Gammella, Maddalena (2016) Local adaptation and gene flow in serpentine and limestone populations of D. sylvestris. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Local adaptation and gene flow in serpentine and limestone populations of D. sylvestris
Date: 31 March 2016
Number of Pages: 100
Institution: Università degli Studi di Napoli Federico II
Department: Biologia
Scuola di dottorato: Scienze biologiche
Dottorato: Biologia avanzata
Ciclo di dottorato: 28
Coordinatore del Corso di dottorato:
Cozzolino, SalvatoreUNSPECIFIED
Date: 31 March 2016
Number of Pages: 100
Keywords: heavy metal content, edaphic factor, microsatellite
Settori scientifico-disciplinari del MIUR: Area 05 - Scienze biologiche > BIO/07 - Ecologia
Area 05 - Scienze biologiche > BIO/11 - Biologia molecolare
Area 05 - Scienze biologiche > BIO/18 - Genetica
Date Deposited: 08 Apr 2016 09:46
Last Modified: 02 May 2018 01:00
DOI: 10.6093/UNINA/FEDOA/11109

Collection description

Patchy distribution and stressful conditions of environment can induce the emergence of locally adapted phenotypes. Evolutionary theory supports that local adaptation is drown by strength of divergent selection to favor the genotype that better performs in a specific habitat. Nevertheless, adaptation could occur also via phenotypic plasticity that allows individuals to rapidly change their phenotypic response to environment and this ability may even slow down the effect of adaptive genetic divergence. Plants from serpentine represent a typical model for studying local adaptation to soil type as selection in this environment is very intense and leads to the evolution of locally adapted populations, a phenomenon known as “serpentine syndrome”. Dianthus sylvestris Wulfen (Caryophyllaceae) is frequently found both on serpentine and limestone bedrocks along Apennine chain. Here we investigated populations of D. sylvestris in North-Center of Italy in order to clarify if phenotypic variation among populations of D. sylvestris, on both serpentine and limestone soils, could be defined as an example of local adaptation or is due to strong phenotypic plasticity. We used a molecular approach based on EST SSR marker to infer on genetic diversity and populations structure. Moreover, to verify if serpentine populations are locally adapteted we use an ecologiac approach based on transplanting field experiment and morphological and physiological measurements. Population genetic analyses showed a high percentage of polymorphic loci (ranging from 71% to 100%) and the distribution of allele frequencies showed no significant differences among populations from the two soil types. Similarly, allele richness was comparable among populations of serpentine and limestone. Both ANOVA and the low values of differentiation among populations (mean Fst= 0.119, among populations) confirmed the low overall genetic differentiation. Bayesian (STRUCTURE) and multivariate approach (PCoA) ruled out that populations from limestone and serpentine soils cluster in two genetically differentiated groups, even if according to Mantel test, subdivision was on geographic distribution more than on edaphic base. Thus, no evident genetic differentiation among D. sylvestris populations from serpentine and limestone was found with neutral markers. To determine the contribution of selective factors and/or phenotypic plasticity to local adaptation of D. sylvestris to serpentine, from populations already examined in the genetic analysis, we estimated the metal content in plant aerial parts, collected data on morphological traits, and performed field reciprocal transplantations. High metal content (Ni, Cr) in plants aerial part confirmed, as in previous studies, the bioaccumulation of heavy metals in D. sylvestris plants from serpentine soils. In these plants, several morphological traits were found statistically decreased when compared to plants from limestone so highlighting that serpentine is a less permissive habitat than limestone. However, most of the morphological differences disappeared in transplanted individuals suggesting a large contribution of phenotypic plasticity in determining the observed morphological divergences. Nevertheless, in transplanted plants from serpentine soil to limestone, a two-way ANOVA resulted in a significant difference in biomass with an effect of the original soil on the transplanting soil. Significant differences were also found in flowering time, as plants from serpentine, when transplanted on limestone, flowered before than resident limestone plants. These differences, persisting independently from the original soil type, should have genetic bases. Thus genetic differentiation of populations of D. sylvestris is occurred at least in a few selected loci determining different affinity for the two habitats. This divergence is maintained among populations from different soil types even in the face of extensive gene flow as observed at neutral loci.


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