Genetic and morphological variability in a population of Diphyllobothrium dendriticum (Nitzsch, 1824)

Plerocercoids of Diphyllobothrium dendriticum were isolated from whitefish (Coregonus clupeaformis) from McGregor Lake, Alberta. Adult D. dendriticum were obtained by infection of golden hamsters (Mesocricetus auratus). Analysis of morphological variables indicated high variability and some overlap with D. latum. Correlations in morphology were due to the covariance of shape variables. Isozyme analysis also showed high variability, with two thirds of the enzymes studied being polymorphic. Correlations with morphology indicate a relationship between rare patterns for malate dehydrogenase and esterase and increased size of adults. Southern hybridisation with ribosomal gene probes produced two common patterns and a rare intermediate form, indicating that the species is variable even within a local population. Correlations between rDNA pattern type and morphological variables supported the hypothesis of a genetic base for the morphological variability.     

Inter- and intra-specific characterization of tapeworms of the genus Diphyllobothrium (Cestoda: Diphyllobothriidea) from Switzerland,using nuclear and mitochondrial DNA targets

Human diphyllobothriosis is caused by at least 14 species of cestodes belonging to the genus Diphyllobothrium. Molecular analysis by sequencing of nuclear and mitochondrial targets identifies some species at inter- and intra-specific level, and helps to reconstruct their phylogenetic relationships. Nevertheless, the suitability of further molecular targets deserves to be widened, and the comparison of samples of different geographical origin could allow their intra-specific characterization, which could also be useful for epidemiological purposes. In this study, we investigated inter- and intra-specific variability among tapeworms of the genus Diphyllobothrium, with focus on Diphyllobothrium latum, originated from Switzerland. Samples were analyzed by comparing the sequences of two nuclear and two mitochondrial DNA targets. We analyzed 27 samples belonging to 4 species (D. latum, Diphyllobothrium nihonkaiense, Diphyllobothrium dendriticum and Diphyllobothrium ditremum), 15 of which isolated from clinical cases (adults and eggs), 2 from wild canines, and 2 from fish of Swiss lakes (plerocercoid larvae); 8 samples of homologous species from other geographic origins were also sequenced and compared with the Swiss ones. Sequences of partial small subunit ribosomal RNA (18S rRNA) gene and partial internal transcribed spacers 1 and 2 (ITS1-2) were not useful even in inter-specific identification, whereas sequences of complete cytochrome c oxidase subunit 1 (cox1) and cytochrome b (cob) genes allowed us to assess inter- and intra-specific variations among the samples. Cox1 and cob could differentiate 3 and 5 haplotypes within the species D. latum. The results are discussed in the light of the anamneses provided by part of the patients.     

Comparative cytogenetics of Diphyllobothrium ditremum (Creplin, 1925) and Ligula intestinalis (Linnaeus, 1758) (Cestoda: Pseudophyllidea)

An investigation carried out on two species of pseudophyllidean cestodes belonging to different families showed very close karyological affinity between them. The karyotypes of Diphyllobothrium ditremum and Ligula intestinalis both consist of 18 bi-armed chromosomes and are almost identical with respect to the relative length and the centromeric indices of corresponding chromosomes. Statistically significant differences exist in the morphology of chromosomes 2 and 4, but they are not striking and may be due in part to errors of measurement. Differences in the absolute length of the chromosomes were noted: the chromosomes of D. ditremum are somewhat larger (from 2.7 to 8.5 μm) than those of L. intestinalis (from 1.9 to 5.4 μm). The results obtained were compared with data existing for other pseudophyllidean cestodes and preliminary conclusions on the karyotypic evolution in that group of helminths were made.     

