TY - JOUR

T1 - How an Ecological Race Is Forming: Morphological and Genetic Disparity among Thermal and Non-Thermal Populations of Aquatic Lymnaeid Snails (Gastropoda: Lymnaeidae)

AU - Vinarski, Maxim V.

AU - Aksenova, Olga V.

AU - Bespalaya, Yulia V.

AU - Kondakov, Alexander V.

AU - Gofarov, Mikhail Yu.

AU - Khrebtova, Irina S.

AU - Makhrov, Alexander A.

AU - Bolotov , Ivan N.

N1 - Vinarski, M.V.; Aksenova, O.V.; Bespalaya, Y.V.; Gofarov, M.Y.; Kondakov, A.V.; Khrebtova, I.S.; Makhrov, A.A.; Bolotov, I.N. How an Ecological Race Is Forming: Morphological and Genetic Disparity among Thermal and Non-Thermal Populations of Aquatic Lymnaeid Snails (Gastropoda: Lymnaeidae). Diversity 2023, 15, 548. https://doi.org/10.3390/d15040548

PY - 2023/4/12

Y1 - 2023/4/12

N2 - Hot (geothermal) pools and streams, a specific type of aquatic biotopes having almostworldwide distribution, maintain rich faunas of animals belonging to various taxa. Snails (Gastropoda) represent one of such groups, which form populations in geothermal waterbodies of all continents. Some freshwater snail species produce morphologically distinct hot-water populations,whose rank is often debated (full species or thermal ‘ecotype’, or ‘race’). In this study, we used sixspecies of pond snails (family Lymnaeidae) to investigate the morphological and genetic consequences of infiltration of freshwater snails into geothermal habitats. In particular, we aimed at studying the changes in shell shape and proportions as well as the formation of unique hot-water haplotypes and the occurrence of the latter beyond geothermal waterbodies. All six species studieddemonstrate diminutive body size in hot sites accompanied, in four species, by apparent alterationsin shell proportions. A phenomenon of phenotypic ‘juvenilization’, when adult and able to reproduce individuals demonstrate shell proportions characteristic for full-grown individuals living under ‘normal’ conditions, is described. Unique ‘thermal’ haplotypes, not found beyond the geothermal sites, were normally restricted to a single locality, and no signs of frequent ‘travels’ of snailsfrom one thermal habitat to another are seen. In the vast majority of cases, these exclusive haplotypes are separated from their ancestors by only a few (1–3) mutational steps, which may indicatetheir relatively recent origin. We are inclined to relate both size reduction and ‘juvenilization’ to thelife-cycle re-adjustment following the penetration of lymnaeids to thermal habitats. The ecological(‘thermal’) intraspecific races of different species, forming in geothermal habitats, exhibit, to a greatextent, evolutionary predictability (= convergent evolution; = parallelisms). The dilemma ‘ecologicalrace vs. young species’ in application to the taxonomy of these hot-water populations is briefly discussed.

AB - Hot (geothermal) pools and streams, a specific type of aquatic biotopes having almostworldwide distribution, maintain rich faunas of animals belonging to various taxa. Snails (Gastropoda) represent one of such groups, which form populations in geothermal waterbodies of all continents. Some freshwater snail species produce morphologically distinct hot-water populations,whose rank is often debated (full species or thermal ‘ecotype’, or ‘race’). In this study, we used sixspecies of pond snails (family Lymnaeidae) to investigate the morphological and genetic consequences of infiltration of freshwater snails into geothermal habitats. In particular, we aimed at studying the changes in shell shape and proportions as well as the formation of unique hot-water haplotypes and the occurrence of the latter beyond geothermal waterbodies. All six species studieddemonstrate diminutive body size in hot sites accompanied, in four species, by apparent alterationsin shell proportions. A phenomenon of phenotypic ‘juvenilization’, when adult and able to reproduce individuals demonstrate shell proportions characteristic for full-grown individuals living under ‘normal’ conditions, is described. Unique ‘thermal’ haplotypes, not found beyond the geothermal sites, were normally restricted to a single locality, and no signs of frequent ‘travels’ of snailsfrom one thermal habitat to another are seen. In the vast majority of cases, these exclusive haplotypes are separated from their ancestors by only a few (1–3) mutational steps, which may indicatetheir relatively recent origin. We are inclined to relate both size reduction and ‘juvenilization’ to thelife-cycle re-adjustment following the penetration of lymnaeids to thermal habitats. The ecological(‘thermal’) intraspecific races of different species, forming in geothermal habitats, exhibit, to a greatextent, evolutionary predictability (= convergent evolution; = parallelisms). The dilemma ‘ecologicalrace vs. young species’ in application to the taxonomy of these hot-water populations is briefly discussed.

KW - geothermal ecosystems

KW - Lymnaeidae

KW - Thermal adaptation

KW - variability

KW - Progenesis

KW - geometric morphometry

KW - ecological race

KW - phylogeography

UR - https://www.mdpi.com/1424-2818/15/4/548

M3 - Article

VL - 15

JO - Diversity

JF - Diversity

SN - 1424-2818

IS - 4

M1 - 548

ER -