Relación entre la composición florística y los nutrientes del suelo en comunidades de palmas del Chocó biogeográfico en Colombia y Ecuador

En ecología una de las preguntas más importantes es: ¿cuáles son los factores ambientales que explican la alta diversidad de especies de plantas en los bosques tropicales? En este trabajo, se estudiaron las comunidades de palmas y su relación con los nutrientes del suelo en dos localidades del Chocó biogeográfico. Específicamente, se investigó: (1) cómo varían los nutrientes del suelo entre las dos localidades; (2) cuál es la relación entre los nutrientes del suelo y la composición florística de palmas; (3) cuáles son los nutrientes más importantes que explican la variación en la composición florística de las comunidades de palmas; y (4) cómo varía la abundancia de las especies dominantes de sotobosque y de dosel a lo largo del gradiente de concentración de los nutrientes más importantes. Se realizaron 20 transectos de 500 x 5 m (5 ha), en los cuales se identificaron y contaron todos los individuos de palmas en sus diferentes estadios de crecimiento. Las muestras de suelo se tomaron en cada uno de los transectos a los 0 , 250 y 500 m. Los cationes (Al, Ca, Mg, K, P) se extrajeron con la técnica Mehlich-III y las concentraciones se analizaron con espectrometría de emisión con plasma de acoplamiento inductivo (ICP-OES). La concentración de macronutrientes se relacionó con la composición florística mediante el test de Mantel, el test parcial de Mantel, regresiones lineales y escalamiento multidimensional no métrico (NMDS). Se encontraron 9 158 individuos y 33 especies de palmas en las 5 ha cubiertas por los transectos. La composición florística presentó una correlación positiva y significativa con los nutrientes del suelo (rM = 0.63-0.69) y con la distancia geográfica entre los transectos (rM = 0.71-0.75), mientras que las variables edáficas mostraron una alta correlación con la distancia geográfica (rM = 0.72). Asimismo, se encontró una débil relación significativa entre la fertilidad del suelo y la abundancia de palmas de sotobosque, pero ninguna con las palmas del dosel. Nuestros resultados demuestran que los suelos juegan un papel importante en la composición de las comunidades de palmas a escalas locales en la región del Chocó, y que los suelos más pobres y ricos en fósforo presentan la mayor diversidad de palmas.

One of the most important questions in ecology is: which are the environmental factors that explain the high plant diversity of tropical forests? We studied the floristic composition of palm communities and their relationship to soil nutrients in two localities of the Chocó region to understand (1) how soil nutrients vary between the two localities; (2) what is the relationship between soil nutrients and palm floristic composition; (3) what are the most important nutrients that explain the variation in floristic composition of palm communities; and (4) how does the abundance of the most exuberant understory and canopy palm species vary along the concentration gradient of the most important nutrients? We established 20 transects (5 x 500 m) and identified all palm individuals of all growth stages. Soil samples were taken at each transect at the beginning, middle, and end. Macronutrients (Al, Ca, Mg, K, P) were extracted with the Mehlich-III technique and their concentrations were analyzed by inductively coupled plasma emission spectrometry (ICP-OES). We used Mantel test, partial Mantel tests, linear regressions, and non-metric multidimensional scaling to determine if the concentration of nutrients was related to the floristic composition. We found a total of 9 158 individuals and 33 species of palms in the 5 ha covered by our transects. Floristic composition had a positive and significant correlation with soil nutrients (rM = 0.63-0.69) and with geographical distance between transects (rM= 0.71-0.75), whereas the soil nutrients were highly correlated with geographical distance (rM = 0.72). We also found a small, yet significant, relationship between soil fertility and the abundance of understory palms, but no relationship with canopy palms. Our results demonstrate for the first time that soils play an important role in the composition of palm communities at local scales in the Chocó region, and that infertile and phosphorus-rich soils have the highest palm diversity.

Continental-scale analysis reveals deep diversification within the polytypic Red-crowned Ant Tanager (Habia rubica, Cardinalidae).

We explored the phylogeographic patterns of intraspecific diversity in the Red-crowned Ant Tanager (Habia rubica) throughout its continent-wide distribution, in order to understand its evolutionary history and the role of evolutionary drivers that are considered to promote avian diversification in the Neotropics. We sampled 100 individuals of H. rubica from Mexico to Argentina covering the main areas of its disjunct distribution. We inferred phylogenetic relationships through Bayesian and maximum parsimony methodologies based on mitochondrial and nuclear markers, and complemented genetic analyses with the assessment of coloration and behavioral differentiation. We found four deeply divergent phylogroups within H. rubica: two South American lineages and two Mexican and Middle American lineages. The divergence event between the northern and southern phylogroups was dated to c. 5.0 Ma, seemingly related to the final uplift of the Northern Andes. Subsequently, the two South American phylogroups split c. 3.5 Ma possibly due to the development of the open vegetation corridor that currently isolates the Amazonian and Atlantic forests. Diversification throughout Mexico and Middle America, following dispersion across the Isthmus of Panama, was presumably more recent and coincident with Pleistocene climatic fluctuations and habitat fragmentations. The analyses of vocalizations and plumage coloration showed significant differences among main lineages that were consistent with the phylogenetic evidence. Our findings suggest that the evolutionary history of H. rubica has been shaped by an assortment of diversification drivers at different temporal and spatial scales resulting in deeply divergent lineages that we recommend should be treated as different species.

