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The pace-of-life syndrome describes covariation between life-history, behavioral and physiological traits; while, the emerging behavioral–bioenergetics theory proposes mechanistic links between those traits in a spatial–ecological context. However, little is known about the association between the limits to metabolic rate and spatial performance (i.e., mobility, home range size) in free-living individuals. Here we show, for the first time at the intra-specific level, that mobility traits increased with the aerobic exercise capacity (VO₂max) in a wild rodent, the bank vole (Myodes glareolus): VO₂max affected directly the movement intensity, which in turn affected home ranges. The results show that evolution of high VO₂max could be driven by selection for spatial performance traits, and corroborate one of the key assumptions of the behavioral–bioenergetics theory. However, the minimum maintenance metabolism, measured as the basal metabolic rate (BMR), was not correlated with movement intensity, and the direction of the BMR–home range correlation tended to change with age of the voles. The latter result indicates that testing the theory will be particularly challenging.

Telomeres, the protective structures at the ends of chromosomes, can be shortened when individuals are exposed to stress. In some species, the enzyme telomerase is expressed in adult somatic tissues, and potentially protects or lengthens telomeres. Telomeres can be damaged by ionizing radiation and oxidative stress, although the effect of chronic exposure to elevated levels of radiation on telomere maintenance is unknown for natural populations. We quantified telomerase expression and telomere length (TL) in different tissues of the bank vole Myodes glareolus , collected from the Chernobyl Exclusion Zone, an environment heterogeneously contaminated with radionuclides, and from uncontaminated control sites elsewhere in Ukraine. Inhabiting the Chernobyl Exclusion Zone was associated with reduced TL in the liver and testis, and upregulation of telomerase in brain and liver. Thus upregulation of telomerase does not appear to associate with longer telomeres but may reflect protective functions other than telomere maintenance or an attempt to maintain shorter telomeres in a stressful environment. Tissue specific differences in the rate of telomere attrition and apparent radiosensitivity weaken the intra-individual correlation in telomere length among tissues in voles exposed to radionuclides. Our data show that ionizing radiation alters telomere homeostasis in wild animal populations in tissue specific ways.

A cataract is a clouding of the lens that reduces light transmission to the retina and it decreases the visual acuity of the bearer. The prevalence of cataracts in natural populations of mammals and their potential ecological significance, is poorly known. Cataracts have been reported to arise from high levels of oxidative stress and a major cause of oxidative stress is ionizing radiation. We investigated whether elevated frequencies of cataracts are found in eyes of bank voles Myodes glareolus collected from natural populations in areas with varying levels of background radiation in Chernobyl. We found high frequencies of cataracts in voles collected from different areas in Chernobyl. The frequency of cataracts was positively correlated with age and in females also with the accumulated radiation dose. Furthermore, the number of offspring in female voles was negatively correlated with cataract severity. The results suggest that cataracts primarily develop as a function of ionizing background radiation, most likely as a plastic response to high levels of oxidative stress. It is therefore possible that the elevated levels of background radiation in Chernobyl affect the ecology and fitness of local mammals both directly through, for instance, reduced fertility and indirectly, through increased cataractogenesis.

The Afar Triangle in easternmost Africa is one of biogeographically important regions, whose recent biota is virtually unknown. Here we evaluated the level of evolutionary uniqueness of biodiversity of this region in a wide regional and continental biogeographical context, using rodents as a model group. By combining our recent collections with historical records, and based on genetic data and phylogenetic approaches, we specifically tested whether and to what extent the geographical isolation of the Afar Depression is reflected in allopatric diversification of arid-adapted mammals. We documented the presence of 16 rodent species (four are reported for the first time in Ethiopia and one rediscovered there after more than 100 years) and eight additional species are likely present based on literature data. Comparative phylogeographic analysis suggests that the Afar Triangle can be considered as a part of a larger Somalian biogeographical region, but its fauna is genetically distinct, including the presence of narrow Afar endemics. To a lesser extent, there are taxa with evolutionary affinities to the eastern Sahara–Sahelian region and to the southern Arabian Peninsula. Compared to the Ethiopian Highlands, the rodent fauna of Afar is relatively poor. However, similarly to highlands, the evolutionary distinctiveness of mammals in the Afar Triangle is very high and it can be considered a unique centre of endemism. Our first comprehensive summary of Afar rodents significantly fills the gap in the knowledge of the mammalian fauna of arid regions in Ethiopia and the Horn of Africa in general and highlights the significance of the region for nature conservation.

