Current state of research on the systematics and zoogeography of graylings (Thymallus) throughout the world, with notes on the recent advances and applications of genomics.
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1
University of Graz, Institute of Biology, Austria
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2
Interdisciplinary Center for Marine and Environmental Research, Abel Salazar Institute of Biomedical Sciences, University of Porto, Portugal
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3
Departament of Biology, Faculty of Sciences, University of Porto, Portugal
Graylings (Thymallus) are an important faunal component of north temperate to arctic freshwater habitats throughout Eurasia and much of western North America. Their taxonomic diversity has gained increasing attention over the last decades, due to the advent of molecular genetic methods, the re-evaluation of historical descriptive studies and more detailed studies in relatively remote regions of the genus’s range. The systematics of the genus has also proved to be a relatively good model reflecting the history of the hydrological network, where the formation, isolation, and re-distribution of river catchments coincide with cladogenetic events. Unusual for some other salmonid genera, partial to complete reproduction isolation occurs often where lineages come into contact, exemplified by the Amur basin, where as many as four species (at least three documented in sympatry) occur in a single river. For the most part, it has been shown that Arctic grayling (Thymallus arcticus) in Eurasia are limited to the lower reaches of major north flowing rivers or coastal rivers flowing both into the Arctic Sea as well as the Sea of Okhotsk. More interior systems or headwaters of the Lena, Enisey and Ob river systems are occupied by taxa that are considerably divergent from the wide-spread Arctic grayling. Phenotypic studies primarily highlight significant differences in coloration (with some exceptions) among taxa, especially for sexual characteristics such as the colour patterns of the male dorsal fin, presumed to help re-enforce reproductive isolation via lineage specific mate choice. Within species, some grayling show remarkable fine-scaled population structure (e.g. in Scandinavia) whereas elsewhere (such as Lake Baikal), little such structure has been found. Phenotypic polymorphism within water bodies, a common occurrence in other salmonid genera, is rare in grayling, but putatively present in Western Mongolia, where the large-growing piscivorous Thymallus brevirostris co-occurs with an invertebrate-feeding phenotype of undescribed genetic divergence. The recent publication of an annotated genome of European grayling (Thymallus thymallus) has opened up tremendous potential for unraveling genetic mechanisms behind grayling diversity and evolution. Our research program is targeting some of the last undescribed or controversial aspects of grayling systematics and taxonomy in remote regions of Eurasia and North America and aims to apply NGS-based sequencing technologies to describe zones of contact and hybridization between different taxa as well as the active evolutionary mechanisms behind to the polymorphism of Mongolian grayling.
Acknowledgements
This work was supported by the Doctoral Academy of the Natural Sciences Faculty at the University of Graz and FCT - Foundation for Science and Technology - (SFRH/BD/139069/2018) to GS and the Strategic Funding UID/Multi/04423/2019 through national funds provided by FCT.
Keywords:
Eurasia,
salmonids,
Thymallus,
Genome sequencing,
polymorphism,
Population structure /
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Key-note Presentation
Topic:
GRAYLING (GENUS THYMALLUS): EVOLUTION, SYSTEMATICS, MANAGEMENT AND CONSERVATION
Citation:
Weiss
SJ,
Englmaier
GK,
Secci-Petretto
G and
Froufe
E
(2019). Current state of research on the systematics and zoogeography of graylings (Thymallus) throughout the world, with notes on the recent advances and applications of genomics..
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00064
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Received:
21 Jul 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Prof. Steven J Weiss, University of Graz, Institute of Biology, Graz, Austria, steven.weiss@uni-graz.at