Ocorrência e conservação de Touit melanonotus (Aves, Psittacidae) no sul do Brasil / Occurrence and conservation of Touit melanonotus (Aves, Psittacidae) in southern Brazil

The Brown-backed Parrotlet [Touit melanonotus (Wied, 1820)] is a rare forest species restricted to the Brazilian Atlantic Forest, and is included in the endangered category for species threatened of extinction. As there is a lack of knowledge about the species’ natural history and occurrence, new observations can provide helpful information for parrotlet conservation. Here we reevaluate the first record for the species and present new records for the state of Paraná (southern Brazil). The vocalizations previously attributed to T. melanonotus, and which were used to infer its occurrence in the state, were examined by spectrogram analysis. These were actually found to be vocalizations of the Red-capped Parrot [Pionopsita pileata (Scopoli, 1769)], representing a case of misidentification. Even so, the Brown-backed Parrotlet occurs with some regularity in the state of Paraná, as shown by 12 records spread through seven localities spanning the entire Paraná coast. The Brown-backed Parrotlet was recorded mostly in lowland areas, and as these forest types suffer intense pressures, conservation efforts aiming the species preservation should focus in the maintenance of these habitats.

O apuim-de-costas-pretas [Touit melanonotus (Wied, 1820)] é uma espécie florestal endêmica da Mata Atlântica Brasileira e de relevante interesse conservacionista. Trata-se de uma ave com poucas informações disponíveis acerca de sua história natural e distribuição geográfica e novas observações são importantes fontes de informação para auxiliar na conservação da espécie. Aqui reavaliamos o primeiro registro da espécie e apresentamos novas observações no estado do Paraná, sul do Brasil. As vocalizações atribuídas a T. melanonotus e que consubstanciaram sua ocorrência no estado foram examinadas com auxílio de espectrogramas e identificadas como vozes de Pionopsitta pileata (Scopoli, 1769). Não obstante, T. melanonotus ocorre com certa regularidade no Paraná, como indicado por novos registros da espécie em sete localidades distribuídas por todo o litoral do estado. Esta ave foi registrada principalmente em florestas de terras baixas e, uma vez que esta fisionomia sofre intensas pressões antrópicas, sugerimos que esforços de conservação da espécie devem priorizar a preservação desses hábitats.

Ocorrência e conservação de Touit melanonotus (Aves, Psittacidae) no sul do Brasil / Occurrence and conservation of Touit melanonotus (Aves, Psittacidae) in southern Brazil

The Brown-backed Parrotlet [Touit melanonotus (Wied, 1820)] is a rare forest species restricted to the Brazilian Atlantic Forest, and is included in the endangered category for species threatened of extinction. As there is a lack of knowledge about the species natural history and occurrence, new observations can provide helpful information for parrotlet conservation. Here we reevaluate the first record for the species and present new records for the state of Paraná (southern Brazil). The vocalizations previously attributed to T. melanonotus, and which were used to infer its occurrence in the state, were examined by spectrogram analysis. These were actually found to be vocalizations of the Red-capped Parrot [Pionopsita pileata (Scopoli, 1769)], representing a case of misidentification. Even so, the Brown-backed Parrotlet occurs with some regularity in the state of Paraná, as shown by 12 records spread through seven localities spanning the entire Paraná coast. The Brown-backed Parrotlet was recorded mostly in lowland areas, and as these forest types suffer intense pressures, conservation efforts aiming the species preservation should focus in the maintenance of these habitats.(AU)

O apuim-de-costas-pretas [Touit melanonotus (Wied, 1820)] é uma espécie florestal endêmica da Mata Atlântica Brasileira e de relevante interesse conservacionista. Trata-se de uma ave com poucas informações disponíveis acerca de sua história natural e distribuição geográfica e novas observações são importantes fontes de informação para auxiliar na conservação da espécie. Aqui reavaliamos o primeiro registro da espécie e apresentamos novas observações no estado do Paraná, sul do Brasil. As vocalizações atribuídas a T. melanonotus e que consubstanciaram sua ocorrência no estado foram examinadas com auxílio de espectrogramas e identificadas como vozes de Pionopsitta pileata (Scopoli, 1769). Não obstante, T. melanonotus ocorre com certa regularidade no Paraná, como indicado por novos registros da espécie em sete localidades distribuídas por todo o litoral do estado. Esta ave foi registrada principalmente em florestas de terras baixas e, uma vez que esta fisionomia sofre intensas pressões antrópicas, sugerimos que esforços de conservação da espécie devem priorizar a preservação desses hábitats.(AU)