Egg formation and the pre-laying period of the Common guillemot Una aalge

The patterns of colony attendance of male and female Common guillemots, relative to calendar date and relative to the female's laying date during the three weeks prior to egg laying, are presented. The probability of a male being at the colony was consistently higher than that for females. Male attendance peaked in the three days before his mate laid: female attendance was lowest at this time. Examination of the yolk showed that the egg was formed over 14–15 days, with yolk deposition (of first eggs) taking 11–5 days, and a lag period (between the end of yolk deposition and laying) of 3–4 days. Yolk deposition occurred over a shorter period (9–3 days) in replacement eggs, and followed a different pattern from first eggs.     

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.     

Soil microfungal communities of 'Evolution Canyons' in Israel – extreme differences on a regional scale

On a regional scale, we compared the local adaptive patterns of soil mycobiota revealed in four 'Evolution Canyons' located in the northern and southern parts of Israel. These microsites were chosen according to the framework of the Institute of Evolution, University of Haifa programme, focusing on the effect of interslope environmental divergence on biodiversity patterns. The comparative analysis demonstrated remarkable differences in spatiotemporal structure of the microfungal communities and their biodiversity level (species richness, heterogeneity and equitability). In the desert 'Evolution Canyon', stress-selected, slow-reproducing, dark-coloured species with large, multicelled conidia were dominant. At the same time, in the forest localities of the northern canyons, as well as in the agriculturally disturbed locality with soil degradation, ruderal-selected, fast-reproducing Penicillium species predominated. Environmental natural selection appeared to be the major factor affecting adaptive diversity patterns of soil microfungi in the studied area.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 157–163.     

Differential expression of dehydrin genes in wild barley, Hordeum spontaneum, associated with resistance to water deficit

Dehydrin gene (Dhn) expression is associated with plant response to dehydration. The aim of the present study was to investigate the association of differential expression of Dhn genes (Dhn 1, 3, 5, 6, and 9) with drought tolerance found in wild barley (Hordeum spontaneum). Tolerant and sensitive genotypes were identified from Israeli (Tabigha microsite) and Jordanian (Jarash and Waddi Hassa) populations (based on scoring of water loss rate of 390 genotypes). The five Dhn genes were up‐regulated by dehydration in resistant and sensitive wild barley genotypes. Notably, differences between resistant and sensitive genotypes were detected, mainly in the expression of Dhn1 and Dhn6 genes, depending on the duration of dehydration stress. Dhn1 tended to react earlier (after 3 h) and higher (12 h and 24 h) in resistant compared to sensitive genotypes. The level of expression of Dhn6 was significantly higher in the resistant genotypes at the earlier stages after stress. However, after 12 and 24 h Dhn6 expression was relatively higher in sensitive genotypes. The present results may indicate that these genes have some functional role in the dehydration tolerance in wild barley. The authors suggest that the observed differences of Dhn expression in wild barley, originating from different micro‐ and macro ecogeographic locations, may be the result of adaptive edaphic and climatic selective pressures.     

Chromosomal polymorphisms in subterranean mole rats: origins and evolutionary significance

Two distinct chromosomal polymorphisms, among others, characterize the short (p) and long (qh) arms of chromosome number 1 of the Spalax ehrenbergi complex in Israel. We have studied the geographic distributions of these two polymorphisms in 60 animals belonging to four chromosomal species (2 n = 52, 54, 58 and 60). These comprised 15 populations: 12 from continuously distributed populations, two from semi-isolates, and one isolate in the northern Negev Desert.
Our results indicate that: (i) the two polymorphisms are widespread not only within populations and species but most strikingly between different bone marrow cells within an individual; this may reflect a diversity generating mechanism; (ii) the two polymorphisms of p and qh, primarily of p, are correlated with climatic factors of water availability and temperature, as well as geographical distances; these correlations are significantly above those expected by chance, (iii) The semi-isolates and the isolate display high levels of polymorphism in both p and qh, but particularly in qh, despite the small size population effects.
We suggest that at least the polymorphism in p is involved in the adaptive radiation of mole rats into diverse climatic regimes. Furthermore, we speculate that the forces generating chromosomal polymorphisms relevant to speciation (i.e. Robertsonian mutations), coupled with the evolutionary forces operating in small peripherally isolated populations, may be appropriate for the origin of new chromosomal species through peripatric speciation.     

Genetic parallelism of protein polymorphism in nature: ecological test of the neutral theory of molecular evolution

We have conducted an ecological test of protein polymorphism in 13 unrelated genera of plants, invertebrates and vertebrates, involving 21 species, 142 populations and 5474 individuals. Each was tested, on average, for 27 enzymatic gene loci. These species varied in population size and structure, life histories and biogeographical origins, but they largely share a geographically short (260 km) and ecologically stressful gradient of increasing aridity in Israel, both eastward and (mainly) southward. We found genetic parallelism across most taxa, and most loci. Observed average heterozygosity, H , and gene diversity, He , were positively and overall significantly correlated with rainfall variation. This result corroborates the environmental theory of genetic diversity, primarily the niche-width variation hypothesis in both space and time. Our results are inconsistent with the neutral theory of molecular evolution and suggest that natural selection appears to be an important differentiating evolutionary force at the protein level.