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Povzetek: 1. Host abundance might favour the maintenance of a high phylogenetic diversity of some parasites via rapid transmission rates. Blood parasites of insular lizards represent a good model to test this hypothesis because these parasites can be particularly prevalent in islands and host lizards highly abundant. 2. We applied deep amplicon sequencing and analysed environmental predictors of blood parasite prevalence and phylogenetic diversity in the endemic lizard Gallotia galloti across 24 localities on Tenerife, an island in the Canary archipelago that has experienced increasing warming and drought in recent years. 3. Parasite prevalence assessed by microscopy was over 94% and a higher proportion of infected lizards was found in warmer and drier locations. A total of 33 different 18s rRNA parasite haplotype were identified and the phylogenetic analyses indicated that they belong to two genera of Adeleorina (Apicomplexa: Coccidia), with Karyolysus as the dominant genus. The most important predictor of between-locality variation in parasite phylogenetic diversity was the abundance of lizard hosts. 4. A combination of climatic and host demographic factors associated with an insular syndrome may be favouring a rapid transmission of blood parasites among lizards on Tenerife, which may favour the maintenance of a high phylogenetic diversity of parasites.
Ključne besede: lizards, parasites, genetics, biogeography, habitat, data
Objavljeno v DiRROS: 27.10.2025; Ogledov: 588; Prenosov: 446
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Povzetek: The skin serves as the outermost barrier between an organism and its environment and fulfills numerous physiological and ecological functions. In lizards, scale morphology is an important adaptive trait that mediates responses to environmental influences such as extreme temperatures, ultraviolet radiation, drought and anthropogenic disturbances. Our study provides an analysis of the environmental drivers influencing intraspecific variation in the scale ecomorphology of the island lizard Gallotia galloti across 3700 m of elevation, taking into account different macro- and microclimatic conditions and varying degrees of anthropogenic influences and across three body regions: dorsal, ventral and tail. We found several correlations suggesting multiple dependencies of scale morphology on environmental variation. The positive correlation between July temperature and wind speed at 3 cm above the ground and dorsal scale density showed that more densely packed scales are associated with hotter and drier environments. This could possibly be related to the thermoregulatory and hydroregulatory function of the skin, since the dorsal side of the body is most exposed. Higher sun exposure was associated with larger dorsal and tail scales, indicating a possible photoprotective function. Ventral scales are not exposed to the pressure of solar radiation and wind. Accordingly, ventral scales showed no correlation with these factors, but we found that a higher ratio of day-to-night temperature variation relative to seasonal changes (isothermality) was associated with a higher density of ventral scales. The human footprint index positively correlated with larger and denser ventral (and not dorsal or tail) scales. Overall, our results illustrate the complexity of responses of scale morphology to different environmental variations. Evidently, G. galloti exhibits morphological diversity in response to climatic conditions and urbanization, highlighting the potential ecological significance of scale size variation. Future research should investigate the genetic basis and possible effects of climate change on scale morphology.
Ključne besede: scale morphology, climatic conditions, human footprint, adaptation, skin, elevational gradient, zoology
Objavljeno v DiRROS: 17.10.2025; Ogledov: 534; Prenosov: 466
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Povzetek: High altitude imposes several extreme constraints on life, such as low oxygen pressure and high levels of ultraviolet radiation, which require specialized adaptations. Many studies have focused on how endothermic vertebrates respond to these challenging environments, but there is still uncertainty on how ectotherms adapt to these conditions. Here, we used whole-genome sequencing of low-altitude (100–600 m) and high-altitude (3,550 m) populations of the wide-ranging Tenerife lizard Gallotia galloti to uncover signatures of selection for altitudinal adaptation. The studied populations show reduced differentiation, sharing similar patterns of genetic variation. Selective sweep mapping suggests that signatures of adaptation to high altitude are not widespread across the genome, clustering in a relatively small number of genomic regions. One of these regions contains BMPER, a gene involved with vascular remodeling, and that has been associated with hypoxia-induced angiogenic response. By genotyping samples across 2 altitudinal transects, we show that allele frequency changes at this locus are not gradual, but rather show a well-defined shift above ca. 1,900 m. Transcript and protein structure analyses on this gene suggest that putative selection likely acts on noncoding variation. These results underline how low oxygen pressure generates the most consistent selective constraint in high-altitude environments, to which vertebrates with vastly contrasting physiological profiles need to adapt in the context of ongoing climate change.
