Local adaptation in shell shape traits of a brooding chiton with strong population genomic differentiation.

Comparing divergence in quantitative traits and neutral molecular markers, such as QST-FST comparisons, provides a means to distinguish between natural selection and genetic drift as causes of population differentiation in complex polygenic traits. Onithochiton neglectus (Rochebrune, 1881) is a morphologically variable chiton endemic to New Zealand, with populations distributed over a broad latitudinal environmental gradient. In this species, the morphological variants cluster into 2 geographically separated shell shape groups, and the phenotypic variation in shell shape has been hypothesized to be adaptive. Here, we assessed this hypothesis by comparing neutral genomic differentiation between populations (FST) with an index of phenotypic differentiation (PST). We used 7,562 putatively neutral single-nucleotide polymorphisms (SNPs) across 15 populations and 3 clades of O. neglectus throughout New Zealand to infer FST. PST was calculated from 18 shell shape traits and gave highly variable estimates across populations, clades, and shape groups. By systematically comparing PST with FST, we identified evidence of local adaptation in a number of the O. neglectus shell shape traits. This supports the hypothesis that shell shape could be an adaptive trait, potentially correlated with the ability to live and raft in kelp holdfasts.

The complete mitochondrial genomes of two chiton species (Sypharochiton pelliserpentis and Sypharochiton sinclairi) obtained using Illumina next generation sequencing.

Using an Illumina platform, we shot-gun sequenced the complete mitochondrial genomes of two sister chiton species (Sypharochiton pelliserpentis and Sypharochiton sinclairi) to an average coverage of 172× and 60×, respectively. We performed a de novo assembly using SOAPdenovo2 and determined the total mitogenome lengths to be 15,048 and 15,028 bps, respectively. The gene organization was similar to that of other chitons, with 13 protein-coding genes, 24 transfer RNAs and 2 ribosomal RNAs. These data will contribute for resolving the taxonomy and population genetic structures of these species.

Phylogenetic species identification in Rattus highlights rapid radiation and morphological similarity of New Guinean species.

The genus Rattus is highly speciose, the taxonomy is complex, and individuals are often difficult to identify to the species level. Previous studies have demonstrated the usefulness of phylogenetic approaches to identification in Rattus but some species, especially among the endemics of the New Guinean region, showed poor resolution. Possible reasons for this are simple misidentification, incomplete gene lineage sorting, hybridization, and phylogenetically distinct lineages that are unrecognised taxonomically. To assess these explanations we analysed 217 samples, representing nominally 25 Rattus species, collected in New Guinea, Asia, Australia and the Pacific. To reduce misidentification problems we sequenced museum specimens from earlier morphological studies and recently collected tissues from samples with associated voucher specimens. We also reassessed vouchers from previously sequenced specimens. We inferred combined and separate phylogenies from two mitochondrial DNA regions comprising 550 base pair D-loop sequences and both long (655 base pair) and short (150 base pair) cytochrome oxidase I sequences. Our phylogenetic species identification for 17 species was consistent with morphological designations and current taxonomy thus reinforcing the usefulness of this approach. We reduced misidentifications and consequently the number of polyphyletic species in our phylogenies but the New Guinean Rattus clades still exhibited considerable complexity. Only three of our eight New Guinean species were monophyletic. We found good evidence for either incomplete mitochondrial lineage sorting or hybridization between species within two pairs, R. leucopus/R. cf. verecundus and R. steini/R. praetor. Additionally, our results showed that R. praetor, R. niobe and R. verecundus each likely encompass more than one species. Our study clearly points to the need for a revised taxonomy of the rats of New Guinea, based on broader sampling and informed by both morphology and phylogenetics. The remaining taxonomic complexity highlights the recent and rapid radiation of Rattus in the Australo-Papuan region.

Paternity assignment and demographic closure in the New Zealand southern right whale.

