Phylogeography of the Mauremys mutica complex and the implications for conservation management.

For more than three decades, the Asian turtle crisis has resulted in the decline of every native species in China. For some species, such as the yellow pond turtle (Mauremys mutica), wild populations have dwindled to near functional extinction. Previous studies show there is deep genetic divergence of M. mutica sensu lato between populations north and south of the Pearl River Drainage but no data to show if phylogeographic structure occurs within these two main types. In this study, we found clear phylogeographic structure. In northern types, we found two main clades, corresponding to mainland China and island clades (Taiwan and Yaeyema Islands) with uncorrected p values of 0.00-2.0% divergence in our 2353 bp concatenated mtDNA data set. For the southern types, we found three main clades corresponding to Hainan, Mainland (Vietnam/Guangxi) and the Annam pond turtle (Mauremys annamensis) with divergence ranging from 1.0-1.8% among these three groups. Moreover, the identification of northern and southern types by phenotype was roughly 98% accurate, which, coupling with the deep genetic divergence in mtDNA (5.5-6.7%) and in the 6056 bp nuDNA data set (0.16-0.37%) provide sufficient evidence for northern M. mutica to be an independent species, and individuals from the southern clade should be regarded as subspecies of M. annamensis. Finally, we provide the most comprehensive database to date which can be used to determine the region of origin for captive stock. Making the large captive populations of M. mutica, under the right conditions, potentially valuable for restocking or augmentation of wild populations.

Extensive species diversification and marked geographic phylogenetic structure in the Mesoamerican genus Stenopelmatus (Orthoptera: Stenopelmatidae: Stenopelmatinae) revealed by mitochondrial and nuclear 3RAD data

The Jerusalem cricket subfamily Stenopelmatinae is distributed from south-western Canada through the western half of the United States to as far south as Ecuador. Recently, the generic classification of this subfamily was updated to contain two genera, the western North American Ammopelmatus, and the Mexican, and central and northern South American Stenopelmatus. The taxonomy of the latter genus was also revised, with 5, 13 and 14 species being respectively validated, declared as nomen dubium and described as new. Despite this effort, the systematics of Stenopelmatus is still far from complete. Here, we generated sequences of the mitochondrial DNA barcoding locus and performed two distinct DNA sequence-based approaches to assess the species’ limits among several populations of Stenopelmatus, with emphasis on populations from central and south-east Mexico. We reconstructed the phylogenetic relationships among representative species of the main clades within the genus using nuclear 3RAD data and carried out a molecular clock analysis to investigate its biogeographic history. The two DNA sequence-based approaches consistently recovered 34 putative species, several of which are apparently undescribed. Our estimates of phylogeny confirmed the recent generic update of Stenopelmatinae and revealed a marked phylogeographic structure within Stenopelmatus. Based on our results, we propose the existence of four species-groups within the genus (the faulkneri, talpa, Central America and piceiventris species-groups). The geographic distribution of these species-groups and our molecular clock estimates are congruent with the geological processes that took place in mountain ranges along central and southern Mexico, particularly since the Neogene. Our study emphasises the necessity to continue performing more taxonomic and phylogenetic studies on Stenopelmatus to clarify its actual species richness and evolutionary history in Mesoamerica.

From Settlers to Subspecies: Genetic Differentiation in Commerson’s Dolphins Between South America and the Kerguelen Islands

Commerson’s dolphins (Cephalorhynchus commersonii) are separated into the subspecies C. c. commersonii, found along southern South America (SA) and the Falkland Islands/Islas Malvinas (FI/IM), and C. c. kerguelenensis, restricted to the subantarctic Kerguelen Islands (KI). Following the dispersal model proposed for the genus, the latter is thought to have originated from SA after a long-distance dispersal event. To evaluate this biogeographic scenario, a distribution-wide, balanced sampling of mitochondrial DNA (mtDNA) control region sequences was designed. New tissue samples from southern Chile, Argentina, FI/IM, and KI were added to published sequences from SA and KI, for a total of 256 samples. Genetic diversity indices, genetic and phylogeographic structure, and migration rates were calculated. One haplotype was shared between subspecies, with which all haplotypes of C. c. kerguelenensis formed a distinct group in the haplotype network. A new haplotype for C. c. kerguelenensis is reported. Differentiation in haplotype frequencies was found among localities within the distribution of C. c. commersonii, yet the phylogeographic signal was only statistically significant between subspecies. Coalescent-based historical gene flow estimations indicated migration between the northern and southern portions of the species’ range in SA as well as between SA and the FI/IM, but not between these and the KI. The net nucleotide divergence between dolphins from SA and the FI/IM was lower than the recommended threshold value suggested for delimiting subspecies, unlike that found between C. c. commersonii and C. c. kerguelenensis. The results are consistent with the model of post-glacial colonization of KI by South American C. commersonii, followed by an ongoing divergence process and subspecies status. Thus, C. c. kerguelenensis may represent the most recent diversification step of Cephalorhynchus, where isolation from their source population is driving a process of incipient speciation.

