Distribution patterns of the two genetic groups of Corbicula fluminea in a lotic–lentic system

Abstract

Differences in local habitat conditions are often implicated as drivers for morphological and genetic divergence in natural populations. However, there are still relatively few studies regarding how divergent habitats influence patterns for morphotypes and genetic lineages in aquatic invertebrates. In this study, we explored the morphological patterns, genetic divergence, and distributions of a bivalve, Corbicula fluminea, in a lotic–lentic system. Sampling locations included lotic, ecotone, and lentic habitats. First, we found two lineages (Lineages A and B) with significant genetic divergence that primarily corresponded to two morphotypes (Morphs D and C) of C. fluminea. Lineage A consisted of 88.68% Morph D (shell sculpture: 8–14 ridges/cmsh) and 11.32% Morph C (shell sculpture: 15 ridges/cmsh) individuals and had genetic similarity to invasive populations. Lineage B consisted of only Morph C (shell sculpture: 15–23 ridges/cmsh). Second, we revealed clear effects of habitat on the spatial distribution patterns for the two lineages of C. fluminea. Lineage A was dominant in lotic habitats, with a significantly higher density than that of Lineage B in these locations. Lineage B was dominant in lentic habitats. However, both lineages had their highest densities in the ecotone habitat, without clear dominance and no significant difference in density between groups. Individuals of Lineages A and B are different in shell morphology, which may be related to a benefit trade‐off between shell shapes that allow for rapid burrowing and holding position in different flow conditions. The distribution patterns indicate that Lineages A and B may not prefer uniquely lotic and lentic habitats, but each lineage is more tolerant to one habitat type, respectively. Generally, our study established a correlation among morphotypes, lineages, and different habitats for C. fluminea along a lotic–lentic gradient system, which has important implementations for fisheries management units and for understanding the role of habitat preference for this species in monitoring for pioneer dispersal in invasive species management.

Morphological and Genetic Assessment of Invasive Corbicula Lineages in Southern South America: A Case Study in Argentina

“…Consequently, the scientific consensus has leaned towards classifying Corbicula as a "complex of polymorphic species" [6]. However, this classification does not imply ecological equivalence among different forms; in fact, there are lineage disparities not only in morphology but also in microhabitat preferences [60,61], individual growth rates [62,63], reproductive event frequency, offspring release numbers [64], and physiological traits such as filtration [65] and metabolic rates [17]. The pronounced segregation of forms and haplotypes discovered across Argentina bolsters this notion.…”

“…The pronounced segregation of forms and haplotypes discovered across Argentina bolsters this notion. It has been suggested that some of the variability in life-history traits may have a genetic basis [11,61], although phenotypic plasticity could also be a contributing factor, as observed in other freshwater invasive bivalves [16]. Further research is necessary to determine their relative significance, as well as to assess the potential adaptive advantages conferred by these differences in various environmental conditions, and their implications for distribution patterns.…”