Evolution Canyon Research Articles

Arachnid Assemblage Composition Diverge between South- and North-Facing Slopes in a Levantine Microgeographic Site

Local microgeographic sites subdivided by sharp ecological and climatic contrasts are important platforms for measuring biodiversity patterns and inferring the possible effect of climatic and ecological variables on species distributions and habitat use. Here, we report results from 24 months (September 2019–August 2021) of continuous pitfall trapping collection in Lower Nahal Keziv, Western Upper Galilee, Israel (“Evolution Canyon” II (hereafter—EC II)). This site receives an average annual rainfall of 784 mm and contains two slopes that differ markedly by solar radiation and plant formation. The first is the south-facing slope (SFS), which is characterized as a semiarid garrigue and open grassland. The second is the contrasting north-facing slope (NFS), which is characterized by a more humid East Mediterranean forest. The slopes are separated by a narrow valley bottom (VB). Analysis of ca. 1750 arachnid specimens, collected from 70 pitfall traps along the slopes and valley, indicates significantly different arachnid assemblages between the NFS and SFS, likely due to the differences in solar radiation that affect plant-cover percentage, which in turn affects the arachnid assemblage composition. In addition to 98 arachnid taxa collected and identified to species and morphospecies level, this study resulted in the discovery of two species new to science, which are described as part of this publication (100 arachnid species and 11 additional taxa that were not identified to species, a total of 111 taxa). Our study, moreover, contributes new ecological data on the spatial and temporal distribution of arachnids, and therefore attests to the importance of year-round sampling in an understudied region. Overall, our study enables a better understanding of arachnid diversity and their distributions and serves as a reference for future research aimed at testing the effect of climate change and other environmental factors that influence arachnid assemblages in natural habitats.

Protease production and molecular characterization of a protease dipeptidyl-aminopeptidase gene from different strains of Sordaria fimicola.

The current research was designed to reach extracellular protease production potential in different strains of Sordaria fimicola which were previously obtained from Dr. Lamb (Imperial College, London) from North Facing Slope and South Facing Slope of Evolution Canyon. After initial and secondary screening, two hyper-producers strains S2 and N6 were selected for submerged fermentation and cultural conditions including temperature, pH, incubation period, inoculum size, substrate concentration, and different carbon and nitrogen sources were optimized for enzyme production. S2 strain showed maximum protease production of 3.291 U/mL after 14 days of incubation at 30 °C with 7 pH, 1% substrate concentration and 1 mL inoculum, While N6 strain showed maximum protease production of 1.929 U/mL under fermentation optimized conditions. Another aim of the present research was to underpin the biodiversity of genetics and post-translational modifications (PTMs) of protease DPAP (peptidyl-aminopeptidase) in Sordaria fimicola. Five polymorphic sites were observed in amino acid sequence of S. fimicola strains with reference to Neurospora crassa. PTMs prediction from bioinformatics tools predicted 38 phosphorylation sites on serine residues for protease peptidyl-aminopeptidase in S1 strain of S. fimicola while 45 phosphorylation sites on serine in N7 strain and 47 serine phosphorylation modifications were predicted in N. crassa. Current research gave an insight that change in genetic makeup effected PTMs which ultimately affected the production of protease enzyme in different strains of same organism (S. fimicola). The production and molecular data of the research revealed that environmental stress has strong effects on the specific genes through mutations which may cause genetic diversity. S. fimicola is non- pathogenic fungus and has a short life cycle. This fungus can be chosen to produce protease enzyme on a commercial scale.

Scattered differentiation of unlinked loci across the genome underlines ecological divergence of the selfing grass Brachypodium stacei.

