Non-overlapping climatic niches and biogeographic barriers explain disjunct distributions of continental Urania moths

Claudia Nuñez-Penichet,Marlon E Cobos,Jorge Soberon

doi:10.21425/f5fbg52142

Abstract

Larvae of Urania moths feed exclusively on Omphalea plants, which are widely distributed in the Neotropics. However, the distributions of the two Urania species in this region are disjunct. This distributional pattern could derive from the presence of the Andes, but it could also be related to differences in ecological niches, the presence of negative interactions, or the absence of conditions that can only be observed at a habitat level. We tested whether differences in the ecological niches of continental Urania moths play a role in their disjunct distribution. Using species records and climatic variables, we characterized the ecological niches of Urania moths and their host plants and analyzed the overlap of the moths' niches. Using ecoregions as a proxy of habitat-level environmental conditions, we explored the role of host plant availability on the moth distributions. Suitable conditions for the species were widespread, with a lack of suitability mostly restricted to the Andean highlands. The two moth distributions were closely related to that of their host plants. There was medium-high overlap of niche models when available conditions were considered; however, niche overlap was not found to be statistically significant. Our results corroborate the barrier effect of the Andes on the dispersal of these moths, but they also show that niche differences contribute to the disjunct distributions of U. fulgens and U. leilus. Furthermore, other non-climatic factors appear to play a crucial role in the disjunction of the species ranges in areas where overlapping suitable conditions are continuous. Our findings support speciation in Urania moths as allopatric and indicate that their disjunct distributions can be attributed to multiple factors. Other studies exploring the causes of similar distributional patterns should consider that a single factor may not be enough to explain such patterns.

Highlights

There are several combined factors that determine the regions of the Earth that a species occupies
We found that the Andean mountain range and ecoregions associated can be the major factors maintaining the disjoint distribution of continental Urania moths
A reduction of suitable areas for U. fulgens was more pronounced in the midHolocene, whereas these areas were even smaller in the Last Glacial Maximum for U. leilus and Omphalea species (Table 2)

Summary

Introduction

There are several combined factors that determine the regions of the Earth that a species occupies. The literature mentions that these factors include suitable climate and habitat, availability of food, lack of natural enemies and competitors, and the capacity to reach favorable localities (Good 1931, Cain 1944, Darwin 1859, Udvardy 1969, Soberón and Peterson 2005). Geographic distributions of species because favorable environmental conditions often occur outside of a species range. Another factor affecting the distribution of a species is habitat suitability, which is understood to be the availability of certain structural conditions in the landscape that are necessary for survival or reproduction. Because habitat-level characteristics can only be appreciated on a finer scale than climatic conditions, and information is often limited (Lindenmayer et al 1991), these factors are usually disregarded in macroecological analyses of species distributions (Soberón 2007)

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