Introgression of mitochondrial DNA among Myodes voles: consequences for energetics?

Background Introgression of mitochondrial DNA (mtDNA) is among the most frequently described cases of reticulate evolution. The tendency of mtDNA to cross interspecific barriers is somewhat counter-intuitive considering the key function of enzymes that it encodes in the oxidative-phosphorylation process, which could give rise to hybrid dysfunction. How mtDNA reticulation affects the evolution of metabolic functions is, however, uncertain. Here we investigated how morpho-physiological traits vary in natural populations of a common rodent (the bank vole, Myodes glareolus) and whether this variation could be associated with mtDNA introgression. First, we confirmed that M. glareolus harbour mtDNA introgressed from M. rutilus by analyzing mtDNA (cytochrome b, 954 bp) and nuclear DNA (four markers; 2333 bp in total) sequence variation and reconstructing loci phylogenies among six natural populations in Finland. We then studied geographic variation in body size and basal metabolic rate (BMR) among the populations of M. glareolus and tested its relationship with mtDNA type. Results Myodes glareolus and its arctic neighbour, M. rutilus, are reciprocally monophyletic at the analyzed nuclear DNA loci. In contrast, the two northernmost populations of M. glareolus have a fixed mitotype that is shared with M. rutilus, likely due to introgressive hybridization. The analyses of phenotypic traits revealed that the body mass and whole-body, but not mass corrected, BMR are significantly reduced in M. glareolus females from northern Finland that also have the introgressed mitotype. Restricting the analysis to the single population where the mitotypes coexist, the association of mtDNA type with whole-body BMR remained but those with mass corrected BMR and body mass did not. Mitochondrial sequence variation in the introgressed haplotypes is compatible with demographic growth of the populations, but may also be a result of positive selection. Conclusion Our results show that the phenotypic traits vary markedly along the north-south axis of populations of M. glareolus. This variation may be related to adaptation to local environments and coincides with the gradient of genome reticulation between M. glareolus and M. rutilus, which was assessed by mtDNA introgression. Introgression of mtDNA may have affected morpho-physiological traits but do not show strong effects on either body mass or basal metabolic rate alone. We discuss the causes and biological meaning of our results and the means to clarify these questions in future research.peerReviewe

Conservation Biogeography of the Sahara‐Sahel: additional protected areas are needed to secure unique biodiversity

Aim Identification of priority conservation areas and evaluation of coverage of the current protected areas are urgently needed to halt the biodiversity loss. Identifying regions combining similar environmental traits (climate regions) and species assemblages (biogroups) is needed for conserving the biodiversity patterns and processes. We identify climate regions and biogroups and map species diversity across the Sahara-Sahel, a large geographical area that exhibits wide environmental heterogeneity and multiple species groups with distinct biogeographical affinities, and evaluate the coverage level of current network of protected areas for biodiversity conservation. Location Sahara-Sahel, Africa. Methods We use spatially explicit climate data with the principal component analysis and model-based clustering techniques to identify climate regions. We use distributions of 1147 terrestrial vertebrates (and of 125 Sahara-Sahel endemics) and apply distance clustering methods to identify biogroups for both species groups. We apply reserve selection algorithms targeting 17% of species distribution, climate regions and biogroups to identify priority areas and gap analysis to assess their representation within the current protected areas. Results Seven climate regions were identified, mostly arranged as latitudinal belts. Concentrations of high species richness were found in the Sahel, but the central Sahara gathers most endemic and threatened species. Ten biogroups (five for endemics) were identified. A wide range of biogroups tend to overlap in specific climate regions. Identified priority areas are inadequately represented in protected areas, and six new top conservation areas are needed to achieve conservation targets. Main conclusions Biodiversity distribution in Sahara-Sahel is spatially structured and apparently related to environmental variation. Although the majority of priority conservation areas are located outside the areas of intense human activities, many cross multiple political borders and require internationally coordinated efforts for implementation and management. Optimized biodiversity conservation solutions at regional scale are needed. Our work contradicts the general idea that deserts are uniform areas and provide options for the conservation of endangered species.info:eu-repo/semantics/publishedVersio

Maintenance costs of male dominance and sexually antagonistic selection in the wild

International audience1. Variation in dominance status determines male mating and reproductive success, butnatural selection for male dominance can be detrimental or antagonistic for female per-formance, and ultimately their fitness. Attaining and maintaining a high dominance statusin a population of competing individuals is physiologically costly for males. But how maledominance status is mediated by maintenance energetics is currently not well under-stood, nor are the corresponding effects of male energetics on his sisters recognized.2. We conducted laboratory and field experiments on rodent populations to testwhether selective breeding for male dominance status (dominant vs. subordinatebreeding lines) antagonistically affected basal metabolic rate (BMR) and fitness offemales under wild conditions.3. Our results showed elevated BMR in females, but not in males, from the dominantbreeding line. However, phenotypically dominant males from the subordinatebreeding line had the highest BMR.4. Males from the dominant line with low BMR sired the most litters and offspring inthe field. Similarly, females from the dominant selection line tended to have moreoffspring if they had lower BMR, while the opposite trend was found in femalesfrom the subordinate selection line. Females with high and low BMR reproducedmost often, as indicated by a significant quadratic selection gradient.5. The increased female BMR resulting from selection for male dominance suggestsgenetic incompatibility between sexes in metabolism inheritance. Elevated BMRin behaviourally dominant males, but not in males from the dominant breedingline, suggests physiological costs in males not genetically suited for dominance.6. Fitness costs of elevated maintenance costs (measured as BMR) shown here sup-port the energetic compensation hypothesis where high BMR is selected againstas it would trade off energy required for other important life-history attributes

