The larval attachment organ of the tropical gar Atractosteus tropicus Gill, 1863 (Lepisosteiformes: Lepisosteidae)

Larval attachment organs (LAOs) are unicellular or multicellular organs that allow larvae to adhere to a substrate before yolk-sac absorption and the free-swimming stage. This study documents the LAO of tropical gar, Atractosteus tropicus, using a combination of scanning electron microscopy and light microscopy. It is shown that the LAO of A. tropicus is a super-organ surrounded by a wall and containing at its centre many smaller multicellular organ units, each comprised of attachment and support cells. Attachment cells are secretory and house large vacuoles filled with a glycoprotein. At hatching, the super-organ is well developed and occupies almost the entire anteroventral surface of the head. During subsequent development, the smaller individual units begin to regress, until at 6 days post-hatching the super-organ and its individual units are no longer visible.     

Acute toxicity and cholinesterase inhibition of the nematicide ethoprophos in larvae of gar Atractosteus tropicus (Semionotiformes: Lepisosteidae)

Biomarkers are a widely applied approach in environmental studies. Analyses of cholinesterase (ChE), glutathione S-transferase (GST) and lipid peroxidation (LPO) are biomarkers that can provide information regarding early effects of pollutants at different biochemical levels on an organism. The aim of this study was to evaluate the biomarker approach on a Costa Rican native and relevant species. For this, larvae of gar (Atractosteus tropicus) were exposed to the organophosphorus nematicide, ethoprophos. Acute (96hr) exposure was conducted with pesticide concentrations ranging from 0.1 microg/L to 1 500 microg/L. The 96hr LC50 calculated was 859.7 microg/L. After exposure, three biomarkers (ChE, GST and LPO) were analyzed in fish that survived the acute test. The lowest observed effect concentration (LOEC) regarding ChE activity inhibition was 50 microg/L. This concentration produced a significant inhibition (p<0.05) of the enzyme by 20%. The highest concentration tested without showing any effect on ChE activity and therefore considered as no observed effect concentration (NOEC) was 10 microg/L. Ethoprophos concentration of 400 microg/L caused a ChE inhibition by 79%. In this study, no significant variations (p>0.05) in GST activity and LPO were observed in A. tropicus larvae after exposure to ethoprophos.     

Molecular population genetics of the red kangaroo (Macropus rufus): mtDNA variation

The genetic population structure of a large, wide-ranging marsupial, the red kangaroo ( Macropus rufus ) was assessed using sequence and haplotype frequency data of mitochondrial DNA (mtDNA) from locations across the species range in Australia. Results from sequence data revealed extensive haplotype diversity within the red kangaroo (32/34 sequences were unique). Sequence diversity was distributed within rather than between geographical regions across the species range. Genetic connectivity across the range of the species has therefore been maintained over the long term. On a smaller within-region scale, significant genetic structuring was evident from heterogeneity of haplotype frequencies amongst sampling sites. The geographical scale of panmictic populations differed across the continent with more restricted genetic populations occurring in areas with greater topographic and habitat complexity. We propose that these differences in area of genetic populations are the result of population responses to limiting ecological factors during drought.     

Genetic structure and demographic history of the melon fly Zeugodacus cucurbitae (Coquillet) (Diptera: Tephritidae) in Thailand

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Phylogeography and population genetic structure of the European roe deer in Switzerland following recent recolonization

In the early 1800s, the European roe deer (Capreolus capreolus) was probably extirpated from Switzerland, due to overhunting and deforestation. After a federal law was enacted in 1875 to protect lactating females and young, and limiting the hunting season, the roe deer successfully recovered and recolonized Switzerland. In this study, we use mitochondrial DNA and nuclear DNA markers to investigate the recolonization and assess contemporary genetic structure in relation to broad topographic features, in order to understand underlying ecological processes, inform future roe deer management strategies, and explore the opportunity for development of forensic traceability tools. The results concerning the recolonization origin support natural, multidirectional immigration from neighboring countries. We further demonstrate that there is evidence of weak genetic differentiation within Switzerland among topographic regions. Finally, we conclude that the genetic data support the recognition of a single roe deer management unit within Switzerland, within which there is a potential for broad‐scale geographic origin assignment using nuclear markers to support law enforcement.     

