We calculate β1 and β2 diversities under the equivalent number approach (Ricotta and Szeidl, 2009), using the third proposition of the Rao index of diversity in Pavoine et al. (2016, https://doi.org/10.1111/2041-210X.12591) specifically developed for unbalanced samplings.
Statistical analyses
We compare each of the β1 and β2 TD, FD and PPD with 999 randomly simulated β1 and β2 values in order to establish whether the observed values significantly differ from those randomly simulated (p < 0.05).
When significant, we compare observed and simulated results to determine whether the observed β1 or β2 are greater or lower than expected at random. This allows determining whether parasite communities from fish of the same species (β1) or of different fish species (β2) are more similar (the observed value is lower than simulated values) or more dissimilar (the observed value is greater than simulated values) to each other than expected by chance. Finally, we use the standardised β1 and β2 given by EqRao function ((observed β – mean of randomly simulated βs)/ standard deviation of randomly simulated βs)) to infer if the parasite species, traits or the phylogenetic proxy are overdispersed (negative standardised β) or clustered (positive standardised β) (Head et al., 2018, https://doi.org/10.1002/ece3.3969) within a level of a factor (β1) or between levels of a factor (β2).
eqrao1TDbeta1rt_s2 <- rtestEqRao(host1_s2, NULL,
structure=as.data.frame(h1data_s2$host.species,
row.names=row.names(host1_s2)),
formula="QE", level=1, nrep=999,
option="normed1", alter="two-sided",
wopt="speciesab")
eqrao1TDbeta2rt_s2 <- rtestEqRao(host1_s2, NULL,
structure=as.data.frame(h1data_s2$host.species,
row.names=row.names(host1_s2)),
formula="QE", level=2, nrep=999,
option="normed1", alter="two-sided",
wopt="speciesab")
eqrao1TDbeta1rt_s2
## Monte-Carlo test
## Call: rtestEqRao(comm = host1_s2, dis = NULL, structures = as.data.frame(h1data_s2$host.species,
## row.names = row.names(host1_s2)), formula = "QE", option = "normed1",
## wopt = "speciesab", level = 1, nrep = 999, alter = "two-sided")
##
## Observation: 0.1047394
##
## Based on 807 replicates
## Simulated p-value: 0.00990099
## Alternative hypothesis: two-sided
##
## Std.Obs Expectation Variance
## -2.6382911249 0.1653243891 0.0005273329
eqrao1TDbeta2rt_s2
## Monte-Carlo test
## Call: rtestEqRao(comm = host1_s2, dis = NULL, structures = as.data.frame(h1data_s2$host.species,
## row.names = row.names(host1_s2)), formula = "QE", option = "normed1",
## wopt = "speciesab", level = 2, nrep = 999, alter = "two-sided")
##
## Observation: 0.2721615
##
## Based on 999 replicates
## Simulated p-value: 0.001
## Alternative hypothesis: two-sided
##
## Std.Obs Expectation Variance
## 1.389996e+01 2.226948e-02 3.232049e-04
eqrao1FDbeta1rt_s2 <- rtestEqRao(host1_s2, traits1dist_s2,
structure=as.data.frame(h1data_s2$host.species,
row.names=row.names(host1_s2)),
formula="QE", level=1, nrep=999,
option="normed1", alter="two-sided",
wopt = "speciesab")
eqrao1FDbeta2rt_s2 <- rtestEqRao(host1_s2, traits1dist_s2,
structure=as.data.frame(h1data_s2$host.species, row.names=row.names(host1_s2)),
formula="QE", level=2, nrep=999,
option="normed1", alter="two-sided",
wopt="speciesab")
eqrao1FDbeta1rt_s2
## Monte-Carlo test
## Call: rtestEqRao(comm = host1_s2, dis = traits1dist_s2, structures = as.data.frame(h1data_s2$host.species,
## row.names = row.names(host1_s2)), formula = "QE", option = "normed1",
## wopt = "speciesab", level = 1, nrep = 999, alter = "two-sided")
##
## Observation: 0.06511553
##
## Based on 815 replicates
## Simulated p-value: 0.08455882
## Alternative hypothesis: two-sided
##
## Std.Obs Expectation Variance
## -1.7272504950 0.0893893150 0.0001974987
eqrao1FDbeta2rt_s2
