Butterflies on the dry edge of the Atlantic Forest: water availability determines community structure at the Northern limit of Atlantic Forest

Abstract

The composition of communities of fruit‐feeding butterflies in the Brazilian Atlantic forest changes in response to landscape fragmentation and can be used as an indicator of habitat quality. Landscape fragmentation, aridity, and early signs of global warming at the northernmost distribution of this biome may impose extra challenges for species persistence. We aim to clarify the drivers of fruit‐feeding butterflies' metacommunity structure in the northernmost portion of the Brazilian Atlantic Forest. We propose to disentangle consequences of habitat loss from fragmentation per se by using both habitat amount and patch scale metrics. We sampled fruit‐feeding butterflies in 15 forest fragments of up to ~30 ha during 1 year. We used fragment size, shape, distance to nearest perennial stream, Euclidean distance to nearest neighbour, forest habitat amount, proximity index, and the percentage of sugarcane within a buffer to elucidate patterns of species richness, abundance, and beta diversity. A configuration metric, stream distance, was the only variable predicting metacommunity total abundance and richness: fragments farther from water had fewer species and individuals. However, forest habitat amount and sugar cane were important to rarefied richness and species replacement between fragments. Our findings suggest that streams and associated riparian zones provide source populations for the butterfly metacommunities in this landscape, which fits the mass effect model. We also emphasise that small forest patches have high conservation value for persistence of butterfly populations, because each fragment preserves a substantial portion of the total species pool.

Fostering biodiversity in Neotropical savannahs: fire as a diversity driver for fruit-feeding butterfly assemblages in the Brazilian Cerrado

“…Therefore, safeguarding the rich variety of landscapes in the Cerrado becomes crucial to provide suitable habitats with distinct microclimate conditions. This is extremely relevant for conservation of small-bodied butter y species as they are more vulnerable to desiccation, especially in the face of the current climate changes in Cerrado (Freire-Jr et al 2023;Brito et al, 2021;Hofmann et al 2021;Krupp et al, 2020).…”

The effect of habitat amount on flight‐related traits in the butterflyHamadryas februais sex‐dependent

“…The total sampling effort was 3600 trap days. Additional sampling details are described in Brito et al (2021). Individuals used in the present study come from 14 of these originally bait‐trapped forest fragments (focal patches that are labelled A to N in Figure 1).…”

“…There is no apparent sexual dimorphism in the species (Marini-Filho & Benson, 2010;Muyshondt & Muyshondt, 1975). Individual H. februa were collected between October 2015 and September 2016 in 15 Atlantic Forest fragments in Northeastern Brazil (Brito et al, 2021). Each forest fragment, here called a focal patch, had a sampling unity installed in its centroid.…”

“…Northeastern Brazil presents early signs of global warming impact, with diminishing annual rainfall and increasing desertification spots (Tomasella et al, 2018; Vieira et al, 2021). Locally, the sampled landscape retains 18.6% of the native Atlantic Forest mostly in small‐size forest fragments (80% are up to 50 ha) scattered in a matrix dominated by sugar cane monoculture (Brito et al, 2021). Climate is rainy tropical, with a marked dry season during the summer and a wet season in the winter (INMET, 2021).…”

“…Due to physiological and behavioural differences between sexes, we expect that responses to landscape variables would be sex specific. We used individuals sampled from a previous study which investigated the community structure of fruit‐feeding butterflies in a fragmented landscape (Brito et al, 2021). In addition to exploring sex differences in response to landscape change, we aim to contrast the relative importance of habitat amount and patch area in modulating the species' flight‐related morphological traits.…”