Latitudinal gradient and spatial covariance in species richness of tropical Lepidoptera in the Andes

Abstract

We investigated whether Lepidoptera species richness in the tropical Andes is distributed evenly across the latitudinal gradient, explored the spatial correlations between different taxonomic groups, and investigated historical and ecological factors responsible for shaping the observed patterns. We interpolated species richness from collecting records of nine ecologically diverse taxa of montane Lepidoptera, eight of butterflies (Ithomiini, Acraeini, Callicorini, Pronophilina, Aporiina, Leptophobia, Penaincisalia, and Forsterinaria) and one of moths (Geometridae: Erateina) along elevational transects from 1000 to 3500 m every two degrees in latitude between 11°N and 27°S. We used multiple regression to assess the role of climatic and historical variables in shaping their species richness patterns, and Spearman's correlation coefficient to examine the correlation of species richness gradients between pairs of taxa. We found that Lepidoptera species richness in the tropical Andes is distributed unevenly across the latitudinal gradient, differing considerably between the least and the most diverse transects, with a peak at 3–11°S, and is strongly correlated among all nine taxa. Geological age of the Andes, area and climatic seasonality explained the most variation in species richness, with age dominating in the north and seasonality in the south. The latitudinal gradient in east Andean Lepidoptera species richness is likely a result of historical and contemporary factors, in particular temperature seasonality and the greater age of the Andes south of the Equator. Local aspects of species richness patterns are due to small‐scale geological or climatic phenomena, for example, the peak at 3–5°S which results from local mixing of east‐west Andean faunas in the Huancabamba Deflection area.

Spatial diversity patterns of Pristimantis frogs in the Tropical Andes

“…The dramatic decrease in species richness in the Bolivian Andes has been observed in other taxa (birds: Rahbek and Graves ; insects: Pyrcz et al. ). This phenomenon has been related to increased seasonality in southern Bolivia, which has been recognized as a crucial limiting factor for tropical species (Pyrcz and Gareca ; Pyrcz et al.…”

“…However, in these butterflies and moths, the peak of highest richness is reached at southern latitudes between the Huancabamba depression and central Peru (Pyrcz et al. ). In Lepidoptera species, the latitudinal gradient has been explained as a result of greater area, age of the southern tropical Andes, and seasonal temperatures of the Andes south of the Equator (Pyrcz et al.…”

“…In Lepidoptera species, the latitudinal gradient has been explained as a result of greater area, age of the southern tropical Andes, and seasonal temperatures of the Andes south of the Equator (Pyrcz et al. ). However, as the highest richness of Pristimantis frogs was found in the northern tropical Andes, we consider that area and geological age may not represent the main factors shaping the latitudinal diversity of the genus.…”

“…; McCain , , ; Pyrcz et al. ; among others), refining our understanding of elevational gradients. For example, early naturalists (von Humboldt, Darwin, and Wallace) proposed that a decreasing pattern was typical along tropical altitudinal gradients (Lomolino ), but other patterns of diversity have been observed over recent years (McCain and Grytnes ).…”

Geographical patterns of species richness and beta diversity of Larentiinae moths (Lepidoptera: Geometridae) in two temperate biodiversity hotspots

“…Spatial turnover results from species replacement across space, while the nestedness component represents species loss across sites. Although both spatial turnover and nestedness are forms of beta diversity, so far at least two different abiotic processes have been suggested as drivers of these patterns Hortal et al 2011;Paknia et al 2013). Spatial turnover is associated with small distribution ranges and high endemism, whereas nested patterns are caused by species losses due to physiological constraints.…”