Ecological divergence without geographic isolation, as an early speciation process that may lead finally to reproductive isolation through natural selection, remains a captivating topic in evolutionary biology. However, the pattern of genetic divergence underlying this process across the genome may vary between species and mating systems. Here, we present evidence that Brachypodium stacei, an annual and highly selfing grass model species, has undergone sympatric ecological divergence without geographic isolation. Genomic, transcriptomic, and metabolomic analyses together with lab experiments mimicking the two opposite environmental conditions suggest that diploid B. stacei populations have diverged sympatrically in two slopes characterized by distinct biomes at Evolution Canyon I (ECI), Mount Carmel, Israel. Despite ongoing gene flow, primarily facilitated by seed dispersal, the level of gene flow has progressively decreased over time. This local adaptation involves the scattered divergence of many unlinked loci across the total genome that include both coding genes and noncoding regions. Additionally, we have identified significant differential expressions of genes related to the ABA signaling pathway and contrasting metabolome composition between the arid- vs. forest-adapted B. stacei populations in ECI. These results suggest that multiple small loci involved in environmental responses act additively to account for ecological adaptations by this selfing species in contrasting environments.

Wild Oats Offer New Possibilities for Forage Because of the Higher Nutrition Content and Feed Value

Oats (Avena sativa L.) are mostly used as a germplasm resource for forage. This experiment showed the differences in the nutrient composition and the forage quality of five wild leather oat populations from Israel and one cultivated leather oat population from China. It also showed the correlation of the indicators with the geo-environmental factors in the places of origin of the six populations that were analysed. Three replicated experiments were conducted during a three-year period from 2018.10 to 2020.03, mainly from 11 indicators of nutrient composition and forage quality. In this experiment, Spearman’s correlation was used to analyse the differences between different groups (p < 0.05), the relationship between components was analysed by principal component analysis (PCA), and the kinship relationship between six groups was also analysed based on the data of 11 components. In terms of nutrient content, the cultivated group Hu had significantly lower ash (8.92%), crude protein (11.96%), and soluble sugar content (10.51%) than the wild oat groups. In terms of forage quality, the lignin content (3.31%) of the Hu population was 2.3 times higher than that of Evolution Canyon, and the fibre content was 8 times higher than that of Sede Boqer. This indicates that wild oats have better nutritional value and palatability. Following the correlation analysis, it was found that the environmental factors of the origin had a significant effect on the indexes of ash, crude protein, and soluble sugar of oat straw, but had less effect on the content of crude fat, total phosphorus, and total potassium. Meanwhile, the annual rainfall and the number of rainfall days in the origin had a significant effect on the fibre content. In conclusion, the higher variability of wild oat populations due to the influence of different environmental and geographical factors may be a new possibility brought by forage oats.

High-quality wild barley genome assemblies and annotation with Nanopore long reads and Hi-C sequencing data

Wild barley, from “Evolution Canyon (EC)” in Mount Carmel, Israel, are ideal models for cereal chromosome evolution studies. Here, the wild barley EC_S1 is from the south slope with higher daily temperatures and drought, while EC_N1 is from the north slope with a cooler climate and higher relative humidity, which results in a differentiated selection due to contrasting environments. We assembled a 5.03 Gb genome with contig N50 of 3.53 Mb for wild barley EC_S1 and a 5.05 Gb genome with contig N50 of 3.45 Mb for EC_N1 using 145 Gb and 160.0 Gb Illumina sequencing data, 295.6 Gb and 285.35 Gb Nanopore sequencing data and 555.1 Gb and 514.5 Gb Hi-C sequencing data, respectively. BUSCOs and CEGMA evaluation suggested highly complete assemblies. Using full-length transcriptome data, we predicted 39,179 and 38,373 high-confidence genes in EC_S1 and EC_N1, in which 93.6% and 95.2% were functionally annotated, respectively. We annotated repetitive elements and non-coding RNAs. These two wild barley genome assemblies will provide a rich gene pool for domesticated barley.

