Polymorphism in the aggressive mimicry lure of the parasitic freshwater mussel
Comparative biology published in PeerJ (2024)
Abstract
Unionoid freshwater mussels (Bivalvia: Unionidae) are free-living apart from a brief, obligately parasitic, larval stage that infects fish hosts, and gravid female mussels have evolved a spectrum of strategies to infect fish hosts with their larvae. In many North American species, this involves displaying a mantle lure: a pigmented fleshy extension that acts as an aggressive mimic of a host fish prey, thereby eliciting a feeding response that results in host infection. The mantle lure of Lampsilis fasciola is of particular interest because it is apparently polymorphic, with two distinct primary lure phenotypes. One, described as "darter-like", has "eyespots", a mottled body coloration, prominent marginal extensions, and a distinct "tail". The other, described as "worm-like", lacks those features and has an orange and black coloration. We investigated this phenomenon using genomics, captive rearing, biogeographic, and behavioral analyses. Within-brood lure variation and within-population phylogenomic (ddRAD-seq) analyses of individuals bearing different lures confirmed that this phenomenon is a true polymorphism. The relative abundance of the two morphs appears stable over ecological timeframes: the ratio of the two lure phenotypes in a River Raisin (MI) population in 2017 was consistent with that of museum samples collected at the same site six decades earlier. Within the River Raisin, four main "darter-like" lure motifs visually approximated four co-occurring darter species (Etheostoma blennioides, E. exile, E. microperca, and Percina maculata), and the "worm-like" lure resembled a widespread common leech, Macrobdella decora. Darters and leeches are typical prey of Micropterus dolomieui (smallmouth bass), the primary fish host of L. fasciola. In situ field recordings of the L. fasciola "darter" and "leech" lure display behaviors, and the lure display of co-occurring congener L. cardium, were captured. Despite having putative models in distinct phyla, both L. fasciola lure morphs have largely similar display behaviors that differ significantly from that of sympatric L. cardium individuals. Some minor differences in the behavior between the two L. fasciola morphs were observed, but we found no clear evidence for a behavioral component of the polymorphism given the criteria measured. Discovery of discrete within-brood inheritance of the lure polymorphism implies potential control by a single genetic locus and identifies L. fasciola as a promising study system to identify regulatory genes controlling a key adaptive trait of freshwater mussels.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Резюме
Documents lure polymorphism in parasitic freshwater mussels — comparator system for understanding hematophagy host-targeting biology in leeches and surveillance applications.
Почему это важно для гирудотерапии
В данном исследовании изучался полиморфизм мантийной приманки пресноводного двустворчатого моллюска Lampsilis fasciola, который использует агрессивную мимикрию для инфицирования рыб-хозяев. Одна из двух морф приманки, описываемая как «червеобразная» с оранжево-чёрной окраской, визуально напоминает обыкновенную пиявку (Macrobdella decora) — типичный пищевой объект рыбы-хозяина малого окуня (smallmouth bass). С использованием геномных методов, разведения в неволе и поведенческого анализа авторы подтвердили, что это истинный полиморфизм внутри популяции, потенциально контролируемый одним генетическим локусом. Связь с областью ASH крайне косвенная: вид пиявки служит лишь визуальной моделью для мимикрии моллюска, и никакие пиявки не изучались, не собирались и иным образом не были задействованы. Исследование не предоставляет никакой информации, значимой для гирудотерапии, биологии пиявок или секретома пиявок.
Цитирование
Polymorphism in the aggressive mimicry lure of the parasitic freshwater mussel.
Hewitt TL et al. · PeerJ, 2024
Связанный клинический контекст
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