Greater Genetic Differentiation Research Articles

Seasonal Changes in the Genetic Diversity of Two Rodent Populations, Midday Gerbil (Meriones meridianus) and Northern Three-Toed Jerboa (Dipus sagitta), Detected by ISSR

Seasonal changes in genetic diversity of Meriones meridianus and Dipus sagitta populations in the Ningxia Hui Autonomous Region were monitored using inter-simple sequence repeats. There were 45 discernible DNA fragments isolated from 33 samples of M. meridianus, and 25 from 40 samples of D. sagitta. The differences in gene frequencies are statistically significant for some alleles. Nei's index revealed that the greatest genetic differentiation was distributed within the seasonal groups. Nei's and Shannon's indexes exhibited similar seasonal trends, indicating that the spring group has the highest level of genetic diversity and that genetic diversity changes with the seasons. Correlation analysis found no statistically significant correlation between genetic diversity and population density. The results suggest that the seasonal changes in genetic diversity of the two species depend mainly on reproduction and dispersal.

Population genetic structure of white‐tailed deer: Understanding risk of chronic wasting disease spread

AbstractUnderstanding factors that influence the spread of wildlife diseases can assist in designing effective surveillance programs and appropriate management strategies. Chronic wasting disease (CWD), a fatal prion disease of cervids, was detected in south‐central Wisconsin in 2002 and over time has been identified increasingly farther west in the state leading to concerns about CWD spreading to Iowa. Our objective was to characterize genetic connectivity between white‐tailed deer (Odocoileus virginianus) populations in eastern Iowa and western Wisconsin to assess the risk of CWD‐infected deer dispersing to Iowa. We hypothesized that the Mississippi River, which separates the states, may restrict the movement of deer and thus disease. We genotyped hunter‐harvested female deer collected from both states at 12 nuclear microsatellite loci (n = 249) and sequenced a portion of the mitochondrial DNA (mtDNA) control region (n = 173). Microsatellite data indicated there was low genetic differentiation (ΦPT = 0.005) between states and weak spatial genetic structure across the study area as a whole. Verifying expectations that dispersal in deer is male‐biased, maternally inherited mtDNA data showed stronger spatial structuring across the study area and greater genetic differentiation between the states (ΦPT = 0.052) such that clustering analysis grouped the majority of deer from Iowa and Wisconsin into separate clusters. The low level of genetic differentiation between deer in northeast Iowa and southwest Wisconsin, primarily the result of dispersing males who have greater CWD prevalence than females, indicates that the Mississippi River is unlikely to prohibit the westward spread of CWD, and underscores the importance of continued CWD surveillance in Iowa. © 2011 The Wildlife Society.

Divergent patterns in the mitochondrial and nuclear diversity of the specialized butterfly Plebejus argus (Lepidoptera: Lycaenidae)

Plebejus argus is a model species for studying the biology, population ecology and genetics of butterflies. It is patchily distributed throughout most of its European range and considered to be sedentary. Habitats of the butterfly have to encompass two vital larval-resources, i.e. specific food plants and ants, since caterpillars are obligatorily myrmecophilous. The genetic structure of nine P. argus populations (85 individuals) was studied at an intermediate geographical scale (Eastern Poland, diameter of about 400 km) using two kinds of molecular markers i.e. COI (mtDNA) and EF-1D (nuclear gene). Both markers were highly variable with as many as 16 haplotypes and 39 alleles, respectively. Great genetic differentiation in the COI gene was detected (overall FST = 0.411, P < 0.001) but little genetic differentiation in the EF-1D gene (FST = 0.021, P < 0.001). The number of COI haplotypes (ranging from one to seven) and their distribution varied considerably among P. argus populations. The possibility that this heterogeneity was related to Wolbachia was excluded as this endoparasitic bacterium was not detected in samples from any of the populations studied. PCA and SAMOVA analyses divided the sampled populations into two or three groups, which could indicate different colonization routes. Moreover, the differences in genetic differentiation with respect to mtDNA and nuclear markers may suggest male-biased dispersal of P. argus at a larger scale. The hypothesis that females are philopatric is consistent with direct observations of the restricted colonization abilities of the butterfly, while the relatively homogeneous genetic structure revealed by previous allozyme studies in some areas might be explained by the possible higher mobility of males.

