Vol.:(0123456789) 1 3 Zoomorphology (2020) 139:361–371 https://doi.org/10.1007/s00435-020-00480-7 ORIGINAL PAPER Variation in external morphology between the native and invasive populations of the round goby, Neogobius melanostomus (Actinopterygii: Gobiidae) Dimitriy Dashinov 1  · Przemysław Czerniejewski 3  · Sigal Balshine 4  · Caitlyn Synyshyn 4  · Elena Tasheva‑Terzieva 2  · Tihomir Stefanov 5  · Petia Ivanova 6  · Nicolas Mandrak 7  · Eliza Uzunova 1 Received: 18 August 2019 / Revised: 16 February 2020 / Accepted: 20 February 2020 / Published online: 22 April 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Fish established outside their native range often express various changes in external morphology, which may result in signifcant variation between individuals inhabiting diferent regions. In the current study we aim to explore diferences in morphology among several populations of the round goby (Neogobius melanostomus), an invasive fsh in Europe and North America. A total of 753 round gobies were collected from several invasive and native populations, including marine, brack- ish, freshwater, lake and river ecosystems belonging to the Black Sea, Baltic Sea and Great Lakes watersheds. We analysed 35 metric and meristic characters using ANOVA, discriminant analysis and allometric coefcients. Our results indicate signifcant diferences between most of the populations in characters such as inter orbital distance, eye diameter, head width, second dorsal fn length and depth. River dwelling round gobies had elongated ventral fns compared to those from standing water bodies—a possible adaptation for upstream dispersal in fowing habitats. Most of the morphologic characters expressed positive allometry with signifcant diferences in allometric coefcients between populations. Probably due to their recent invasive history, some of the head characters and allometric models grouped together round gobies from the Great Lakes watershed with those from a newly established population in the Danube tributaries. Similarities between geographically distant round goby populations might refect common adaptations in external morphology during the course of invasion. Keywords Neogobius melanostomus · Geographic range · Invasive species · Morphological variation · Allometry Introduction Introduction of alien fshes is considered as one of the main causes for loss of aquatic biodiversity, especially in highly sensitive freshwater ecosystems (e.g. Walther et al. 2009; Blackburn et al. 2011; Poulos et al. 2012). Diferent envi- ronmental and geographic factors can lead to variation in body shape, single morphological characteristics or growth patterns within and among invasive populations (Záhorská et al. 2009; Firmat et al. 2012; Polačik et al. 2012; Apos- tolou et al. 2016; Vila-Gispert et al. 2017). Morphological variability in alien fshes can be associated with diferences between native and non-native habitat conditions, preda- tory regimes, founder efects and others (Langerhans and DeWitt 2004; Firmat et al. 2012; Cerwenka et al. 2014; Vila- Gispert et al. 2017). Both adaptations to the environment and unequal history (clade, genotype, geographic region) play important roles in determining the external morphology of Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00435-020-00480-7) contains supplementary material, which is available to authorized users. * Dimitriy Dashinov ddashinov@abv.bg 1 Department of General and Applied Hydrobiology, Sofa University “St. Kliment Ohridski”, Sofa, Bulgaria 2 Department of Zoology and Anthropology, Sofa University “St. Kliment Ohridski”, Sofa, Bulgaria 3 Department of Fisheries Management and Water Protection, West Pomeranian University of Technology, Szczecin, Poland 4 Aquatic Behavioral Ecology Laboratory (ABEL), McMaster University, Hamilton, Canada 5 National Museum of Natural History, Sofa, Bulgaria 6 Institute of Oceanology “Prof. Fridtjof Nansen”, Bulgarian Academy of Science, Varna, Bulgaria 7 Department of Biological Science at Scarborough, University of Toronto, Toronto, Canada