Skull Morphology Variation as Related to Trophic Specialization in Three Forms of Salvelinus malma (Salmonidae) from the Kamchatka River Basin

Melnik, Nikolay O.; Есин, Е. В.

doi:10.1134/s0012496620030059

Cited by 2 publications

(1 citation statement)

References 7 publications

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“…The description of the species was based on morphological features. WC can be actually distinguished by an enlarged visceral skeleton and a wider lower jaw (Medvedeva‐Vasilyeva, 1978; Melnik & Esin, 2020). It has a reduced number of vertebrae and fin rays (Savvaitova & Kochmenko, 1971), and the number of pores of the head seismosensory branches (Chebanova, 1974).…”

Section: Discussionmentioning

confidence: 99%

Life‐history variation as a source of diversity for endemic white charr (Salmonidae) of the lower Kamchatka River

Есин

Мельник

Маркевич

2022

Journal of Fish Biology

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Sympatric fish morphs diversifying in their feeding pattern in fresh waters typically implement alternative migratory tactics so that omnivores become migrants and specialists‐residents. Charrs of the genus Salvelinus populating the lower Kamchatka River (Northeast Asia) are a rare example wherein two related sympatric morphs both implement a variety of life‐history tactics in parallel. Here the authors analyse the ecological diversity in the endemic piscivorous “white” morph that exploits resources of the Kamchatka River in sympatry with the partially anadromous invertivorous “Dolly Varden” (DV) morph. Eco‐morphological criteria allowed the authors to validate the morph identification. The white charr (WC) was found to subdivide into the small‐sized (up to 1.6 kg) fish inhabiting the lacustrine part of the ecosystem and the large‐sized (up to 3.4 kg) fish inhabiting the main river channel. The persistent spatial segregation of the sub‐groups was confirmed by significant differences in the life span, muscle δ13С signature and parasite load. According to contrasting patterns of strontium accumulation in otoliths, the riverine WC is represented by resident and semi‐anadromous individuals. At the same time, the lack of microsatellite DNA differentiation and allometric nature of the morphometric discrepancy point to the intra‐population source of the WC polymorphism. The authors suggest that WC diverged from DV as a result of feeding specialization on the threespine stickleback numerous in the ecosystem since the temporary flooding by marine waters in the middle Holocene. The modern stickleback division into local stocks following the ecosystem differentiation into a river, side lake and estuary resulted in the WC life‐history split and ecological radiation.

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Section: Discussionmentioning

confidence: 99%

Life‐history variation as a source of diversity for endemic white charr (Salmonidae) of the lower Kamchatka River

Есин

Мельник

Маркевич

2022

Journal of Fish Biology

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Trophic Diversification Out of Ancestral Specialization: An Example from a Radiating African Cyprinid Fish (Genus Garra)

2022

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Trophic resource partitioning is one of the main ecological mechanisms of adaptive radiation. The Garra is a highly specialized periphyton feeder that has widened jaws equipped with a horny cutting scraper. In a river located in the Ethiopian Highlands in East Africa, a diversification of Garra composed of six sympatric ecomorphs which were strikingly diverse in trophic morphology was revealed. A hypothesis on trophic resource partitioning was tested using data on diet composition, gut length, and stable isotopes. The obtained results confirmed the trophic diversification of Garra ecomorphs. Three feeding modes were revealed: (i) periphytonophagy, (ii) mixed periphytonophagy and zoophagy, and (iii) zoophagy. The periphyton feeders had a long gut and were enriched in δ13C values compared to the shorter gut and lowered δ13C values in the zoophagous ecomorphs. Therefore, Garra could respecialize out of its ancestral specialization. This finding does not support the generalists-to-specialists hypothesis on the origin of specializations, and suggests that Liem’s paradox is a more common phenomenon. In the case of specialists, we assume that new ecological opportunities can be ‘visible’ to specialists if they are preceded by relaxed selection constrains that lead to the widening of the ecological/morphological plasticity to jump out of a canalized mode of ancestral specialization.

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Skull Morphology Variation as Related to Trophic Specialization in Three Forms of Salvelinus malma (Salmonidae) from the Kamchatka River Basin

Cited by 2 publications

References 7 publications

Life‐history variation as a source of diversity for endemic white charr (Salmonidae) of the lower Kamchatka River

Life‐history variation as a source of diversity for endemic white charr (Salmonidae) of the lower Kamchatka River

Trophic Diversification Out of Ancestral Specialization: An Example from a Radiating African Cyprinid Fish (Genus Garra)

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