Genomic evidence for population-specific responses to coevolving parasites in a New Zealand freshwater snail

Abstract

28Reciprocal coevolving interactions between hosts and parasites are a primary source of strong 29 selection that can promote rapid and often population-or genotype-specific evolutionary change. 30These host-parasite interactions are also a major source of disease. Despite their importance, very 31 little is known about the genomic basis of coevolving host-parasite interactions in natural 32 populations, especially in animals. Here, we use gene expression and sequence evolution 33 approaches to take critical steps towards characterizing the genomic basis of interactions between 34 the freshwater snail Potamopyrgus antipodarum and its coevolving sterilizing trematode parasite, 35Microphallus sp., a textbook example of natural coevolution. We found that Microphallus-36 infected P. antipodarum exhibit systematic downregulation of genes relative to uninfected P. 37antipodarum. The specific genes involved in parasite response differ markedly across lakes, 38 consistent with a scenario where population-level coevolution is leading to population-specific 39 host-parasite interactions and evolutionary trajectories. We also used an

De novotranscriptome characterization of a sterilizing trematode parasite (Microphallussp.) from two species of New Zealand snails

“…2009). Consistent with the expectation of local adaptation, M. livelyi infection is associated with population-specific patterns of gene expression and genetic differentiation in P. antipodarum (Bankers et al . in review).…”

“…We thank Gery Hehman for RNA sequencing assistance, Curt Lively, Daniela Vergara, Katelyn Larkin, and Mike Winterbourn for field collections, and Joel Sharbrough for the custom python script (github.com/jsharbrough/grabContigs). This project was funded by Sigma-Xi (grant number 18911100 BR01; L. Bankers), the Iowa Science Foundation (grant number 14-03; M.…”

“…Bankers), the Iowa Science Foundation (grant number 14-03; M. Neiman and L. Bankers), the National Geographic Society (grant number 9595-14; K. Larkin) and the National Science Foundation (NSF-MCB grant number 1122176; M.…”

Adaptive phenotypic plasticity in a clonal invader

“…Twenty‐three of these SNPs were already available (https://www.ncbi.nlm.nih.gov/projects/SNP/snp_viewBatch.cgi?sbid=1059300; Paczesniak et al., ), and 39 SNPs were newly developed. For the latter, we mapped RNA‐Seq reads obtained from the NCBI Sequence Read Archive (SRA) of a female P. antipodarum individual from New Zealand lake Alexandria (SRA accession: ) against 3200 randomly selected contigs from the P. antipodarum transcriptome assembly (Bankers et al., ; DDBJ/EMBL/GenBank accession: GFLZ00000000) with Bowtie2 (Langmead & Salzberg, ). We then used SAMtools MPileup version 2.0 (Li et al., ) to call single‐nucleotide variants of the mapped reads.…”

Genomic and phenotypic consequences of asexuality

“…The population structure I observed here reflects patterns of haplotype structure at the mitochondrial genomic level , providing an orthogonal line of evidence for genetic variation underlying phenotypic variation in this species. Evidence from other work agrees with this conclusion: sympatric trematode parasites infect snail hosts at a higher rate than allopatric parasites (Lively et al 2004), and gene expression profiles (Bankers et al 2016) and responses to nutrient limitation are lake specific, such that lake of origin appears to be an important predictor of phenotype.…”