Selection of p53 pathway in adaptive evolution and reproductive isolation in incipient sympatric speciation ofDrosophilaat Evolution Canyon

AbstractSympatric speciation (SS) refers to the origin of new species within a freely breeding population. The ‘Evolution Canyon’ (EC) in Israel is a natural microsite model for SS of species across phylogenies from viruses and bacteria to mammals, adapting to, and speciating in, interslope microclimates. The cosmopolitan Drosophila melanogaster at EC I, Mount Carmel, is undergoing incipient SS in response to sharply divergent interslope microclimate stresses, including solar radiation, temperature, humidity and pathogenicity. We demonstrated here a selective interslope divergence of single nucleotide polymorphism (SNP) distribution in the Drosophila p53 pathway. This involves a total of 71 genes, which are associated with DNA repair, heat response, and fungal and bacterial resistant pathways. This distribution pattern links the previously observed thermotolerance and ageing divergence of D. melanogaster between the opposite canyon slopes: the south-facing slope (SFS, or African slope: tropical, savannoid and dry) and the abutting north-facing slope (NFS, or European slope; temperate, forested, cool and humid). The genes with interslope-significant differential SNPs link the p53 pathway with pathways related to the responses to microclimates through protein-protein interaction. Moreover, for the first time we provide evidence that the p53 pathway is linked to reproductive isolation, and is thus actively participating in incipient SS of D. melanogaster. This is the first demonstration of a link between the p53 pathway and reproductive isolation, thereby contributing to adaptive incipient sympatric speciation.

Asymmetry as an indicator of stress: From population statistics to clinical life-saving applications

Most symmetrical objects can be efficiently described in terms of their deviation from a specific symmetry group, whether it be a mirror, radial, or translatory symmetry, among other groups. Fundamentally, asymmetry is an individual trait, but the asymmetry distribution of a given population may provide valuable information about the well-being of that population. Quantification of these deviations from perfect symmetry evolved from counts and linear measures of distances to landmarks conducive to structures with consistent topology, and then to Continuous Symmetry Measures (CSM) conducive to structures with no consistent topology. We demonstrate the usefulness of this approach on quantification of leaf veins that mirror bifurcating structures. Deviations from a given symmetry group can be described in terms of (i) Fluctuating Asymmetries (FA) or (ii) broken asymmetries. Fluctuating Asymmetry (FA) is a controversial indicator of stress, and therefore tackling the problem needs a large number of species and populations in habitats with well-known stressors. We found such a site at “Evolution Canyon”, Israel, and we examine and discuss a study of twenty-four species that live in the canyon’s opposing slopes. We conclude with examples from asymmetry as a neurophysiological bioindicator by presenting several studies on Amyotrophic Lateral Sclerosis (ALS), Parkinson’s disease, and stroke. We show how machine-learning methods, applied on asymmetry indicators (in addition to the traditional signal processing features), can improve the sensitivity of the system and provide reliable diagnostic results.

Genome coding and noncoding structure function and evolution in Spalax ehrenbergi superspecies and Hordeum spontaneum in Israel: a review (Rodentia: Spalacidae)

The structure and function of the intergenic noncoding genome (repeatome) whether “selfish” and “junk” or “biochemically functional and regulatory” is still hotly debated, despite the mounting empirical and theoretical evidence supporting the regulatory role, provided by transposable elements, and the ENCODE results. In our studies in Israel on sympatric speciation (SS) in two evolutionary speciation models of abutting divergent ecologies, microclimatic at “Evolution Canyon” and geologic-edaphic at “Evolution Plateau”, we showed genomically that SS is a common speciation model across life from bacteria to mammals. Since such contrasting and abutting ecologies, climatic, geologic, edaphic, abiotic and biotic abound globally, SS might be a common speciation model across the planet. During our SS studies we discovered an additional remarkable result supporting the regulatory role of the repeatome. We found that the noncoding genome, in both subterranean mammals and wild barley at “Evolution Plateau” present a genomic mirror image of the coding genome supporting the regulatory hypothesis of the repeatome. Moreover, the repeatome also succeeded to identify the four subterranean chromosomal climatically adaptive mole rat species in Israel. This genomic mirror imaging and repeatome function is now open to genomic exploration across life.

Molecular evidence for adaptive evolution of drought tolerance in wild cereals.

