Positive and negative frequency dependent parasitism in naturally co-occurring lineages of diploid sexual and polyploid asexual Lumbriculus variegatus

Polyploidisation is an important evolutionary force. It drives sympatric speciation through reproductive isolation of different cytotypes, and often leads to loss of sexual reproduction in polyploid lineages. Polyploidisation and asexuality can change how other species engage in ecological interactions with the polyploid lineage and may change coevolutionary dynamics. Here, we quantified the phenotypic divergence in the freshwater oligochaete worm Lumbriculus variegatus, the California blackworm, among its co-occurring sexual diploid (Lineage II) and asexual polyploid (Lineage I) lineages. We further investigated variation in parasite communities and infection prevalence among sympatric and allopatric diploid/polyploid populations. Ten out of 18 populations showed co-existence of both lineages, with 7 populations harbouring only the polyploid lineage. Both worm lineages hosted  endoparasitic nematodes, an ectoparasitic rotifer, and one potentially symbiotic gut ciliate. The parasit..., , , # Positive and negative frequency dependent parasitism in naturally co-occurring lineages of diploid sexual and polyploid asexual Lumbriculus variegatus

[https://doi.org/10.5061/dryad.18931zd76](https://doi.org/10.5061/dryad.18931zd76)

## Description of the data and file structure

This study examined the distribution of facultative sexual diploid and asexual polyploid aquatic oligochaetes, Lumbriculus variegatus in Switzerland.

A total of 40 samples (with three exceptions, locations HCH =39, location FLO = 39, location KBS = 19) were examined from each of the total 18 locations. The worms were measured using the pipeline phenopype ([https://www.phenopype.org/](https://www.phenopype.org/)) on 1 - 19 pictures per worm (see folder \"pictures_LV\").

Additionally, this study examined the presence and frequency of infections with endoparasitic nematodes, ectoparasitic rotifers and potentially symbiotic ciliates. A few of the nematode samples were sequenced by Sanger sequencing, see sequenc...,