Biology subjects

Alia, R.

Publications and source records attributed to Alia, R..

3 recordsLinked to original sources

bioRxiv2019

Adaptive Introgression Promotes Fast Adaptation In Oaks Marginal Populations

Range shifts and species range limits are two fundamental, related processes in population and evolutionary genetics that have received much attention since a large impact of climate change in species distributions was predicted. In general, there is a broad consensus on the effects of abiotic interactions on range limits, but comprehensive evidence supporting/rejecting the impact of biotic interactions is lacking. Hybridization has long been recognized as a biotic interaction favoring marginal populations establishment and range expansion through transgressive segregation or adaptive introgression, but recently new roles have been claimed for hybridization, such as the trigger of adaptive radiations, or indirect effects on population sizes that would allow persistence until new mutations arises or the environment changes. In this work, we selected two Mediterranean oak species with ecological discrimination based on soil pH, and intensively sampled three interspecific pairs of marginal populations from taxon-extreme environments under heterogeneous climate conditions. We genotyped 110 EST-SSR markers evenly distributed across their genomes and applied a variety of population and landscape genetics models to validate candidate genes for local adaptation. Then, several introgression screens on shared candidates showed that the three inter-specific population pairs contain evidences of adaptive introgression and that events occur in both directions. Other significant findings from our work are: (i) Aproximate Bayesian Computation coupled to coalescent simulations supports small hybridization rates since recent secondary contact in two population pairs affected by Quaternary climatic oscillations but continuous old interspecific gene flow in the pair less affected by climate, (ii) introgression at loci involved in local adaptations leads to strong geographic structure of marginal oak populations when sampling is large enough, and (iii) sampling efforts can be targeted to reveal different components of populations structure. Finally, we review evidences that support our conclusions and discuss some evolutionary implications of adaptive introgression on range expansion.

evolutionary biology↗

bioRxiv2019

Patterns of phenotypic plasticity among populations of three Mediterranean pine species and implications for evolutionary responses to climate change

AimUnder rapid environmental change, phenotypic plasticity, if adaptive, could increase the odds for organisms to persist. Environmental variation over time is an important source of phenotypic plasticity. Likewise, phenotypic plasticity can vary with age in many organisms. However, little is known on phenotypic plasticity variation across species ranges. Our aims are: (i) to assess whether populations phenotypic plasticity is related to the inter-annual climate variation under which populations have evolved during the last century; (ii) to compare phenotypic plasticity among developmental classes; and (iii) to predict phenotypic plasticity across species ranges.\n\nLocationEurope and North-Africa.\n\nTime period1901-2014.\n\nMajor taxa studiedPinus nigra, P. pinaster and P. pinea.\n\nMethodsWe used 372 646 individual tree height measurements at three developmental classes from a wide network of 38 common gardens in Europe and North Africa with provenances covering the distribution range of the species. With this data, we: i) build linear mixed-effect models of tree height as a function of tree age, population and climate; ii) estimate populations reaction norms from the fitted models; iii) calculate populations phenotypic plasticity indexes; iv) build models of populations phenotypic plasticity indexes as a function of inter-annual climate variation during the last century.\n\nResultsWe found that i) most populations that have evolved under high inter-annual climate variation, in either maximum or minimum values in temperature or precipitation, exhibited high values of plasticity in tree height; ii) phenotypic plasticity for tree height was higher in young trees than in older ones, iii) phenotypic plasticity did not follow any particular geographical pattern across species ranges.\n\nMain conclusionsPhenotypic plasticity across the three Mediterranean pines ranges is related with the climate variation experienced over time and calls into question whether this plasticity could be adaptive and hence beneficial to cope with climate change in the short-term.

ecology↗

bioRxiv2019

Genetic basis of susceptibility to Diplodia sapinea and Armillaria ostoyae in maritime pine

Forest ecosystems are increasingly challenged by extreme events, e.g. drought, storms, pest and pathogenic fungi outbreaks, causing severe ecological and economical losses. Understanding the genetic basis of adaptive traits in tree species is of key importance to preserve forest ecosystems, as genetic variation in a trait (i.e. heritability) determines its potential for human-mediated or evolutionary change. Maritime pine (Pinus pinaster Aiton), a conifer widely distributed in southwestern Europe and northwestern Africa, grows under contrasted environmental conditions promoting local adaptation. Genetic variation at adaptive phenotypes, including height, growth phenology and susceptibility to two fungal pathogens (Diplodia sapinea and Armillaria ostoyae) and an insect pest (Thaumetopoea pityocampa), were assessed in a range-wide clonal common garden of maritime pine. Broad-sense heritability was significant for height (0.219), growth phenology (0.165-0.310) and pathogen susceptibility (necrosis length caused by D. sapinea, 0.152; and by A. ostoyae, 0.021) measured after inoculation under controlled conditions, but not for pine processionary moth incidence in the common garden. The correlations of trait variation among populations revealed contrasting trends for pathogen susceptibility to D. sapinea and A. ostoyae with respect to height. Taller trees showed longer necrosis length caused by D. sapinea while shorter trees were more affected by A. ostoyae. Moreover, maritime pine populations from areas with high summer temperatures and frequent droughts were less susceptible to D. sapinea but more susceptible to A. ostoyae. Finally, an association study using 4,227 genome-wide SNPs revealed several loci significantly associated to each trait (range of 3-26), including a possibly disease-induced translation initiation factor, eIF-5. This study provides important insights to develop genetic conservation and breeding strategies integrating species responses to biotic stressors.

genetics↗