Fig 1.
Geographic distribution of sympatric E. fulvus and E. mongoz across dry-deciduous forests in the Boeny region, northwestern Madagascar.
Also marked are the locations of Mariarano Classified Forest (MCF) and Ankarafantsika National Park (ANP). Map includes species ranges reprinted from the IUCN Red List of Threatened Species™ under a CC BY 4.0 license, with permission from IUCN, original copyright IUCN, 2024.
Table 1.
Partial ROC evaluation summary for final E. fulvus and E. mongoz MaxEnt models within accessible area M. Partial ROC ratio and 95% bootstrap CI focus on the high-sensitivity (low-omission) region defined by E and summarizes performance as an AUC ratio. Also present is a summary of the parameters for the evaluation and an estimate of the full AUC value for each species’ model.
Table 2.
(A) Estimates of the total occurrence area (ha) and zonal aggregation (Contagion) based on the classified output of our species distribution models for sympatric E. fulvus and E. mongoz populations. (B) Estimates of the total area (ha) for zones where only ones of the E. mongoz and E. fulvus populations are predicted, as well as their predicted zones of co-occurrence.
Fig 2.
Probability distribution of E. fulvus (red) and E. mongoz (blue) across ANP (A, B) and MCF (D, E).
Also present is the comparison of their distribution patterns in each landscape, marking zone of occurrence unique to each species (EF – red and EM – blue) as well as their zone of co-occurrence (white). Basemap hillshade (greyscale) derived from the Shuttle Radar Topography Mission (SRTM) DEM (U.S. Geological Survey/NASA). Protected-area boundary for ANP digitized by the authors from an official Madagascar National Parks map provided during fieldwork (georeferenced using field control points); MCF boundary delineated by the authors to encompass surveyed forest patches. MaxEnt model outputs (10-percentile training presence) are original to this study.
Table 3.
Estimates of the relative permutation importance of 10 independent environmental covariates to our species distribution models for sympatric E. mongoz and E. fulvus populations.
Fig 3.
Partial response curves (PRCs) for the top E. fulvus and E. mongoz SDMs.
PRCs show how the probability of occurrence of each species varies because of variation in each environmental covariate, while keeping all other covariates at their mean sampled value.
Fig 4.
Niche comparison of the environmental conditions occupied by populations of E. fulvus and E. mongoz in northwestern Madagascar.
Panel A includes the PC correlation biplot and the proportion of variance in the environmental data that can be presented in 2-dimensional E-space. The environmental covariates included in this portion of our analysis are presented inside the correlation biplot, projected onto the 2-dimensional E-space to represent their influence on the niche patterns of both species. The length of each arrow represents how well the covariate explains the distribution of the data. If two arrows point in the same direction, those covariates are correlated. Any two arrows pointing in orthogonal (90-degree angles) are unrelated to each other. Arrows pointing in opposite directions are negatively correlated. Panels B and C include kernel density isopleths mapping differences between the E-space of environmental conditions in the sampled range of E. fulvus and E. mongoz for our niche overlap (NOT) and niche divergence (NDT) tests respectively. Interpretation of the isopleths should follow the key listed in the legend. These two panels also list the amount of correlation present in the E-space of both species before correcting for the abundance of common environmental ranges.
Fig 5.
Comparison of niche equivalence and niche background tests between populations of E. fulvus and E. mongoz in northwestern Madagascar.
Panels A and B visualize each species’ distribution across environmental space (E-space) using kernel density isopleths, thereby illustrating how each species’ E-space use clusters and overlaps relative to the other. Panel A shows kernel density isopleths used for the niche overlap test (NOT), and Panel B shows isopleths used for the niche divergence test (NDT), mapping differences between the E-space conditions where E. fulvus and E. mongoz where observed and indicating the correlation structure of the environmental variables before correction. Panels C and D present summaries of our niche overlap (NOT) and niche divergence (NDT) tests, including estimates of niche equivalence in the E-space of E. fulvus and E. mongoz as measured by Schoener’s D niche similarity index, as well as the results of our tests of niche equivalence and background comparison.