Metapopulation Structure of Two Species of Pikeworm (Triaenophorus, Cestoda) Parasitizing the Postglacial Fish Community in an Oligotrophic Lake

In the present study, we estimated the levels of infestation of the main fish species that are hosts for two Triaenophorus species: T. crassus and T. nodulosus. The prevalence of T. crassus and T. nodulosus infestations in the intestine of their definitive host–pike Esox lucius was similar (71.0% and 77.4%, respectively). At the same time, the prevalence of T. crassus infestation in muscle tissue was significantly different between the second intermediate hosts, Coregonus lavaretus pidschian (31.4%) and Cor. l. pravdinellus (91.2%), due to considerable differences in their diets. For T. nodulosus, we found significant variations in the levels of prevalence among the second intermediate hosts—100% for Lota lota, 81.8% for Cottus sibiricus 31.9% for Thymallus arcticus, and 24.5% for Perca fluviatilis—that we also explained using different diets. Moreover, analysis of the symmetry of parasite infestations did not reveal any asymmetry between the number of cysts in the left and right body surfaces of the “planktivorous” form/species of whitefish, whereas in the ‘‘benthivorous”, an asymmetry of parasite infestations was found.The research of 2020 was partially supported by the Russian Foundation for Basic Research (grant number 19-34-60028), the data curation in 2021 was partially supported by the Russian Science Foundation (project No. 19-74-10054), and for 2022 was partially supported by the Russian international scientific collaboration program Mega-grant (mega-grant No. 075-15-2022-1134).info:eu-repo/semantics/publishedVersio

Data from: Basic description and some notes on the evolution of seven sympatric morphs of Dolly Varden Salvelinus malma from the Lake Kronotskoe Basin

The paper examines the basic morphological and ecological features of Dolly Varden from Lake Kronotskoe (Russia, Kamchatka). Seven valid morphs different in head proportions, feeding, timing and place of spawning have been determined in this ecosystem. The basic morphometric characteristics clearly separate Lake Kronotskoe morphs from each other, as well as from its potential ancestor (Dolly Varden). According to CVA analysis, the most notable morphological characteristics determining the mouth position are: the length of a lower jaw and rostrum. Furthermore, five of seven morphs inhabit different depth zones of the lake and feed on different food resources. Our data suggest that reproductive isolation may be maintained by temporal/spatial isolation for two morphs with lacustrine spawning, and by spatial isolation only for the rest of the morphs with riverine spawning. The sympatric diversity of the Lake Kronotskoe charrs is exceptionally wide and there are no other examples for seven sympatric morphs of genus Salvelinus to coexist within a single ecosystem. This study puts forward a three-step hypothetical model of charr divergence in Lake Kronotskoe as a potential ground for future studies

linear_morphometrics

The juveniles with a fork length of 61–124 mm (parrs with 2-3 annual rings on otoliths, age 2+ to 3+) were used to analysis of body shape. The extraction of truss distances from the digital images of seven Lake Kronotskoe morphs and Dolly Varden was conducted using tpsUtil and tpsDig2 v2.16 software platforms (Rohlf, 2010)

NN2_bottom_landmarks

Tps file for Nosed2 (N2-) morph (bottom view

bones_development

The skeletal elements measured were ranked by developmental rate to perform a comparative analysis of osteogenesis. A score-scale ranking was used for bones, which were classified according to Jollie (1986

The riverine dwelling groups of endemic Dolly Varden (Salvelinus malma, Salmonidae) morphs from lake Kronotskoe (Kamchatka, Russia)

Dwarf males and fluvial groups were found in the population structure of endemic Dolly Varden (Salvelinus malma) morphs dwelling the Lake Kronotskoe basin. Apart from the lacustrine-riverine charrs, dwarf males and fluvial groups stay in the vicinity of their own spawning grounds for their whole life at the upper reaches of the lake tributaries. Fluvial males and females were found only for white charr morph which can be defined as the biggest generalist among the endemic Lake Kronotskoe charrs. It was found that propensity for dwarf males' formation for different morphs of nosed charrs corresponds to the complexity of the river habitats i.e. amount of the covers and lateral branches. No fluvial individuals were registered for longhead charr regarded as one of deep-specialised predatory morph. It was revealed that all riverine dwelling groups are defined by a similar lifestyle; however they are distant from each other by body shape and closer to the corresponding morph representatives rather than to each other or to the ancestral Dolly Varden. The morphology data underlines that riverine dwelling groups are an inherent part of each morph and should be considered as a life strategy variance, but not as distant morphs. The unidirectional patterns of the morphological development for riverine-lacustrine and fluvial groups point to the heritability bases for those traits. The conserving of specific morphology within the fluvial groups lets us suggest an approach for allowing a reconstruction of the populations heavily damaged by anthropogenic activity

NN1_landmarks

Tps file for Nosed1 (N1-) morph (side view

NN3_landmarks

Tps file for Nosed3 (N3-) morph (side view

landmarks_SS

Tps file for Smallmouth (S-) morp

landarks BB

Tps file for Bigmouth (B-) morp