Abstract
AbstractStudying the environmental characteristics of the localities in which different taxa have been observed could help to estimate probable niche differences. Previous studies on local distribution and reproductive behavior of the two subspecies of Canthon rutilans support their allopatry. Here we estimated the geographical distribution of these taxa to examine the congruency between the environmental characteristics of the occurrence localities derived from geographical and local data, in order to facilitate the future study of the causal factors that are more likely to explain their segregation. To do so, a database including most of the available distributional information about these subspecies was compiled. The data derived from 23 environmental variables in the occurrence cells were used to estimate those variables with different mean values among the two subspecies, and also to generate distributional maps reflecting the probable distribution of the two subspecies. Ten variables have statistically significant different values among both subspecies. Canthon rutilans rutilans would be present in colder places, living in the high elevation localities of the Atlantic Forest or Pampas biomes, whereas C. rutilans cyanescens seems to be restricted to lowland forested areas. Probable distribution maps show geographical sympatry in almost half of the distribution range of C. r. rutilans. As former results suggest that they are in allopatry at a local scale, these results propose that fine‐grain environmental factors would be promoting the segregation of taxa, but also that coarse‐grain data should be used with caution when the aim is to estimate niche differences.
Highlights
The multidimensional environmental space defined by the values of non-interactive variables in the occurrence localities of a species could help to delimit their Grinnellian niche (Grinnell 1917; Soberón 2007)
Data coming from a total of 192 individuals of C. r. rutilans belonging to 46 different 2.50 cells and 523 individuals of C. r. cyanescens belonging to 120 different 2.50 cells were compiled during visits to the entomological collections
Mean values for 10 of the 23 considered environmental variables significantly differed between the localities in which both taxa have been observed (Table 1), showing that C. r. cyanescens specimens occur in lowland localities with higher temperature values and lower aridity, opposite to C. r. rutilans
Summary
The multidimensional environmental space defined by the values of non-interactive variables in the occurrence localities of a species could help to delimit their Grinnellian niche (Grinnell 1917; Soberón 2007). A study using fine-grain survey data (≈1 km resolution) suggests that these two subspecies probably do not overlap spatiotemporally (Hensen et al 2018). This supposition is based on the data obtained by a yearly survey in six sites located along an elevational gradient from 200 to 1600 m a.s.l. with an approximate length of 100 km. Further studies will be necessary to corroborate this spatial segregation, recent laboratory breeding experiments (Hensen et al 2020) suggest that these two subspecies could have different thermal preferences in their reproductive behavior and larval development
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