Ključne besede: high altitude, adaptations, ectotherms, whole-genome sequencing, selective sweep, BMPER gene, hypoxia, genomics
Objavljeno v DiRROS: 08.10.2024; Ogledov: 1792; Prenosov: 1133
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Povzetek: Aim: Physiological and metabolic performance are key mediators of the functional response of species to environmental change. Few environments offer such a multifaceted array of stressors as high-altitude habitats, which differ markedly in temperature, water availability, UV radiation and oxygen pressure compared to low-altitude habitats. Species that inhabit large altitudinal gradients are thus excellent models to study how organisms respond to environmental variation. Location: Tenerife island, Canary Islands archipelago (Spain). Taxon: Tenerife lizard (Gallotia galloti, Lacertidae). Methods: We integrated data on age structure, thermal and hydric regulatory behaviour and four metabolic and stress-related biomarkers for an insular lizard that inhabits an extreme altitudinal range (sea level to 3700 m a.s.l.), to understand how an ectotherms' age, ecophysiology and metabolism can be affected by extreme environmental variation. Results: We found marked differences in metabolic stress markers associated with altitude (particularly in the abundance of carbonyl metabolites and relative telomere length), but without a linear pattern along the altitudinal cline. Contrary to expectations, longer telomeres and lower carbonyl content were detected at the highest altitude, suggesting reduced stress in these populations. Evaporative water loss differed between populations but did not follow a linear altitudinal gradient. Lizard age structure or thermal physiological performance did not markedly change across different altitudes. Mixed signals in life-history and thermal ecology across populations and altitude suggest complex responses to variable conditions across altitude in this species. Main Conclusions: Our integrative study of multiple functional traits demonstrated that adaptation to highly divergent environmental conditions in this lizard is potentially linked to an interplay between plasticity and local adaptation variably associated with different functional traits.
Ključne besede: ecophysiology, evaporative water loss, metabolic activity, oxidative stress, preferred temperatures, relative telomere length, skeletochronology, lizard
Objavljeno v DiRROS: 12.07.2024; Ogledov: 1586; Prenosov: 1793
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Povzetek: Host abundance might favour the maintenance of a high phylogenetic diversity of some parasites via rapid transmission rates. Blood parasites of insular lizards represent a good model to test this hypothesis because these parasites can be particularly prevalent in islands and host lizards highly abundant. We applied deep amplicon sequencing and analysed environmental predictors of blood parasite prevalence and phylogenetic diversity in the endemic lizard Gallotia galloti across 24 localities on Tenerife, an island in the Canary archipelago that has experienced increasing warming and drought in recent years. Parasite prevalence assessed by microscopy was over 94%, and a higher proportion of infected lizards was found in warmer and drier locations. A total of 33 different 18s rRNA parasite haplotypes were identified, and the phylogenetic analyses indicated that they belong to two genera of Adeleorina (Apicomplexa: Coccidia), with Karyolysus as the dominant genus. The most important predictor of between-locality variation in parasite phylogenetic diversity was the abundance of lizard hosts. We conclude that a combination of climatic and host demographic factors associated with an insular syndrome may be favouring a rapid transmission of blood parasites among lizards on Tenerife, which may favour the maintenance of a high phylogenetic diversity of parasites.
Ključne besede: Canary Islands, climate change, next-generation sequencing, phylogenetic analyses, zoology, ecology
Objavljeno v DiRROS: 16.05.2024; Ogledov: 1467; Prenosov: 1132
Celotno besedilo (1,76 MB)
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