Territorial hypothesis predicts the trade-off between reproductive opportunities and parental care in three species of damselfishes (Pomacentridae: Actinopterygii)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Study of the venom glands in Ectatomma quadridens (Hymenoptera: Formicidae). Evolutionary hypothesis in subfamily ponerinae

The venom glands of worker ants of the species Ectatomma quadridens morphologically resemble an elongated sac or reservoir ending in a narrower portion that has the function of releasing the secretion to the exterior. Two external secretory filaments are individually inserted into the proximal portion of the gland and end inside the convoluted gland. The venom gland of workers of E. quadridens is, therefore, morphologically subdivided into four distinct portions: a) sac-shaped reservoir measuring approximately 1mm in length; b) excretory duct, proximal portion of the reservoir that joins the gland to the sting apparatus; c) convoluted gland, final portion of the external secretory filaments located inside the reservoir; and d) two secretory filaments measuring about 2 mm in length; their free extremities end blindly and are individually inserted into the reservoir wall at the proximal region of the venom gland. The histological data showed that the filaments and the convoluted gland are composed of cubic cells of secretory function. The reservoir consists of a simple cubical epithelium externally surrounded by muscle fibers. A thick cuticle internally coats the epithelium of the reservoir. The application of histochemical tests allowed us to establish that the final secretion of the venom gland of Ectatomma quadridens is of glycoproteic nature. This secretion undergoes several modifications at the secretory filaments, at the convoluted gland, and in the reservoir before reaching the excretory duct, the point at which the secretion is released in its final composition, namely the venom. Based on the differences among various Ponerinae species we propose a hypothesis suggesting a probable evolutionary process that the venom glands of members of this subfamily might have undergone.

Reinforcing and expanding the predictions of the disturbance vicariance hypothesis in Amazonian harlequin frogs: A molecular phylogenetic and climate envelope modelling approach

The disturbance vicariance hypothesis (DV) has been proposed to explain speciation in Amazonia, especially its edge regions, e. g. in eastern Guiana Shield harlequin frogs (Atelopus) which are suggested to have derived from a cool-adapted Andean ancestor. In concordance with DV predictions we studied that (i) these amphibians display a natural distribution gap in central Amazonia; (ii) east of this gap they constitute a monophyletic lineage which is nested within a pre-Andean/western clade; (iii) climate envelopes of Atelopus west and east of the distribution gap show some macroclimatic divergence due to a regional climate envelope shift; (iv) geographic distributions of climate envelopes of western and eastern Atelopus range into central Amazonia but with limited spatial overlap. We tested if presence and apparent absence data points of Atelopus were homogenously distributed with Ripley's K function. A molecular phylogeny (mitochondrial 16S rRNA gene) was reconstructed using Maximum Likelihood and Bayesian Inference to study if Guianan Atelopus constitute a clade nested within a larger genus phylogeny. We focused on climate envelope divergence and geographic distribution by computing climatic envelope models with MaxEnt based on macroscale bioclimatic parameters and testing them by using Schoener's index and modified Hellinger distance. We corroborated existing DV predictions and, for the first time, formulated new DV predictions aiming on species' climate envelope change. Our results suggest that cool-adapted Andean Atelopus ancestors had dispersed into the Amazon basin and further onto the eastern Guiana Shield where, under warm conditions, they were forced to change climate envelopes. © 2010 The Author(s).

Fruit color and contrast in seasonal habitats - a case study from a cerrado savanna

Communication contributes to mediate the interactions between plants and the animals that disperse their genes. As yet, seasonal patterns in plant-animal communication are unknown, even though many habitats display pronounced seasonality e.g. when leaves senescence. We thus hypothesized that the contrast between fruit displays and their background vary throughout the year in a seasonal habitat. If this variation is adaptive, we predicted higher contrasts between fruits and foliage during the fruiting season in a cerrado-savanna vegetation, southeastern Brazil. Based on a six-year data base of fruit ripening and a one-year data set of fruit biomass, we used reflectance measurements and contrast analysis to show that fruits with distinct colors differed in the beginning of ripening and the peak of fruit biomass. Black, and particularly red fruits, that have a high contrast against the leaf background, were highly seasonal, peaking in the wet season. Multicolored and yellow fruits were less seasonal, not limited to one season, with a bimodal pattern for yellow ones, represented by two peaks, one in each season. We further supported the hypothesis that seasonal changes in fruit contrasts can be adaptive because fruits contrasted more strongly against their own foliage in the wet season, when most fruits are ripe. Hence, the seasonal variation in fruit colors observed in the cerrado-savanna may be, at least partly, explicable as an adaptation to ensure high conspicuousness to seed dispersers. © 2013 The Authors.

Leaf senescence in tomato mutants as affected by irradiance and phytohormones

We explored the interaction between radiation of different wavelength and jasmonic acid (JA) or brassinosteroids (BR) on leaf senescence-induced oxidative stress. Three approaches were used: 1) jasmonic acid insensitive1-1 (jai1-1) and brassinosteroid-deficient [dumpy (dpy)] mutants were treated with red (R) or far-red (FR) radiation; 2) phytochromedeficient aurea (au) and high pigment-1 (hp-1) (radiation exaggerated response) mutants were treated with methyl jasmonate (MeJA) or epibrassinolide (epiBL); and 3) double mutants au jai1-1 and au dpy were produced. Leaf chlorophyll content, lipid peroxidation, and antioxidant enzyme activities were determined. After senescence induction in detached leaves, we verified that the patterns of chlorophyll degradation of hormonal and photomorphogenic mutants were not significantly different in comparison with original cv. Micro-Tom (MT). Moreover, there was no significant change in lipid peroxidation measured as malondialdehyde (MDA) production, as well as catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities in the hormonal mutants. Exogenous BR increased CAT and APX activities in MT, au, and hp-1. As concerns the double mutants, severe reduction in H2O2 production which was not accompanied by changes in MDA content, and CAT and APX activities was observed during senescence in au dpy. The results suggest that JA and BR do not participate in light signaling pathway during leaf senescence-induced oxidative stress. © 2013 Springer Science+Business Media Dordrecht.

Densidades e arranjos populacionais de milho e componentes agronômicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

População de plantas e uso de piraclostrobina na cultura do milho: alterações agronômicas e fisiológicas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação de cultivares de milho em função de populações de plantas e épocas de semeadura

Pós-graduação em Agronomia (Agricultura) - FCA

Court cleaning behavior of the white-bearded manakin (manacus manacus) and a test of the anti-predation hypothesis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of training status and eNOS haplotypes on plasma nitrite concentrations in normotensive older adults: a hypothesis-generating study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Occurrence of Isarachnanthus (Cnidaria: Anthozoa: Ceriantharia) at Ascension Island: a test of hypothesis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Leaf colleters in Tabernaemontana catharinensis (Apocynaceae, Rauvolfioideae): structure, ontogenesis, and cellular secretion

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

First description of B chromosomes in the Hyphessobrycon (Characiformes, Characidae) genus: a hypothesis for the extra element of Hyphessobrycon eques Steindachner, 1882

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)