Parasitic helminths infection in Coho salmón, Oncorhynchus kisutch, during their return to Simpson river, Chile]

Between may and july 1994, 17 adult returning salmons, Oncorhynchus kisutch, were collected in the River Simpson, Chile. All fishes showed infection by plerocercoids of Diphyllobothrium sp. in different locations: stomach, spleen, liver, mesenteries and gonads. Infection with larval cestodes of an unidentified species of Phillobothriidae was determined in the intestine of seven (41.2%) salmons and its prevalences of infection showed significant differences between female and male salmons. The 94.4% of total plerocercoids of Diphyllobothrium were isolated from the stomach wall. Prevalence and mean intensity of infection by Diphyllobothrium sp. did not show significant differences between fishes of different sex.     

Genetic diversity in Passiflora species determined by morphological and molecular characteristics

Morphological and molecular characteristics were studied in six wild species of Passiflora. There were statistically significant differences among these six species for all characteristics studied. Intra-specific variability was observed for number of flowers, number of fruits, number of seeds, fruit length, fruit width and leaf area. Cluster analysis using morphological data showed three groups: 1) P. palmeri var. sublanceolata, P. morifolia and P. foetida var. foetida, 2) P. coriacea and P. micropetala, and 3) P. suberosa. The dendrogram constructed using randomly amplified polymorphic DNA (RAPD) data showed six different groups for each species. The genetic distances among the 24 accessions ranged from 0.05 (between P. morifolia accessions P1 and P3) to 0.95 (P. coriacea accession 31 and P. palmeri var. sublanceolata accession 49). The species showed high morphological and molecular inter- and intraspecific variability.     

Two Human Cases of Diphyllobothrium nihonkaiense Infection in Korea

Diphyllobothrium latum and Diphyllobothrium nihonkaiense are the 2 reported main causes of human diphyllobothriasis in the Republic of Korea. However, the differentiation of these 2 species based on morphologic features alone is difficult. The authors used nucleotide sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene to diagnose Diphyllobothrium spp. Two patients visited the emergency room at Kyungpook National University Hospital on 3 April and 12 April 2013, respectively, with fragments of parasites found while defecating. The parasites were identified as Diphyllobothrium spp. based on morphologic characteristics, and subsequent cox1 gene sequencing showed 99.9% similarity (1,478/1,480 bp) with D. nihonkaiense. Our findings support the hypothesis that D. nihonkaiense is a dominant species in Korea.     

Biometric and reproductive aspects of the pen shell Atrina seminuda (Bivalvia: Pinnidae) in northeastern Venezuela

The pen shell Atrina seminuda is a target for a small artisanal Caribbean fishery; however, little is known about its biology. The length frequency distribution, biometric relations and reproduction of this species were studied in northeastern Venezuela. Using transects selected from among 360 stations a population was sampled monthly by SCUBA diving. An analysis of 1748 individuals showed a shell height (SH) between 4?cm and 23.6?cm, with an average of 16.7?±?2.5?cm. For both sexes, statistical differences in mean SH were observed (analysis of variance F (1, 1113)?=?69.538; P?SL), total weight (TW) and adductor muscle weight (MW) as a function of SH. In all cases there were statistical differences between males and females, with males presenting positive allometry and females showing isometry. Mean SH at maturity for males (8.24?cm) was lower than for females (11.88?cm), and for sexes combined was estimated at 8.71?cm. Gametogenic activity was observed throughout the year, with two main peaks of spawning (April and August/September 2008). All this information is crucial for demographic modelling and stock assessment for managing this species.     

