Family data from Larkin et al. 2015 Ecol Evol

Family means and variance

Mitochondrial (cytochrome b) haplotypes in Potamopyrgus antipodarum (with outgroup)

Sequences of unique haplotypes of mitochondrial cytochrome-b fragment in Potamopyrgus antipodarum. Homologous sequence for related species (P. estuarinus) is included an an outgroup

Ploidy level, gender and nuclear (SNP) genotypes for Potamopyrgus antipodarum snails from 16 New Zealand lake populations

Ploidy level, gender and nuclear (SNP) genotypes for Potamopyrgus antipodarum snails from 16 New Zealand lake population

Mean SGR of snails in the high-P <i>vs</i>. low-P treatments. Error bars are 95% confidence intervals.

<p><i>Potamopyrgus antipodarum</i> fed the low-P diet grew at a significantly lower rate than snails fed the high-P diet. There were also significant differences in SGR among lakes, driven by significantly higher SGR in Brunner (N = 41) and Selfe (N = 54) snails relative to Hawdon (N = 81; <i>p</i><0.001 for both comparisons) and a marginally significant lake by diet treatment interaction (<i>F</i>_{2, 170} = 2.52, <i>p</i> = 0.083).</p

More snails attained the 3.0<i>P. antipodarum</i> in the high-P <i>vs</i>. low-P diet treatment (Fisher's exact test, <i>p</i><0.0001).

<p>More snails attained the 3.0<i>P. antipodarum</i> in the high-P <i>vs</i>. low-P diet treatment (Fisher's exact test, <i>p</i><0.0001).</p

Response to Phosphorus Limitation Varies among Lake Populations of the Freshwater Snail <i>Potamopyrgus antipodarum</i>

<div><p>Local adaptation – typically recognized as higher values of fitness-related traits for native <i>vs</i>. non-native individuals when measured in the native environment - is common in natural populations because of pervasive spatial variation in the intensity and type of natural selection. Although local adaptation has been primarily studied in the context of biotic interactions, widespread variation in abiotic characteristics of environments suggests that local adaptation in response to abiotic factors should also be common. <i>Potamopyrgus antipodarum</i>, a freshwater New Zealand snail that is an important model system for invasion biology and the maintenance of sexual reproduction, exhibits local adaptation to parasites and rate of water flow. As an initial step to determining whether <i>P. antipodarum</i> are also locally adapted to phosphorus availability, we examined whether populations differ in their responses to phosphorus limitation. We found that field-collected juvenile <i>P. antipodarum</i> grew at a lower rate and reached an important size threshold more slowly when fed a relatively low <i>vs</i>. a relatively high- phosphorus diet. We also detected significant across-population variation in individual growth rate. A marginally significant population-by-dietary phosphorus interaction along with a two-fold difference across populations in the extent of suppression of growth by low phosphorus suggests that populations of <i>P. antipodarum</i> may differ in their response to phosphorus limitation. Local adaptation may explain this variation, with the implication that snails from lakes with relatively low phosphorus availability should be less severely affected by phosphorus limitation than snails from lakes with higher phosphorus availability.</p></div

Core OTUs across 75% of all 60 snail samples.

<p>Core OTUs across 75% of all 60 snail samples.</p

Results from random forests classifiers.

<p>Results from random forests classifiers.</p

Distinct Bacterial Microbiomes in Sexual and Asexual <i>Potamopyrgus antipodarum</i>, a New Zealand Freshwater Snail

<div><p>Different reproductive strategies and the transition to asexuality can be associated with microbial symbionts. Whether such a link exists within mollusks has never been evaluated. We took the first steps towards addressing this possibility by performing pyrosequencing of bacterial 16S rRNA genes associated with <i>Potamopyrgus antipodarum</i>, a New Zealand freshwater snail. A diverse set of 60 tissue collections from <i>P</i>. <i>antipodarum</i> that were genetically and geographically distinct and either obligately sexual or asexual were included, which allowed us to evaluate whether reproductive mode was associated with a particular bacterial community. 2624 unique operational taxonomic units (OTU, 97% DNA similarity) were detected, which were distributed across ~30 phyla. While alpha diversity metrics varied little among individual samples, significant differences in bacterial community composition and structure were detected between sexual and asexual snails, as well as among snails from different lakes and genetic backgrounds. The mean dissimilarity of the bacterial communities between the sexual and asexual <i>P</i>. <i>antipodarum</i> was 90%, largely driven by the presence of Rickettsiales in sexual snails and <i>Rhodobacter</i> in asexual snails. Our study suggests that there might be a link between reproductive mode and the bacterial microbiome of <i>P</i>. <i>antipodarum</i>, though a causal connection requires additional study.</p></div

Analysis of similarity (ANOSIM) of Bray-Curtis distances among snail bacterial communities by sample factor.

<p>Analysis of similarity (ANOSIM) of Bray-Curtis distances among snail bacterial communities by sample factor.</p