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

Abstract

Species distribution models (SDMs) have conventionally been used for evaluating the distribution of individual species, but they can also be used, through comparing different SDMs, to evaluate the geographic similarity between taxa. In this study, we used a parasite and host system to infer the geographic overlaps between species with tight biological interaction, for example, parasites and their obligate host. Specifically, we used the horsehair worm Chordodes formosanus and its three mantis hosts to study the extent of niche overlap. We retrieved presence points for the host species and the parasite, and then we built SDMs with MaxEnt implemented in ENMeval using selected bioclim variables (based on variance inflation factor values) at 30s scale. The models showed that the hosts and parasite do not occur in the high elevation areas in Taiwan, which is 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 a high similarity of SDM predictions between hosts and the parasite. There were differences among metrics for which host shared the highest similarity with the parasite, but the majority of the results indicated that the Japanese boxing mantis had the highest niche similarity with the horsehair worm. The choice of the niche overlap metric to use can uncover information 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 improve our understanding of parasite biology and ecology.

Testing the efficacy of different molecular tools for parasite conservation genetics: a case study using horsehair worms (Phylum Nematomorpha)

“…Therefore, dispersal by host (intermediate and/or final ones) with or without a multigenerational process can be a possible explanation for this pattern. Previous modelling efforts noticed a very high similarity between the mantis hosts’ range and the range of C. formosanus , hinting at a potential dispersal by definitive hosts (De Vivo and Huang, 2022). Currently, the intermediate hosts of C. formosanus are only partially known (Chiu, 2017) and include non-biting midges in the family Chironomidae, the caddisfly Chimarra formosana and stoneflies in the genus Kamimuria (Chiu et al , 2016; Chiu, 2017), with a seeming preference for the dipteran family (Chiu et al , 2016).…”

“…Therefore, A. taiwanensis may have gone extinct in some areas in Taiwan due to human intervention, especially in areas where agricultural land expanded in the past or in recent years (Chen et al , 2019). This potential extirpation may also explain the lack of C. formosanus reports in highly farmed areas (De Vivo and Huang, 2022) and highlight the possible reaction of hairworms to pesticides (Achiorno et al ., 2018).…”

“…That said, it is surprising that this species, which is regarded as the most common in Taiwan, is showing signs of decline-although the current Ne should still be way larger than enough to sustain the population (Franklin, 1980;Pérez Pereira et al, 2022). The recent demographic decrease might be the result of extirpation events (Legendre et al, 2008) possibly caused by changes in land use in Taiwan (De Vivo and Huang, 2022), given that hairworms are sensitive to human activities and pollution (Poinar, 2008;Sato et al, 2014;Chiu et al, 2016;Achiorno et al, 2018).…”

Testing the efficacy of different molecular tools for parasite conservation genetics: a case study using horsehair worms (Phylum: Nematomorpha)

“…Furthermore, the presence of this species in Lyudao (Chiu et al ., 2011 ), a volcanic island that has never been connected to the main island of Taiwan (Yang et al ., 1996 ), implies sea crossing. Previous modelling efforts noticed a very high similarity between the mantis hosts' range and the range of C. formosanus , hinting at dispersal by definitive hosts, although the dispersal by paratenic ones cannot be excluded (De Vivo and Huang, 2022 ; Sup. Info).…”

The past, present, and future of predator–prey interactions in a warming world: Using species distribution modeling to forecast ectotherm–endotherm niche overlap

“…It is often difficult to determine the degree of importance of biotic interactions on the distribution of a species' suitable habitat, and calculating niche overlap can be an alternative method to direct integration in models (Warren et al., 2008). This method has been used previously to examine overlap between predator and prey (Holt et al., 2018) and host–parasite species pairs (De Vivo & Huang, 2022). Additionally, overlap metrics have been used recently to examine similarities in ecological factors such as space use and foraging habits, as climate change leads to species colonizing new areas (Berlusconi et al., 2022; Chen et al., 2022).…”