Trouts in karstic watersheds – diversity, origin and perspective
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1
Faculty of Science, University of Zagreb, Croatia
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2
Faculty of Teacher Education, University of Zagreb, Croatia
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3
Ministry of Environmental Protection and Energy (Croatia), Croatia
Watersheds of the Dinaric karstic region have already been recognized as one of ichthyological "hot spots" in Europe, harboring exceptional ichthyodiversity and many endemic species. Remarkable diversity of cypriniform fishes in the mentioned area has been explained by complex, yet favorable evolutionary history, as well as isolation of karstic watersheds promoting speciation. However, it was not thought that salmonid species follow the same pattern. Moreover, regardless older descriptions of more trout species from the Adriatic watershed, many authors consider that a single brown trout species, Salmo trutta is widely distributed in waters of Palearctic region. The problem of underestimation of salmonid diversity in southern Europe is a consequence of a lack of comprehensive investigation, but also still unresolved taxonomy of the genus Salmo in Europe.
In this investigation we have obtained samples from all salmonid watersheds in Croatia, as well as several in Bosnia and Herzegovina, and performed phylogenetic analyses, divergence time and ancestral ranges reconstruction, estimation of genetic diversity and differentiation, analyses of fixed differences and shared polymorphisms, as well as probabilistic tests of species limits. We have based our analyses on mitochondrial (gene for cytochrome b, mitochondrial control region) and nuclear genetic markers (recombination activating gene 1, gene for rhodopsin, microsatellites), including both, maternally and bi-parentally inherited genes.
Our analyses revealed that at least four distinct species of the genus Salmo can be considered native to karstic watersheds in Croatia and Bosnia and Herzegovina. Since evolutionary isolation of the mentioned units is of older origin that previously considered, and concordant with the Bayes factors comparison for different taxonomic hypotheses, we consider those units as species, rather than intraspecific lineages. Besides S. labrax, S. farioides and S. obtusirostris, distinct species inhabiting the Cetina River in the Adriatic watershed was recognized, but also hybrid individuals of various origin, including introgression of S. marmoratus DNA. Noteworthy, pure populations of all four native species are still present in Croatian watersheds. However, as a consequence of a long-term stocking, mixed populations nowadays inhabit many localities, with various proportions of S. trutta individuals.
Significant anthropogenic impact on salmonid populations, coupled with bottlenecks that occurred in recent evolutionary history, resulted in several problems in genetic structure of populations (such as very to extremely low genetic diversity, inbreeding depression, small or non-existing gene flow among populations) that reduce their viability and evolutionary potential. In order to enable effective conservation of the revealed salmonid diversity, we have performed population viability analysis and identified measures that are most likely to be efficient in population conservation.
Keywords:
genus Salmo,
evolutionary history,
species richness,
karstic rivers,
Viability analyses
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Oral
Topic:
TAXONOMY, PHYLOGENY AND ZOOGEOGRAPHY
Citation:
Buj
I,
Ivić
L,
Raguz
L,
Ćaleta
M,
Marčić
Z,
Duplić
A,
Zanella
D,
Tomašić
A,
Horvatić
S,
Karlović
R and
Mustafić
P
(2019). Trouts in karstic watersheds – diversity, origin and perspective.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00114
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Received:
07 Jun 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Mx. Ivana Buj, Faculty of Science, University of Zagreb, Zagreb, Zagreb, 10000, Croatia, ivaradic@biol.pmf.hr