The effect of spatial and temporal scale on camouflage in North African rodents

Background matching, a common form of camouflage, is a widespread anti-predator adaptation that hinders detection or recognition by increasing the resemblance of prey to its environment. However, the natural environment is complex and both spatially and temporally variable, which constrains effective background matching as an anti-predator strategy. Here, using remote sensing data (publicly available satellite imagery), we investigated how variation of habitat parameters predicts background matching in 16 Sahara–Sahel rodent species across spatial and temporal scales. All fur colour parameters (hue, saturation and brightness) strongly matched the respective habitats of the different species. Background matching in terms of hue was best at the microscale, whereas results for saturation and brightness showed more variation across spatial scales among species. Camouflage across the temporal scale (from 1 to 3 years before capture) was variable among species for all colour parameters. These complex interactions suggest that, in desert rodents, colour parameters are differentially sensitive to the respective scale of the habitat, plausibly reflecting the behaviour and life history of the species and the ecological properties determining their activity patterns. Consequently, the division between habitat (camouflage) generalists and specialists might become blurred in temporally changing and spatially variable environments.peerReviewe

Diversity of Rickettsia spp. in ticks from wild mammals of Morocco and Mauritania

Summary: Ticks are known as vectors and reservoirs of rickettsiae and, wildlife vertebrate hosts as suitable dispersers of ticks contributing to the life cycle of rickettsial agents in nature. In the herein study, the presence of rickettsiae was investigated in ticks from wild mammals (Gerbillus and Jaculus, Vulpes rueppellii, Canis anthus, Felis lybica and Felis margarita) in Mauritania and Morocco. Morphological and molecular analysis of ticks allowed their identification as Rhipicephalus sanguineus sensu lato and Hyalomma impeltatum. A total of 126 partially engorged adult ticks, collected from 40 animals, were screened for the presence of rickettsial DNA by conventional PCR targeting the ompB gene, followed by ompA and gltA targets and bidirectional sequencing. As a result of the sequence analyses, that at least three different species of pathogenic spotted fever group rickettsiae were detected. Rickettsia parkeri-like was detected in a R. sanguineus s.l. (n=1) collected from an African wildcat from Morocco. Rickettsia aeschlimannii was detected in a H. impeltatum (n=1) collected from a gerbil rodent. Rickettsia massiliae was detected in R. sanguineus s.l. ticks (n=5) collected from two Ruppells’ foxes. The herein study demonstrates that pathogenic Rickettsia species are circulating in Morocco and Mauritania wildlife

Maintenance costs of male dominance and sexually antagonistic selection in the wild

Variation in dominance status determines male mating and reproductive success, but natural selection for male dominance can be detrimental or antagonistic for female performance, and ultimately their fitness. Attaining and maintaining a high dominance status in a population of competing individuals is physiologically costly for males. But how male dominance status is mediated by maintenance energetics is currently not well understood, nor are the corresponding effects of male energetics on his sisters recognized. We conducted laboratory and field experiments on rodent populations to test whether selective breeding for male dominance status (dominant vs. subordinate breeding lines) antagonistically affected basal metabolic rate (BMR) and fitness of females under wild conditions. Our results showed elevated BMR in females, but not in males, from the dominant breeding line. However, phenotypically dominant males from the subordinate breeding line had the highest BMR. Males from the dominant line with low BMR sired the most litters and offspring in the field. Similarly, females from the dominant selection line tended to have more offspring if they had lower BMR, while the opposite trend was found in females from the subordinate selection line. Females with high and low BMR reproduced most often, as indicated by a significant quadratic selection gradient. The increased female BMR resulting from selection for male dominance suggests genetic incompatibility between sexes in metabolism inheritance. Elevated BMR in behaviourally dominant males, but not in males from the dominant breeding line, suggests physiological costs in males not genetically suited for dominance. Fitness costs of elevated maintenance costs (measured as BMR) shown here support the energetic compensation hypothesis where high BMR is selected against as it would trade off energy required for other important life‐history attributes.peerReviewe

Phylogeography of two cryptic species of African desert jerboas (Dipodidae: Jaculus) (vol 107, pg 27, 2012) - Erratum

International audienceThe Corresponding Author (*) apologises for the fact that three of the authors, L. Granjon, C. Tatard and J. F. Cosson, had been unaware of the authorship and content of the paper. The correct authorship, which now includes J. M. Duplantier, G. Dobigny and K. Hima, who all contributed significantly to the work, is given here, together with the GenBank accession numbers for the sequences used

Phylogeography of two cryptic species of African desert jerboas (Dipodidae: Jaculus)

International audienceThe lesser Egyptian jerboa Jaculus jaculus is a desert dwelling rodent that inhabits a broad Arabian–Saharan arid zone. Recently, two distant sympatric lineages were described in North-West Africa, based on morphometric and molecular data, which may correspond to two cryptic species. In the current study, phylogenetic relationships and phylogeographical structure among those lineages and geographical populations from North Africa and the Middle East were investigated. The phylogeographical patterns and genetic diversity of the cytochrome b gene (1110 bp) were addressed on 111 jerboas from 41 localities. We found that the variation in Africa is partitioned into two divergent mitochondrial clades (10.5% divergence relating to 1.65–4.92 Mya) that corresponds to the two cryptic species: J. jaculus and J. deserti. Diversifications within those cryptic species/clades were dated to 0.23–1.13 Mya, suggesting that the Middle Pleistocene climatic change and its environmental consequences affected the evolutionary history of African jerboas. The third distant clade detected, found in the Middle East region, most likely represents a distinct evolutionary unit, independent of the two African lineage