The considerable drought tolerance of wild cereal crop progenitors has diminished during domestication in the pursuit of higher productivity. Regaining this trait in cereal crops is essential for global food security but requires novel genetic insight. Here, we assessed the molecular evidence for natural variation of drought tolerance in wild barley (Hordeum spontaneum), wild emmer wheat (Triticum dicoccoides), and Brachypodium species collected from dry and moist habitats at Evolution Canyon, Israel (ECI). We report that prevailing moist vs dry conditions have differentially shaped the stomatal and photosynthetic traits of these wild cereals in their respective habitats. We present the genomic and transcriptomic evidence accounting for differences, including co-expression gene modules, correlated with physiological traits, and selective sweeps, driven by the xeric site conditions on the African Slope (AS) at ECI. Co-expression gene module 'circadian rhythm' was linked to significant drought-induced delay in flowering time in Brachypodium stacei genotypes. African Slope-specific differentially expressed genes are important in barley drought tolerance, verified by silencing Disease-Related Nonspecific Lipid Transfer 1 (DRN1), Nonphotochemical Quenching 4 (NPQ4), and Brassinosteroid-Responsive Ring-H1 (BRH1). Our results provide new genetic information for the breeding of resilient wheat and barley in a changing global climate with increasingly frequent drought events.

Sympatric Speciation in Mole Rats and Wild Barley and Their Genome Repeatome Evolution: A Commentary.

The theories of sympatric speciation (SS) and coding and noncoding (cd and ncd =repeatome) genome function are still contentious. Studies on SS in our two new models, "Evolution Canyon" and "Evolution Plateau", in Israel, divergent microclimatically and geologically-edaphically, respectively, indicated that in ecologically divergent microsites SS is a common speciation model across life from bacteria to mammals. Genomically, the intergenic ncd repeatome was and is still regarded by many biologists as "selfish," "junk," and non-functional. In contrast, it is considered by the encyclopedia of DNA elements discovery as biochemically functional and regulatory, and the transposable elements were considered earlier by Barbara McClintock as "controlling elements" of genes. Remarkably, it is found that repeated elements can statistically identify significantly, the five species of subterranean mole rats of Spalax ehrenbergi superspecies adapted to increasingly arid climatic trend southward in Israel. Moreover, it is first discovered in the SS studies in two distant taxa, subterranean mole rats and wild barley, and later also in spiny mice in Israel and subterranean zokors in China, that the noncoding repeatome is genomically mirroring the image of the protein-coding genome in divergent ecologies. It is shown that this mirroring image is statistically significant both within and between the ecologically divergent taxa supporting the hypothesis that much of the repeatome might be regulatory and selected as the protein-coding genome by the same ecological stresses.

Evaluation of extracellular cellulolytic potential of selected natural strains of a novel fungus Sordaria fimicola isolated from evolutionary canyon under submerged fermentation

Industrial biotechnology has a great emerging demand and sustainable expansion for mankind to utilize a variety of biodegradable material for the production of various alternative energy resources such as biogas and bioethanol. Researchers are interested in exploitation of novel fungal strains for the production of extracellular cellulase from the last few decades. This study was designed to assess the extracellular cellulase production potential of novel fungal strains of Sordaria fimicola first isolated from the evolution canyon, three located on South facing slope with xeric (S1, S2, S3) and other three on North facing slope with mesic (N5, N6, N7) environmental conditions. Based on initial and secondary screening two hyper producer strains from each slope were selected. The best activity for S2 was 3.125 U/ml and N6 exhibited 2.829 U/mL under optimized conditions of 14 d of incubation at 30 oC, pH 6.0, 1 mL inoculum and with 2% substrate (carboxy-methyl cellulose) concentration. Among the tested carbon and nitrogen sources, glucose proved to be best for both strains with S2 exhibiting maximum activity. Peptone and beef extract proved to be the best nitrogen sources for S2 and N6 respectively. The cellulase after characterization for temperature and pH showed slightly thermophilic nature. The cellulase was partial purification the highest cellulase activities as surviving in more xeric conditions which contribute more resistive and productive features in those microorganisms living in the harsh environment.