The identification and characterization of reproductively isolated subpopulations or 'stocks' are essential for effective conservation and management decisions. This can be difficult in vagile marine species like marine mammals. We used paternity assignment and 'gametic recapture' to examine the reproductive autonomy of southern right whales (Eubalaena australis) on their New Zealand (NZ) calving grounds. We derived DNA profiles for 34 mother-calf pairs from skin biopsy samples, using sex-specific markers, 13 microsatellite loci and mtDNA haplotypes. We constructed DNA profiles for 314 adult males, representing 30% of the census male abundance of the NZ stock, previously estimated from genotypic mark-recapture modelling to be 1085 (95% CL 855, 1416). Under the hypothesis of demographic closure and the assumption of equal reproductive success among males, we predict: (i) the proportion of paternities assigned will reflect the proportion of the male population sampled and (ii) the gametic mark-recapture (GMR) estimate of male abundance will be equivalent to the census male estimate for the NZ stock. Consistent with these predictions, we found that the proportion of assigned paternities equalled the proportion of the census male population size sampled. Using the sample of males as the initial capture, and paternity assignment as the recapture, the GMR estimate of male abundance was 1001 (95% CL 542, 1469), similar to the male census estimate. These findings suggest that right whales returning to the NZ calving ground are reproductively autonomous on a generational timescale, as well as isolated by maternal fidelity on an evolutionary timescale, from others in the Indo-Pacific region.

A multi-locus analysis of phylogenetic relationships within cheilostome bryozoans supports multiple origins of ascophoran frontal shields.

Phylogenetic relationships within the bryozoan order Cheilostomata are currently uncertain, with many morphological hypotheses proposed but scarcely tested by independent means of molecular analysis. This research uses DNA sequence data across five loci of both mitochondrial and nuclear origin from 91 species of cheilostome Bryozoa (34 species newly sequenced). This vastly improved the taxonomic coverage and number of loci used in a molecular analysis of this order and allowed a more in-depth look into the evolutionary history of Cheilostomata. Maximum likelihood and Bayesian analyses of individual loci were carried out along with a partitioned multi-locus approach, plus a range of topology tests based on morphological hypotheses. Together, these provide a comprehensive set of phylogenetic analyses of the order Cheilostomata. From these results inferences are made about the evolutionary history of this order and proposed morphological hypotheses are discussed in light of the independent evidence gained from the molecular data. Infraorder Ascophorina was demonstrated to be non-monophyletic, and there appears to be multiple origins of the ascus and associated structures involved in lophophore extension. This was further supported by the lack of monophyly within each of the four ascophoran grades (acanthostegomorph/spinocystal, hippothoomorph/gymnocystal, umbonulomorph/umbonuloid, lepraliomorph/lepralioid) defined by frontal-shield morphology. Chorizopora, currently classified in the ascophoran grade Hippothoomorpha, is phylogenetically distinct from Hippothoidae, providing strong evidence for multiple origins of the gymnocystal frontal shield type. Further evidence is produced to support the morphological hypothesis of multiple umbonuloid origins of lepralioid frontal shields, using a step-wise set of topological hypothesis tests combined with examination of multi-locus phylogenies.

A worldwide perspective on the population structure and genetic diversity of bottlenose dolphins (Tursiops truncatus) in New Zealand.

Bottlenose dolphins (Tursiops truncatus) occupy a wide range of coastal and pelagic habitats throughout tropical and temperate waters worldwide. In some regions, "inshore" and "offshore" forms or ecotypes differ genetically and morphologically, despite no obvious boundaries to interchange. Around New Zealand, bottlenose dolphins inhabit 3 coastal regions: Northland, Marlborough Sounds, and Fiordland. Previous demographic studies showed no interchange of individuals among these populations. Here, we describe the genetic structure and diversity of these populations using skin samples collected with a remote biopsy dart. Analysis of the molecular variance from mitochondrial DNA (mtDNA) control region sequences (n = 193) showed considerable differentiation among populations (F(ST) = 0.17, Phi(ST) = 0.21, P < 0.001) suggesting little or no female gene flow or interchange. All 3 populations showed higher mtDNA diversity than expected given their small population sizes and isolation. To explain the source of this variation, 22 control region haplotypes from New Zealand were compared with 108 haplotypes worldwide representing 586 individuals from 19 populations and including both inshore and offshore ecotypes as described in the Western North Atlantic. All haplotypes found in the Pacific, regardless of population habitat use (i.e., coastal or pelagic), are more divergent from populations described as inshore ecotype in the Western North Atlantic than from populations described as offshore ecotype. Analysis of gene flow indicated long-distance dispersal among coastal and pelagic populations worldwide (except for those haplotypes described as inshore ecotype in the Western North Atlantic), suggesting that these populations are interconnected on an evolutionary timescale. This finding suggests that habitat specialization has occurred independently in different ocean basins, perhaps with Tursiops aduncus filling the ecological niche of the inshore ecotype in some coastal regions of the Indian and Western Pacific Oceans.