Equation 3 calculates, for every host (in either habitat) that shares parasitoids with host j i in habitat the expected per capita attack rate on host of parasitoids that were reared A, i from host This expected per capita attack rate on host due to parasitoids from host is j. i j then multiplied by the + 1 abundance of species to convert the rate to a number of t j parasitism events. When summed over all this gives the expected number of attacks H, (not rate) on species at time + 1, which can then be divided by the abundance of i t species at time + 1 to give the expected parasitism rate (Fig. 1i). In cases where more i t attacks were predicted than hosts were collected in the + 1 collection, expected t parasitism rates were greater than one. We reduced these expected parasitism rates to 1 in our analysis because our definition of parasitism rate was parasitized hosts / total hosts (i.e. host centric), so rates greater than one are not possible. Equation 3 is written such that the expected parasitism rate of host increases in i proportion to the abundance of host Thus, it assumes apparent competition between j. hosts that share parasitoids, rather than apparent mutualism. A positive correlation between expected and observed parasitism rate would therefore suggest that apparent competition is more important than apparent mutualism, whereas a negative correlation would suggest that apparent mutualism is more important than apparent competition. For the entire herbivore assemblage, we tested whether this expected parasitism rate significantly predicted the observed parasitism rate of each host species at time + i t 1, which was calculated as: (4) where all variables are defined and calculated as in equation 3 (Fig. 1j).
Equation 3 calculates, for every host j (in either habitat) that shares parasitoids with host i in habitat A, the expected per capita attack rate on host i of parasitoids that were reared from host j. This expected per capita attack rate on host i due to parasitoids from host j is then multiplied by the t + 1 abundance of species j to convert the rate to a number of parasitism events. When summed over all H, this gives the expected number of attacks (not rate) on species i at time t + 1, which can then be divided by the abundance of species i at time t + 1 to give the expected parasitism rate (Fig. 1i). In cases where more attacks were predicted than hosts were collected in the t + 1 collection, expected parasitism rates were greater than one. We reduced these expected parasitism rates to 1 in our analysis because our definition of parasitism rate was parasitized hosts / total hosts (i.e. host centric), so rates greater than one are not possible. Equation 3 is written such that the expected parasitism rate of host i increases in proportion to the abundance of host j. Thus, it assumes apparent competition between hosts that share parasitoids, rather than apparent mutualism. A positive correlation between expected and observed parasitism rate would therefore suggest that apparent competition is more important than apparent mutualism, whereas a negative correlation would suggest that apparent mutualism is more important than apparent competition. For the entire herbivore assemblage, we tested whether this expected parasitism rate significantly predicted the observed parasitism rate of each host species i at time t + 1, which was calculated as: (4) where all variables are defined and calculated as in equation 3 (Fig. 1j).
NCOMMS-16-01466B_main%20text_AMK_CFFinal.docx