Desynapsis and precocious cytokinesis in Brachiaria humidicola (Poaceae) compromise meiotic division.

The forage grass species Brachiaria humidicola is native to African savannas. Owing to its good adaptation to poorly drained and infertile acid soils, it has achieved wide utilization for pastures in Brazilian farms. Among the 55 accessions of B. humidicola analysed from the Embrapa Beef Cattle collection, one (H022), presented desynapsis and an abnormal pattern of cytokinesis in the first meiotic division. Among 28 inflorescences analysed in this accession, 12 were affected by the anomaly. In affected meiocytes, the first cytokinesis occurred in metaphase I and was generally perpendicular to a wide-metaphase plate, dividing the genome into two parts with an equal or unequal number of chromosomes. The normal cytokinesis after telophase I did not occur, and the meiocytes entered metaphase II, progressing to the end of meiosis with the occurrence of the second cytokinesis. As the first cytokinesis occurred precociously, whereas the second was normal, tetrads were formed but with unbalanced chromosome numbers in microspores. Abnormal cytokinesis occurred only in those meiocytes that underwent desynapsis after diakinesis. The implications of this abnormality in the Brachiaria breeding programme are discussed.

Neotropical Siluriformes as a Model for Insights on Determining Biodiversity of Animal Groups.

We performed an analysis of the descriptions of new species of Neotropical Siluriformes (catfishes) to estimate the number of new species that remain to be described for a complete knowledge on biodiversity of this order, to verify the effectiveness of taxonomic support, and to identify trends and present relevant information for future policies. We conducted a literature review of species descriptions between January 1990 and August 2014. The following metadata were recorded from each article: year of publication, number of species, journal and impact factor, family(s) of the described species, number of authors, age of the authors and coauthors, country of the first author's institution and ecoregion of the type-locality. From accumulation of descriptions, we built an estimate model for number of species remaining to be described. We found 595 described species in 402 articles. The data demonstrated that there has been an increased understanding of the diversity of Siluriformes over the last 25 years in the Neotropical region, although 35% of the species still remain to be described. The model estimated that with the current trends and incentives, the biodiversity will be known in almost seven decades. We have reinforced the idea that greater joint efforts should be made by society and the scientific community to obtain this knowledge in a shorter period of time through enhanced programs for promoting science, training and the advancement of professionals before undiscovered species become extinct. The model built in this study can be used for similar estimates of other groups of animals.

Ichthyofauna of headwater streams from the rio Ribeira de Iguape basin, at the boundaries of the Ponta Grossa Arch, Paraná, Brazil / Ictiofauna de riachos de cabeceira da bacia do rio Ribeira de Iguape, nos limites do Arco de Ponta Grossa, Paraná, Brasil

Abstract: The rio Ribeira de Iguape basin (Paraná State) is highly relevant for the preservation of remnants of the Atlantic Forest. Its high levels of diversity and fish endemism explain the river dynamics promoted by the Ponta Grossa Arch, a geological structure that promotes headwater capture and isolation between the upper rio Paraná drainage, the rio Iguaçu and the rio Ribeira de Iguape. Here, our objective was to provide an unprecedented inventory for headwater streams of the rio Ribeira de Iguape basin at the boundaries of the Ponta Grossa Arch. We found 29 species of fish representing four orders and nine families. Siluriformes was the richest order followed by Characiformes. Nine species presented high abundance of sampled individuals, contributing with 87.8% of the collections. Four species appeared in less than 25% of the sampled sites (occasional), and six species appeared in more than 50% (constant). We identified three non-described species and one non-native (Coptodon rendalli). Two species had their geographical distribution extended and the presence of Astyanax bifasciatus, endemic to the Iguaçu river basin, ratifies recent events of headwater capture between coastal drainages and those that flow into the continent. Studies of biogeographic divisors are necessary to explain the origin and dispersion processes of species in order to direct studies on diversity and preventive management actions. Coptodon rendalli (Tilapia) is an alarming record on the introduction of species in the region.

