Morphological divergence of lake and stream Phoxinus of Northern Italy and the Danube basin based on geometric morphometric analysis

• Published in: Ecology and evolution Vol. 7; no. 2; pp. 572 - 584
• Main Authors: Ramler, David, Palandačić, Anja, Delmastro, Giovanni B., Wanzenböck, Josef, Ahnelt, Harald
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.01.2017; John Wiley and Sons Inc
• Subjects: body shape; Climatic zones; Cyprinidae; Divergence; Fins; Foraging habitats; freshwater fishes; general Procrustes analysis; Genetic variability; geometric morphometrics; Habitats; Lakes; Landmarks; Mathematical morphology; Mitochondria; Morphology; Morphometry; Original Research; Phenotypic plasticity; Phoxinus; Phoxinus lumaireul; Phoxinus phoxinus; Populations; Running waters; Streams; Swimming; Italy; MED, Italy; Europe, Danube R; freshwater fishes; body shape; Phoxinus phoxinus; Cyprinidae; general Procrustes analysis; Phoxinus lumaireul; geometric morphometrics
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.2648

Minnows of the genus Phoxinus are promising candidates to investigate adaptive divergence, as they inhabit both still and running waters of a variety of altitudes and climatic zones in Europe. We used landmark‐based geometric morphometric methods to quantify the level of morphological variability in Phoxinus populations from streams and lakes of Northern Italy and the Danube basin. We analyzed body shape differences of populations in the dorsal, lateral, and ventral planes, using a large array of landmarks and semilandmarks. As the species identification of Phoxinus on morphological characters is ambiguous, we used two mitochondrial genes to determine the genetic background of the samples and to ensure we are comparing homogenous groups. We have found significant body shape differences between habitats: Minnow populations inhabiting streams had a deeper body and caudal peduncle and more laterally inserted pectoral fins than minnows inhabiting lakes. We have also found significant body shape differences between genetic groups: Italian minnows had deeper bodies, deeper and shorter caudal peduncles, and a shorter and wider gape than both groups from the Danube. Our results show that the morphology of Phoxinus is highly influenced by habitat and that body shape variation between habitats was within the same range as between genetic groups. These morphological differences are possibly linked to different modes of swimming and foraging in the respective habitats and are likely results of phenotypic plasticity. However, differences in shape and interlandmark distances between the groups suggest that some (though few) morphometric characters might be useful for separating Phoxinus species. We have examined morphological divergence between Phoxinus populations inhabiting different habitats (lakes, streams), as well as from different genetic groups (Northern Italy, Danube basin). By comparing morphological differences between groups (habitats, genetics), we seek to disentangle environmental effects on body shape from genetic ones, which shall also serve as a basis for future taxonomy studies.