莱州湾春季鱼卵仔稚鱼群落结构和物种多样性

于2007—2010年春季(5月)利用大型浮游生物网对莱州湾海域位置相同的12个站位进行4个航次拖网调查,研究分析了该海域鱼卵仔稚鱼群落组成、优势种、空间分布及其多样性特征。结果表明:4个航次共获得鱼卵、仔稚鱼26种,隶属于6目16科24属,1种衔科鱼卵鉴定到科,另有1种鱼卵未能鉴定种类。鱼卵、仔稚鱼分布不均匀,莱州湾西部还湾底海域分布较多。斑鰶(Konosiruspunctatus)为该海域鱼卵的第一优势种;鳀(Engraulisjaponicus)在2007年和2008年作为仔稚鱼的第一优势种出现,而2009年和2010年仔稚鱼的第一优势种则是虾虎鱼。调查期间该海域鱼卵、仔稚鱼的均匀度指数和生物多样性指数变化趋势一致,均表现为从2007年开始随年代递减的趋势;种类数和丰富度指数则从2008年开始呈现随年代递减的趋势。2007—2010年4a鱼卵仔稚鱼聚类结果显示,2007年和2008年鱼卵仔稚鱼群落结构相似,与2009年和2010年均有差异。与1982年山东省近岸调查结果相比,莱州湾海域鱼卵仔稚鱼群落结构发生明显变化,斑鰶取代鳀成为第一优势种,小黄鱼等经济鱼类数量逐渐降低。     

Fatty acids differentiate consumers despite variation within prey fatty acid profiles

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Foraging ecology and niche overlap in pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales from waters of the U.S. mid‐Atlantic coast

A complementary approach of stomach content and stable isotope analyses was used to characterize the foraging ecology and evaluate niche overlap between pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales stranded on the U.S. mid‐Atlantic coast between 1998 and 2011. Food habits analysis demonstrated both species were primarily teuthophagous, with 35 species of cephalopods, and 2 species of mesopelagic fishes represented in their overall diets. Pianka's Index of niche overlap suggested high overlap between whale diets (O_n = 0.92), with squids from the families Histioteuthidae, Cranchidae, and Ommastrephidae serving as primary prey. Pygmy sperm whales consumed slightly larger prey sizes (mean mantle length [ML] = 10.8 cm) than dwarf sperm whales (mean ML = 7.8 cm). Mean prey sizes consumed by pygmy sperm whales increased with growth, but showed no trend in dwarf sperm whales. Significant differences were not detected in δ¹⁵N and δ¹³C values of muscle tissues from pygmy (10.8‰ ± 0.5‰, ?17.1‰ ± 0.6‰), and dwarf sperm whales (10.7‰ ± 0.5‰, ?17.0‰ ± 0.4‰), respectively. Isotopic niche widths also did not differ significantly and dietary overlap was high between the two species. Results suggest the feeding ecologies of the pygmy and dwarf sperm whales are similar and both species occupy equivalent trophic niches in the region.     

Distribution and species composition of juvenile and adult scombropids (Teleostei,Scombropidae) in Japanese coastal waters

Two scombropid fishes, Scombrops boops and Scombrops gilberti, are closely related and commercially important species in Japan. These species are often confused in commercial markets because of their morphological similarity. In this study, scombropid specimens collected from various Japanese coastal waters were subjected to polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis and phylogenetic analysis of the 16S rRNA gene in mitochondrial DNA. These analyses showed that all the scombropid specimens collected from localities in the Sea of Japan were identified as S. boops, whereas those from the Pacific Ocean included two species, S. boops and S. gilberti. Almost all juvenile (<200 mm standard body length, S_L) S. gilberti originated from the Pacific coastal waters of the northern Japan, whereas adults (>400 mm S_L) were found only in deep water off the Izu Peninsula to the Izu Islands. This suggests that S. gilberti might migrate extensively during its life cycle. In addition, differences in the number of specimens and the distribution between the two species suggest that S. gilberti is less abundant than S. boops in Japanese waters.     

A Case of Diphyllobothrium nihonkaiense Infection as Confirmed by Mitochondrial COX1 Gene Sequence Analysis

Diphyllobothrium nihonkaiense has been reported in Korea as Diphyllobothrium latum because of their close morphologic resemblance. We have identified a human case of D. nihonkaiense infection using the mitochondrial cytochrome c oxidase subunit I (cox1) gene sequence analysis. On 18 February 2012, a patient who had consumed raw fish a month earlier visited our outpatient clinic with a long tapeworm parasite excreted in the feces. The body of the segmented worm was 2 m long and divided into the scolex (head) and proglottids. It was morphologically close to D. nihonkaiense and D. latum. The cox1 gene analysis showed 99.4% (340/342 bp) homology with D. nihonkaiense but only 91.8% (314/342 bp) homology with D. latum. The present study suggested that the Diphyllobothrium spp. infection in Korea should be analyzed with specific DNA sequence for an accurate species identification.     