Cystoopsis atractostei n. sp. (Nematoda: Cystoopsidae) from the subcutaneous tissue of the tropical gar,Atractosteus tropicus (Pisces), in Mexico

A new species of parasitic nematode, Cystoopsis atractostei (Trichinelloidea: Cystoopsidae), is described based on female specimens recovered from the subcutaneous tissue of the tropical gar, Atractosteus tropicus Gill (Lepisosteiformes: Lepisosteidae), from 2 localities (Canal Nueva Esperanza and Canal Tabasquillo) of the Pantanos de Centla Biological Reserve, State of Tabasco, southeastern Mexico, collected in April 2001. The total prevalence was 13%, and the mean intensity of infection was 1 nematode per fish. The new species differs from females of the only other adequately described congeneric species, C. acipenseris Wagner, 1867, mainly in possessing a bulbous inflation at the anterior end of the muscular esophagus, the vulva situated well posterior to the nerve ring, smooth cuticle, and in the shape of the posterior vesicular portion of the body (markedly transversely oval) in the largest specimens. Both species also differ in their host types (Lepisosteiformes vs. Acipenseriformes) and in geographical distribution (tropical southern Mexico vs. temperate zones of the Holarctic).     

A new species of the genus Argulus (Crustacea: Branchiura) parasitic on Atractosteus tropicus (Pisces: Lepisosteidae) from Tabasco,Mexico

A new species of Argulus is described from the garfish Atractosteus tropicus in the Tabasco wetlands, Mexico. Comparisons are made with what appear to be its closest relatives. This species is characterised by the presence of two notches in the inner margin of the large respiratory area, seven to nine supporting sclerites in the suckers, and the characteristic shape of the sexual modifications of the second, third and fourth legs in the male.     

Phylogeography and population history of the endangered golden sun moth (Synemon plana) revealed by allozymes and mitochondrial DNA analysis

A combination of allozyme and mitochondrial DNA markers were used to determine the contribution of recent and ancient causes of patterns of genetic variation within and among 46 populations of the endangered golden sun moth, Synemon plana. Allozyme analysis grouped the 46 populations into 5 major genetic clusters that corresponded closely with geographic location following a classic isolation-by-distance model. Phylogenetic analysis of 14 mtDNA haplotypes revealed two reciprocally monophyletic groups. One of these groups (containing 4 geographically distant populations) was clearly identified by allozyme analysis and represents a distinct evolutionary unit. The remaining 4 allozyme groups were not distinguishable by mtDNA analysis. The evidence suggests that the populations within these groups derived from a small founding population that underwent rapid demographic expansion in ancient times. This was followed by more recent population bottlenecks resulting from habitat fragmentation associated with the widespread introduction of agriculture into the region. The generally low levels of allozyme and nucleotide diversity within these populations support this hypothesis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Isolation and characterization of microsatellite loci for alligator gar (Atractosteus spatula) and their variability in two other species (Lepisosteus oculatus and L. osseus) of Lepisosteidae

We report on the isolation of 17 polymorphic microsatellite loci from alligator gar (Atractosteus spatula), a large-bodied species that has experienced population declines across much of its range. These loci possessed 2-19 alleles and observed heterozygosities of 0-0.974. All loci conformed to Hardy-Weinberg equilibrium expectations, and none exhibited linkage disequilibrium. Nine and eight of these loci were found to be polymorphic in the related species Lepisosteus oculatus and L. osseus, respectively. These microsatellite loci should prove useful in conservation efforts of A. spatula through the study of population structure and hatchery broodstock management.     