ISSR analysis shows low genetic diversity versus high genetic differentiation for giant bamboo, Dendrocalamus giganteus (Poaceae: Bambusoideae), in China populations

Dendrocalamus giganteus Munro is a high-value woody bamboo widely grown in Southeast Asia and China’s Yunnan Province. We investigated its genetic diversity in Yunnan as a prelude to considering effective breeding programs and the protection of germplasm resources. Inter-simple sequence repeat (ISSR) markers were used to assess the genetic structure and differentiation of seven populations. Seven ISSR primers generated 140 bands, of which 124 were polymorphic (88.57%). Genetic diversity within populations was relatively low, averaging 11.33% polymorphic bands (PPB), while diversity was considerably higher among populations, with PPB = 88.57%. Greater genetic differentiation was detected among populations (G ST = 0.8474). We grouped these seven populations into two clusters within an UPGMA dendrogram—one comprised the Xinping and Shiping populations from central Yunnan, the other included the remaining five populations. Mantel tests indicated no significant correlation between genetic and geographic distances among populations. Breeding system characteristics, genetic drift, and limited gene flow (N m = 0.0901) might be important factors for explaining this differentiation. Based on the overall high genetic diversity and differentiation among D. giganteus populations in Yunnan, we suggest the implementation of in situ conservation measures for all populations and sufficient sampling for ex situ conservation collections.

Genetic relationships among pumpkinseed (Lepomis gibbosus) ecomorphs in freshwater reservoirs of Portugal

Abstract – High levels of morphological differentiation have been found among pumpkinseeds (Lepomis gibbosus) occupying four habitat types in Portuguese reservoirs. To investigate the underlying mechanism behind the phenotypic differentiation among ecomorphs, we used six microsatellite markers to assess patterns of genetic differentiation among and within eight naturalised reservoir populations. Greater genetic differentiation was seen among reservoir populations than within reservoirs (FST &gt; 0.041, P &lt; 0.002). structure analysis revealed the presence of two distinct genetic groups among the set of eight reservoir populations. However, an analysis of co‐occurring forms that were identified a priori by their respective habitats was consistent with a single panmictic group, suggesting that morphological differentiation has arisen in sympatry (i.e., within a reservoir, postintroduction). The observed relationships within and among reservoir populations, combined with the timeframe of ecomorph divergence, suggest the strong likelihood of phenotypic plasticity as the underlying mechanism of diversification in the introduced pumpkinseed.

Evolution of MicroRNAs and the Diversification of Species

MicroRNAs (miRNAs) are ancient, short noncoding RNA molecules that regulate the transcriptome through post-transcriptional mechanisms. miRNA riboregulation is involved in a diverse range of biological processes, and misregulation is implicated in disease. It is generally thought that miRNAs function to canalize cellular outputs, for instance as “fail-safe” repressors of gene misexpression. Genomic surveys in humans have revealed reduced genetic polymorphism and the signature of negative selection for both miRNAs themselves and the target sequences to which they are predicted to bind. We investigated the evolution of miRNAs and their binding sites across cichlid fishes from Lake Malawi (East Africa), where hundreds of diverse species have evolved in the last million years. Using low-coverage genome sequence data, we identified 100 cichlid miRNA genes with mature regions that are highly conserved in other animal species. We computationally predicted target sites on the 3′-untranslated regions (3′-UTRs) of cichlid genes to which miRNAs may bind and found that these sites possessed elevated single nucleotide polymorphism (SNP) densities. Furthermore, polymorphic sites in predicted miRNA targets showed higher minor allele frequencies on average and greater genetic differentiation between Malawi lineages when compared with a neutral expectation and nontarget 3′-UTR SNPs. Our data suggest that divergent selection on miRNA riboregulation may have contributed to the diversification of cichlid species and may similarly play a role in rapid phenotypic evolution of other natural systems.

