Browsing by Author "Baldanzi, Simone"

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    Contrasting environments shape thermal physiology across the spatial range of the sandhopper Talorchestia capensis
    (2015) Baldanzi, Simone; Weidberg, Nicolas F.; Fusi, Marco; Cannicci, Stefano; McQuaid, Christopher D.; Porri, Francesca
    Integrating thermal physiology and species range extent can contribute to a better understanding of the likely effects of climate change on natural populations. Generally, broadly distributed species show variation in thermal physiology between populations. Within their distributional ranges, populations at the edges are assumed to experience more challenging environments than central populations (fundamental niche breadth hypothesis). We have investigated differences in thermal tolerance and thermal sensitivity under increasing/decreasing temperatures among geographically separated populations of the sandhopper Talorchestia capensis along the South African coasts. We tested whether the thermal tolerance and thermal sensitivity of T. capensis differ between central and marginal populations using a non-parametric constraint space analysis. We linked thermal sensitivity to environmental history by using historical climatic data to evaluate whether individual responses to temperature could be related to natural long-term fluctuations in air temperatures. Our results demonstrate that there were significant differences in the thermal response of T. capensis populations to both increasing/decreasing temperatures. Thermal sensitivity (for increasing temperatures only) was negatively related to temperature variability and positively related to temperature predictability. Two different models fitted the geographical distribution of thermal sensitivity and thermal tolerance. Our results confirm that widespread species show differences in physiology among populations by providing evidence of contrasting thermal responses in individuals subject to different environmental conditions at the limits of the species' spatial range. When considering the complex interactions between individual physiology and species ranges, it is not sufficient to consider mean environmental temperatures, or even temperature variability; the predictability of that variability may be critical.
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    Epigenetic variation among natural populations of the South African sandhopper Talorchestia capensis
    (2017) Baldanzi, Simone; Watson, Ralph; McQuaid, Christopher D.; Gouws, Gavin; Porri, Francesca
    Ecological epigenetics is gaining importance within the field of Molecular Ecology, because of its novel evolutionary implications. Linking population ecology to the variation in epigenetic profiles can help explain the effect of environmental conditions on phenotypic differences among populations. While epigenetic changes have largely been investigated through the examination of DNA methylation under laboratory conditions, there is a limited understanding of the extent of DNA methylation variation in wild populations. Assuming that epigenetic variation is important in nature, the conditions experienced by different conspecific populations should result in levels of DNA methylation that are independent of their genetic differentiation. To test this, we investigated levels of DNA methylation among populations of the sandhopper Talorchestia capensis that show phenotypic (physiological) differences in their response to environmental conditions, at the same time evaluating their genetic relationships. Given the high levels of inter-individual physiological variation observed within populations, we further hypothesised that inter-individual differences in methylation would be high. Levels of genetic and epigenetic variation were assessed within and among populations from five localities using the methylation sensitive amplified polymorphism technique. Population differentiation was higher for epigenetics than genetics, with no clear geographical pattern or any relation to biogeography. Likewise, individuals showed greater variability in their epigenetic than their genetic profiles. Four out of five populations showed significant negative relationships between epigenetic and genetic diversity. These results show uncoupling between epigenetic and genetic variation and suggest that: (1) epigenetics are more responsive to local, site-specific environmental conditions than genetics and (2) individual differences in epigenetic profiles drive phenotypic variation within (and most likely among) natural populations. Within populations, epigenetics could offer a level of phenotypic flexibility beyond genetic constraint that allows rapid responses to variable or unpredictable environments, potentially compensating for low genetic variability.
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    Latitudinal variation in maternal investment traits of the kelp crab Taliepus dentatus along the coast of Chile
    (2018) Baldanzi, Simone; Storch, Daniela; Navarrete C., Sergio; Graeve, Martin; Fernández, Miriam
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    Long term environmental variability modulates the epigenetics of maternal traits of kelp crabs in the coast of Chile
    (2022) Baldanzi, Simone; Saldias, Gonzalo S.; Vargas, Cristian A.; Porri, Francesca
    The methylation of DNA is an environmentally inducible epigenetic mechanism reflecting the short-term ecological and environmental background of populations. Marine invertebrate populations, which spread along a latitudinal cline, are particularly suitable for profiling DNA methylation, due to the heterogenous environmental conditions experienced. We used the MSAP (Methylation Sensitive Amplified Polymorphism) technique to investigate the natural variation in DNA methylation of different female's tissues (muscle, gonads, and gills) and early-stage eggs from five populations of the kelp crab Taliepus dentatus, distributed along a latitudinal cline in the coast of Chile. We assessed whether, (1) the distribution of DNA methylation profiles can be associated with the temporal variability of long term (18 years) climatologies (sea surface temperature, turbidity and productivity) and (2) the epigenetic diversity of eggs is related to the population-level phenotypic variability of several maternal investment traits (egg volume, egg weight, egg lipids and fecundity). The DNA methylation of eggs correlated positively and negatively with the long term variability in productivity and sea surface temperature, respectively. Furthermore, the diversity of DNA methylation of eggs correlated positively with the population-level phenotypic variability of several maternal investment traits, suggesting a key role of epigenetic mechanisms in generating phenotypic variability at population level for this species. We provide evidence of a strong link between the temporal variability of long term climatologies with the epigenetic profiles of key early ontogenetic traits associated with the maternal investment of kelp crabs. These modulating mechanisms can hence contribute early to phenotypic variability at population levels in response to local and past environmental fluctuation.
