Phylogeography of New Zealand’s coastal benthos

During the past 30 years, 42 molecular studies have been undertaken in New Zealand to examine the phylogeography of coastal benthic invertebrates and plants. Here, we identify generalities and/or patterns that have emerged from this research and consider the processes implicated in generating genetic structure within populations. Studies have used various molecular markers and examined taxonomic groups with a range of life histories and dispersal strategies. Genetic disjunctions have been identified at multiple locations, with the most frequently observed division occurring between northern and southern populations at the top of the South Island. Although upwelling has been implicated as a cause of this disjunction, oceanographic evidence is lacking and alternative hypotheses exist. A significant negative correlation between larval duration and genetic differentiation (r2 = 0.39, P < 0.001, n = 29) across all studies suggests that larval duration might be used as a proxy for dispersal potential. However, among taxa with short larval durations (<10 days) there was greater variability in genetic differentiation than among taxa with longer pelagic periods. This variability implies that when larval duration is short, other factors may determine dispersal and connectivity among populations. Although there has been little congruence between the phylogeographic data and recognised biogeographic regions, recent research has resolved population subdivision at finer spatial scales corresponding more closely with existing biogeographic classifications. The use of fast-evolving and ecologically significant molecular markers in hypothesis-driven research could further improve our ability to detect population subdivision and identify the processes structuring marine ecosystems

Genetic Differentiation Among Three Species of \u3ci\u3eParadosa\u3c/i\u3e (Arachnida: Lycosidae)

Allozymic variation in nine protein producing loci was examined in three species of Pardosa using starch gel electrophoresis. Allozyme frequencies showed a high degree of geographic uniformity among conspecific populations. Estimated heterozygosities for the three species ranged from 0.05 to 0.15. Rogers\u27 coefficients of genetic similarity based on allozyme frequencies averaged over conspecific populations ranged from 0.16 to 0.37 fo rthe three species

No more time to stay ‘single’ in the detection of Anisakis pegreffii, A. simplex (s. s.) and hybridization events between them: a multi-marker nuclear genotyping approach

A multi-marker nuclear genotyping approach was performed on larval and adult specimens of Anisakis spp. (N = 689) collected from fish and cetaceans in allopatric and sympatric areas of the two species Anisakis pegreffii and Anisakis simplex (s. s.), in order to: (1) identify specimens belonging to the parental taxa by using nuclear markers (allozymes loci) and sequence analysis of a new diagnostic nuclear DNA locus (i.e. partial sequence of the EF1 α−1 nDNA region) and (2) recognize hybrid categories. According to the Bayesian clustering algorithms, based on those markers, most of the individuals (N = 678) were identified as the parental species [i.e. A. pegreffii or A. simplex (s. s.)], whereas a smaller portion (N = 11) were recognized as F1 hybrids. Discordant results were obtained when using the polymerase chain reaction–restriction fragment length polymorphisms (PCR–RFLPs) of the internal transcribed spacer (ITS) ribosomal DNA (rDNA) on the same specimens, which indicated the occurrence of a large number of ‘hybrids’ both in sympatry and allopatry. These findings raise the question of possible misidentification of specimens belonging to the two parental Anisakis and their hybrid categories derived from the application of that single marker (i.e. PCR–RFLPs analysis of the ITS of rDNA). Finally, Bayesian clustering, using allozymes and EF1 α−1 nDNA markers, has demonstrated that hybridization between A. pegreffii and A. simplex (s. s.) is a contemporary phenomenon in sympatric areas, while no introgressive hybridization takes place between the two species

