Rewilding shows differential fitness of sympatric Physella acuta (Draparnaud, 1805) snail lineages

Abstract

The globally invasive freshwater snail, Physella acuta (Draparnaud, 1805) is genetically diverse, with cox1 haplotype markers identifying an invasive lineage (A) and a non-invasive lineage (B) restricted to its native North American habitat. This study investigated the differential fitness of A and B lineages within the species. Field-collected P. acuta were genetically characterized to establish laboratory strains representing mitotypes A and B. While the nuclear rDNA cassette (7,023 nt) differed only by 0.03% between A and B, the mitogenome haplotypes differed in size (14,383 vs. 14,333 bp) and sequence content (~ 9%). Fitness (growth rate, age and size at maturity, reproductive output) of A and B did not differ under laboratory conditions. A rewilding approach (exposure to native range field conditions) revealed greater fitness of P. acuta A relative to B snails, indicated by greater population-level fecundity, greater realized fecundity of A versus B, and higher survival rates of A in 3 of 7 experiments. While laboratory-based studies indicated only minor differences, the rewilding approach revealed significant differential fitness between A and B lineages of the species P. acuta, potentially influencing geographical distribution.