Life‐history predicts past and present population connectivity in two sympatric sea stars

Life‐history traits, especially the mode and duration of larval development, are expected to strongly influence the population connectivity and phylogeography of marine species. Comparative analysis of sympatric, closely related species with differing life histories provides the opportunity to specifically investigate these mechanisms of evolution but have been equivocal in this regard. Here, we sample two sympatric sea stars across the same geographic range in temperate waters of Australia. Using a combination of mitochondrial DNA sequences, nuclear DNA sequences, and microsatellite genotypes, we show that the benthic‐developing sea star, Parvulastra exigua, has lower levels of within‐ and among‐population genetic diversity, more inferred genetic clusters, and higher levels of hierarchical and pairwise population structure than Meridiastra calcar, a species with planktonic development. While both species have populations that have diverged since the middle of the second glacial period of the Pleistocene, most P. exigua populations have origins after the last glacial maxima (LGM), whereas most M. calcar populations diverged long before the LGM. Our results indicate that phylogenetic patterns of these two species are consistent with predicted dispersal abilities; the benthic‐developing P. exigua shows a pattern of extirpation during the LGM with subsequent recolonization, whereas the planktonic‐developing M. calcar shows a pattern of persistence and isolation during the LGM with subsequent post‐Pleistocene introgression.     

云南中华按蚊的遗传变异和种群结构

为了掌握云南省各地中华按蚊种群间的遗传变异和种群结构特征,测序并分析了采自云南9个样本点5个种群组的89头中华按蚊的线粒体COII基因。结果表明这些中华按蚊种群的COII基因序列平均单倍型多样性指数和核苷酸多样性指数分别为h=0.933,π=0.00406,共有51个变异位点,占分析的739个碱基总数的6.9%;定义了39个单倍型,有2个频率最高的单倍型H1和H9,分别占个体序列数的20.2%和12.4%;系统发育分析表明单倍型与地理位置没有明显的对应关系,单倍型网络图显示大部分单倍型分布没有明显的亲缘地理格局,主要以单倍型H1、H9、H4、H33和H2为中心呈星状分布,但元江和元阳构成的种群组(YU)单倍型存在明显地域分布特征;AMOVA结果表明种群组间遗传变异为12.58%,达到显著水平(P=0.04888),地理种群组间具有明显种群遗传结构。不同地区两两种群组间的Fst值和Nm值显示大部分种群组间存在基因交流,没有形成明显的遗传分化,但YU种群组和其他种群组间缺乏明显的基因交流,这主要是因为哀牢山的阻隔,使云南东西部形成两种不同的气候,产生了明显的遗传分化;歧点分布图显示为明显单峰分布,中性检测结果均为显著负值,说明云南省的中华按蚊种群在近期经历过复杂的种群扩张事件。掌握中华按蚊遗传多样性及分化特征,对中华按蚊及疟疾控制具有重要的作用。     

Genetic variation and population structure in Scandinavian wolverine (Gulo gulo) populations

Wolverine (Gulo gulo) numbers in Scandinavia were significantly reduced during the early part of the century as a result of predator removal programmes and hunting. Protective legislation in both Sweden and Norway in the 1960s and 1970s has now resulted in increased wolverine densities in Scandinavia. We report here the development of 15 polymorphic microsatellite markers in wolverine and their use to examine the population sub-structure and genetic variability in free-ranging Scandinavian wolverine populations as well as in a sample of individuals collected before 1970. Significant subdivision between extant populations was discovered, in particular for the small and isolated population of southern Norway, which represents a recent recolonization. Overall genetic variability was found to be lower than previously reported for other mustelids, with only two to five alleles per locus and observed heterozygosities (H(O)) ranging from 0.269 to 0.376 across the examined populations, being lowest in southern Norway. Analysis of the mitochondrial DNA control region revealed no variation throughout the surveyed populations. As the historical sample did not show higher levels of genetic variability, our results are consistent with a reduction in the genetic variation in Scandinavian wolverines that pre-dates the demographic bottleneck observed during the last century. The observed subdivision between populations calls for management caution when issuing harvest quotas, especially for the geographically isolated south Norwegian population.     

