Virulence and transmission biology of the widespread, ecologically important pathogen of zooplankton, Spirobacillus cienkowskii

Spirobacillus cienkowskii (Spirobacillus, hereafter) is a widely distributed bacterial pathogen that has significant impacts on the population dynamics of zooplankton (Daphnia spp.), particularly in months when Daphnia are asexually reproducing. Yet little is known about Spirobacillus’ virulence, transmission mode and dynamics. As a result, we cannot explain the dynamics of Spirobacillus epidemics in nature or use Spirobacillus as a model pathogen, despite Daphnia’s tractability as a model-host. Here, we work to fill these knowledge gaps experimentally. We found that Spirobacillus is among the most virulent of Daphnia pathogens, killing its host within a week and reducing host fecundity. We further found that Spirobacillus did not transmit horizontally among hosts unless the host died or was destroyed (i.e., it is an “obligate killer”). In experiments aimed at quantifying the dynamics of horizontal transmission among asexually reproducing Daphnia, we demonstrated that Spirobacillus tran..., Data was collected in the laboratory of M.A. Duffy (U. Michigan) between 2016-2019, according to the experimental methods described in the publication. Broadly, individual Daphnia or cohorts of Daphnia were exposed to Spirobacillus cienkowskii and their symptoms (coloration) and fitness (survival, reproduction) was tracked. , , # Data from: Virulence and transmission biology of the widespread, ecologically important pathogen of zooplankton, *Spirobacillus cienkowskii*

[https://doi.org/10.5061/dryad.d51c5b0c4](https://doi.org/10.5061/dryad.d51c5b0c4)

## Description of the data and file structure

### Files and variables

In all cases, missing values indicated by \"NA\"

#### File: ephippia\_survey.csv

Data from a field survey of ephippia for *Spirobacillus cienkowskii*

##### Variables

* sample_id: unique id of each ephippium
* concentration_ul: no. copies gene per microliter. Note that samples containing <0.048 = are deemed negative. 
* total_sample: no. copies gene per sample. Note that samples containing <0.048= are deemed negative. 
* lake: lake from which sample collected
* species: species of *Daphnia* to which ephippium belongs

#### File: exp\_5b.csv

Data from experiment 5b.

##### Variables

* exp.day: experimental day, where 0 is the day recipients were exposed to putatively infectious materi...