Supplementary materials for "Modeling the geographical distributions of Chordodes formosanus and its mantis hosts in Taiwan, with considerations for their niche overlaps"

Species distribution model (SDM) has conventionally been used for evaluating the
distribution of single species, but comparisons between different SDMs are possible for
evaluating the geographic similarity between taxa. Here we used a parasite and host system
to infer the geographic overlaps between species with tight biological interaction, e.g.
parasites and their obligate host; specifically, we used the horsehair worm Chordodes
formosanus and its three different mantis hosts to study the extent of niche overlap. We
retrieved presence points for the host species and the parasite and we built the SDMs with
MaxEnt implemented in ENMeval by using selected bioclim variables (based on VIF values)
at a 30 seconds scale. The models showed that the hosts and parasite do not occur in the high
elevation areas in Taiwan, which was expected based on their biology. Interestingly, the
predicted parasite distribution included areas without collection records, implying local
extinction or sampling bias. We subsequently evaluated niche overlap between hosts and the
parasite according to five similarity indices (Schoener’s D, I statistic, relative rank, Pearson
correlation coefficient and the rank correlation coefficient rho). Our models showed high
similarity of SDM predictions between hosts and the parasite. There were differences among
metrics about which host shared the highest similarity with the parasite, but the majority of
the results indicated that the Japanese boxing mantis has the highest niche similarity with the
horsehair worm. The choice of the niche overlap metric to use can be seen as a way to get
informations on the parasite’s ecology, which can be important for endangered species SDMs
are reliable tools for host and parasite conservation management and could help to improve
biological and ecological knowledge of parasites.