Person:
Llanos Garrido, Alejandro

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First Name
Alejandro
Last Name
Llanos Garrido
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Biológicas
Department
Biodiversidad, Ecología y Evolución
Area
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Now showing 1 - 7 of 7
  • Publication
    Lizard thermoregulation revisited after two decades of global warming
    (Wiley, 2022-09-28) Díaz González-Serrano, José A.; Izquierdo Santiago, Raúl; Llanos Garrido, Alejandro
    1.Although the effects of global warming on thermoregulation are usually explored using predictions of climate envelop modelling, such effects should best be analysed empirically, studying the same population with the same methods after a long enough period of temperature rise. 2. We used a 30-year long database about body temperatures (Tbs) of field-active Psammodromus algirus lizards inhabiting a well-conserved temperate open forest, and we focused on the summers of 1997 and 2017 to compare Tbs, environmental operative temperatures (Tes), their proximity to the selected thermal range (Tsel), and the selection of sunlit and shaded patches all along the day. From these data, we estimated the precision (standard deviation of Tbs), accuracy (average distance between Tbs and Tsel) and effectiveness (extent to which Tbs are closer to Tsel than Tes) of thermoregulation. 3. Of the highest 5% of all Tbs in the database, 95% were recorded in 2017, when the adjustment to Tsel was much better for Tbs selected in a laboratory thermogradient than for field Tbs (percentages of Tbs above Tsel of 2% and 52% respectively). 4. In 2017, especially after 12:00 h, the selection of shaded patches (87% of lizards in full shade vs. <1% in full sun) was more intense than in 1997, contributed more to overall thermoregulation, and produced a larger difference between Tes and Tbs. In spite of this, Tbs were lower—and closer to Tsel—in 1997 (when most shaded patches offered favourable thermal opportunities, with Tes within or below Tsel) than in 2017 (when only 33% of full shade Tes, and 8% of all Tes, were within or below Tsel). As a consequence, estimates of the accuracy and effectiveness of thermoregulation decreased over the 20-year period examined. 5. We conclude that given the low availability of Tes within or below Tsel, lizards cannot longer prevent the rise of their Tbs above Tsel, at least in hot summer days. Thus, the effects of global warming are already hindering the ability of lizards to buffer environmental change by behavioural means, even in temperate forests with a fine-grained mosaic of sun and shade patches.
  • Publication
    Variation in male ornaments in two lizard populations with contrasting parasite loads
    (Wiley, 2017-05-27) Llanos Garrido, Alejandro; Díaz González-Serrano, José A.; Pérez Rodríguez, Antón David; Arriero Higueras, Elena
    In the context of the immunocompetence handicap hypothesis, we explored how differences in parasite load affect the way in which sexual ornaments codify information about individual quality. We studied variation in sexual signals in two Iberian populations of the lizard Psammodromus algirus, a species in which sexually active males display a red head coloration. In one population, males were free of tick nymphs, whereas in the other one all males were tick-infested (mean of 12.7 tick nymphs/individual).At the onset of the breeding season, the red-coloured surface was larger in the non-parasitized population than in the parasitized one, whereas the opposite was true for colour saturation. We experimentally simulated a bacterial infection (by intraperitoneal injection of lipopolysaccharide) to examine the effects of immune activation on the expression of this sexual ornament. In the non-parasitized population, our treatment caused a reduction in the red-coloured surface of experimental males, whereas in the parasitized population it caused a decrease in colour saturation. In the parasitized population, males that displayed sexual coloration were larger, and had fewer parasites, than uncoloured ones, and inflammatory response to lipopolysaccharide injection in the palm of the hind paw was negatively correlated with colour saturation, but not with colour extension. Thus, we suggest parasites not only constrained the expression of sexual ornaments, but they also changed the signal properties that conveyed useful information about the quality of their bearers.
  • Publication
    Variación genética y fenotípica en "Psammodromus algirus" (lagartija colilarga: implicaciones ecológicas y evolutivas
    (Universidad Complutense de Madrid, 2019-08-06) Llanos Garrido, Alejandro; Díaz González-Serrano, José Augusto; Pérez Tris, Javier
    Esta tesis trata de, una vez explorados los rasgos fenotípicos que pueden interpretarse como adaptaciones locales, contestar a preguntas que tienen que ver con cómo responde el genoma a las presiones selectivas divergentes que subyacen a la diferenciación de dichos rasgos. En general, no se pretende descubrir la base genética de la adaptación a los gradientes ambientales que generan adaptación local; lo que se busca es desentrañar cómo la evolución provee la variación genética necesaria para afrontar diferentes retos ecológicos en una especie capaz de subsistir en una gran variedad de ambientes.Mediante escaneos genómicos a gran escala, conseguimos definir fracciones del genoma relacionadas con la adaptación a distintos ambientes, revelando patrones de convergencia y divergencia adaptativa gracias a procesos tanto de mantenimiento de diversidad genética ancestral como de innovación genética...
  • Publication
    Increased individual homozygosity is correlated with low fitness in a fragmented lizard population
    (Oxfrod University Press, 2019-09-05) Pérez Tris, Javier; Llanos Garrido, Alejandro; Bloor, Paul; Carbonell Alanís, Roberto; Tellería Jorge, José Luis; Santos Martínez, Tomás; Díaz González-Serrano, José A.