Land clearing reduces gene flow in the granite outcrop-dwelling lizard, Ctenophorus ornatus

An important question for the conservation of species dwelling in fragmented habitats is whether changes to the intervening landscape create a barrier to gene flow. Here, we make use of the spatial distribution of the granite outcrop-dwelling lizard, Ctenophorus ornatus, to compare inferred levels of gene flow between outcrops in a nature reserve with that between outcrops in the adjacent agricultural land. Genetic variation, relatedness and subdivision were compared within groups of individuals from different outcrops similar in size and distance apart at each site. In the agricultural land, we found significantly lower genetic variation within outcrops and greater genetic differentiation between outcrops than in the reserve. Further, the rate at which genetic divergence between outcrops increased over geographical distance was significantly greater in the agricultural land than in the reserve. We also found that individuals were more closely related within outcrops but more distantly related between outcrops in the cleared land. These effects occur over a small spatial scale with an average distance between outcrops of less than five kilometres. Thus, even though land clearing around the outcrops leaves outcrop size unchanged, it restricts gene flow, reducing genetic variation and increasing population structure, with potentially negative consequences for the long-term persistence of the lizards on these outcrops.

Low-high season variation inPlasmodium falciparumerythrocyte binding antigen 175 (eba-175) allelic forms in malaria endemic area of Burkina Faso

To assess the impact of seasonal variation on the distribution of the eba-175 allelic forms in the area where malaria transmission is markedly seasonal. Blood samples were collected from 291 and 239 children under 5 years of age during the low and the high malaria transmission season, respectively, in four villages named Dawelgué, Kounda, Tanghin and Watenga of Saponé Health District, then screened for eba 175 F- and C- alleles by nested PCR analysis. F- alleles were more prevalent than C-alleles in the low [0.66 vs. 0.34 (P < 0.0001)] and high transmission season [0.67 vs. 0.33 (P < 0.0001)]. No significant seasonal variation was observed in the distribution of the two alleles. However, according to Sewall Wright rules, the population pairwise F(ST) values, between Dawelgué and Tanghin during the low transmission season (F(ST_) value = 0.10415, P-value = 0.0090 and during the high season (F(ST_)value = 0.08244, P-value < 0.00001), between Tanghin and Watenga during the low season (F(ST) value = 0.07414, P-value = 0.009) indicated a moderate but statistically significant genetic differentiation. Although there was a moderate but significant genetic differentiation between some study villages at different times of the year, this study result in the seasonal stability of eba-175 allele's distribution in the study area.

Is Cupressus sempervirens native in Italy? An answer from genetic and palaeobotanical data

This study represents the first large-scale analysis using nuclear molecular markers to assess genetic diversity and structure of Cupressus sempervirens L.. Genetic and fossil data were combined to infer the possible role of human activity and evolutionary history in shaping the diversity of cypress populations. We analysed 30 populations with six polymorphic nuclear microsatellite markers. Dramatic reductions in heterozygosity and allelic richness were observed from east to west across the species range. Structure analysis assigned individuals to two main groups separating central Mediterranean and eastern populations. The two main groups could be further divided into five subgroups which showed the following geographical distributions: Turkey with the Greek islands Rhodes and Samos, Greece (Crete), Southern Italy, Northern Italy, Tunisia with Central Italy. This pattern of genetic structure is also supported by SAMOVA and Barrier analyses. Palaeobotanical data indicated that Cupressus was present in Italy in the Pliocene, Pleistocene and Holocene. Furthermore, our molecular survey showed that Italian cypress populations experienced bottlenecks that resulted in reduced genetic diversity and allelic richness and greater genetic differentiation. Recent colonization or introduction may also have influenced levels of diversity detected in the Italian populations, as most individuals found in this range today have multilocus genotypes that are also present in the eastern range of the species. The data reveal a new interpretation of the history of cypress distribution characterized by ancient eastern populations (Turkey and Greek islands) and a mosaic of recently introduced trees and remnants of ancient, depauperate populations in the central Mediterranean range.