Resumo: A bacia do rio Ribeira de Iguape (Estado do Paraná) é altamente relevante para a preservação de remanescentes da Mata Atlântica. Os seus altos níveis de diversidade e de endemismo de peixes explicam a dinâmica fluvial promovida pelo Arco de Ponta Grossa, estrutura geológica que promove eventos de captura de cabeceira e de isolamento entre as drenagens do alto rio Paraná, do rio Iguaçu e do rio Ribeira de Iguape. Aqui, nosso objetivo foi fornecer um inventário inédito para riachos de cabeceira da bacia do rio Ribeira de Iguape nos limites do Arco de Ponta Grossa. Encontramos 29 espécies de peixes representando quatro ordens e nove famílias. Siluriformes foi a ordem mais rica seguida por Characiformes. Nove espécies apresentaram alta abundância de indivíduos amostrados, contribuindo com 87,8% das coletas. Quatro espécies apareceram em menos de 25% dos locais amostrados (ocasionais), e seis espécies apareceram em mais de 50 % (constantes). Identificamos três espécies não descritas e uma (Coptodon rendalli) não nativa. Duas espécies tiveram sua distribuição geográfica ampliada e, a presença de Astyanax bifasciatus, endêmica para a bacia do rio Iguaçu, ratifica eventos recentes de captura de cabeceira entre drenagens costeiras e aquelas que fluem para dentro do continente. Estudos de divisores biogeográficos são necessários para explicar os processos de origem e dispersão de espécies a fim de direcionar estudos sobre diversidade e ações de manejo preventivas. Coptodon rendalli (Tilápia) é um registro alarmante sobre a introdução de espécies na região.

Foraging behavior interactions between the invasive Nile Tilapia (Cichliformes: Cichlidae) and three large native predators

The predator-prey relationships between juvenile Nile Tilapia Oreochromis niloticus and native fish species of the Paraná River basin, Brazil, were experimentally examined. Juveniles of O. niloticus were offered to three native predator species (Salminus brasiliensis, Pseudoplatystoma corruscans, and Brycon orbignyanus) in 2,000-L tanks with four levels of habitat complexity (0%, 50%, 100% and RD (rocks and driftwood)). Predator efficiency was more variable among species (S. brasiliensis consumed 86.6% of the prey, P. corruscans 22.5% and B. orbignyanus 18.3%) than among levels of habitat complexity, and S. brasiliensis was faster than the others in detecting and consuming the prey. The higher predatory efficiency observed for S. brasiliensis can be partially explained by its more aggressive behavior (it fed earlier and for longer) and its presence in the surface layer. Here, the presence of predators led to O. niloticus juveniles spending more time at the surface or remaining in schools to coexist at the bottom with the predators, as expected for cichlids under predatory pressure in natural environments. Our results suggest that preserving and restoring populations of S. brasiliensis (and also to some extent P. corruscans and B. orbignyanus) might help to control O. niloticus in the Paraná River basin.(AU)

As relações predador-presa entre alevinos de Tilápia-do-Nilo Oreochromis niloticus e espécies de peixes nativos da bacia do rio Paraná, Brasil, foram examinadas experimentalmente. Dez alevinos de O. niloticus foram oferecidos a três espécies nativas de predadores (Salminus brasiliensis, Pseudoplatystoma corruscans e Brycon orbignyanus) em tanques de 2000L com quatro níveis de complexidade ambiental (0%, 50%, 100% e RD (rochas e galhos)). A eficiência predatória foi mais variável entre espécies (S. brasiliensis consumiu 86,6%, P. corruscans 22,5% e B. orbignyanus 18,3% dos alevinos) do que para complexidade ambiental, e S. brasiliensis foi mais rápido do que os outros em detectar e consumir a presa. A eficiência predatória de S. brasiliensis pode ser parcialmente explicada pelo seu comportamento mais agressivo (alimentou-se mais cedo e por mais tempo de experimento) e pela presença na área de superfície. A presença de predadores levou os alevinos de O. niloticus a passar mais tempo na superfície ou formar cardume para coexistir no fundo com os predadores, como o esperado para ciclídeos sob pressão predatória no campo. Nossos resultados sugerem que preservar e restaurar as populações de S. brasiliensis (principalmente, mas também P. corruscans e B. orbignyanus) podem ajudar no controle de O. niloticus na bacia do rio Paraná.(AU)

