Trait Variation in Moths Mirrors Small-Scaled Ecological Gradients in A Tropical Forest Landscape

Abstract

Along environmental gradients, communities are expected to be filtered from the regional species pool by physical constraints, resource availability, and biotic interactions. This should be reflected in species trait composition. Using data on species-rich moth assemblages sampled by light traps in a lowland rainforest landscape in Costa Rica, we show that moths in two unrelated clades (Erebidae-Arctiinae; Geometridae) are much smaller-sized in oil palm plantations than in nearby old-growth forest, with intermediate values at disturbed forest sites. In old-growth forest, Arctiinae predominantly show aposematic coloration as a means of anti-predator defense, whereas this trait is much reduced in the prevalence in plantations. Similarly, participation in Müllerian mimicry rings with Hymenoptera and Lycidae beetles, respectively, is rare in plantations. Across three topographic types of old-growth forests, community-weighted means of moth traits showed little variation, but in creek forest, both types of mimicry were surprisingly rare. Our results emphasize that despite their mobility, moth assemblages are strongly shaped by local environmental conditions through the interplay of bottom–up and top–down processes. Assemblages in oil palm plantations are highly degraded not only in their biodiversity, but also in terms of trait expression.

Aposematic Coloration of Moths Decreases Strongly along an Elevational Gradient in the Andes

“…Therefore, we expected to observe gradients in species attributes along these stark ecological contrasts. However, even along much less extensive topographic gradients in the lowland tropical forest, distinct variation in the extent of aposematism and mimicry has recently been reported from Costa Rica [33]. Hence, the perspective on communitywide patterns in traits such as defense against visually hunting predators could become a rewarding paradigm that is accessible from the morphological study of samples alone, without the need for experimentation, which may often not be feasible in species-rich tropical conservation areas, due to the rarity and unknown life histories of most component species.…”

“…In brief, CWMs denote the average value any trait attains within a community, i.e., the trait value one expects to encounter when drawing a random individual from that community. The analysis of CWMs has proven to be a valuable and powerful tool for analyzing light-trap samples of moths along environmental gradients [33,34]. We also calculated the contribution of the tribe Lithosiini and of five Arctiini subtribes (Euchromiina, Ctenuchina, Phaegopterina, Arctiina, Pericopina) to each local assemblage.…”

Lepidoptera as a tool for the assessment of human disturbance impacting ecological and taxonomic diversity in the Choke Mountains, Ethiopia

“…The effects of habitat perturbation and loss are reflected in declining populations and species loss (Pimm et al 2014). These impacts affect not only rare and specialized organisms but often widely distributed species as well (Gaston and Fuller Several studies have investigated the effects of landscape-level changes due to human activities, such as deforestation and habitat fragmentation, on moth communities in tropical areas (Ricketts et al 2001;Hawes et al 2009;Rabl et al 2020;Correa-Carmona et al 2022). The present study focused on a tropical mountain area, the Choke Mountains in Ethiopia, which is highly fragmented and under extreme pressure from grazing and extensive crop cultivation.…”

“…Several studies have investigated the effects of landscape-level changes due to human activities, such as deforestation and habitat fragmentation, on moth communities in tropical areas (Ricketts et al 2001; Hawes et al 2009; Rabl et al 2020; Correa-Carmona et al 2022). The present study focused on a tropical mountain area, the Choke Mountains in Ethiopia, which is highly fragmented and under extreme pressure from grazing and extensive crop cultivation.…”

Functional and taxonomic responses of tropical moth communities to deforestation

“…Indeed, it is commonly accepted that body size in most arthropod taxa tends to decrease with the intensification of land-use and the increased simplification of the landscape (Gamez-Virues et al, 2015;Simons et al, 2016). In Lepidoptera, Rabl et al (2020) showed that two moth taxa (i.e. Arctiinae and Geometridae) were much smaller-sized in oil palm plantations than in nearby old-growth forest.…”