Molecular genetic variation and population structure in morphologically differentiated cave and surface populations of the freshwater amphipod Gammarus minus

Gammarus minus is an important component of surface spring and cave ecosystems throughout Appalachia, and is a useful indicator of the hydrology and gene flow in freshwater communities. Gammarus minus populations occupying large cave passages (> 2 km) are usually troglomorphic, having reduced eyes, fewer ommatidia, larger body size, longer antennae, and reduced pigmentation relative to surface populations. We surveyed five cave stream and 10 surface spring populations for DNA sequence variation in the cytochrome c oxidase I (COI) and internal transcribed spacer 1 (ITS-1) genes with an aim towards characterizing phylogeographical structure and comparing the nature of genetic variation in cave vs. surface populations. Although standing variation at both loci was rather low within populations, a significant degree of divergence and spatial structuring of populations was observed. Levels of genetic variation within cave and spring populations differed substantially, with caves harbouring significantly less variation at the COI locus than surface springs. Codon usage bias was significantly lower in caves, indicating that cave streams harbour smaller and/or more recently colonized populations. Overall these data indicate limited gene flow among populations and suggest that the cave populations sampled in this study are prone to bottlenecks, possibly due to larger temperature fluctuations and more frequent incidence of drought conditions associated with these particular cave habitats.     

Genetic divergence, population structure and historical demography of rare springsnails (Pyrgulopsis) in the lower Colorado River basin

Springsnails of the genus Pyrgulopsis are the most diverse group of freshwater gastropods in North America and current estimates show that Pyrgulopsis contains ~120 different species, many of which are at risk of extinction. Some factors contributing to their exceptional diversity include poor dispersal ability and extreme habitat specificity based on water availability, chemistry and depth. Most taxa exhibit high degrees of endemism, with many species occurring only in a single spring or seep, making springsnails ideal for studies of speciation and population structure. Here I present data from a survey of genetic variation at the mitochondrial gene cytochrome oxidase I from 37 populations and over 1000 individuals belonging to 16 species of Pyrgulopsis distributed throughout the lower Colorado River basin. High levels of interspecific sequence divergence indicate that Pyrgulopsis may have colonized this region multiple times beginning in the late Miocene (~6 Ma); earlier than previous estimates based on fossil evidence. Estimates of nucleotide diversity differ greatly among species and may reflect differences in demographic processes. These results are used to identify factors contributing to radiation of species in this region. The implications of this evolutionary history and genetic variation are discussed in relation to future management and conservation.     

Genetic population structure, fitness variation and the importance of population history in remnant populations of the endangered plant Silene chlorantha (Willd.) Ehrh. (Caryophyllaceae)

Habitat fragmentation can lead to a decline of genetic diversity, a potential risk for the survival of natural populations. Fragmented populations can become highly differentiated due to reduced gene flow and genetic drift. A decline in number of individuals can result in lower reproductive fitness due to inbreeding effects. We investigated genetic variation within and between 11 populations of the rare and endangered plant Silene chlorantha in northeastern Germany to support conservation strategies. Genetic diversity was evaluated using AFLP techniques and the results were correlated to fitness traits. Fitness evaluation in nature and in a common garden approach was conducted. Our analysis revealed population differentiation was high and within population genetic diversity was intermediate. A clear population structure was supported by a Bayesian approach, AMOVA and neighbour-joining analysis. No correlation between genetic and geographic distance was found. Our results indicate that patterns of population differentiation were mainly caused by temporal and/or spatial isolation and genetic drift. The fitness evaluation revealed that pollinator limitation and habitat quality seem, at present, to be more important to reproductive fitness than genetic diversity by itself. Populations of S. chlorantha with low genetic diversity have the potential to increase in individual number if habitat conditions improve. This was detected in a single large population in the investigation area, which was formerly affected by bottleneck effects.     

Genetic variation and population structure in the endangered greater horseshoe bat Rhinolophus ferrumequinum

Following a dramatic decline last century, the British population of the endangered greater horseshoe bat Rhinolophus ferrumequinum is highly fragmented. To examine the consequences of fragmentation and limited dispersal on patterns of genetic structure and variation, we used microsatellite markers to screen bats from around 50% of the known maternity colonies in Britain, and two areas from continental Europe. Analyses revealed that Welsh and English colonies were genetically isolated. This, and lower variability in Britain than north France, may result from either genetic drift, or the species' colonization history. Gene flow among most neighbouring colonies was not generally restricted, with one exception. These findings have important implications for the ongoing conservation management of this species.     

