Title:
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Life history parameters and phylogenetic relationships of the European bitterling
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Bitterling fishes lay their eggs on the gills of living freshwater mussels and are
valuable models in behavioural and evolutionary ecology. To develop a fuller
understanding of the coevolutionary relationship between European bitterling and
mussels an aim of this study was to conduct a phylogenetic reconstruction of the
colonisation of Europe by bitterling, and to resolve the taxonomic question of whether
eastern and western populations ofbitterling represent the same species using genetic
and traditional morphological/meristic methods. A second aim was to obtain a better
understanding of the life-history parameters of R. amarus in Europe, including larval
growth parameters.
Previous studies have suggested the European bitterling is either a single
species with a wide but discontinuous geographic distribution, or a complex of
species. Morphometric and meristic data identified differences between three putative
species; with a clear distinction between the eastern Asian Rhodeus sericeus sensu
stricto, western European bitterling R. amarus and colchian bitterling, R. colchicus.
Polymorphism. in the mitochondrial DNA control region was predominantly due to
insertion/deletion events, making phylogenetic inference difficult. Cytochrome b data
produced a phylogeny with strongly-supported differentiation between a clade of two
R. sericeus haplotypes and a clade of six R. amarus/colchicus haplotypes. The starlike
topology of the R. amarus/colchicus haplotypes in a minimum spanning network
suggested a rapid radiation in this clade. The results are consistent with an hypothesis
of relatively ancient divergence of R. sericeus from R. a11larus/colchicus and more
recent and rapid differentiation between R. a11larus and R. colchicus.
Analysis of otolith microstructure demonstrated a relationship between mussel
availability for spawning and length of spawning season. In addition, these data
strongly suggest the onset of exogenous feeding by larval R. amarus while still in
their mussel host.
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