The Mediterranean region is known to be a hotspot for diversity and endemism, and one of the regions that apparently will be more strongly affected by global climate change. The risk of extinction is particularly high for taxa that are unable to migrate to more favorable regions like primary freshwater fish, which are confined to the rivers where they occur.
As Portugal benefits from a geographic location that is at the transition from an Atlantic climate to a Mediterranean one, the main goal of the FISHATLAS project is to exhaustively characterize the genetic structure of populations from Atlantic- and Mediterranean-type rivers with contrasting hydrology and climate (past and present) and to assess the possible effects of future climatic changes.
An extensive coverage of the Portuguese hydrographical network (21 species from 81 sub-basins) and an innovative and well supported phylogeographic approach (by the concerted use of three molecular markers with different rates of evolution), will allow three different approaches, concerning the past, present and future of populations.
First, assess the present: we aim to test how contrasting conditions of hydrology and climate (both past and present) affected the genetic structure of freshwater fish populations of Atlantic- and Mediterranean-type streams. Indeed, fish from Mediterranean-type streams are subjected to extreme seasonal instability and frequent bottlenecks caused by massive extirpations from many river sections during summer droughts. However, they were spared to the cold extremes of glacial conditions and, moreover, the fragmentation of rivers in different disjunt pools during summer means that even under intense genetic drift different alleles may be retained in different pools so that re-colonization of the rivers will come from many sources. Thus, our hypothesis is that in Mediterranean-type streams both past and present evolutionary processes contribute to high levels of genetic diversity. In contrast, it is expected that in Atlantic-type streams fish populations show lower levels of genetic diversity due to the effects of glaciations that were much more dramatic than in the southern rivers and less intrabasin genetic diversity, with lineage sorting operating on a much broader geographic scale.
Second, analyze the past: as these confined fish species are excellent models for paleobiogeographic studies since close relationships between populations from adjacent rivers corroborate ancient contacts between them, it is our goal to reconstruct the colonization routes of the Iberian Peninsula by primary freshwater fishes, using concordant patterns of phylogeny and phylogeography. Although a considerable amount of work has been done regarding phylogeny and phylogeography of Iberian cyprinid fish, these studies were limited due to the inadequate sampling design and molecular markers selected. Thus, we propose that for the first time phylogeographic considerations about Iberian cyprinids will be postulated taking into account the analysis of a wide number of species, from a large number of independent river basins, and the evolutionary processes will be, also for the first time, analyzed at different time scales by the concerted use of mitochondrial and nuclear markers with different rates of evolution.
Finnally, guard the future: since the majority of the selected target-species are considered to be “Endangered” or “Critically Endangered” by the Portuguese Red Book and since this project involves a extensive coverage of the national territory, we also aim to contribute with valuable data on the biodiversity distribution patterns, the genetic structure and the demographic parameters of populations, and other central issues for scientists and managers concerned with the current risk of extinction threatening Iberian freshwater fish. A National Genetic Atlas for native cyprinid fish is now available online, with maps illustrating the levels of genetic diversity of all the sampled populations. Such data may be used by the decision-makers and authorities not only in the present context of the management of the hydrological resources aiming to minimize the effects of climate changes, but also in the implementation of conservation and management plans aiming to preserve species and, specifically, to assign priorities in conservation policies when choices have to be made concerning which populations of each species must be preserved first, a decision that must take into account the maximization of standing genetic diversity. Thus, this project assumes particular relevance in a context of climate change and of an increasing awareness about the valuable biological patrimony in terms of diversity and endemism that Mediterranean rivers harbor.
This site is being permanently updated with new data, as several scientific papers are soon to be published in international journals.