Joint species distributions reveal the combined effects of host plants, abiotic factors and species competition as drivers of species abundances in fruit flies

Abstract

The relative importance of ecological factors and species interactions for phytophagous insect species distributions has long been a controversial issue. Using field abundances of eight sympatric Tephritid fruit flies on 21 host plants, we inferred flies’ realized niches using joint species distribution modelling and network inference, on the community as a whole and separately on three groups of host plants. These inferences were then confronted to flies’ fundamental niches estimated through laboratory-measured fitnesses on host plants. Community structure was mainly determined by host plants followed by climatic factors, with a minor role for competition between species sharing host plants. The relative importance of these factors was mildly modulated by host plants. Despite overlapping fundamental niches, specialists and generalists flies almost behaved as separate communities, with possible competitive exclusion of generalists by specialists on Cucurbitaceae and different assembly rules: specialists were mainly influenced by their adaptation to host plants while generalist abundances varied regardless of their fundamental host use.

Sequential invasions by fruit flies (Diptera: Tephritidae) in Pacific and Indian Ocean islands: A systematic review

“…Although researchers have recently followed changes in relationships between species and host range associated with changes in tephritid food webs (Moquet et al, 2021), these analyses should be expanded to additional cases so as to determine which patterns are general for different species and areas. Also needed are studies of life‐history traits of tephritids on numerous resources in the laboratory; the results of such studies can be used to determine fundamental niches, to predict distributions and abundance of tephritid populations in the field, and to better understand and estimate interspecific interactions (Facon et al, 2021). This work has been done for some of the studied species (Charlery de la Masselière, Facon, et al, 2017; Facon et al, 2021; Hafsi, Facon, et al, 2016), but it should be very informative to compare realized and fundamental niches at a larger scale including numerous islands and fruit fly species.…”

“…In the Tephritidae family, abundance and distribution are mainly structured by both abiotic factors, such as temperature and humidity, and biotic ones, mostly host plant distribution and abundance (Duyck et al, 2004; Facon et al, 2021). Although interspecific competition among Tephritidae may not be very important in native communities (Clarke, 2017), in an unstable situation, such as occurs when resident species interact with closely related invasive species, this interspecific exploitative competition may be very strong and asymmetrical, leading to the competitive exclusion or displacement of resident species (Duyck et al, 2004, 2006; Ekesi et al, 2009; Moquet et al, 2021).…”

Metacommunity dynamics and the detection of species associations in co‐occurrence analyses: Why patch disturbance matters

“…Obviously, the amount of spurious species associations detected generally declined with sample size (Table 1), but so would the power to detect genuine species association signals. Moreover, the range of sample sizes we used may quickly become conservative, as more and more ecological studies now have datasets with several hundreds or thousands of patches sampled (Dubart et al., 2019; Facon et al., 2021; Opedal, Ovaskainen, et al., 2020). The development of metagenomics and microbiome studies will undoubtedly contribute to this upward trend in sample sizes, and so the phenomenon reported here could become more and more prevalent.…”

“…We varied the sample size (number of patches in the co‐occurrence matrices) between 300 and 1,500, with intermediate values 500 and 1,000 (for recent studies using similar sample sizes, see Dubart et al., 2019; Facon et al., 2021; Opedal, Ovaskainen, et al., 2020). Finally, we also considered the possibility that not all species might be affected by patch disturbance: some species might be immune to disturbance (‘immune species’).…”

Metacommunity dynamics and the detection of species associations in co-occurrence analyses: why patch disturbance matters

“…We varied the sample size (number of patches in the co-occurrence matrices) between 300 and 1500, with intermediate values 500 and 1000 (for recent studies using similar sample sizes, see Dubart et al, 2019; Opedal et al, 2020a; Facon et al, 2021). Finally, we also considered the possibility that not all species might be affected by patch disturbance: some species might be immune to disturbance (“immune species”).…”