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Lardies, M. A., Arias, M. B., & Bacigalupe, L. D. (2010). Phenotypic covariance matrix in life-history traits along a latitudinal gradient: a study case in a geographically widespread crab on the coast of Chile. Mar. Ecol.-Prog. Ser., 412, 179–187.
Abstract: Geographically widely spread species can cope with environmental differences among habitats by genetic differentiation and/or phenotypic flexibility. In marine crustaceans, intraspecific variations in life-history traits are pervasive along latitudinal clines. Replicated latitudinal clines are of evolutionary interest because they provide evidence of the occurrence of natural selection. If the means of traits along the latitudinal gradient are expected to be the result of natural selection, there is no reason why variances and covariances will not also be subject to selection, since selection is essentially a multivariate phenomenon. We studied life-history changes in means, variances, and covariances (i.e. P matrix) in 6 populations of the endemic crab Cyclograpsus cinereus (Decapoda: Grapsidae) along a latitudinal gradient over 19 degrees on the Chilean coast. Trait means differed among localities for all traits analyzed (i.e. female size, number and size of eggs, and reproductive output), and the variation displayed a clinal pattern. In general, the main result that emerged from planned comparisons of P matrices is that, when detected, differences between localities mainly reflect differences in the magnitude of phenotypic variation (i.e. eigenvalues), rather than in the relationships between traits (i.e. eigenvectors). Sea-surface temperature was only correlated with the covariance between egg numbers and reproductive output. Matrices comparisons for Flury and jackknife methods were highly linked, with limits of biogeographic provinces described for the coast of Chile. Our study strongly highlights the importance of estimating the P matrix, not only mean values, in order to understand the evolution of life-history traits along a latitudinal gradient. Furthermore, the study of the variation in the P matrix might provide important insights into those evolutionary forces acting on it.
Keywords: Intertidal; Reproduction; Crustacea; Plasticity; Clinical variation
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Manriquez, P. H., Jara, M. E., Torres, R., Mardones, M. L., Lagos, N. A., Lardies, M. A., et al. (2014). Effects of ocean acidification on larval development and early post-hatching traits in Concholepas concholepas (loco). Mar. Ecol.-Prog. Ser., 514, 87–103.
Abstract: Larval stages represent a bottleneck influencing the persistence of marine populations with complex life cycles. Concholepas concholepas is a gastropod species that sustains the most important small-scale artisanal fisheries of the Chile-Peru Humboldt Coastal current system. In this study, newly-laid egg capsules of C. concholepas collected from 3 localities along the Chilean coast were used to evaluate the potential consequences of projected near-future ocean acidification (OA) on larval development and early post-hatching larval traits. We compared hatching time, hatching success and early survivorship of encapsulated larvae reared under contrasting average levels of pCO(2): 382 (present-day), ca. 715 and ca. 1028 μatm CO2 (levels expected in near-future scenarios of OA). Moreover, we compared morphological larval traits such as protoconch size, thickness and statolith size at hatching. Some of the developmental traits were negatively affected by pCO(2) levels, source locality, female identity, or the interaction between those factors. Meanwhile, the effect of pCO(2) levels on morphological larval traits showed significant interactions depending on differences among egg capsules and females. Our results suggest that OA may decouple hatching time from oceanographic processes associated with larval transport and reduce larval survivorship during the dispersive phase, with a potential impact on the species' population dynamics. However, the results also show geographic variability and developmental plasticity in the investigated traits. This variation may lead to an increased acclimatization ability, facilitate the persistence of natural populations and mitigate the negative effects that OA might have on landings and revenues derived from the fishery of this species.
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Orostica, M. H., Hawkins, S. J., Broitman, B. R., & Jenkins, S. R. (2021). Performance of a warm-water limpet species towards its poleward range edge compared to a colder-water congener. Mar. Ecol.-Prog. Ser., 656, 207–225.
Abstract: The demography and individual performance of species at their range edges provide important insight into how climate warming is impacting species distributions. The boreal limpet Patella vulgata and the Lusitanian limpet P. depressa have overlapping geographic ranges and local distributions in Britain. We measured individual performance at the 2 leading edges of P. depressa distribution (North Wales and South/South-east England) and in non-range edge populations in South-west England. Individuals of P. depressa towards both leading edges were expected to have reduced growth rates and higher mortality rates when compared with non-range edge populations. Conversely, P. vulgata was expected to have equivalent performance across regions, coinciding with the centre of its range. Tagged individuals did not show betweenspecies differences in growth and mortality over a 12 mo period. Nonetheless, individual growth rates and population mortality rates of both Patella species were higher towards the range edge of P. depressa in South/South-east England, when compared with populations at its poleward edge and those in South-west England. Further analysis showed that growth and mortality rates were higher in denser populations for both P. depressa and P. vulgata, with equivalent site-specific performance patterns for both species in all regions. Thus, performance patterns of P. depressa reflected local factors in the same way as P. vulgata, overriding patterns of declining performance expected towards species borders. Comparisons between key congeneric species and their unexpected patterns of performance across their ranges provide insights into processes setting species boundaries and thereby their responses to climate change.
Keywords: Climate change; Range edges; Leading edge; Intertidal ecology; Patella spp.
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Ramajo, L., Prado, L., Rodriguez-Navarro, A. B., Lardies, M. A., Duarte, C. M., & Lagos, N. A. (2016). Plasticity and trade-offs in physiological traits of intertidal mussels subjected to freshwater-induced environmental variation. Mar. Ecol.-Prog. Ser., 553, 93–109.
Abstract: Environmental gradients play an important role in shaping geographic variability in coastal marine populations. Thus, the ability of organisms to cope with these changes will depend on their potential to acclimatize, or adapt, to these new environmental conditions. We investigated the spatial variability in biological responses shown by Perumytilus purpuratus mussels collected from 2 intertidal areas experiencing contrasting freshwater input influences (river-influenced vs. marine conditions). To highlight the role of plasticity and adaptive potential in biological responses, we performed a reciprocal-transplant experiment and measured relevant phenotypic traits including mortality, growth, calcification, metabolism, and chemical composition of the shell periostra cum. We determined that mussels exposed to river-influenced conditions had increased metabolic rates and reduced growth rates, as compared to mussels experiencing marine conditions (p < 0.05). While the energy investment strategies of the 2 local populations resulted in similar net calcification rates, these rates decreased significantly when mussels were transplanted to the river-influenced site. Stressful conditions at the river-influenced site were evidenced by decreased survivorship across treatments. Freshwater inputs modify the organic composition of the shell periostracum through a significant reduction in polysaccharides. Although our field experiment did not identify specific environmental factors underlying these contrasting phenotypic changes, the results imply that plasticity plays a strong role when P. purpuratus is exposed to some combination of natural (e.g. salinity) and anthropogenic influences (e.g. pollution), and that the lack of exposure to freshwater may promote less tolerant mussels with greater potential for local adaptation.
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