Microclimatic, climatic, and anthropogenic factors strongly affect cultivable soil microfungal communities at a canyon in the Mediterranean region

In this study, we focused on the effects of microclimatic, climatic, and anthropogenic factors on culturable microfungal communities in the soil of the north-facing slope (NFS) and the south-facing slope (SFS) at the Metzar “Evolution Canyon” in the Golan Heights, Israel. Using the soil dilution plate method, 94 species from 47 genera were isolated. The communities’ composition was subjected to pronounced interslope variations in both summer and winter. Whereas xerotolerant melanin-containing species and thermotolerant Aspergillus spp. predominated in the SFS soil, peaking in the summer, mesophilic Penicillium spp. were especially abundant in the NFS soil. The quantitative parameter—density of microfungal isolates—exhibited the strongest seasonal variations, showing that it was the most sensitive to the fluctuation in soil temperature and moisture. Comparison of microfungal communities in the currently recovered and previously disturbed SFS soil showed that intensive pasturage followed by soil degradation led to the simplification of communities, decreased their diversity level, and resulted in the prevalence of species with different ecological preferences. Comparison of the native NFS communities isolated in the summers of 2002 and 2019 revealed changes in the community structure, which could be related to global warming. These changes were associated with stress-tolerant fungal traits, which may be useful under increasing soil temperature and desiccation.

Sympatric speciation of the spiny mouse from Evolution Canyon in Israel substantiated genomically and methylomically

SignificanceWhether sympatric speciation (SS) is rare or common is still debated. Two populations of the spiny mouse, Acomys cahirinus, from Evolution Canyon I (EC I) in Israel have been depicted earlier as speciating sympatrically by molecular markers and transcriptome. Here, we investigated SS both genomically and methylomically, demonstrating that the opposite populations of spiny mice are sister taxa and split from the common ancestor around 20,000 years ago without an allopatric history. Mate choice, olfactory receptors, and speciation genes contributed to prezygotic/postzygotic reproductive isolation. The two populations showed different methylation patterns, facilitating adaptation to their local environment. They cope with abiotic and biotic stresses, due to high solar interslope radiation differences. We conclude that our new genomic and methylomic data substantiated SS.

Silica Particles Trigger the Exopolysaccharide Production of Harsh Environment Isolates of Growth-Promoting Rhizobacteria and Increase Their Ability to Enhance Wheat Biomass in Drought-Stressed Soils.

In coming decades, drought is expected to expand globally owing to increased evaporation and reduced rainfall. Understanding, predicting, and controlling crop plants’ rhizosphere has the potential to manipulate its responses to environmental stress. Our plant growth-promoting rhizobacteria (PGPR) are isolated from a natural laboratory, ‘The Evolution Canyon’, Israel, (EC), from the wild progenitors of cereals, where they have been co-habituating with their hosts for long periods of time. The study revealed that commercial TM50 silica particles (SN) triggered the PGPR production of exopolysaccharides (EPS) containing D-glucuronate (D-GA). The increased EPS content increased the PGPR water-holding capacity (WHC) and osmotic pressure of the biofilm matrix, which led to enhanced plant biomass in drought-stressed growth environments. Light- and cryo-electron- microscopic studies showed that, in the presence of silica (SN) particles, bacterial morphology is changed, indicating that SNs are associated with significant reprogramming in bacteria. The findings encourage the development of large-scale methods for isolate formulation with natural silicas that ensure higher WHC and hyperosmolarity under field conditions. Osmotic pressure involvement of holobiont cohabitation is also discussed.