Environmental pressures shape animal colouration, facilitating adaptation to local conditions. However, the extent to which climatic gradients drive colour variation in a species across its distributional range remains unclear. Here, we tested whether the dorsal colouration of Lusitanian wall lizards (Podarcis lusitanicus) varies spatially in response to environmental gradients across its distribution in the north‐western Iberian Peninsula. We estimated dorsal colour brightness (i.e., lightness) from multispectral photographs of 463 animals, originating from 21 locations distributed across the species range. We studied direct and indirect (mediated by body mass) relationships between environmental variables and the lightness of lizards, by piecewise structural equation modelling. We simultaneously tested predictions from Gloger's (darker colouration in warm and humid environments), thermal melanism (darker colouration in colder environments), photoprotection (darker colouration in areas with higher intensity of solar radiation) and Bergmann's (larger body size in colder environments) hypotheses. We found that the lightness of lizards best follows predictions of Gloger's hypothesis for humidity, but not supporting the photoprotection hypothesis, independent of the populations' shared ancestry and geographic location. We found no support for direct thermal melanism, as temperature was not directly associated with lightness. Instead, the indirect effect of temperature on lightness through body size was detected. Consistent with Bergmann's hypothesis, lizards in colder regions tended to be larger and darker. Our study indicates that the evolution of lizard dorsal colouration is driven by variable climatic factors. Experimental tests are necessary to assess the mechanisms driving climatic effects on colouration across diverse environments, advancing beyond the simplistic correlations suggested by ecogeographic hypotheses. In our study, we examined how environmental gradients influence dorsal colour variation in Lusitanian wall lizards across their range in the Iberian Peninsula. We found that lizard dorsal lightness is primarily associated with humidity, supporting Gloger's hypothesis, while body size influences dorsal lightness indirectly through Bergmann's hypothesis, with lizards being larger and darker in colder regions. Further experimental research is needed to clarify the mechanisms behind these climatic effects on colouration.

Detailed knowledge about biodiversity distribution is critical for monitoring the biological effects of global change processes. Biodiversity knowledge gaps hamper the monitoring of conservation trends and they are especially evident in the desert biome. Mauritania constitutes a remarkable example on how remoteness and regional insecurity affect current knowledge gaps. Mammals remain one of the least studied groups in this country, without a concerted species checklist, the mapping of regions concentrating mammal diversity, or a national assessment of their conservation status. This work assessed the diversity, distribution, and conservation of land mammals in Mauritania. A total of 6,718 published and original observations were assembled in a spatial database and used to update the occurrence status, distribution area, and conservation status. The updated taxonomic list comprises 107 species, including 93 extant, 12 Regionally Extinct, and 2 Extinct in the Wild. Mapping of species distributions allowed locating concentrations of extant mammal species richness in coastal areas, along the Senegal River valley, and in mountain plateaus. Recent regional extinction of large-sized Artiodactyla and Carnivora has been very high (11% extinct species). From the extant mammals, 11% are threatened, including flagship species (e.g., Addax nasomaculatus and Panthera pardus ). Species richness is poorly represented by the current protected areas. Despite the strong advances made, 23% of species categorise as Data Deficient. Persisting systematics and distribution uncertainties require further research. Field surveys in currently unexplored areas (northern and south-eastern regions) are urgently needed to increase knowledge about threatened mammals. The long-term conservation of land mammals in Mauritania is embedded in a complex web of socioeconomic and environmental factors that call for collaborative action and investment in sustainable human development. The current work sets the baseline for the future development of detailed research studies and to address the general challenges faced by mammals and biodiversity in the country.