## Monte-Carlo test
## Call: rtestEqRao(comm = host1_s2, dis = traits1dist_s2, structures = as.data.frame(h1data_s2$host.species,
## row.names = row.names(host1_s2)), formula = "QE", option = "normed1",
## wopt = "speciesab", level = 2, nrep = 999, alter = "two-sided")
##
## Observation: 0.06919576
##
## Based on 999 replicates
## Simulated p-value: 0.001
## Alternative hypothesis: two-sided
##
## Std.Obs Expectation Variance
## 1.246912e+01 7.453016e-03 2.451885e-05
eqrao1PDbeta1rt_s2 <- rtestEqRao(host1_s2, phylo1dist_s2,
structure=as.data.frame(h1data_s2$host.species,
row.names=row.names(host1_s2)),
formula="QE", level=1, nrep=999,
option="normed1", alter="two-sided",
wopt="speciesab")
eqrao1PDbeta2rt_s2 <- rtestEqRao(host1_s2, phylo1dist_s2,
structure=as.data.frame(h1data_s2$host.species,
row.names=row.names(host1_s2)),
formula="QE", level=2, nrep=999,
option="normed1", alter="two-sided",
wopt="speciesab")
eqrao1PDbeta1rt_s2
## Monte-Carlo test
## Call: rtestEqRao(comm = host1_s2, dis = phylo1dist_s2, structures = as.data.frame(h1data_s2$host.species,
## row.names = row.names(host1_s2)), formula = "QE", option = "normed1",
## wopt = "speciesab", level = 1, nrep = 999, alter = "two-sided")
##
## Observation: 0.0570059
##
## Based on 842 replicates
## Simulated p-value: 0.1696323
## Alternative hypothesis: two-sided
##
## Std.Obs Expectation Variance
## -1.391586659 0.074635884 0.000160503
eqrao1PDbeta2rt_s2
## Monte-Carlo test
## Call: rtestEqRao(comm = host1_s2, dis = phylo1dist_s2, structures = as.data.frame(h1data_s2$host.species,
## row.names = row.names(host1_s2)), formula = "QE", option = "normed1",
## wopt = "speciesab", level = 2, nrep = 999, alter = "two-sided")
##
## Observation: 0.04934041
##
## Based on 999 replicates
## Simulated p-value: 0.001
## Alternative hypothesis: two-sided
##
## Std.Obs Expectation Variance
## 1.413003e+01 5.034587e-03 9.831846e-06
ADEgS(c(plot(eqrao1TDbeta1rt_s2,
main=expression(paste("(a) Case 1, autumn 2004, TD, ",beta,"1")),
plot=F),
plot(eqrao1TDbeta2rt_s2,
main=expression(paste("(d) Case 1, autumn 2004, TD, ",beta,"2")),
plot=F),
plot(eqrao1FDbeta1rt_s2,
main=expression(paste("(b) Case 1, autumn 2004, FD, ",beta,"1")),
plot=F),
plot(eqrao1FDbeta2rt_s2,
main=expression(paste("(e) Case 1, autumn 2004, FD, ",beta,"2")),
plot=F),
plot(eqrao1PDbeta1rt_s2,
main=expression(paste("(c) Case 1, autumn 2004, PPD, ",beta,"1")),
plot=F),
plot(eqrao1PDbeta2rt_s2,
main=expression(paste("(f) Case 1, autumn 2004, PPD, ",beta,"2")),
plot=F)),
layout = c(3, 2))
Figure 2. Observed and simulated β diversity values (Case 1: autumn 2004). (a, b, c) β1 diversity or extent of dissimilarity in the diversity of parasite communities among host individuals within each host species (Chelon auratus, Mugil cephalus and Chelon ramada). (d, e, f) β2 diversity or extent of dissimilarity in the diversity of parasite communities between host species. Diversity was measured in terms of (a, d) Taxonomic Diversity (TD), (b, e) Functional Diversity (FD) and (c, f) the Proxy of Phylogenetic Diversity (PPD). Samples are from Santa Pola Lagoon and autumn 2004 (Case 1). Observed β values (black diamond on the top of the black vertical line) and distribution of the simulated (x-axis: sim) β values (grey bars).