Changes in Fish Taxonomy Affect Freshwater Biogeographical Regionalisations: Insights from Greece

Vavalidis Vavalidis,Zogaris Zogaris,Economou Economou,Bobori Bobori,Kallimanis Kallimanis

doi:10.3390/w11091743

Vavalidis Vavalidis, Zogaris Zogaris + Show 3 more

Open Access

https://doi.org/10.3390/w11091743

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Abstract

Freshwater fishes are key indicators for delineating biogeographical maps worldwide. However, controversy in regional-scale ichthyogeographic boundaries still persists, especially in areas of high species endemicity, such as in Greece. One problem concerns the taxonomy of the fishes because there have been extensive changes, mainly due to an increased splitting of species in recent years in Europe. Here, we explore why ichthyogeographic boundary disagreements and uncertainties in region-scale biogeographical units persist. We compare cluster analyses of river basin fish fauna in Greece using two taxonomic datasets: the older fish taxonomy (from 1991) and the current taxonomy that now follows the phylogenetic species concept (PSC), which has become widely established in Europe after 2007. Cluster analyses using the older fish taxonomy depicts only two major biogeographical regional divisions, while the current taxonomy defines four major regional divisions in mainland Greece. Interestingly, some older maps from the pre-PSC taxonomy era also similarly show four ichthyogeographic divisions in Greece and we can assume that the older biogeographical work did not solely use numerical taxonomy but followed an expert-guided synthesis; the older regional definitions have persisted quite well despite radical changes in Europe’s fish taxonomy. Through the prism of biodiversity conservation planning, we hope this review may help identify ways to help standardize policy-relevant biogeographical mapping.

Highlights

Biogeographical maps are of outstanding importance for conservation evaluations, protected area planning, water management and education [1,2,3]
The delineated regional areas, often called ichthyogeographic regions, are defined by a characteristic pool of freshwater fish species, which are the outcome of long evolutionary histories, climatic refugia, local and global extinctions, and natural colonisation processes [16,17]
Since current fish distributions are well known compared to so many other aquatic organisms, basin area fish assemblages are instrumental for defining freshwater faunal break boundaries [8] and so-called freshwater ecoregional

Summary

Introduction

Biogeographical maps are of outstanding importance for conservation evaluations, protected area planning, water management and education [1,2,3]. Despite two centuries of active interest [4], and recent methodological advances in delineating biogeographic regions [5,6,7] many map boundary lines often incite controversy (e.g., [8,9,10]). Zoogeographers have long recognised the biogeographic importance of the long-term freshwater-specific isolation of fishes within river and lake basins [14,15]. The delineated regional areas, often called ichthyogeographic regions, are defined by a characteristic pool of freshwater fish species, which are the outcome of long evolutionary histories, climatic refugia, local and global extinctions, and natural colonisation processes [16,17]. Since current fish distributions are well known compared to so many other aquatic organisms, basin area fish assemblages are instrumental for defining freshwater faunal break boundaries [8] and so-called freshwater ecoregional

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