Morphologic and genetic characterisation of Corsican and Sardinian trout with comments on Salmo taxonomy

Abstract

Both morphological and molecular data are presented and discussed for indigenous Salmo sp. from Corsica and Sardinia, here called Tyrrhenian trout. For comparison, morphological data obtained from museum specimens, including the Algerian S. macrostigma, are discussed in the light of recent and new molecular findings. In total, 29 measurements and 20 meristic characters were taken from each specimen. Out of the meristic characters, 12 were obtained by means of X-ray. One important morphometric character in the present study is the size of the head measured from premaxilla to posterior margin of preoperculum. This character was particularly stable in all Tyrrhenian trout, showing relatively large head compared to Atlantic trout and to S. macrostigma. On the contrary, other characters like body punctuations, black and white edges of fins, body depth or number of epurals in the caudal skeleton are quite polymorphic. In certain meristic characters, range of variation of Tyrrhenian trout even exceeds that of the extensive comparative material. Each trout has been genetically characterized. New haplotypes from Tyrrhenian trout were discovered, belonging to three mitochondrial lineages viz. Adriatic, marble and Mediterranean, however, Adriatic haplotypes are dominant. Comparing morphological and genetic data, observed morphology lacks any obvious correlation to mitochondrial lineages and it is concluded that Tyrrhenian trout show no particular affinity to S. macrostigma from Algeria.

Diversity and biogeography of Mediterranean freshwater blennies (Blenniidae, Salaria)

“…Corsica was naturally colonized by two freshwater species, the Salmo cf. trutta complex and S. fluviatilis , but the catadromic eel ( Anguilla anguilla ) is also widespread (Delling et al., 2020; Roché, 2001). The island is considered as the southernmost area that has been partly covered by an ice sheet during the LGM (Conchon, 1988; Kuhlemann et al., 2005) and was not connected to the mainland during this period (Patarnello et al., 2007).…”

Present and Future Salmonid Cytogenetics

“…However, many molecular phylogeneticists and phylogeographers question this biological species concept of taxonomic diversity of the genus Salmo by pointing to negligible and/or weak genetic differentiation among some of those populations/taxa (to cite from numerous ones e.g., [13,89,[94][95][96][97][98][99]). Yet, other colleagues detected significantly larger genetic differences (e.g., [100][101][102][103][104]). How can the cytotaxonomy of the genus Salmo contribute to this debate?…”

Application of the geometric morphometrics approach in the discrimination of morphological traits between brown trout lineages in the Danube Basin of Croatia

“…Separation was more obvious between pure Mediterranean and Atlantic lineages, while hybrid individuals tended to overlap with the Mediterranean lineage, making hybrid identification difficult. Other morphometry studies have shown that either body height (or body elongation) (Monet et al, 2006;Fruciano et al, 2014;Ninua et al, 2018), head length (Simonović et al, 2007;Delling et al, 2020), or both (Pakkasmaa, 2001;Hermida et al, 2009) are distinctive features among different lineages or forms within the brown trout complex. The present study has demonstrated that body height, head length, and eye size were the main differentiating characteristics between the Danubian trout lineage and introduced Atlantic specimens.…”

“…This wide distribution is primarily related to human interests, given its commercially importance in both aquaculture and angling (Saint-Pé et al, 2019). Eurasian brown trout exhibit high phenotypic diversity linked to their complex evolutionary history (Bernatchez, 2001;Leitwein et al, 2017), and are thus often referred to as the brown trout complex (Delling et al, 2020). This diverse evolutionary history results from the ability of brown trout to use the sea and coastal zone to migrate long distances in the past, successfully invading suitable habitats (Berrebi, 2015).…”

“…Several studies have employed classical morphometric and meristic traits to analyse and discriminate populations between and within brown trout lineages (Simonović et al, 2007;Hermida et al, 2009;Liasko et al, 2012;Lorenzoni et al, 2019;Delling et al, 2020;Piria et al, 2020). Less attention has been given to the analysis of body size and shape variation using the geometric morphometrics (GM) approach, even though the GM method has proven suitable for confirming the discrimination of alien and native lineages previously differentiated by molecular analyses (Monet et al, 2006;Fruciano et al, 2014).…”