Glacial survival, phylogeography, and a comparison of microsatellite evolution models for resolving population structure in two species of dwarf yams (Borderea, Dioscoreaceae) endemic to the central Pyrenees

Background: Borderea is a relict genus in the Pyrenees comprising only two extant allopolyploid species. The pre-Pyrenean, cliff-dweller B. chouardii is confined to a single critically endangered population, whereas the subalpine B. pyrenaica is more widely distributed in the mobile scree-habitats of the central Pyrenees and pre-Pyrenees. Aims: To determine the genetic structure and relationships among individuals and populations of both taxa to understand their origin. To compare two alternative evolutionary models, the Infinite Allele Model (IAM) and the Stepwise Mutation Model (SMM), in an examination of the primary factors responsible for population divergence during the Quaternary. Methods: A survey of nuclear microsatellite (Simple Sequence Repeat, SSR) variation was conducted to infer relationships among allelic phenotypes and genotypes and to evaluate the relative contributions of migration and mutation to population genetic structure. Results: The occurrence of shared ancestral alleles among populations of both Borderea species supported a presumably late-Tertiary divergence of the species in the low-altitudinal pre-Pyrenees. Borderea chouardii exhibited strong genetic differentiation between two sub-populations separated by only 150 m of vertical distance. In B. pyrenaica, populations from the pre-Pyrenees and southern Pyrenees showed greater genetic differentiation and more allelic diversity relative to populations from the northern Pyrenees. Conclusions: These results suggest that B. pyrenaica experienced glacial survival in warm southern pre-Pyrenean refugia followed by rapid postglacial migration towards the northern Pyrenees. Despite the a priori high suitability of the SMM for microsatellite markers, genotypic relationships among individuals and populations and genotypic assignments to predefined groups of B. pyrenaica were always better resolved by the IAM than by the SMM. This points towards the overwhelming influence of migration and genetic drift over mutation in the Quaternary history of the B. pyrenaica populations. However, for B. chouardii a similar pattern was shown by both evolutionary models, suggesting that sub-population divergence of this species could have also been favoured by mutation.

Conservation genetics of endangeredBrasenia schreberi based on RAPD and AFLP markers

Brasenia schreberi J.F. Gmelin is a declared endangered species found in the lakes and ponds of South Korea. For planning its conservation strategy, we examined the genetic diversity within and among six populations, using randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). Polymorphisms were more frequently detected per loci with AFLP (69.3%) than RAPD (36.8%). High genetic diversity was recognized within populations: polymorphic loci (PPL) values ranged from 36.3% in the CJM population to 74.5% in the GGT population, with a mean value of 47.8% based on AFLP markers. Great genetic differentiation (θB) was detected among the six populations (0.670 on RAPD and 0.196 on AFLP), and we calculated a low rate of gene flow (Nem), i.e., 0.116 on RAPD and 0.977 on AFLP. Furthermore, a Mantel test revealed that no correlation existed between genetic distances and geographical distances among the six local populations, based on RAPD or AFLP markers. These results are attributed to a number of factors, including an insufficient length of time for genetic diversity to be reduced following a natural decline in population size and isolation, adaptation of the genetic system to small population conditions, and a restricted gene flow rate. Based on both its genetic diversity and population structure, we suggest that a strategy for conserving and restoringB. schreberi must focus on maintaining historical processes, such as high levels of outbreeding, while monitoring increased gene flow among populations. This is because a reduction in genetic diversity as a result of genetic drift is undesirable.