Levels of genetic polymorphism: marker loci versus quantitative traits

Species are the units used to measure ecological diversity and alleles are the units of genetic diversity. Genetic variation within and among species has been documented most extensively using allozyme electrophoresis. This reveals wide differences in genetic variability within, and genetic distances among, species, demonstrating that species are not equivalent units of diversity. The extent to which the pattern observed for allozymes can be used to infer patterns of genetic variation in quantitative traits depends on the forces generating and maintaining variability. Allozyme variation is probably not strictly neutral but, nevertheless, heterozygosity is expected to be influenced by population size and genetic distance will be affected by time since divergence. The same is true for quantitative traits influenced by many genes and under weak stabilizing selection. However, the limited data available suggest that allozyme variability is a poor predictor of genetic variation in quantitative traits within populations. It is a better predictor of general phenotypic divergence and of postzygotic isolation between populations or species, but is only weakly correlated with prezygotic isolation. Studies of grasshopper and planthopper mating signal variation and assortative mating illustrate how these characters evolve independently of general genetic and morphological variation. The role of such traits in prezygotic isolation, and hence speciation, means that they will contribute significantly to the diversity of levels of genetic variation within and among species

Genetic differentiation in Scottish populations of the pine beauty moth Panolis flammea (Lepidoptera: Noctuidae)

Pine beauty moth, Panolis flammea (Denis & Schiffermüller), is a recent but persistent pest of lodgepole pine plantations in Scotland, but exists naturally at low levels within remnants and plantations of Scots pine. To test whether separate host races occur in lodgepole and Scots pine stands and to examine colonization dynamics, allozyme, randomly amplified polymorphic DNA (RAPD) and mitochondrial variation were screened within a range of Scottish samples. RAPD analysis indicated limited long distance dispersal (FST = 0.099), and significant isolation by distance (P < 0.05); but that colonization between more proximate populations was often variable, from extensive to limited exchange. When compared with material from Germany, Scottish samples were found to be more diverse and significantly differentiated for all markers. For mtDNA, two highly divergent groups of haplotypes were evident, one group contained both German and Scottish samples and the other was predominantly Scottish. No genetic differentiation was evident between P. flammea populations sampled from different hosts, and no diversity bottleneck was observed in the lodgepole group. Indeed, lodgepole stands appear to have been colonized on multiple occasions from Scots pine sources and neighbouring populations on different hosts are close to panmixia.A.J. Lowe, B.J. Hicks, K. Worley, R.A. Ennos, J.D. Morman, G. Stone and A.D. Wat

PHYLOGENY OF SOME MIDDLE AMERICAN PITVIPERS BASED ON A CLADISTIC ANALYSIS OF MITOCHONDRIAL 12S AND 16S DNA SEQUENCE INFORMATION

The cladistic relationships of several Middle American pitvipers representing the genera Bothrops (sensu stricto), Bothriechis, Cerrophidion, Lachesis and Porthidium were determined using mitochondrial 12S and 16S DNA sequence information. Maximum parsimony analyses were performed using PAUP on aligned sequences that included published information for related taxa. Two sets of analyses were conducted: one disregarding gaps in the aligned matrix, and another with gaps treated as a fifth base. When gaps were excluded resolution declined, although the general arrangement of the taxa changed little. A consistent relationship was the grouping of ((Porthidium, Bothriechis) Lachesis). The placement of Lachesis, as nested within other bothropoid genera, is only partially supported by results of other authors. The arrangement of Crotalus, Bothrops and Cerrophidion was ambiguous when gaps were discounted. In both trees, Agkistrodon was basal to the New World forms. The remaining genera, Trimeresurus (Protobothrops), Vipera, Azemiops, and Coluber, were uniformly distant to the former taxa. Also of interest is the lack of close relationship, based on the DNA data here and elsewhere, between Bothrops and Porthidium. This is in striking contrast to results based on morphologic and allozymic analyses of previous studies. It is concluded that additional DNA sequence information from a larger sample of taxa will be necessary to better assess the phylogenetic relationships among Middle American and related pitvipers

Gene Flow Between Great Lakes Region Populations of the Canadian Tiger Swallowtail Butterfly, \u3ci\u3ePapilio Canadensis\u3c/i\u3e, Near the Hybrid Zone With \u3ci\u3eP. Glaucus\u3c/i\u3e (Lepidoptera: Papilionidae)