    Isolation owing to anthropogenic habitat fragmentation is expected to increase the homozygosity of individuals, which might reduce their fitness as a result of inbreeding depression. Using samples from a fragmented population of the lizard Psammodromus algirus, for which we had data about two correlates of fitness, we genotyped individuals for six microsatellite loci that correctly capture genome-wide individual homozygosity of these lizards (as validated with an independent sample of lizards genotyped for both these microsatellites and > 70 000 single nucleotide polymorphisms). Our data revealed genetic structure at a very small geographical scale, which was compatible with restricted gene flow among populations disconnected in a matrix of inhospitable habitat. Lizards from the same fragment were genetically more related to one another than expected by chance, and individual homozygosity was greater in small than in large fragments. Within fragments, individual homozygosity was negatively associated with adult body size and clutch mass, revealing a link among reduced gene flow, increased homozygosity and lowered fitness that might reduce population viability deterministically. Our results contribute to mounting evidence of the impact of the loss of genetic diversity on fragmented wild populations.
  • Publication
    Environmental association modelling with loci under divergent selection predicts the distribution range of a lizard
    (Wiley, 2021-05-21) Llanos Garrido, Alejandro; Briega Álvarez, Andrea; Pérez Tris, Javier; Díaz González-Serrano, José A.
    During the historical building of a species range, individual colonizers have to confront different ecological challenges, and the capacity of the species to broaden its range may depend on the total amount of adaptive genetic variation supplied by evolution. We set out to increase our understanding of what defines a range and the role of underlying genetics by trying to predict an entire species’ range from the geographical distribution of its genetic diversity under selection. We sampled five populations of the western Mediterranean lizard Psammodromus algirus that inhabit a noticeable environmental gradient of temperature and precipitation. We correlated the genotypes of 95 individuals (18–20 individuals per population) for 21 SNPs putatively under selection with environmental scores on a bioclimatic gradient, using 1 × 1 km2 grid cells as sampling units. By extrapolating the resulting model to all possible combinations of alleles, we inferred all the geographic cells that were theoretically suitable for a given amount of genetic variance under selection. The inferred distribution range overlapped to a large extent with the realized range of the species (77.46% of overlap), including an accurate prediction of internal gaps and range borders. Our results suggest an adaptability threshold determined by the amount of genetic variation available that would be required to warrant adaptation beyond a certain limit of environmental variation. These results support the idea that the expansion of a species’ range can be ultimately linked to the arising of new variants under selection (either newly selected variants from standing genetic variation or innovative mutations under selection).
  • Publication
    Comparative metagenomics of Palearctic and Neotropical avian cloacal viromes reveal geographic bias in virus discovery
    (MDPI, 2020-11-26) Truchado, Daniel A.; Llanos Garrido, Alejandro; Oropesa Olmedo, David A.; Cerrada, Belén; Cea, Pablo; Moens, Michaël André Jean; Gómez-Lucía Duato, Esperanza; Doménech, Ana; Milá, Borja; Pérez Tris, Javier; Cadar, Daniel; Benítez Rico, Laura
    Our understanding about viruses carried by wild animals is still scarce. The viral diversity of wildlife may be best described with discovery-driven approaches to the study of viral diversity that broaden research efforts towards non-canonical hosts and remote geographic regions. Birds have been key organisms in the transmission of viruses causing important diseases, and wild birds are threatened by viral spillovers associated with human activities. However, our knowledge of the avian virome may be biased towards poultry and highly pathogenic diseases. We describe and compare the fecal virome of two passerine-dominated bird assemblages sampled in a remote Neotropical rainforest in French Guiana (Nouragues Natural Reserve) and a Mediterranean forest in central Spain (La Herrería). We used metagenomic data to quantify the degree of functional and genetic novelty of viruses recovered by examining if the similarity of the contigs we obtained to reference sequences differed between both locations. In general, contigs from Nouragues were significantly less similar to viruses in databases than contigs from La Herrería using Blastn but not for Blastx, suggesting that pristine regions harbor a yet unknown viral diversity with genetically more singular viruses than more studied areas. Additionally, we describe putative novel viruses of the families Picornaviridae, Reoviridae and Hepeviridae. These results highlight the importance of wild animals and remote regions as sources of novel viruses that substantially broaden the current knowledge of the global diversity of viruses.
  • Publication
    Low genome‐wide divergence between two lizard populations with high adaptive phenotypic differentiation
    (Willey, 2021-12) Llanos Garrido, Alejandro; Pérez Tris, Javier; Díaz González-Serrano, José A.
    Usually, adaptive phenotypic differentiation is paralleled by genetic divergence between locally adapted populations. However, adaptation can also happen in a scenario of nonsignificant genetic divergence due to intense gene flow and/or recent differentiation. While this phenomenon is rarely published, findings on incipient ecologically driven divergence or isolation by adaptation are relatively common, which could confound our understanding about the frequency at which they actually occur in nature. Here, we explore genome-wide traces of divergence between two populations of the lacertid lizard Psammodromus algirus separated by a 600 m elevational gradient. These populations seem to be differentially adapted to their environments despite showing low levels of genetic differentiation (according to previously studies of mtDNA and microsatellite data). We performed a search for outliers (i.e., loci subject to selection) trying to identify specific loci with FST statistics significantly higher than those expected on the basis of overall, genome-wide estimates of genetic divergence. We find that local phenotypic adaptation (in terms of a wide diversity of characters) was not accompanied by genome-wide differentiation, even when we maximized the chances of unveiling such differentiation at particular loci with FSTbased outlier detection tests. Instead, our analyses confirmed the lack of genomewide differentiation on the basis of more than 70,000 SNPs, which is concordant with a scenario of local adaptation without isolation by environment. Our results add evidence to previous studies in which local adaptation does not lead to any kind of isolation (or early stages of ecological speciation), but maintains phenotypic divergence despite the lack of a differentiated genomic background.