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    Molecular evidence of distinct evolutionary units in the sandhopper Talorchestia capensis (Amphipoda, Talitridae) along South African coasts
    (2016) Baldanzi, Simone; Gouws, Gavin; Barker, Nigel P.; Fratini, Sara
    Marine geographical and ecological barriers often reflect intraspecific genetic discontinuities among populations which may experience different selective pressures and undergo evolutionary divergence. While the phylogeography of marine intertidal invertebrates across the Atlantic/Indian Ocean transition received more attention, the population genetic structures of supralittoral direct developers across such transition area have been poorly investigated. Sandhoppers are supralittoral invertebrates characterised by a direct developmental mode (low dispersal ability), and Talorchestia capensis (Amphipoda, Talitridae) represents the most abundant species of sandhoppers along the South African coasts. To define population structure of T. capensis, we used a mitochondrial marker (the cytochrome oxidase subunit I gene, COX1). T. capensis showed a clean population structure with three main haplogroups genetically well separated, although this separation is not perfectly in line with geographical boundaries described for this area. The presence of separate evolutionary significant units is also confirmed by the shape of mismatch distribution, as well as the p distance values among groups. The overall results confirm the importance of mtDNA to retrieve information on the evolutionary history of species. This study suggests the evidence of a complex-species for this sandhoppers, which have never been considered before, providing fundamental basis for further studies.
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    Morphological and epigenetic variation in mussels from contrasting environments
    (2018) Watson, R. G. A.; Baldanzi, Simone; Perez-Figueroa, A.; Gouws, G.; Porri, F.
    The impact of contrasting environments on organisms can result in the establishment of distinct phenotypic traits. Environmentally induced epigenetic mechanisms directly regulate gene expression and potentially lead to long-lasting effects. How phenotypic, epigenetic, and genetic components of wild populations relate to each other is, however, still largely debated. We examined the effect of broad coastline topography (as bay versus open coast) on the morphological, genetic, and epigenetic (i.e., DNA methylation) traits of the brown mussel Perna perna from four natural populations along the south coast of South Africa (between 33.9 S, 25.7 E and 34.2 S, 22.1 E) collected in April 2014. Several morphometric measurements were taken on the mussel body and byssal thread. The epigenetic and genetic structure of P. perna was assessed using the methylation sensitive analysis of polymorphisms technique. Morphological traits differed among populations, but no clear effect of topography on both morphology and genetics was found. Bay and Open Coast sites differed in the patterns of DNA methylation of selected loci, suggesting that topography shaped the epigenetic profile of populations of P. perna. The environmentally induced changes in the DNA methylation of selected loci were neither correlated with the morphological traits analysed, nor explained by the underlying genetic variance among populations. The relationship amongst epigenetics, morphology, and genetics of P. perna populations was shown to be complex and dynamic. Although inconsistent, the topographically linked variability in epigenetic and the phenotypic differences in genetically close populations of mussels highlights the potential role of the local environment in driving mesoscale differences among populations.
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    Temperate rocky reef fish community patterns in a coastal marine protected area (MPA) from northern Chile, utilizing remote underwater video cameras (RUVs)
    (2024) Gres, Mateo; Hune, Mathias; Baldanzi, Simone; Perez-Matus, Alejandro; Landaeta, Mauricio F.
    Shallow water seascapes are complex systems, important for the life history and connectivity of many marine fish species. Remote Underwater Video cameras (RUVs) are an increasingly used, non-lethal technique able to record the occurrence of reef fish species with little disturbance. In this study, RUVs were installed in a Marine Protected Area (Cha & ntilde;aral Island, northern Chile, 29 degrees 2'S, 71 degrees 34'W) at three different depth strata (5, 10, 15 m) in three different habitats (sand and boulder, bedrock, and kelp forest) during October 2018, July 2021 and October 2021. The RUV system recorded a total of 20 species belonging to 16 families over 73.5 h of videotaping. The most recurrent fishes were damselfish Chromis crusma, Chilean sandperch Pinguipes chilensis, and marblefish Aplodactylus punctatus. There was a significant difference in fish assemblage composition among depth strata and seasons, but not among habitats. In July 2021 (austral winter) higher densities of small cryptobenthic fish (Helcogrammoides spp.) and medium-sized carnivorous Chirodactylus variegatus were detected, whereas P. chilensis was associated to the deeper stratum, and the herbivorous blenny Scartichthys viridis was related to the shallower depths, which is likely due to differences in the habitat structure and composition. Winter 2021 showed a higher species richness than in spring 2018, while the evenness (Pielou's J') was significantly higher in spring 2018 than winter/spring 2021. There was no other strong or consistent pattern, which suggests that most fish species use the entire depth gradient throughout the year. Finally, the results suggest that the use of RUVs for the estimation of biodiversity of rocky reef fishes is a cost-effective way to improve our understanding of nearshore community shifts in relation to environmental forcing.