Phenotypic and genetic differentiation of two major phylogeographical lineages of arctic grayling Thymallus arcticus in the Lena River, and surrounding Arctic drainages

Two phylogeographical lineages of arctic grayling, Thymallus arcticus , in Siberia are extensively characterized based on both molecular genetic (mtDNA control region sequences) and phenotypic (12 meristic characters) data. One lineage, occurring in the delta region of the Lena River as well as all other Arctic draining rivers sampled, corresponds to the subspecific taxon Thymallus arcticus pallasii , whose type locality is the Kolyma River. This taxon is proposed to be a postglacial colonizer of the Lena delta. The second lineage occurs throughout the rest of the Lena basin and is proposed to have survived in a glacial refugium in the middle reaches of the Lena. These lineages form reciprocally monophyletic groups based on mtDNA sequences (net divergence 3.2%), a relationship that is concordant with phenotypic data, and thus reflects distinct taxa. The upper Lena taxon is given the preliminary name of Thymallus arcticus lenensis . Phylogenetic analysis, together with previously published data from North America, reveals that mtDNA sequences from North American populations group within the diverse clade corresponding to T. a. pallasii in Siberia. Despite the relatively close genetic relationship of most North American haplotypes with those in northern Siberia, inferences of fragmentation between the continents are supported, but bidirectional movements between the two continents are seen as likely. Despite inclusion in the clade representing T. a. pallasii in Siberia, the source of the relatively divergent Nahanni refuge haplotypes in North America is not resolved. Otherwise, inferences of postglacial expansion across several thousand kilometres are well supported within North America, but only smaller-scale colonization events among drainages are supported in Siberia.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 511–525.     

Adaptive microclimatic structural and expressional dehydrin 1 evolution in wild barley, Hordeum spontaneum, at 'Evolution Canyon', Mount Carmel, Israel

'Evolution Canyon' (ECI) at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unravelling evolution in action highlighting the twin evolutionary processes of adaptation and speciation. A major model organism in ECI is wild barley, Hordeum spontaneum , the progenitor of cultivated barley, which displays dramatic interslope adaptive and speciational divergence on the 'African' dry slope (AS) and the 'European' humid slope (ES), separated on average by 200 m. Here we examined interslope single nucleotide polymorphism (SNP) sequences and the expression diversity of the drought resistant dehydrin 1 gene ( Dhn1 ) between the opposite slopes. We analysed 47 plants (genotypes), 4–10 individuals in each of seven stations (populations) in an area of 7000 m², for Dhn1 sequence diversity located in the 5' upstream flanking region of the gene. We found significant levels of Dhn1 genic diversity represented by 29 haplotypes, derived from 45 SNPs in a total of 708 bp sites. Most of the haplotypes, 25 out of 29 (= 86.2%), were represented by one genotype; hence, unique to one population. Only a single haplotype was common to both slopes. Genetic divergence of sequence and haplotype diversity was generally and significantly different among the populations and slopes. Nucleotide diversity was higher on the AS, whereas haplotype diversity was higher on the ES. Interslope divergence was significantly higher than intraslope divergence. The applied Tajima D rejected neutrality of the SNP diversity. The Dhn1 expression under dehydration indicated interslope divergent expression between AS and ES genotypes, reinforcing Dhn1 associated with drought resistance of wild barley at 'Evolution Canyon'. These results are inexplicable by mutation, gene flow, or chance effects, and support adaptive natural microclimatic selection as the major evolutionary divergent driving force.     

The long-term costs of traumatic stress: intertwined physical and psychological consequences

The gradual emergence of symptoms following exposure to traumatic events has presented a major conceptual challenge to psychiatry. The mechanism that causes the progressive escalation of symptoms with the passage of time leading to delayed onset post-traumatic stress disorder (PTSD) involves the process of sensitization and kindling. The development of traumatic memories at the time of stress exposure represents a major vulnerability through repeated environmental triggering of the increasing dysregulation of an individual’s neurobiology. An increasing body of evidence demonstrates how the increased allostatic load associated with PTSD is associated with a significant body of physical morbidity in the form of chronic musculoskeletal pain, hypertension, hyperlipidaemia, obesity and cardiovascular disease. This increasing body of literature suggests that the effects of traumatic stress need to be considered as a major environmental challenge that places individual’s physical and psychological health equally at risk. This broader perspective has important implications for developing treatments that address the underlying dysregulation of cortical arousal and neurohormonal abnormalities following exposure to traumatic stress.     