A latitudinal cline in a courtship song character of Drosophila melanogaster

The courtship song of male Drosophila melanogaster is generated by wing vibration and contains an interpulse interval (IPI) which is species-specific and usually falls in the mean range of 30–40 ms. The IPI is extremely temperature-sensitive, so we wondered whether flies collected along the eastern coast of Australia between latitudes 16.9°S and 42.9°S might have adapted to the different thermal conditions and show differences in mean IPI. We observe a significant correlation between IPI and latitude in addition to the well-known association between latitude and body size (Bergmannn’s Rule). However, somewhat surprisingly we could not detect a significant association between body size and IPI. We also examined flies collected from the North and South-facing slopes of ‘Evolution Canyon’ in Israel and observed differences in IPI that support the view that thermal adaptation can shape this important song character. We also examined the songs of flies from Kenya and observed no correlation between altitude of collection and IPI. In all three experiments, body size did not correlate with IPI. A global analysis of all three sets of populations on three continents revealed a strong association between IPI and latitude. We speculate that IPI is shaped by thermal and sexual selection whereas body size is also shaped by natural selection.

Genetic mapping of a novel powdery mildew resistance gene in wild emmer wheat from "Evolution Canyon" in Mt. Carmel Israel.

A single dominant powdery mildew resistance gene MlNFS10 was identified in wild emmer wheat and mapped within a 0.3cM genetic interval spanning a 2.1Mb physical interval on chromosome arm 4AL. Wheat powdery mildew caused by Blumeria graminis forma specialis tritici (Bgt) is a globally devastating disease. The use of powdery mildew resistance genes from wild relatives of wheat is an effective method of disease management. Our previous research has shown that disruptive ecological selection has driven the discrete adaptations of the wild emmer wheat population on the south facing slope (SFS) and north facing slope (NFS) at the microsite of "Evolution Canyon" at Mount Carmel, Israel and demonstrated that 16 accessions in the NFS population display high resistance to 11 powdery mildew isolates (collected from different wheat fields in China). Here, we constructed bi-parental population by crossing the accession NFS-10 (resistant to 22 Bgt races collected from China in seedling resistance screen) and the susceptible line SFS2-12. Genetic analysis indicated that NFS-10 carries a single dominant gene, temporarily designated MlNFS10. Ultimately, 13 markers were successfully located within the long arm of chromosome 4A, thereby delineating MlNFS10 to a 0.3cM interval covering 2.1Mb (729275816-731365462) in the Chinese Spring reference sequence. We identified disease resistance-associated genes based on the RNA-seq analysis of both parents. The tightly linked InDel marker XWsdau73447 and SSR marker XWsdau72928 were developed and used for marker-assisted selection when MlNFS10 was introgressed into a hexaploid wheat background. Therefore, MlNFS10 can be used for improvement of germplasm in breeding programs for powdery mildew resistant cultivars.

Genome-wide analysis revisits incipient sympatric and allopatric speciation in a beetle

Abstract The grain beetle, Oryzaephilus surinamensis, is a widespread species distributed in the wild and in granaries. Our earlier extensive biological studies indicated that the beetle shows incipient sympatric speciation (SS) in the wild at Evolution Canyon I (EC-I), Israel, and allopatric speciation, in a granary. Here we provide genome-wide evidence supporting our adaptive evolution scenario involving two models of speciation, SS in the wild, and allopatric in the granary. The EC-I microsite is a hot spot of SS across life from bacteria to mammals caused by the sharp opposite microclimates. The tropical hot, dry and savannoid biome dubbed the “African” slope (AS), sharply contrasts with the opposite temperate, cool, humid, and forested biome on the European” slope (ES), separated by only ~250 meters. The third allopatric granary population is 26 km north of EC-I. The granary population showed larger genomic, morphological, and behavioral distances, smaller genome size, more unique transposable elements, and reproductive isolation, displaying faster genomic divergence than between the wild populations at EC-I. The incipient SS of the wild populations, and the speciation of the granary population are reinforced by the substantial genomic divergence among the three beetle populations, supporting again the evolutionary scenario of incipient SS with gene flow at EC-I, and allopatric speciation in the granary population. We propose additional studies in Israel, the Mediterranean basin, and worldwide, to negate alternative explanations, based on a broader sampling and analysis.