Homogenized Phylogeographic Structure across the Indo-Burma Ranges of a Large Monoecious Fig, Ficus altissima Blume

As well as bountiful natural resources, the Indo-Burma biodiversity hotspot features high rates of habitat destruction and fragmentation due to increasing human activity; however, most of the Indo-Burma species are poorly studied. The exploration of plants closely associated with human activity will further assist us to understand our influence in the context of the ongoing extinction events in the Anthropocene. This study, based on widely and intensively sampled F. altissima across Indo-Burma and the adjacent south China ranges, using both the chloroplast psbA-trnH spacer and sixteen newly developed nuclear microsatellite markers (nSSRs), aims to explore its spatial genetic structure. The results indicated low chloroplast haplotype diversity and a moderate level of nuclear genetic diversity. Although limited seed flow was revealed by psbA-trnH, no discernible phylogeographic structure was shown due to the low resolution of cpDNA markers and dominance of an ancestral haplotype. From the nSSRs data set, phylogeographic structure was homogenized, most likely due to extensive pollen flow mediated by pollinating fig wasps. Additionally, human cultivation and human-mediated transplanting further confounded the analyses of population structure. No geographic barriers are evident across the large study range, with F. altissima constituting a single population, and extensive human cultivation is likely to have had beneficial consequences for protecting the genetic diversity of F. altissima.

It takes two to tango – Phylogeography, taxonomy and hybridization in grass snakes and dice snakes (Serpentes: Natricidae: Natrix natrix, N. tessellata)

Using two mitochondrial DNA fragments and 13 microsatellite loci, we examined the phylogeographic structure and taxonomy of two codistributed snake species (Natrix natrix, N. tessellata) in their eastern distribution area, with a focus on Turkey. We found evidence for frequent interspecific hybridization, previously thought to be extremely rare, and for backcrosses. This underscores that closely related sympatric species should be studied together because otherwise the signal of hybridization will be missed. Furthermore, the phylogeographic patterns of the two species show many parallels, suggestive of a shared biogeographic history. In general, the phylogeographies follow the paradigm of southern richness to northern purity, but the dice snake has some additional lineages in the south and east in regions where grass snakes do not occur. For both species, the Balkan Peninsula and the Caucasus region served as glacial refugia, with several mitochondrial lineages occurring in close proximity. Our results show that the mitochondrial divergences in both species match nuclear genomic differentiation. Yet, in the former glacial refugia of grass snakes there are fewer nuclear clusters than mitochondrial lineages, suggesting that Holocene range expansions transformed the glacial hotspots in melting pots where only the mitochondrial lineages persisted, bearing witness of former diversity. On the other hand, the deep mitochondrial divergences in N. tessellata across its entire range indicate that more than one species could be involved, even though lacking microsatellite data outside of Turkey prevent firm conclusions. On the contrary, our microsatellite and mitochondrial data corroborate that N. megalocephala is invalid and not differentiated from sympatric populations of N. natrix. For Cypriot grass snakes, our analyses yielded conflicting results. A critical assessment of the available evidence suggests that N. natrix is a genetically impoverished recent invader on Cyprus and taxonomically not distinct from a subspecies also occurring in western Anatolia and the southern Balkans. Based on combined mitochondrial and nuclear genomic evidence we propose that for grass snakes the following subspecies should be recognized in our study region: (1) Natrix natrix vulgaris Laurenti, 1768, southeastern Central Europe and northern Balkans; (2) Natrix natrix moreoticus (Bedriaga, 1882), southern Balkans, western Anatolia, and Cyprus; and (3) Natrix natrix scutata (Pallas, 1771), eastern Anatolia, Caucasus region, Iran, northeastern distribution range (from eastern Poland and Finland to Kazakhstan and the Lake Baikal region). Thus, Natrix natrix cypriaca (Hecht, 1930) becomes a junior synonym of N. n. moreoticus and Natrix natrix persa (Pallas, 1814) becomes a junior synonym of N. n. scutata. Due to insufficient material, we could not resolve the status of Natrix natrix syriaca (Hecht, 1930) from the Gulf of İskenderun, southeastern Turkey.

