Predicted distribution and climate envelope comparison
The distribution of G. platensis in South America could be driven
by an expansion into novel environments. Thus, our ENM approach focused
on evaluating areas of potentially suitable climate that the species
could invade. This model had good performance and obtained a true
positive fraction of 98% across all known unique localities of the
invaded range (AUC = 0.956, BI = 0.883; Fig. 3). Notably, the ENM
predicted highly suitable climates for G. platensis in the Andes
of Colombia, Ecuador, and Northern Peru. The coastal portion Chile, from
Santiago to Puerto Montt, also showed high suitability, whereas areas at
the southeast of Brazil and Uruguay, east Argentina and the Andes of
Bolivia showed intermediate suitability. In Ecuador, we found three
areas of high suitability in the northern (where we collected the
specimens analyzed in this study), central and southern parts of the
Ecuadorian Andes. Comparison of climate envelopes of the four top
contributing climatic factors and elevation for Ecuador and the rest of
South America highlighted some variation in the occupied niches (Table
1; Fig. 4). For example, the range of G. platensis in Ecuador
revealed significant climate envelope differences related to seasonality
and elevation (Table 1; Fig. 4). Across South America, these beetles
occupy a wide breadth of climatic conditions and elevations. They exist
in elevational ranges spanning low and high altitudes, from 7 m to 3351
m above sea level (a.s.l.). In Ecuador, G. platensis occupies the
highest elevational range with a mean of ca. 2600 (2233–3351) m a.s.l.
(Fig. 4). The lowest elevation ranges were found in Argentina, Chile,
and Uruguay, generally found from 7 to 327 m a.s.l.