Susanne Reier


Elucidating phylogeographic patterns of minnows in complex aquifers of the Dinaric Karst

PhD Student
Supervisors: Luise Kruckenhauser, Anja Palandačić

Natural History Museum Vienna;
Unit for Integrative Zoology, Department of Evolutionary Biology
University of Vienna


Karst landscapes, spanning 14% of Earth's land, harbor complex ecosystems shaped by geological processes such as the dissolution of soluble rocks. These landscapes feature complex underground water systems connected to surface water, underscoring the importance of understanding underground pathways within karst aquifers for both karst hydrology and biodiversity studies. The Dinaric Karst boasts rich biodiversity, notably characterized by its endemic freshwater fish fauna. Chapter 1 presents a comprehensive analysis of distribution patterns and biology based on the mitochondrial genetic lineages of four genera of Dinaric Karst minnows: Delminichthys, Phoxinellus, Phoxinus, and Telestes. In this chapter, the influence of vicariance and dispersal in shaping species ranges was assessed. While some genera are confined to sinking streams within karst poljes, the genus Phoxinus shows widespread distribution, potentially facilitated by underground dispersal. Chapters 2 and 3 focus on the species Phoxinus lumaireul, exploring the influence of karst hydrology on its genetic structure and dispersal. Chapter 2, based on mitochondrial DNA and one nuclear gene, identified significant genetic diversity and highlighted the influence of ongoing gene flow through underground connections and remnants of past hydrological networks on population structure. Building upon the results of Chapter 2, Chapter 3 further explored the impact of karstification on the genetic diversity and adaptation of P. lumaireul by comparing genetic structure between populations connected through underground water links with those connected through surface water network. Genome-wide data suggest historical climatic fluctuations play a larger role than karst hydrology in population structure. Despite widespread distribution, localized adaptations and limited gene flow between river systems render P. lumaireul populations vulnerable to extinction events, particularly due to anthropogenic disturbances and habitat degradation. In conclusion, this thesis advances understanding of the complex dynamics of the Dinaric Karst ecosystem by integrating genetic, hydrological, and geological insights, emphasizing the need for conservation strategies.