Abstract
The region of Balkans is often considered as an ichthyologic “hot spot”, with a great number of species and high portion of endemics living in fresh waters in a relatively small area. The Adriatic watershed in Croatia and Herzegovina is inhabited by six spined loach species (genus Cobitis) whose extinction risk estimations were based solely on their extent of occurrence (and/or area of occupancy) and its fragmentation, and conservation proposals do not consider diversity below species level. In this investigation we employed molecular genetic methods to describe present genetic structure of the Adriatic spined loaches and reveal their demographic history. The divergence of the Adriatic lineages inside the genus Cobitis started in Miocene and lasted until Pleistocene epoch. Geological events responsible for shaping recent diversity of spined loaches in the Adriatic basin are: the Dinarid Mountains upwelling, the evolution of Dinaric Lake system, local tectonic activity, river connections during glaciations and differences in sea level. Even though all the investigated species inhabit karstic rivers located in the same geographic area and that were subject of similar geological events, the results obtained reveal great differences in their genetic diversity and structure and point out the necessity of different conservation measures to ensure their future viability. High level of genetic polymorphism is characteristic for species located more to the south. Two species comprised of more than one population have completely different intraspecific structure; populations of C. illyrica are genetically distinct and represent separate evolutionary significant units, whereas intraspecific structure of C. narentana corresponds to metapopulational pattern. Without population genetic data, evolutionary significant units could be easily misidentified. Furthermore, the obtained results affirm that population genetic measurements are able to detect differences among closely located and related species and estimate extinction risk even more accurately than currently applied IUCN criteria.
Highlights
The International Union for Conservation of Nature and Natural resources (IUCN) recognizes the need to conserve biodiversity at three levels: genetic diversity, species and ecosystems [1]
Our results confirm that molecular studies describing intraspecific genetic structure, as well as patterns of gene flow and evolutionary history of a species are fundamental to effective conservation efforts [49]
Considering that population mean genetic diversity is usually positively correlated with population size, and with mean fitness [50], it is obvious that species with lower genetic diversity have less chance of future survival due to smaller effective population size, and because of smaller capacity to adopt to changed environmental conditions
Summary
The International Union for Conservation of Nature and Natural resources (IUCN) recognizes the need to conserve biodiversity at three levels: genetic diversity, species and ecosystems [1]. Since it is not possible to protect all biodiversity features due to time and financial limitations [7], it is important to implement methods that will, in shortest time, allow most accurate estimation of the extinction risk, as well as identification of units below species level that will most likely ensure evolutionary course of the endangered species concerned. Cobitis bilineata Canestrini, 1865 in Croatia inhabits the Zrmanja R., but is distributed in Slovenia, Italy, France and Spain It is included as the least concern species (LC) in the IUCN Red List. Cobitis dalmatina Karaman, 1928 inhabits a single river in the middle Dalmatia, the Cetina R., while C. narentana Karaman, 1928 is endemic to the Neretva R. basin. Those two species are estimated as vulnerable (VU). Knowledge on population genetic structure and diversity, as well as understanding of evolutionary and demographic history of certain species has a great importance for its conservation since it enables prediction of its future trend and estimation of survival probability
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