Isozyme polymorphism and genetic differentiation in natural populations of an endemic tetraploid species Avena maroccana in Morocco

A wild tetraploid oat Avena maroccana Gdgr. was collected from the 11 populations in the periphery of Rommani and Casablanca geographic groups of Morocco. Genetic diversity of the species was investigated using six allozyme systems. Allelic frequencies were scored representing eight polymorphic and five monomorphic loci. Coefficient of gene differentiation (Gst) was 0.3019, which indicated great genetic differentiation. The number of alleles per locus was 2.6154, the percentage of polymorphic loci was 61.54, and the expected heterozygosity was 0.2462 in all populations. Genetic diversity in A. maroccana was high in comparison to self-pollinated species. In total, nine heterozygotes resulting from outcrossing were found in the progeny from M1, M3, M4, M22 and M26. The population of M7 had peculiar alleles Pgd-2SS and Pgd-1SS in high frequency. M9 had the lowest level of diversity out of the 11 populations. Geographic and genetic distances between all the populations were not significantly correlated with each other (r = 0.0996). Cluster analysis showed that two groups, (M1, M22, M2 and M4) and (M3, M23, M8, M5 and M26) were apparently differentiated. Two populations of the Casablanca group, M7 and M9 were independent from each other, and were separated distinctly from the other populations. Genetic diversity of the Rommani and Casablanca groups was almost the same in all the parameters. This was due to the similar man-made habitat such as roadside or rich fertile soil and brown clay soils. The population size of A. maroccana was small and restricted to the narrow central Morocco with great genetic differentiation so that genetic diversity may be reflected from the results of genetic drift and outcrossing heterozygote segregation.

Genetic variation across species’ geographical ranges: the central–marginal hypothesis and beyond

There is growing interest in quantifying genetic population structure across the geographical ranges of species to understand why species might exhibit stable range limits and to assess the conservation value of peripheral populations. However, many assertions regarding peripheral populations rest on the long-standing but poorly tested supposition that peripheral populations exhibit low genetic diversity and greater genetic differentiation as a consequence of smaller effective population size and greater geographical isolation relative to geographically central populations. We reviewed 134 studies representing 115 species that tested for declines in within-population genetic diversity and/or increases in among-population differentiation towards range margins using nuclear molecular genetic markers. On average, 64.2% of studies detected the expected decline in diversity, 70.2% of those that tested for it showed increased differentiation and there was a positive association between these trends. In most cases, however, the difference in genetic diversity between central and peripheral population was not large. Although these results were consistent across plants and animals, strong taxonomic and biogeographical biases in the available studies call for a cautious generalization of these results. Despite the large number of studies testing these simple predictions, very few attempted to test possible mechanisms causing reduced peripheral diversity or increased differentiation. Almost no study incorporated a phylogeographical framework to evaluate historical influences on contemporary genetic patterns. Finally, there has been little effort to test whether these geographical trends in putatively neutral variation at marker loci are reflected by quantitative genetic trait variation, which is likely to influence the adaptive potential of populations across the geographical range.

Genetic and phenotypic variation among geographically isolated populations of the globally threatened Dupont’s lark Chersophilus duponti