There are two main factors explaining variation among species and the evolution of characters along phylogeny: adaptive change, including phenotypic and genetic responses to selective pressures, and phylogenetic inertia, or the resemblance between species due to shared phylogenetic history. Phenotype-habitat colour match, a classic Darwinian example of the evolution of camouflage (crypsis), offers the opportunity to test the importance of historical versus ecological mechanisms in shaping phenotypes among phylogenetically closely related taxa. To assess it, we investigated fur (phenotypic data) and habitat (remote sensing data) colourations, along with phylogenetic information, in the species-rich Gerbillus genus. Overall, we found a strong phenotype-habitat match, once the phylogenetic signal is taken into account. We found that camouflage has been acquired and lost repeatedly in the course of the evolutionary history of Gerbillus . Our results suggest that fur colouration and its covariation with habitat is a relatively labile character in mammals, potentially responding quickly to selection. Relatively unconstrained and substantial genetic basis, as well as structural and functional independence from other fitness traits of mammalian colouration might be responsible for that observation.

Background Climatic variation and geologic change both play significant roles in shaping species distributions, thus affecting their evolutionary history. In Sahara-Sahel, climatic oscillations shifted the desert extent during the Pliocene-Pleistocene interval, triggering the diversification of several species. Here, we investigated how these biogeographical and ecological events have shaped patterns of genetic diversity and divergence in African Jerboas, desert specialist rodents. We focused on two sister and cryptic species, Jaculus jaculus and J. hirtipes, where we (1) evaluated their genetic differentiation, (2) reconstructed their evolutionary and demographic history; (3) tested the level of gene flow between them, and (4) assessed their ecological niche divergence. Results The analyses based on 231 individuals sampled throughout North Africa, 8 sequence fragments (one mitochondrial and seven single copy nuclear DNA, including two candidate genes for fur coloration: MC1R and Agouti), 6 microsatellite markers and ecological modelling revealed: (1) two distinct genetic lineages with overlapping distributions, in agreement with their classification as different species, J. jaculus and J. hirtipes, with (2) low levels of gene flow and strong species divergence, (3) high haplotypic diversity without evident geographic structure within species, and (4) a low level of large-scale ecological divergence between the two taxa, suggesting species micro-habitat specialization. Conclusions Overall, our results suggest a speciation event that occurred during the Pliocene-Pleistocene transition. The contemporary distribution of genetic variation suggests ongoing population expansions. Despite the largely overlapping distributions at a macrogeographic scale, our genetic results suggest that the two species remain reproductively isolated, as only negligible levels of gene flow were observed. The overlapping ecological preferences at a macro-geographic scale and the ecological divergence at the micro-habitat scale suggest that local adaptation may have played a crucial role in the speciation process of these species.

We tested the camouflage hypothesis, or the linkage between animal (Saharan rodent) and habitat coloration, on the largest geographical scale yet conducted. We aimed to determine whether phenotypic variation is explained by micro-habitat variation and/or genetic polymorphism to determine 1) the strength of linkage between fur color and local substrate color, and 2) the divergence in fur coloration between two genetic clades, representing cryptic species, throughout the complete range of the African desert jerboas (Jaculus jaculus). We used a combination of museum and field-collected specimens, remote sensing tools, satellite and digital photography and molecular genetic and phylogenetic methods to investigate the above hypotheses. Along with showing that the two divergent genetic clades of jerboas occur sympatrically throughout their African distribution, we showed significant covariation between dorsal fur coloration of the animals and the color of their habitat. We also described significant phenotypic divergence in fur color, consistent with genetic divergence between the sympatric clades. The linkage between environment and phenotype supports the idea that the selection promoting cryptic coloration is persistent in contemporary populations of jerboas, however the phenotypic divergence indicates that it has different strengths (or optima) in the two clades. The mosaic distribution of micro-habitats occupied by geographically sympatric clades suggests that it may influence both ecological and evolutionary dynamics between these two cryptic species.

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.