10.5061/DRYAD.WH70RXWNM
Tadiri, Christina
0000-0002-9305-1960
McGill University
Fussmann, Gregor
McGill University
Scott, Marilyn
0000-0002-3553-4550
McGill University
Individual fish infection data from metapopulation epidemics used to
calculate resistance, tolerance and competence
Dryad
dataset
2021
parasite ecology
Fonds de Recherche du Québec – Nature et Technologies
https://ror.org/00b9f9778
Natural Sciences and Engineering Research Council
https://ror.org/01h531d29
2021-07-09T00:00:00Z
2021-07-09T00:00:00Z
en
47805 bytes
4
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Host competence, defined as the likelihood that a host will transmit
infection, may be affected by an individual’s resistance to infection and
its ability to withstand damage caused by infection (tolerance). Host
competence may therefore be one of the most important factors to impact
host-parasite dynamics, yet the relationships among resistance, tolerance,
and competence are poorly understood. The objective of the present study
was to determine whether individual host resistance (ability to resist or
minimize infection) and/or tolerance (ability to withstand or minimize
reduction in fitness due to infection) contributed to the competence
(ability to spread infection) of hosts using guppies infected with the
ectoparasite, Gyrodactylus turnbulli. This individual-fish level analysis
used data collected from a previous metapopulation experiment that had
tracked host-parasite dynamics at the metapopulation scale using
individually marked guppies that were moved among experimental tanks
within replicate metapopulations. Fish tolerance was measured as the
residual from a fish’s expected survival post-infection for a given
parasite burden. Fish resistance was measured as the peak parasite load (
- log-transformed). Host competence was measured as the incidence (number
of new infections over two days after the arrival of a fish to a tank)
weighted by the density of available uninfected fish in the tank. In
contrast to the assumption of a trade-off between resistance and
tolerance, individual fish tolerance and resistance were both negatively
associated with competence. Connectivity (the number of fish with which an
individual came into contact) was not associated with competence. Our
results indicate that resistance and tolerance are both important to
disease spread. These findings highlight the importance of understanding
how individual defence against parasites may contribute to its competence
as a host, and therefore impact metapopulation-level dynamics.
Fish were weight, measured, marked and assembled into metapopulations
consisting of 4 tanks each of 8 fish. Parasites were then introduced to
the metapopulations either by infecting one fish in each tank with 2
parasites, or by infection four fish in one tank with two parasites.
Infections on each individual were then monitored every two days either
for 120 days or until no parasites were found in the whole metapopualtion
for two consecutive counting days. Additionally, every 10 days one fish
from each tank was haphazardly selected and moved to the next tank in the
metapopulation in a unidirectional looped manner
(A->B->C->D->A). The raw data recorded for
each fish (uploaded here) were initial weight and length, location within
the metapopulation for each 10-day interval and parasite load every two
days. These raw data were then used to calculate our variables of
interest. Resistance to parasites was calculated as the fish's
maximum parasite burden (-log-transformed). Tolerance to parasites was
calculated as the residual from a fitted exponential decay curve of
survival post-infection and maximum parasite load. Competence of an
individual fish was measured as the number of uninfected fish in a tank
that became infected two days after that fish was introduced to that tank,
multiplied by the density of uninfected fish in the tank and excluding
cases where all fish in the tank were already infected or the migrating
fish was uninfected to account for opportunity. For infected fish that
moved to tanks with uninfected fish more than once, an average of this
competence was used.