Reconstructing the Mexican Tropical Dry Forests via an Autoecological Niche Approach: Reconsidering the Ecosystem Boundaries.

We used Ecological Niche Modeling (ENM) of individual species of two taxonomic groups (plants and birds) in order to reconstruct the climatic distribution of Tropical Dry Forests (TDFs) in Mexico and to analyze their boundaries with other terrestrial ecosystems. The reconstruction for TDFs' distribution was analyzed considering the prediction and omission errors based upon the combination of species, obtained from the overlap of individual models (only plants, only birds, and all species combined). Two verifications were used: a primary vegetation map and 100 independent TDFs localities. We performed a Principal Component (PCA) and Discriminant Analysis (DA) to evaluate the variation in the environmental variables and ecological overlap among ecosystems. The modeling strategies showed differences in the ecological patterns and prediction areas, where the "all species combined" model (with a threshold of ≥10 species) was the best strategy to use in the TDFs reconstruction. We observed a concordance of 78% with the primary vegetation map and a prediction of 98% of independent locality records. Although PCA and DA tests explained 75.78% and 97.9% of variance observed, respectively, we observed an important overlap among the TDFs with other adjacent ecosystems, confirming the existence of transition zones among them. We successfully modeled the distribution of Mexican TDFs using a number of bioclimatic variables and co-distributed species. This autoecological niche approach suggests the necessity of rethinking the delimitations of ecosystems based on the recognition of transition zones among them in order to understand the real nature of communities and association patterns of species

Ant Presence in Acacias: An Association That Maximizes Nesting Success in Birds?

Volume: 118Start Page: 563End Page: 56

Burrowing habit in Smilisca frogs as an adaptive response to ecological niche constraints in seasonally dry environments

As environmental conditions change over time, some species can follow the spatial footprint of their ecological niches or can adapt physiologically to the new conditions; modifying behavior can offer an alternative means of adapting to novel environments. The burrowing habit allows organisms to avoid adverse climatic conditions during part of the year by remaining inside burrows. Smilisca fodiens and S. dentata are two burrowing hylid frogs that inhabit areas beyond the northernmost distributional limits of the other six arboreal species of their genus, and indeed beyond of most American hylids. In this study, we tested whether burrowing habit allows these species to adapt to drier conditions while conserving the climatic niche of the arboreal species. We compared the annual niches of the arboreal species to those of the burrowing species under two assumptions: true seasonal niches and full annual niches. Through ecological niche similarity tests, we performed 24 comparisons in both geographic and environmental spaces. In geographic space, when considering burrowing annual niches, only five of 24 tests indicated similarity, yet as regards seasonal niche, 18 of 24 tests indicated similarity. In environmental space, all tests failed to reject null hypotheses. The analyses showed clearly that burrowing and arboreal species were closer in environmental space when seasonal niches of the burrowing species were used, rather than annual niches. That is, climatic conditions in seasonal niches of burrowing species resemble the annual niches of arboreal species, supporting the proposition that reduction of activity to certain periods of the year is a strategy in burrowing species to conserve their tropical niches while living in dry regions

Identifying priority conservation areas for birds associated to endangered Neotropical dry forests

Neotropical dry forests (NDF) are widely distributed and possess important levels of species richness and endemism; however, they are considered a highly endangered ecosystem. Today, the protected areas network (PAs) located within NDF covers 36% the ranges of all species and, particularly, 62% for the most-priority species. Priority conservation areas identified are mainly distributed in Peru (23.1%), Brazil (21.3%), Ecuador (18.8%), and Bolivia (11.4%). Our novel results represent an important step to guide future establishment of new and efficient conservation areas across the NDF.Fil: Prieto Torres, David Alexander. Instituto de Ecología. Laboratorio de Bioclimatología. Red de Biología Evolutiva; México. Universidad Nacional Autónoma. Facultad de Ciencias. Departamento de Biología Evolutiva. Museo de Zoología; MéxicoFil: Nori, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Rojas Soto Octavio R. Instituto de Ecología. Laboratorio de Bioclimatología. Red de Biología Evolutiva; Méxic

Burrowing habit in Smilisca frogs as an adaptive response to ecological niche constraints in seasonally dry environments

As environmental conditions change over time, some species can follow the spatial footprint of their ecological niches or can adapt physiologically to the new conditions; modifying behavior can offer an alternative means of adapting to novel environments. The burrowing habit allows organisms to avoid adverse climatic conditions during part of the year by remaining inside burrows. Smilisca fodiens and S. dentata are two burrowing hylid frogs that inhabit areas beyond the northernmost distributional limits of the other six arboreal species of their genus, and indeed beyond of most American hylids. In this study, we tested whether burrowing habit allows these species to adapt to drier conditions while conserving the climatic niche of the arboreal species. We compared the annual niches of the arboreal species to those of the burrowing species under two assumptions: true seasonal niches and full annual niches. Through ecological niche similarity tests, we performed 24 comparisons in both geographic and environmental spaces. In geographic space, when considering burrowing annual niches, only five of 24 tests indicated similarity, yet as regards seasonal niche, 18 of 24 tests indicated similarity. In environmental space, all tests failed to reject null hypotheses. The analyses showed clearly that burrowing and arboreal species were closer in environmental space when seasonal niches of the burrowing species were used, rather than annual niches. That is, climatic conditions in seasonal niches of burrowing species resemble the annual niches of arboreal species, supporting the proposition that reduction of activity to certain periods of the year is a strategy in burrowing species to conserve their tropical niches while living in dry regions

Consensus maps of TDFs in Mexico representing the sum of Ecological Niche Models for the species modeled.

<p>Maps from (a) to (c) represent the Mexican TDFs reconstruction by the accumulation of species modeled (from pale to dark black shading indicates accumulation of models). Map (d) represent the TDFs distribution based on a single-ecosystem model approach. White dots represent the known TDFs localities used for evaluation. To the right of maps (a-c), the number of pixels evaluated on the base of TDFs range predicted for each set of species, including the omission (triangles and line dark gray), commission (squares and lines light gray) and prediction (circles and lines black) values for each set. Values were reported based on primary vegetation maps of Mexico (INEGI, 2003). Letters correspond to: sums for only plants species models (a), sums for only bird species models (b), and sums for all species models (c).</p

Species modeled and used for Tropical Dry Forests reconstruction in Mexico.

<p>Families and species were assigned according to: IOC World Bird List (Gill & Donsker, 2015), APG III (APG, 2009), and The Plant List (2013).</p