences

Identification of extremely high levels of mitochondrial DNA (mtDNA) sequence divergence within reptiles from North Africa is commonplace. This high divergence often compares with interspecific levels among widely accepted species, leading to the hypothesis of the occurrence of species complexes. Indeed, in many examples, data from nuclear markers support such taxonomic recognition. Such is the case of two recently recognized ocellated lizard species of the genus Timon, T. nevadensis, from Spain, and T. kurdistanicus, from the Middle East, which both showed notable genetic differentiation from their sister taxa. In North Africa, highly divergent mtDNA lineages of Timon tangitanus were previously identified but not corroborated with nuclear markers. Here we expand geographic sampling across the range of Timon tangitanus and complement mtDNA sequences with data from nuclear markers (MC1R and ACM4). We identify four divergent mtDNA lineages, at a level similar to some reptile species. However, the nuclear markers show limited differentiation and lack of lineage sorting. This and some other recent assessments within reptiles discourage the use of mtDNA data alone as a proxy for taxonomic units, demonstrating once more the need for integrative taxonomic approaches.

Cultural variation impacts paternal and maternal genetic lineages of the Hmong-Mien and Sino-Tibetan groups from Thailand

The Hmong-Mien (HM) and Sino-Tibetan (ST) speaking groups are known as hill tribes in Thailand; they were the subject of the first studies to show an impact of patrilocality vs. matrilocality on patterns of mitochondrial (mt) DNA vs. male-specific portion of the Y chromosome (MSY) variation. However, HM and ST groups have not been studied in as much detail; here we report and analyze 234 partial MSY sequences (∼2.3 mB) and 416 complete mtDNA sequences from 14 populations that, when combined with our previous published data, provides the largest dataset yet for the hill tribes. We find a striking difference between Hmong and IuMien (Mien-speaking) groups: the Hmong are genetically different from both the IuMien and all other Thai groups, whereas the IuMien are genetically more similar to other linguistic groups than to the Hmong. In general, we find less of an impact of patrilocality vs. matrilocality on patterns of mtDNA vs. MSY variation than previous studies. However, there is a dramatic difference in the frequency of MSY and mtDNA lineages of Northeast Asian (NEA) origin vs. Southeast Asian (SEA) origin in HM vs. ST groups: HM groups have high frequencies of NEA MSY lineages but lower frequencies of NEA mtDNA lineages, while ST groups show the opposite. A potential explanation is that the ancestors of Thai HM groups were patrilocal, while the ancestors of Thai ST groups were matrilocal. Overall, these results attest to the impact of cultural practices on patterns of mtDNA vs. MSY variation.

New insights into population structure of the European golden eagle (Aquila chrysaetos) revealed by microsatellite analysis

Connectivity between golden eagle (Aquila chrysaetos) populations is poorly understood. Field studies exploring natal dispersal suggest that this raptor is a philopatric species, but with the ability to roam far. However, little is known about the population structure of the species in Europe. Our study is based on 14 microsatellite loci and is complemented by new and previously published mitochondrial control region DNA data. The present dataset includes 121 eagles from Scotland, Norway, Finland, Estonia, the Mediterranean and Alpine regions. Our sampling focused on the Alpine and Mediterranean populations because both mitochondrial DNA (mtDNA) lineages found in golden eagles, the Holarctic and the Mediterranean, are known to co-occur there. Cluster analyses of nuclear DNA support a shallow split into northern and southern populations in Europe, similar to the distribution of the two mtDNA lineages, with the Holarctic lineage occurring in the north and the Mediterranean lineage predominating in the south. Additionally, Scotland shows significant differentiation and low relative migration levels that indicate isolation from the mainland populations. Alpine and Mediterranean golden eagles do not show nuclear structure corresponding to divergent mtDNA lineages. This indicates that the presence of northern Holarctic mitochondrial haplotypes in the Alps and the Mediterranean is attributable to past admixture rather than recent long-distance dispersal.