Microsatellite variation and fine-scale population structure in the wood frog (Rana sylvatica)

We investigated genetic population structure in wood frogs (Rana sylvatica) from a series of Prairie Pothole wetlands in the northern Great Plains. Amphibians are often thought to exist in demographic metapopulations, which require some movement between populations, yet genetic studies have revealed strong subdivision among populations, even at relatively fine scales (several km). Wood frogs are highly philopatric and studies of dispersal suggest that they may exhibit subdivision on a scale of approximately 1-2 km. We used microsatellites to examine population structure among 11 breeding assemblages separated by as little as 50 m up to approximately 5.5 km, plus one population separated from the others by 20 km. We found evidence for differentiation at the largest distances we examined and among a few neighbouring ponds, but most populations were strikingly similar in allele frequencies, suggesting high gene flow among all but the most distant populations. We hypothesize that the few significant differences among neighbouring populations at the finest scale may be a transient effect of extinction-recolonization founder events, driven by periodic drying of wetlands in this hydrologically dynamic landscape.     

Genetic variation and population structure ofCarex breviculmis (Cyperaceae) in Korea

We determined the genetic diversity and population structures ofCarex breviculmis (Cyperaceae) populations in Korea, using genetic variations at 23 allozyme loci.C. breviculmis is a long-lived herbaceous species that is widely distributed in eastern Asia. A high level of genetic variation was found in 15 populations. Twelve enzymes revealed 23 loci, of which 11 were polymorphic (47.8%). Genetic diversity at the speciesand population levels were 0.174 and 0.146, respectively. Total genetic diversity (H_T = 0.363) and within-population genetic diversity (H_s = 0.346) were high, whereas the extent of the population divergence was relatively low (G_ST = 0.063). Deviation from random mating (Fis) within the 15 populations was 0.206. An indirect estimate of the number of migrants per generation(Nm = 3.69) indicated that gene flow was extensive among Korean populations of this species. Analysis of fixation indices revealed a substantial heterozygote deficiency in some populations and at some loci. Genetic identity between popu-lations was high, exceeding 0.956.     

Mitochondrial DNA variation and population genetic structure of the white-clawed crayfish, Austropotamobius pallipes pallipes

Here we report a high level of mtDNA variationfrom RFLP analysis within A. p. pallipes from 21 French and 4British populations. Seventeen haplotypes were recorded among 269individuals. Nucleotide sequence divergence (p) among mtDNAhaplotypes ranged from 0.0019 to 0.0425. Nucleotide diversity ()ranged from 0.01 to 0.006 (mean = 0.0031) and from 0 to 0.001(mean = 0.00037) for populations located in southern and northernFrance, respectively. Graphical representation from principalcoordinate analysis based on Nei's genetic distance values amongpopulations showed two groups, cluster A, including the 16populations sampled in the north-western and north-easternFrance, England and Wales and cluster B containing 9 populationssampled in the central and southern of France. No geneticdifferences were noted among the most northern French and Englishpopulations whereas marked interpopulation genetic diversity wasobserved in southern populations. Such genetic heterogeneityamong populations of A. p. pallipes appears to be related tohabitat fragmentation and subsequent recolonizations fromrefugial areas during the Pleistocene. Implications for theconservation of A. p. pallipes are discussed.     

Genetic variation and population structure of the mosquito Anopheles jeyporiensis in southern China

Genetic differentiation among populations of Anopheles jeyporiensis was examined using 76 mtDNA COII sequences from 16 sites throughout southern China and northern Vietnam. The COII sequences are AT-rich (74.58%) and reveal high levels of diversity with 39 of 685 sites polymorphic and 50 different haplotypes present. Genetic variation is high within populations and significant geographical structure was detected at both population and regional levels. In the larger samples, the distributions of haplotypes suggest recent population expansion.