Contemporary and historic factors influence differently genetic differentiation and diversity in a tropical palm.

Population genetics theory predicts loss in genetic variability because of drift and inbreeding in isolated plant populations; however, it has been argued that long-distance pollination and seed dispersal may be able to maintain gene flow, even in highly fragmented landscapes. We tested how historical effective population size, historical migration and contemporary landscape structure, such as forest cover, patch isolation and matrix resistance, affect genetic variability and differentiation of seedlings in a tropical palm (Euterpe edulis) in a human-modified rainforest. We sampled 16 sites within five landscapes in the Brazilian Atlantic forest and assessed genetic variability and differentiation using eight microsatellite loci. Using a model selection approach, none of the covariates explained the variation observed in inbreeding coefficients among populations. The variation in genetic diversity among sites was best explained by historical effective population size. Allelic richness was best explained by historical effective population size and matrix resistance, whereas genetic differentiation was explained by matrix resistance. Coalescence analysis revealed high historical migration between sites within landscapes and constant historical population sizes, showing that the genetic differentiation is most likely due to recent changes caused by habitat loss and fragmentation. Overall, recent landscape changes have a greater influence on among-population genetic variation than historical gene flow process. As immediate restoration actions in landscapes with low forest amount, the development of more permeable matrices to allow the movement of pollinators and seed dispersers may be an effective strategy to maintain microevolutionary processes.

Crecimiento a largo plazo de pacientes con raquitismo hipofosfatémico familiar (RHF) / Long term growth in patients with familial hypophosphatemic rikets

El raquitismo hipofosfatémico familiar (RHF) es una condición genética trasmitida en la mayoría de los casos en forma dominante ligada al sexo, que se asocia a un pérdida renal de fosfatos, con secundaria hipofosfatemia, déficit de osificación, incurvación de miembros inferiores y retraso de crecimiento. Objetivo: describir el crecimiento y su relación con el cumplimiento del tratamiento a largo plazo, en un grupo de pacientes seguidos en el Hospital Garrahan por los servicios de Crecimiento y Desarrollo, Nefrología y Endocrinología. Tiempo de observación de 1.0 a 16.4 años. Población y Métodos: N= 30 pacientes (18 mujeres y 13 varones). Se midió la estatura según técnica estandarizada y se trataron los pacientes en forma uniforme con sales de fósforo 1-25 (HO2) vitamina. Se definió incumplimiento del tratamiento como la discontinuidad de la ingesta de sales de fósforo de más de un mes por año. Resultados: La edad mediana de inicio de tratamiento fue 4.92 años (r: 0.7/12.7), talla media: -2.85 Ds (r. -42/6.7) y a la última consulta: 15.04 años (r: 4.66/20.73), talla media: -3.31 Ds (r: -0.70/-6.6). En promedio, los niños crecieron entre 2.8/3.0 DS. Hubo 12 niños que perdieron estatura durante el seguimiento. La mayor proporción del déficit de talla ya estaba presente al diagnóstico. La regresión logística entre pérdida de talla en puntajes z (0.5 DS o más), y cuatro variables independientes (edad al diagnóstico), cumplimiento del tratamiento, sexo y talla al diagnóstico, cumplimiento al tratamiento, sexo y talla al diagnóstico) reveló que sólo las dos primeras están significativamente relacionadas al déficit de crecimiento (P 0.02 y 0.03 respectivamente). Conclusión: la edad tardía al diagnóstico y el incumplimiento del tratamiento se asocian a déficit de crecimiento.

Bird attributes, plant characteristics, and seed dispersal of Pera glabrata (Schott, 1858), (Euphorbiaceae) in a disturbed cerrado area

Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas.

As diferentes espécies de plantas apresentam características que podem influenciar na atração das aves frugívoras, como a quantidade de frutos produzidos, o valor nutritivo dos frutos, a presença de compostos secundários e o display de cores. Por outro lado, diversos estudos têm demonstrado que as espécies de aves que consomem frutos não apresentam a mesma eficiência como dispersores das sementes. Embora estudos sobre a frugivoria e dispersão de sementes sejam de grande importância para a realização de planos de manejo e recuperação de áreas degradadas, pouco tem sido pesquisado sobre o assunto no cerrado brasileiro. Neste trabalho são apresentados aspectos da frugivoria e dispersão ornitocórica das sementes de Pera glabrata Schott (Euphorbiaceae) num fragmento de cerrado do sudeste do Brasil. Atributos das aves, como freqüência de visitas, número de diásporos consumidos, tempo de permanência sobre as plantas, métodos de captura e mandibulação dos diásporos, bem como interações antagônicas, foram analisados para se inferir sobre o potencial de cada espécie para atuar como dispersora das sementes. As aves foram os únicos potenciais dispersores dos diásporos. Em 60 horas de observações focais, realizadas entre dezembro de 1999 e janeiro de 2000, foram registradas 414 visitas de 20 espécies de aves pertencentes a sete famílias. No entanto, apenas 14 destas espécies foram consideradas como potenciais dispersores. Os principais potenciais dispersores foram Turdus -leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) e Elaenia spp. (Tyrannidae). O número de visitas não diferiu significativamente entre os diferentes intervalos de hora do dia. Não foi encontrada correlação significativa entre o número de visitas e o número de frutos presentes em cada árvore. As aves generalistas foram as principais potenciais dispersoras de P. glabrata, tendo apresentado altas taxas de visitação, alto consumo de diásporos,...

