Patterns of potential cross-species transmission in planktonic
multihost-multiparasite communities
Abstract
Most parasite species infect multiple host species, and reciprocally,
most hosts are infected by multiple parasites. This leads to complex
webs of interactions that influence disease within the community, making
it challenging to understand and predict disease spread within the
community and epidemics. Here, we used network approaches to analyze a
multi-year time series dataset that includes eight zooplankton host
species (in the Daphnia and Ceriodaphnia genera) and seven microparasite
species to examine patterns of cross-species transmission. These
analyses suggest that parasite species varied in their ability to infect
multiple host species and in which host species they most commonly
infected. Three parasites (the bacteria Pasteuria ramosa and
Spirobacillus cienkowskii and the oomycete Blastulidium paedophthorum)
showed signatures of relatively high cross species transmission, while
the others seemed more restricted. Even for the three common multihost
parasites, our approach also revealed differences in patterns of
potential cross species transmission. For P. ramosa, two host species,
Daphnia dentifera and D. retrocurva, seem particularly likely to
transmit across species; in contrast, for S. cienkowskii, no host
species stands out as particularly important for cross species
transmission. Additionally, these patterns matched those describing
epidemic size, suggesting that infected host density may drive
cross-species transmission. These results are based on observations of
patterns of infection in natural communities, and therefore we cannot
draw definitive conclusions about interspecific transmission in lakes.
However, some of the patterns are supported by additional lines of
evidence, and others point to interesting avenues for future research.
Together, these findings provide additional evidence that network
approaches can provide valuable insights into patterns of transmission
in complex multihost-multiparasite communities in nature.