Display Specificity and Reproductive Isolation in the Fiddler Crabs,Uca panacea and U. pugilator

The factors responsible for reproductive isolation between two sibling species of fiddler crabs (Uca pugilator and U. panacea) were studied under both laboratory and field conditions. ♂♂ showed species differences in their visual and acoustical displays. These differences were exaggerated in the overlap zone, where U. pugilator showed character displacement of its acoustic signals. ♀♀ of U. pugilator confined with ♂♂ of U. panacea produced fewer clutches of young. Occasionally, forced matings took place in the laboratory, resulting in hybrids suffering greater mortality through development. The data indicate that both premating (behavioral) as well as postmating (higher larval mortality) barriers act to prevent interbreeding.     

Genetic diversity within and among populations of Shorea leprosula Miq. and Shorea parvifolia Dyer (Dipterocarpaceae) in Indonesia detected by AFLPs

The genetic diversity within and among populations of Shorea leprosula and Shorea parvifolia from Indonesia was investigated using amplified fragment length polymorphisms (AFLPs). The results indicated that S. leprosula is genetically more variable than S. parvifolia. At the population level, a higher level of genetic diversity was revealed for S. leprosula with a percentage of polymorphic loci (PPL_p) of 53.32% and an expected heterozygosity (H _ep) of 0.16 in comparison with S. parvifolia showing PPL_p of 51.79% and H _ep of 0.14. At the species level, S. leprosula showed PPL_s of 92.86% and H _es of 0.21, while S. parvifolia showed PPL_s of 85.71% and H _es of 0.21. Genetic differentiation (G _st) indicated that 25 and 31% of total genetic diversity in S. leprosula and S. parvifolia, respectively, were attributed to the differences among populations. An analysis of molecular variance (AMOVA) at two hierarchical levels exhibited that most genetic variation resided within populations with proportion of 70.2% for S. leprosula and 66.2% for S. parvifolia. The AMOVA at three hierarchical levels performed for S. leprosula and S. parvifolia together revealed that the genetic difference between the two species was remarkably higher with a proportion of 44.1% than the differences within and among populations (38.1 and 17.8%, respectively). The genetic differentiation between islands was significant for S. leprosula but not for S. parvifolia. The observed genetic diversity agreed with the life history traits of Shorea species. Highly differentiating individual AFLP markers were found for each species, which will serve as diagnostic markers for the identification of wood of different species, from different islands and regions.     

Morphological variability of potato cyst nematodes (Globodera spp.) in the Canary Islands

Thirty populations of potato cyst nematode (Globodera spp.) from the Island of Tenerife and two populations from the UK were assessed for several morphometric and non-morphometric characters thought to discriminate between the species G. rostochiensis and G. pallida. Also 200 cysts from each population were analysed by isoelectric focusing of soluble proteins. Correlation analysis, analysis of variance and principal component analysis were used to investigate relationships between the morphometric characters, how the relationships varied between species and between populations, and which characters were most useful for discriminating between species. The two species differed significantly for each of the four morphometric characters: stylet length, fenestra length, anus-fenestra distance and the number of ridges. The stylet length and fenestra length also showed differences between populations of G. rostochiensis while stylet length and number of ridges showed differences between populations of C. pallida. In general, populations of G. pallida showed greater variation than populations of C. rostochiensis. Principal component analysis of the population means indicated that over 73% of the variation in the characters could be explained by the contrast of stylet and fenestra lengths against the anus-fenestra distance and number of ridges. A plot of the first two principal components separated the two species. Stepwise discriminant analysis provided a linear combination of these four variables which discriminated between the species. Stylet length was found to be the most useful characteristic for distinguishing the species whilst anus-fenestra distance was the least useful.     