Identifying genetically and phenotypically distinct populations of threatened species is critical if we are to delineate appropriate plans for their conservation. We conducted an integrated analysis of population genetic structure, historical demographic events, current gene flow (all based on mtDNA sequences) and morphological variation of three geographically separated groups of populations of Dupont’s lark Chersophilus duponti, located in the Iberian Peninsula (three populations), Morocco (two populations), and Tunisia (one population). Unusually, this lark species is the only one among the genus Chersophilus. Our results revealed the early historical divergence of an eastern Dupont’s lark lineage (in Tunisia) and a western lineage (in Morocco and Spain), consistent with subspecies taxonomy and distribution. The western lineage subsequently split into two lineages, following the isolation of Iberian and African populations. Such pattern of historical differentiation caused great population genetic structure, with differences among geographic areas explaining more than 80% of total genetic variation. Mismatch distributions and coalescent estimates of divergence time showed that lineage divergence was associated with sudden population expansion events, which apparently took place during the last glaciation, when steppe habitats were widespread across the Mediterranean region. Extant populations from different geographic areas hardly shared any haplotype (only one out of 16 ND2 haplotypes was shared by Tunisian and Moroccan Dupont’s larks), and consequently gene flow between geographic areas was found to be virtually absent. Apart from showing great genetic differentiation, Dupont’s larks from different geographic areas were morphologically distinct, showing substantial variation in body size and feeding-related traits (length of feet and bill). We conclude that Dupont’s lark populations isolated in the Iberian Peninsula, Morocco, and Tunisia are distinct evolutionary entities and should be considered as such in conservation plans. Such circumstance sets a daunting conservation challenge that exemplifies the need of incorporating knowledge of historical processes to our general understanding of the demography of threatened species.

Molecular Phylogeny of Grey Mullets (Teleostei: Mugilidae) in Greece: Evidence from Sequence Analysis of mtDNA Segments

Mitochondrial DNA sequence analysis has been used to explore genetic differentiation and phylogenetic relationships among five species of the Mugilidae family, Mugil cephalus, Chelon labrosus, Liza aurata, Liza ramada, and Liza saliens. DNA was isolated from samples originating from the Messolongi Lagoon in Greece. Three mtDNA segments (12s rRNA, 16s rRNA, and CO I) were PCR amplified and sequenced. Sequencing analysis revealed that the greatest genetic differentiation was observed between M. cephalus and all the other species studied, while C. labrosus and L. aurata were the closest taxa. Dendrograms obtained by the neighbor-joining method and Bayesian inference analysis exhibited the same topology. According to this topology, M. cephalus is the most distinct species and the remaining taxa are clustered together, with C. labrosus and L. aurata forming a single group. The latter result brings into question the monophyletic origin of the genus Liza.

A Preliminary Comparative Evaluation of Genetic Diversity between Chinese and Japanese Wild Soybean (Glycine soja) Germplasm Pools using SSR markers

The wild soybean, an annual self-pollinating plant, is the progenitor of soybeans and is extensively distributed in the Far East of Russia, the Korea peninsula, China and Japan. Geographically, Japan is surrounded by sea and insulated from China. We preliminarily evaluate whether the Japanese and Chinese wild soybean germplasm pools are genetically differentiated from each other using SSR markers. The results showed that the two pools have great genetic differentiation. Some loci presented obvious differences in mean genetic divergence (GST) value between the two pools. The GST among the geographic regions in China was higher than that in Japan. The average within-geographic region gene diversity values (HS) in the two pools were completely identical and thus the genetic difference between the two pools was mostly attributed to the relatively high level of between-geographic region gene diversity (DST) in China. We suggest that Japanese and Chinese wild soybeans should be comparatively independently evolving in phylogeny.

Genetic diversity of five Kobresia species along the eastern Qinghai-Tibet plateau in China

Plants of the genus Kobresia are alpine grass species of high ecological and economic importance. Vegetative growth is the dominant means of reproduction for the Kobresia. Studies suggest that substantial vegetative growth can reduce genetic diversity and renders populations less able to buffer changing and extreme conditions. Kobresia are dominant species in the Qinghai-Tibet plateau in China where they face harsh conditions and frequent disturbance. The genetic diversity of five Kobresia species (K. humilis, K. royleana, K. kansuensis , K. tibetica and K. setchwanensis) from the Qinghai-Tibet plateau was assessed. The results reveal high genetic diversity at the population level for all of the species and there does not appear to be a relationship between altitude and genetic diversity. AMOVA analysis shows that most genetic variability resides among individuals within populations, whereas only a minor portion is found among populations. Of the five species, K. royleana and K. kansuensis have the highest levels of gene flow and the lowest genetic differentiation. While K. setchwanensis has the lowest gene flow and the greatest genetic differentiation. The level of gene flow between populations and the mating system play a critical role in the genetic structure of these Kobresia populations. Despite the predominance of vegetative growth enough sexual reproduction occurs to maintain the relatively high genetic diversity in Kobresia populations.