Misguided policy may jeopardize a diverse South brazilian environmental protection area / Política equivocada pode colocar em risco uma área de preservação ambiental do sul do Brasil

Abstract: The Devonian Escarpment (DEEPA), located in the south of Brazil, represents an important area of environmental preservation composed by grasslands, gallery forests, as well as rock outcrops and archaeological sites. A law project (LP 527/2016), which suggests a reduction of the DEEPA area in approximately 70% of its original area (from 393,579 to 125,895 ha), is currently being processed in the Paraná State House of Representatives. Such reduction seems to be related to economic interests (mainly agriculture and mining) in the state of Paraná. If approved, LP 527/2016 will allow farmers to deliberately expand their activities, with the suppression of natural forest as main consequence. Additionally, loss of faunal diversity, contamination of water and soils, and alteration in nutrient cycles are expected, due the intensive use of agrochemicals. In addition to the direct environmental consequences, we expect the disappearance of areas of high geological interest, reducing local geodiversity, as well as substantial economic losses with ecotourism. Brazil is a signatory to the United Nations Convention on Biological Diversity, where it undertakes to develop strategies to prevent biodiversity loss and ecosystem degradation by 2020. An approval of the LP would be contradictory, considering that there are few natural vegetation areas in this region of the country. We emphasize that the proposal of such projects goes against the sustainability in the country and disregard the scientific knowledge generated until then. Thus, it is necessary to develop regional and federal political objectives that guarantee economic development in a balanced way, considering the local bio and geodiversity, not the proposal of mechanisms that destroy them.

Resumo: A Escarpa Devoniana (APAED), localizada no sul do Brasil, representa uma importante área de preservação ambiental composta por campos, matas de galeria, além de afloramentos rochosos e sítios arqueológicos. Atualmente, tramita na câmara dos deputados do estado do Paraná um projeto de lei estadual (PL 527/2016) que sugere a redução da área da APAED em aproximadamente 70% de sua área original (de 393.579 para 125.895 ha). Tal redução parece estar relacionada com interesses econômicos (principalmente agropecuária e mineração) no estado do Paraná. Caso aprovado, o PL 527/2016 permitirá que agricultores expandam suas atividades deliberadamente, tendo como consequência principal a supressão de áreas de floresta nativa. Com isso, espera-se perda de diversidade faunística, contaminação de água e solos e alteração nos ciclos de nutrientes, dado o aumento no uso de agroquímicos. Além das consequências ambientas diretas, podemos esperar o desaparecimento de elevado interesse geológico, reduzindo a geodiversidade local, além de substanciais perdas econômicas com ecoturismo. O Brasil é um dos países signatários da Convenção da Diversidade Biológica das Nações Unidas, onde se compromete a desenvolver estratégias que evitem a perda da biodiversidade e a degradação de ecossistemas até 2020. Assim, a aprovação desse projeto de lei é, no mínimo, contraditória considerando que existem poucas áreas de vegetação natural nessa região do país. Destacamos que a proposta de tais projetos vai contra a sustentabilidade no país e desconsideram o conhecimento científico gerado até então. Dessa forma, é necessário o desenvolvimento de objetivos políticos regionais e federais que garantam o desenvolvimento econômico de forma equilibrada, considerando a bio e geodiversidade local, e não a proposta de mecanismos que as destruam.