Biogeographic Distribution Patterns and Their Correlates in the Diverse Frog Fauna of the Atlantic Forest Hotspot

Abstract

Anurans are a highly diverse group in the Atlantic Forest hotspot (AF), yet distribution patterns and species richness gradients are not randomly distributed throughout the biome. Thus, we explore how anuran species are distributed in this complex and biodiverse hotspot, and hypothesize that this group can be distinguished by different cohesive regions. We used range maps of 497 species to obtain a presence/absence data grid, resolved to 50×50 km grain size, which was submitted to k-means clustering with v-fold cross-validation to determine the biogeographic regions. We also explored the extent to which current environmental variables, topography, and floristic structure of the AF are expected to identify the cluster patterns recognized by the k-means clustering. The biogeographic patterns found for amphibians are broadly congruent with ecoregions identified in the AF, but their edges, and sometimes the whole extent of some clusters, present much less resolved pattern compared to previous classification. We also identified that climate, topography, and vegetation structure of the AF explained a high percentage of variance of the cluster patterns identified, but the magnitude of the regression coefficients shifted regarding their importance in explaining the variance for each cluster. Specifically, we propose that the anuran fauna of the AF can be split into four biogeographic regions: a) less diverse and widely-ranged species that predominantly occur in the inland semideciduous forests; b) northern small-ranged species that presumably evolved within the Pleistocene forest refugia; c) highly diverse and small-ranged species from the southeastern Brazilian mountain chain and its adjacent semideciduous forest; and d) southern species from the Araucaria forest. Finally, the high congruence among the cluster patterns and previous eco-regions identified for the AF suggests that preserving the underlying habitat structure helps to preserve the historical and ecological signals that underlie the geographic distribution of AF anurans.

Planning for conservation and restoration under climate and land use change in the Brazilian Atlantic Forest

“…50% of plant species represented there are endemic to this biome (Forzza et al., ; Werneck, Sobral, Rocha, Landau, & Stehmann, ). Concordant spatial patterns between vegetation and other taxonomic groups have been reported in the region (Ferro & Melo, ; Vasconcelos, Prado, Silva, & Haddad, ). We opted to work with woody plants given both their elevated diversity and endemism, and their ecological importance for providing habitat to other taxonomic groups.…”

Aridity, soil and biome stability influence plant ecoregions in the Atlantic Forest, a biodiversity hotspot in South America

“…They also regarded the issue of how we delimit and map biogeographical regions as critical for continentalscale macroevolutionary and biogeographical studies, in face of the lack of consistency and precision in the way supposed phytogeographic regions are partitioned, categorized and mapped. Recent studies have shown complex internal structure of amphibian and snake species assemblages in the domain (Vasconcelos et al 2014, Moura et al 2017, and a broad plant biogeographical split into its northern and southern parts (Carnaval et al 2014, Zizka et al 2018. The Atlantic Forest is one of the main vegetation domains of the continent, originally covering more than 1 000 000 km 2 with lowland, montane, semi-deciduous and deciduous forests, and coastal heath vegetation.…”

Jumping into a trap: high prevalence of chytrid fungus in the preferred microhabitats of a bromeliad-specialist frog

“…In a region such as the north AF, which is characterized by high temperatures and less precipitation than the rest of the AF (Alvares et al 2013, Vasconcelos et al 2014, Bd might experience limited zoospore growth on its hosts (Becker & Zamudio 2011). Alternately, different Bd strains (Rosenblum et al 2013) may have different climatic tolerances (Stevenson et al 2013), and hence, the observed trends could be influenced by strain type (which is unknown for these bromeliad species), or by local adaptation that makes it possible for Bd to persist in these harsh climatic conditions.…”

“…The climate is subtropical (Köppen's climate classification) with a hot and humid rainy season between April and August and a dry period between November and January (Alvares et al 2013). This forest fragment has an area of 26.28 km 2 and is located at the north biogeographic region of the AF defined as the Pernambuco interior (semi-deciduous) eco-region (Vasconcelos et al 2014). Deforestation has been a major threat in this area (Ribeiro et al 2009) with remaining forests representing about 11.5% (56 400 km 2 ) of the original forest (Ribeiro et al 2009).…”