Re‐Evaluation of the EUK516 Probe for the Domain Eukarya Results in a Suitable Probe for the Detection of Kinetoplastids,an Important Group of Parasitic and Free‐Living Flagellates

ABSTRACT. Two frequently used universal eukaryote probes, EUK1209 and EUK516, are not consistent with one branch of the eukaryotic phylogenetic tree, the Kinetoplastida, which has undergone rapid evolution of their small subunit rRNA gene. Kinetoplastids include medically important parasitic organisms (e.g. Trypanosoma, Leishmania) and free‐living flagellates that occur in all aquatic environments and in soils (e.g. Bodo, Neobodo, Rhynchomonas). A modified probe presented here as KIN516, now based on the kinetoplastid sequence, provides a strong signal with Neobodo designis, Leishmania donovani, and Trypanosoma cruzi using the catalyzed reporter deposition protocol. EUK516 and KIN516 function as competitor probes, thereby greatly increasing discriminatory power when used in combination. The probe pair was tested in field samples collected in a freshwater pond in Norfolk, the mesohaline Elizabeth River, Norfolk, Virginia, and a tropical lagoon in Belize. The combined probes bound to 58–84% of organisms identified as eukaryotic based on having large DAPI‐stained nuclei. The contribution of kinetoplastids to total eukaryotes (positive signal of EUK516+KIN516) was much higher in marine samples (ca. 17%) than in either the freshwater or brackish water sites (<0.2%).     

Effects of coalbed natural gas development on fish assemblages in tributary streams of the Powder and Tongue rivers

1. Extraction of coalbed natural gas (CBNG) often results in disposal of large quantities of CBNG product water, which may affect aquatic ecosystems. We evaluated the effects of CBNG development on fish assemblages in tributary streams of the Powder and Tongue rivers. We used treatment and control, impact versus reference sites comparisons, surveys of CBNG product‐water streams and in situ fish survival approaches to determine if CBNG development affected fish assemblages. 2. Several of our results suggested that CBNG development did not affect fish assemblages. Species richness and index of biotic integrity (IBI) scores were similar in streams with and streams without CBNG development, and overall biotic integrity was not related to the number or density of CBNG wells. Fish occurred in one stream that was composed largely or entirely of CBNG product water. Sentinel fish survived in cages at treatment sites where no or few fish were captured, suggesting that factors such as lack of stream connectivity rather than water quality limited fish abundance at these sites. Fish species richness did not differ significantly from 1994 to 2006 in comparisons of CBNG‐developed and undeveloped streams. Biotic integrity declined from 1994 to 2006; however, declines occurred at both impact and reference sites, possibly because of long‐term drought. 3. Some evidence suggested that CBNG development negatively affected fish assemblages, or may do so over time. Specific conductivity was on average higher in treatment streams and was negatively related to biotic integrity. Four IBI species richness metrics were negatively correlated with the number or density of CBNG wells in the catchment above sampling sites. Bicarbonate, one of the primary ions in product water, was significantly higher in developed streams and may have limited abundance of longnose dace (Rhinichthys cataractae). Total dissolved solids, alkalinity, magnesium and sulphate were significantly higher in developed streams. 4. Biological monitoring conducted before the development of CBNG, and continuing through the life of development and reclamation, together with data on the quantity, quality and fate of CBNG product water will allow robust assessment of potential effects of future CBNG development worldwide.     

Unisexual rock lizard might be outcompeting its bisexual progenitors in the Caucasus

We compared the distributions, abundances and ecological requirements of parthenogenetic lizard Darevskia ‘dahli’ and its bisexual progenitors, D. portschinskii and D. mixta, in Georgia. We developed a regression model relating the species abundances with the distribution of climates. Darevskia portschinskii lives in warmer and drier climates than D. mixta; D. ‘dahli’ has the intermediate requirements. Temperature is more important than humidity for D. portschinskii, humidity is more important for D. mixta and both temperature and humidity are important for D. ‘dahli’. Suitable habitats of all three species overlap broadly; however, the observed ranges partly overlap only for D. ‘dahli’ and D. portschinskii. The observed abundance of each species, related to its predicted abundance, is lower at the sites with potential competitors. Darevskia ‘dahli’ occupies a higher proportion of the suitable habitats and has higher abundances than the progenitor species. Competition with D. ‘dahli’ is an important factor determining current distribution pattern of D. portschinskii and D. mixta. The parthenogen is a stronger competitor than the bisexual breeders and potential advantages of the bisexual reproduction remain unrealized in the given temporal and spatial scale. To explain domination of bisexually breeding lizards on the global scale, considering climate changes in geological timescale is necessary. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 447–460.