Phylogeography of the New Zealand whelks Cominella maculosa and C. virgata

<p>Cominella maculosa and C. virgata are common rocky shore whelk species from New Zealand. This study used DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) to expand an earlier unpublished dataset and examine the phylogeographic structure of both species in the Cook Strait region, of C. maculosa in the Chatham Islands, and of C. virgata in the northern North Island. Both species are found to have a considerable degree of phylogeographic structure, concordant with that reported by an earlier study and for other species with direct development. South Island sites sampled for C. maculosa had several private haplotypes and a high frequency haplotype that is shared with populations from the southern North Island. Together, these formed a ‘southern haplogroup’. Low diversity in ‘southern’ populations may reflect founder effects that would have occurred as part of a southward range expansion during the onset of the present interglacial period. The Chatham Islands samples had two haplotypes that formed a separate sub-group to the ‘southern haplogroup’, suggesting Chatham Islands populations are moderately isolated from those on mainland New Zealand but may have been founded from ‘southern’ populations relatively recently. The high frequency haplotype present in South Island samples of C. virgata is absent in Wellington samples but widespread in those from the north-eastern North Island. South Island populations may have been founded from the Hauraki Gulf through human-mediated translocation events. Phylogenetic analyses with a focus on C. virgata were conducted using the mitochondrial genes CO1 and 16SrRNA, and the nuclear gene 18S rRNA, to expand an earlier published dataset. The purported northern subspecies C. virgata brookesi does not form a monophyletic lineage and voucher specimens fluidly intergrade with the nominal subspecies, with which it is synonymised. A lectotype is designated for Buccinum lineolatum Quoy & Gaimard, 1833, for which Cominella virgata is a replacement name. Potential causes of the disjunct distribution patterns of C. virgata and other mollusc taxa are discussed with particular reference to the formation and timing of marine straits through the Auckland Isthmus and Cook Strait.</p>

Phylogeography of the New Zealand whelks Cominella maculosa and C. virgata

<p>Cominella maculosa and C. virgata are common rocky shore whelk species from New Zealand. This study used DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) to expand an earlier unpublished dataset and examine the phylogeographic structure of both species in the Cook Strait region, of C. maculosa in the Chatham Islands, and of C. virgata in the northern North Island. Both species are found to have a considerable degree of phylogeographic structure, concordant with that reported by an earlier study and for other species with direct development. South Island sites sampled for C. maculosa had several private haplotypes and a high frequency haplotype that is shared with populations from the southern North Island. Together, these formed a ‘southern haplogroup’. Low diversity in ‘southern’ populations may reflect founder effects that would have occurred as part of a southward range expansion during the onset of the present interglacial period. The Chatham Islands samples had two haplotypes that formed a separate sub-group to the ‘southern haplogroup’, suggesting Chatham Islands populations are moderately isolated from those on mainland New Zealand but may have been founded from ‘southern’ populations relatively recently. The high frequency haplotype present in South Island samples of C. virgata is absent in Wellington samples but widespread in those from the north-eastern North Island. South Island populations may have been founded from the Hauraki Gulf through human-mediated translocation events. Phylogenetic analyses with a focus on C. virgata were conducted using the mitochondrial genes CO1 and 16SrRNA, and the nuclear gene 18S rRNA, to expand an earlier published dataset. The purported northern subspecies C. virgata brookesi does not form a monophyletic lineage and voucher specimens fluidly intergrade with the nominal subspecies, with which it is synonymised. A lectotype is designated for Buccinum lineolatum Quoy & Gaimard, 1833, for which Cominella virgata is a replacement name. Potential causes of the disjunct distribution patterns of C. virgata and other mollusc taxa are discussed with particular reference to the formation and timing of marine straits through the Auckland Isthmus and Cook Strait.</p>

Characterisation of the Mitochondrial Genome and the Phylogeographic Structure of Blue Cod (Parapercis colias)