Genetic differentiation and gene flow among populations of the alpine butterfly, Parnassius smintheus, vary with landscape connectivity

Levels of gene flow among populations vary both inter- and intraspecifically, and understanding the ecological bases of variation in levels of gene flow represents an important link between the ecological and evolutionary dynamics of populations. The effects of habitat spatial structure on gene flow have received considerable attention; however, most studies have been conducted at a single spatial scale and without background data on how individual movement is affected by landscape features. We examined the influence of habitat connectivity on inferred levels of gene flow in a high-altitude, meadow-dwelling butterfly, Parnassius smintheus. For this species, we had background data on the effects of landscape structure on both individual movement and on small-scale population genetic differentiation. We compared genetic differentiation and patterns of isolation by distance, based on variation at seven microsatellite loci, among three regions representing two levels of connectivity of high-altitude, nonforested habitats. We found that reduced connectivity of habitats, resulting from more forest cover at high altitudes, was associated with greater genetic differentiation among populations (higher estimated FST), a breakdown of isolation by distance, and overall lower levels of inferred gene flow. These observed differences were consistent with expectations based on our knowledge of the movement behaviour of this species and on previous population genetic analyses conducted at the smaller spatial scale. Our results indicate that the role of gene flow may vary among groups of populations depending on the interplay between individual movement and the structure of the surrounding landscape.

Diagnosis and Population Analysis of Pythium Species Using AFLP Fingerprinting.

Accurate identification of Pythium species, the causal agents of Pythium root rot and dampingoff of seedlings, and characterization of populations within the species would greatly assist in selecting and implementing control strategies for these pathogens. Several molecular techniques offer methods for accurate and rapid identification of species, but provide little information about their populations. In this study, amplified fragment length polymorphism (AFLP) fingerprinting was used to characterize plant-pathogenic Pythium species and intraspecific populations. Species-diagnostic AFLP fingerprints for Pythium aphanidermatum, P. irregulare, and P. ultimum, and tentative fingerprints for six other species, were identified. Intraspecific distance analyses of P. aphanidermatum, P. ultimum, and P. irregulare revealed distinct patterns of intraspecific variation among the three species. P. aphanidermatum showed the smallest mean distance among isolates (15%), followed by P. ultimum (37%). P. irregulare had the largest mean distance among isolates (64%), which were divided into two populations with great genetic differentiation (FST = 0.2), suggesting the presence of a cryptic species boundary within this species.

Genetic and morphological evidence for a single species of pink ling (Genypterus blacodes) in New Zealand waters

Two species of ling, Genypterus blacodes (Forster in Bloch & Schneider, 1801) and G. microstomus (Regan, 1903) have been recorded from New Zealand and Australian waters; a third species, G. tigerinus (Klunzinger, 1872) has been recorded from Australia. Specimens of ling collected from northern, central, and southern localities in the New Zealand Exclusive Economic Zone (EEZ), and specimens of G. blacodes from Australia were shown to be similar with respect to partial sequences of mitochondrial (mt)DNA, and morphometric and meristic characters. DNA sequences of part of the cytochrome b and control region showed that G. blacodes from Tasmania and New Zealand differed by 1/291 and 4/284 nucleotides respectively, but there was much greater genetic differentiation between G. blacodes and G. tigerinus (14/291 and 14/284 nucleotides), and between G. blacodes and G. capensis (23/291 and 8/284 nucleotides). MtDNA haplotypes within New Zealand show that G. blacodes is subdivided into northern and southern stocks. It is concluded that ling in New Zealand represent a single species referable to G. blacodes, and that G. microstomus Regan is a junior synonym.