Sympatric speciation of wild emmer wheat driven by ecology and chromosomal rearrangements

In plants, the mechanism for ecological sympatric speciation (SS) is little known. Here, after ruling out the possibility of secondary contact, we show that wild emmer wheat, at the microclimatically divergent microsite of "Evolution Canyon" (EC), Mt. Carmel, Israel, underwent triple SS. Initially, it split following a bottleneck of an ancestral population, and further diversified to three isolated populations driven by disruptive ecological selection. Remarkably, two postzygotically isolated populations (SFS1 and SFS2) sympatrically branched within an area less than 30 m at the tropical hot and dry savannoid south-facing slope (SFS). A series of homozygous chromosomal rearrangements in the SFS1 population caused hybrid sterility with the SFS2 population. We demonstrate that these two populations developed divergent adaptive mechanisms against severe abiotic stresses on the tropical SFS. The SFS2 population evolved very early flowering, while the SFS1 population alternatively evolved a direct tolerance to irradiance by improved ROS scavenging activity that potentially accounts for its evolutionary fate with unstable chromosome status. Moreover, a third prezygotically isolated sympatric population adapted on the abutting temperate, humid, cool, and forested north-facing slope (NFS), separated by 250 m from the SFS wild emmer wheat populations. The NFS population evolved multiple resistant loci to fungal diseases, including powdery mildew and stripe rust. Our study illustrates how plants sympatrically adapt and speciate under disruptive ecological selection of abiotic and biotic stresses.

Genomic divergence and adaptive convergence in Drosophila simulans from Evolution Canyon, Israel

Biodiversity refugia formed by unique features of the Mediterranean arid landscape, such as the dramatic ecological contrast of "Evolution Canyon," provide a natural laboratory in which local adaptations to divergent microclimate conditions can be investigated. Significant insights have been provided by studies of Drosophila melanogaster diversifying along the thermal gradient in Evolution Canyon, but a comparative framework to survey adaptive convergence across sister species at the site has been lacking. To fill this void, we present an analysis of genomic polymorphism and evolutionary divergence of Drosophila simulans, a close relative of Drosophila melanogaster with which it co-occurs on both slopes of the canyon. Our results show even deeper interslope divergence in D. simulans than in D. melanogaster, with extensive signatures of selective sweeps present in flies from both slopes but enhanced in the population from the hotter and drier south-facing slope. Interslope divergence was enriched for genes related to electrochemical balance and transmembrane transport, likely in response to increased selection for dehydration resistance on the hotter slope. Both species shared genomic regions that underwent major selective sweeps, but the overall level of adaptive convergence was low, demonstrating no shortage of alternative genomic solutions to cope with the challenges of the microclimate contrast. Mobile elements were a major source of genetic polymorphism and divergence, affecting all parts of the genome, including coding sequences of mating behavior-related genes.

Soil translocation at “Evolution Canyon” I (Mount Carmel, Israel) reveals the importance of microclimatic variation for structuring soil microfungal communities

An experimental study involving the translocation of soil from the south-facing, tropical, savannoid, “African” slope (AS) to the north-facing, temperate, forested “European” slope (ES), 250 m apart, and vice versa, was performed at “Evolution Canyon”, Mount Carmel, Israel. The purpose of the study was to explore whether the new microclimatic conditions would affect community structure of culturable fungi. The translocation of soil from the AS to the ES significantly decreased the abundance of xeric and thermotolerant components of microfungal communities – melanin-containing fungi and Aspergillus spp. Simultaneously, the mesic component – Penicillium spp, increased in the abundance. The translocation also caused substantial increases in abundance of fast-growing mycoparasitic Clonostachys rosea and Trichoderma koningii, which are known to produce toxic secondary metabolites and grow over other fungi in culture. High abundance of these species apparently caused the significant decrease in species richness in the AS-to-ES translocated communities and made these communities more similar to the native ES communities as the cluster analysis revealed. Notably, the translocation from the xeric south-facing AS to the temperate north-facing ES caused more substantial changes in the microfungal communities as compared to the opposite soil translocation. The results of the study clearly indicated that translocation of the soil to the opposite slopes of “Evolution Canyon” had changed the community structure of microfungal communities, and these changes were apparently driven by variation in environmental conditions.