Toward reliable estimates of seed removal by small mammals and birds in the Neotropics.

Birds are often considered seed predators of less importance when compared to rodents or granivorous ants in studies of seed predation using selective exclosures. However, it is possible that the role of granivorous birds interacting with seeds on the floor of Neotropical forests is being underestimated, if the selective exclosures designed to allow exclusive access to small rodents do not work properly in the Neotropics. We used an experimental approach to evaluate whether birds could remove seeds from selective exclosures designed to allow exclusive access to rodents. We compared seed removal from two paired treatments in the field: an open treatment (control) allowing the access to all vertebrates, and a selective exclosure treatment, where seeds were placed under a cage staked to the ground and covered on top and on the laterals by wire mesh of varying sizes. Treatments were placed in the center of a sand quadrat in order to record the visit of vertebrates from their footprints. Although the selective exclosures are used to tell apart the small mammal seed removal from that of other animals, birds could persistently remove seeds from selective exclosures. Thus, the role of birds interacting with seeds on the floor of tropical forests may be underestimated for some plant species, due to an artifact of the exclosure method employed. Exclosures of 40 x 40 x 40 cm should be efficient to deter the removal of seeds by birds, allowing the consumption of the seeds by small mammals at the same time.

Toward reliable estimates of seed removal by small mammals and birds in the Neotropics

Birds are often considered seed predators of less importance when compared to rodents or granivorous ants in studies of seed predation using selective exclosures. However, it is possible that the role of granivorous birds interacting with seeds on the floor of Neotropical forests is being underestimated, if the selective exclosures designed to allow exclusive access to small rodents do not work properly in the Neotropics. We used an experimental approach to evaluate whether birds could remove seeds from selective exclosures designed to allow exclusive access to rodents. We compared seed removal from two paired treatments in the field: an open treatment (control) allowing the access to all vertebrates, and a selective exclosure treatment, where seeds were placed under a cage staked to the ground and covered on top and on the laterals by wire mesh of varying sizes. Treatments were placed in the center of a sand quadrat in order to record the visit of vertebrates from their footprints. Although the selective exclosures are used to tell apart the small mammal seed removal from that of other animals, birds could persistently remove seeds from selective exclosures. Thus, the role of birds interacting with seeds on the floor of tropical forests may be underestimated for some plant species, due to an artifact of the exclosure method employed. Exclosures of 40 x 40 x 40 cm should be efficient to deter the removal of seeds by birds, allowing the consumption of the seeds by small mammals at the same time.

Aves são freqüentemente consideradas predadores de sementes de pouca importância, quando comparadas a roedores e formigas granívoras em estudos sobre predação de sementes que utilizam exclusões seletivas. Contudo, é possível que o papel de aves granívoras que interagem com sementes no solo de florestas Neotropicais vem sendo subestimado, se as exclusões seletivas usadas para permitir o acesso exclusivo a pequenos roedores não funcionam de forma apropriada no Neotrópico. Foi usada uma abordagem experimental para avaliar se aves poderiam remover sementes do interior de exclusões seletivas desenhadas para permitir acesso exclusivo a roedores. Comparou-se a remoção de sementes em dois tratamentos no campo: um tratamento aberto (controle) que permite o acesso a todos os vertebrados, e um tratamento de exclusão seletiva, no qual as sementes eram dispostas sob uma gaiola metálica fixada ao solo e recoberta por tela metálica de tamanhos variados. Os tratamentos foram dispostos no centro de uma parcela de areia de forma a registrar a visita de vertebrados por meio de pegadas. Embora as exclusões seletivas sejam usadas para estimar separadamente a remoção de sementes por pequenos mamíferos daquela praticada por outros animais, aves puderam remover sementes das exclusões seletivas. Assim, o papel de aves interagindo com sementes no solo de florestas tropicais pode estar sendo subestimado para algumas espécies de plantas, devido a um artefato do método de exclusão empregado. Exclusões de 40 x 40 x 40 cm devem ser eficientes para deter a remoção de sementes por aves, permitindo o consumo de sementes por pequenos mamíferos ao mesmo tempo.

Bird attributes, plant characteristics, and seed dispersal of Pera glabrata (Schott, 1858), (Euphorbiaceae) in a disturbed cerrado area.

Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas.

Bird attributes, plant characteristics, and seed dispersal of Pera glabrata (Schott, 1858), (Euphorbiaceae) in a disturbed cerrado area

Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas.