<p>This thesis primarily addresses the genetic population structure of blue cod (Parapercis colias) in the New Zealand Exclusive Economic Zone, within which approximately 2800 Tonnes of the endemic fish are harvested annually. Several regions with traditionally healthy blue cod stocks have recently experienced localised depletion due to over-exploitation. This highlights the importance for a clearer understanding of the genetic structure of the species in order to maximise the potential for the fishery to be managed sustainably. Also covered within this thesis are characteristics of the blue cod's mitochondrial genome, and development of a set of genetic tools that can improve the level of understanding for several important fisheries species in New Zealand waters. Chapter two focuses on the characterisation of the blue cod mitochondrial genome, with the use of second-generation sequencing providing the first fully documented sequence for this species. The blue cod mitochondrial genome is identical in organisation to several other documented fish species' mitochondrial genomes, with no unexpected results. Also dealt with in Chapter two is the development and implementation of a set of generic control region primers, designed primarily for use on commercially important inshore New Zealand fish species. Nine of the eleven species which the primer was tested on had the targeted region successfully amplified, though heteroplasmy may be present in at least four species. Chapter three reports the bulk of this research, with the phylogeographic structure of blue cod investigated. Samples were taken from the pectoral and pelvic fins of blue cod from 14 sites around New Zealand. A total of 475 sequences were taken from the hypervariable 5' end of the control region, with each sequence 491 bp in length. The null hypothesis of genetic homogeneity throughout their distribution was rejected, with significant differentiation observed between mainland New Zealand and Chatham Island samples. While pairwise differences between mainland New Zealand sampling sites was limited, a significant trend of isolation by distance was observed. A demographic population expansion occurred more steeply and more recently in mainland populations, with a slower growth curve in Chatham Island populations. With a trend of isolation by distance present between mainland sampling sites, it is suggested that further investigations are made, utilising genetic markers capable of resolving deeper patterns of genetic structure within the population (e.g. microsatellites, SNP's). Finally, Chapter four summarises and contextualises the results from the research components of this thesis, discussing management implications and potential threats to both the commercial and recreational blue cod fishery. A key area of focus for this section is the genetic and demographic risk that the population may face with continued targeting of larger individuals, given the biological trait of protogynous hermaphroditism in the species.</p>

Characterisation of the Mitochondrial Genome and the Phylogeographic Structure of Blue Cod (Parapercis colias)

<p>This thesis primarily addresses the genetic population structure of blue cod (Parapercis colias) in the New Zealand Exclusive Economic Zone, within which approximately 2800 Tonnes of the endemic fish are harvested annually. Several regions with traditionally healthy blue cod stocks have recently experienced localised depletion due to over-exploitation. This highlights the importance for a clearer understanding of the genetic structure of the species in order to maximise the potential for the fishery to be managed sustainably. Also covered within this thesis are characteristics of the blue cod's mitochondrial genome, and development of a set of genetic tools that can improve the level of understanding for several important fisheries species in New Zealand waters. Chapter two focuses on the characterisation of the blue cod mitochondrial genome, with the use of second-generation sequencing providing the first fully documented sequence for this species. The blue cod mitochondrial genome is identical in organisation to several other documented fish species' mitochondrial genomes, with no unexpected results. Also dealt with in Chapter two is the development and implementation of a set of generic control region primers, designed primarily for use on commercially important inshore New Zealand fish species. Nine of the eleven species which the primer was tested on had the targeted region successfully amplified, though heteroplasmy may be present in at least four species. Chapter three reports the bulk of this research, with the phylogeographic structure of blue cod investigated. Samples were taken from the pectoral and pelvic fins of blue cod from 14 sites around New Zealand. A total of 475 sequences were taken from the hypervariable 5' end of the control region, with each sequence 491 bp in length. The null hypothesis of genetic homogeneity throughout their distribution was rejected, with significant differentiation observed between mainland New Zealand and Chatham Island samples. While pairwise differences between mainland New Zealand sampling sites was limited, a significant trend of isolation by distance was observed. A demographic population expansion occurred more steeply and more recently in mainland populations, with a slower growth curve in Chatham Island populations. With a trend of isolation by distance present between mainland sampling sites, it is suggested that further investigations are made, utilising genetic markers capable of resolving deeper patterns of genetic structure within the population (e.g. microsatellites, SNP's). Finally, Chapter four summarises and contextualises the results from the research components of this thesis, discussing management implications and potential threats to both the commercial and recreational blue cod fishery. A key area of focus for this section is the genetic and demographic risk that the population may face with continued targeting of larger individuals, given the biological trait of protogynous hermaphroditism in the species.</p>