Molecular and morphological evidence supports the species status of the Mahachai fighter Betta sp. Mahachai and reveals new species of Betta from Thailand

Two regions of mitochondrial (mt) DNA, cytochrome c oxidase subunit 1 (COI) and 16S rRNA, were sequenced in nine species of Betta from Thailand and Indonesia. Most species showed little intraspecific COI variation (adjusted mean = 0·48%) including the putative species Betta sp. Mahachai, but one species (Betta smaragdina) included three lineages showing much greater divergence (7·03–13·48%) that probably represent overlooked species. These findings were confirmed by maximum likelihood analysis and Bayesian inference, which revealed well‐supported corresponding monophyletic clades. Based on these results and morphological differences, the putative species Betta sp. Mahachai from central Thailand is a species distinct from other members of the B. splendens group and represents a new and hitherto undescribed species. Furthermore, this study also demonstrated the probable existence of two overlooked Betta species found in the Khorat plateau basin, illustrating the utility of mitochondrial genetic markers in the revelation of overlooked diversity.     

The ultrastructure of spermatid development during spermiogenesis within the rosebelly lizard,Sceloporus variabilis (Reptilia,Squamata, Phrynosomatidae)

Several recent studies have mapped out the characters of spermiogenesis within several species of squamates. Many of these data have shown both conserved and possibly apomorphic morphological traits that could be important in future phylogenetic analysis within Reptilia. There, however, has not been a recent study that compares spermiogenesis and its similarities or differences between two species of reptile that reside in the same genus. Thus, the present analysis details the changes to spermiogenesis in Sceloporus variabilis and then compares spermatid morphologies to that of Sceloporus bicanthalis. Many of the morphological changes that the spermatids undergo in these two species are similar or conserved, which is similar to what has been reported in other squamates. There are six main character differences that can be observed during the development of the spermatids between these two sceloporid lizards. They include the presence (S. variabilis) or absence (S. bicanthalis) of a mitochondrial/endoplasmic reticulum complex near the Golgi apparatus during acrosome development, a shallow (S. variabilis) or deep (S. bicanthalis) nuclear indentation that accommodates the acrosomal vesicle, filamentous (S. variabilis) or granular (S. bicanthalis) chromatin condensation, no spiraling (S. variabilis) or spiraling (S. bicanthalis) of chromatin during condensation, absence (S. variabilis) or presence (S. bicanthalis) of the longitudinal manchette microtubules, and the lack of (S. variabilis) or presence (S. bicanthalis) of nuclear lacunae. This is the first study that compares spermiogenic ultrastructural characters between species within the same genus. The significance of the six character differences between two distantly related species within Sceloporus is still unknown, but these data do suggest that spermiogenesis might be a good model to study the hypothesis that spermatid ontogeny is species specific. J. Morphol. 275:258–268, 2014. © 2013 Wiley Periodicals, Inc.     

A multivariate comparison of the stress response in three salmonid and three cyprinid species: evidence for inter‐family differences

The response of six species of freshwater fishes, from the families Cyprinidae (common carp Cyprinus carpio, roach Rutilus rutilus and chub Leuciscus cephalus) and Salmonidae (rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta and Arctic charr Salvelinus alpinus), to a standardized stressor was evaluated. A 6 h period of confinement resulted in changes to plasma cortisol, glucose, amino acid and lactate levels compared with unconfined controls. There were significant differences in the response profiles both within and between families. The cyprinid species exhibited higher and more sustained stress‐induced increases in plasma cortisol and glucose than the salmonid species. In cyprinids, plasma lactate and plasma amino acid concentration showed less disturbance following stress than in salmonids. The results of the study, together with an evaluation of previously published data for eight salmonid species and six cyprinid species, support the hypothesis that differences in core elements of the stress response exist between species of fishes, and that this variation may have a systematic basis.