Papilio canadensis were sampled from three locations on either side of Lake Michigan to study gene flow near and through a butterfly hybrid zone. Allele frequencies at four polymorphic enzyme loci, as indicated by allozyme electrophoresis, were similar in all samples. Values for FST were close to zero, indicating that gene flow is high among these populations, even when separated by Lake Michigan. We developed a mitochondrial DNA marker with diagnostic differences between P. canadensis and its parapatric sister species Papilio glaucus, based on PCR-RFLP. P. glaucus haplotypes of this mtDNA marker and P. glaucus alleles of a diagnostic allozyme locus (PGD) were found in P. canadensis populations sampled in Michigan’s Lower Peninsula but not in the Upper Peninsula or Northern Minnesota. The presence of P. glaucus alleles in P. canadensis populations could be due to introgression through hybridization, or could be remnants of a P. glaucus population that was inundated by an influx of P. canadensis alleles

The Mediterranean European hake, Merluccius merluccius: Detecting drivers influencing the Anisakis spp. larvae distribution

The European hake Merluccius merluccius is one of the most commercially important and widely distributed fish species, occurring both in European and Mediterranean Sea fisheries. We analyzed the distribution and infection rates of different species of Anisakis in M. merluccius (N = 1130 hakes), by site of infection in the fish host (viscera, dorsal and ventral fillets) from 13 different fishing grounds of the Mediterranean Sea (FAO area 37). The fillets were examined using the UV-Press method. A large number of Anisakis specimens (N = 877) were identified by diagnostic allozymes, sequence analysis of the partial EF1 α-1 region of nDNA and mtDNA cox2 gene. Among these, 813 larvae corresponded to A. pegreffii, 62 to A. physeteris, 1 to A. simplex (s. s.), whereas one resulted as a F1 hybrid between A. pegreffii and A. simplex (s. s.). Remarkably high levels of infection with A. pegreffii were recorded in hakes from the Adriatic/Ionian Sea compared to the fish of similar length obtained from the western Mediterranean fishing grounds. A positive correlation between fish length and abundance of A. pegreffii was observed. Concerning the localization of A. pegreffii larvae in the fish, 28.3% were detected in the liver, 62.9% in the rest of the viscera, 6.6% in the ventral part of the flesh, whereas 2.1% in the dorsal flesh

Identifying hybridizing taxa within the Daphnia longispina species complex: a comparison of genetic methods and phenotypic approaches

Daphnia galeata Sars, D. longispina O. F. Muller and D. cucullata Sars (Crustacea: Cladocera) are closely related species which often produce interspecific hybrids in natural populations. Several marker systems are available for taxon determination in this hybridizing complex, but their performance and reliability has not been systematically assessed. We compared results from identifications by three molecular methods. More than 1,200 individuals from 10 localities in the Czech Republic were identified as parental species or hybrids by allozyme electrophoresis and the analysis of the restriction fragment length polymorphism of the internal transcribed spacer (ITS-RFLP); over 440 of them were additionally analyzed and identified by 12 microsatellite loci. Identification by microsatellite markers corresponded well with allozyme analyses. However, consistent discrepancies between ITS-RFLP and other markers were observed in two out of 10 studied localities. Although some marker discrepancies may have been caused by occasional recent introgression, consistent deviations between ITS-RFLP and other markers suggest a long-term maintenance of introgressed alleles. These results warn against its use as a sole identification method in field studies. Additionally, we quantitatively evaluated the discriminatory power of geometric morphometric (elliptic Fourier) analysis of body shapes based on photos of over 1,300 individuals pre-classified by allozyme markers. Furthermore, a randomly selected subset of 240 individuals was independently determined from photos by several experts. Despite a tendency for morphological divergence among parental Daphnia species, some taxa (especially D. galeata, D. longispina, and their hybrids) substantially overlapped in their body shapes. This was reflected in different determination success for particular species and hybrids in discriminant analysis based on shape data as well as from photograph