Abstract
In this pilot study for the first time, ancient DNA has been extracted from bone remains of Salmo trutta. These samples were from a stratigraphic succession located in a coastal cave of Calabria (southern Italy) inhabited by humans from upper Palaeolithic to historical times. Seven pairs of primers were used to PCR-amplify and sequence from 128 to 410 bp of the mtDNA control region of eleven samples. Three haplotypes were observed: two (ADcs-1 and MEcs-1) already described in rivers from the Italian peninsula; one (ATcs-33) belonging to the southern Atlantic clade of the AT Salmo trutta mtDNA lineage (sensu Bernatchez). The prehistoric occurrence of this latter haplotype in the water courses of the Italian peninsula has been detected for the first time in this study. Finally, we observed a correspondence between frequency of trout remains and variation in haplotype diversity that we related with ecological and demographic changes resulting from a period of rapid cooling known as the Younger Dryas.
Highlights
The Pleistocene is a geological epoch characterized by repeated glacial-interglacial cycles that caused drastic environmental changes and impacted the distribution range and the genetic diversity of species and populations [2]
As for the second issue, we retain our results reliable as: i) we avoided contamination during DNA extraction and PCR by mean of a specific decontamination protocol, ii) we obtained comparable haplotypes from different samples of the same layer and from different extraction replicas of the same samples, iii) we observed the haplotype ATcs-33 never observed before in the modern samples analysed in our laboratories and iv) the absence of new mutations and/or chimera sequences suggests that the sequence analysis presented in this study is not altered by the typical PCR errors generated by ancient DNA (aDNA) lesions
Future analyses of a larger number of samples will allow to make sound inferences on the paleo-ecologic dynamic occurring on S. trutta populations from southern Italian Peninsula. This is the first aDNA study performed on brown trout sub-fossil bone remains
Summary
The Pleistocene (from 2.58 to 0.0117Ma, [1]) is a geological epoch characterized by repeated glacial-interglacial cycles that caused drastic environmental changes and impacted the distribution range and the genetic diversity of species and populations [2]. The expansion of ice sheets forced north-temperate species to move southward and survive in warmer refugia, the same species moved northwards in interglacial phases to recolonize their previous habitat This process lead to “southern richness and northern purity” in north-temperate species biodiversity [2, 3]. Species unable to shift their distribution range or adapt to the new environmental conditions became extinct at local or global scale [4, 5].
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