As diferentes espécies de plantas apresentam características que podem influenciar na atração das aves frugívoras, como a quantidade de frutos produzidos, o valor nutritivo dos frutos, a presença de compostos secundários e o display de cores. Por outro lado, diversos estudos têm demonstrado que as espécies de aves que consomem frutos não apresentam a mesma eficiência como dispersores das sementes. Embora estudos sobre a frugivoria e dispersão de sementes sejam de grande importância para a realização de planos de manejo e recuperação de áreas degradadas, pouco tem sido pesquisado sobre o assunto no cerrado brasileiro. Neste trabalho são apresentados aspectos da frugivoria e dispersão ornitocórica das sementes de Pera glabrata Schott (Euphorbiaceae) num fragmento de cerrado do sudeste do Brasil. Atributos das aves, como freqüência de visitas, número de diásporos consumidos, tempo de permanência sobre as plantas, métodos de captura e mandibulação dos diásporos, bem como interações antagônicas, foram analisados para se inferir sobre o potencial de cada espécie para atuar como dispersora das sementes. As aves foram os únicos potenciais dispersores dos diásporos. Em 60 horas de observações focais, realizadas entre dezembro de 1999 e janeiro de 2000, foram registradas 414 visitas de 20 espécies de aves pertencentes a sete famílias. No entanto, apenas 14 destas espécies foram consideradas como potenciais dispersores. Os principais potenciais dispersores foram Turdus -leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) e Elaenia spp. (Tyrannidae). O número de visitas não diferiu significativamente entre os diferentes intervalos de hora do dia. Não foi encontrada correlação significativa entre o número de visitas e o número de frutos presentes em cada árvore. As aves generalistas foram as principais potenciais dispersoras de P. glabrata, tendo apresentado altas taxas de visitação, alto consumo de diásporos, e permaneceram sobre as plantas durante curtos períodos de tempo. Muitas das espécies de aves observadas são bastante abundantes mesmo em ambientes antrópicos, o que deve garantir a dispersão das sementes de P. glabrata em pequenos fragmentos e em áreas que se encontram em estágio de recuperação.

Toward reliable estimates of seed removal by small mammals and birds in the Neotropics

Birds are often considered seed predators of less importance when compared to rodents or granivorous ants in studies of seed predation using selective exclosures. However, it is possible that the role of granivorous birds interacting with seeds on the floor of Neotropical forests is being underestimated, if the selective exclosures designed to allow exclusive access to small rodents do not work properly in the Neotropics. We used an experimental approach to evaluate whether birds could remove seeds from selective exclosures designed to allow exclusive access to rodents. We compared seed removal from two paired treatments in the field: an open treatment (control) allowing the access to all vertebrates, and a selective exclosure treatment, where seeds were placed under a cage staked to the ground and covered on top and on the laterals by wire mesh of varying sizes. Treatments were placed in the center of a sand quadrat in order to record the visit of vertebrates from their footprints. Although the selective exclosures are used to tell apart the small mammal seed removal from that of other animals, birds could persistently remove seeds from selective exclosures. Thus, the role of birds interacting with seeds on the floor of tropical forests may be underestimated for some plant species, due to an artifact of the exclosure method employed. Exclosures of 40 x 40 x 40 cm should be efficient to deter the removal of seeds by birds, allowing the consumption of the seeds by small mammals at the same time.

Aves são freqüentemente consideradas predadores de sementes de pouca importância, quando comparadas a roedores e formigas granívoras em estudos sobre predação de sementes que utilizam exclusões seletivas. Contudo, é possível que o papel de aves granívoras que interagem com sementes no solo de florestas Neotropicais vem sendo subestimado, se as exclusões seletivas usadas para permitir o acesso exclusivo a pequenos roedores não funcionam de forma apropriada no Neotrópico. Foi usada uma abordagem experimental para avaliar se aves poderiam remover sementes do interior de exclusões seletivas desenhadas para permitir acesso exclusivo a roedores. Comparou-se a remoção de sementes em dois tratamentos no campo: um tratamento aberto (controle) que permite o acesso a todos os vertebrados, e um tratamento de exclusão seletiva, no qual as sementes eram dispostas sob uma gaiola metálica fixada ao solo e recoberta por tela metálica de tamanhos variados. Os tratamentos foram dispostos no centro de uma parcela de areia de forma a registrar a visita de vertebrados por meio de pegadas. Embora as exclusões seletivas sejam usadas para estimar separadamente a remoção de sementes por pequenos mamíferos daquela praticada por outros animais, aves puderam remover sementes das exclusões seletivas. Assim, o papel de aves interagindo com sementes no solo de florestas tropicais pode estar sendo subestimado para algumas espécies de plantas, devido a um artefato do método de exclusão empregado. Exclusões de 40 x 40 x 40 cm devem ser eficientes para deter a remoção de sementes por aves, permitindo o consumo de sementes por pequenos mamíferos ao mesmo tempo.