65 resultados para ancestor
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Karyotypes of the blind catfish Pimelodella kronei from three different caves in the southwestern part of the State of São Paulo, Brazil, and of its presumed ancestor Pimelodella transitoria were examined. Chromosome number and formula, as well as C-banding pattern and NOR location were found to be the same in both species, supporting the hypothesis of a close relationship and even conspecificity of P. kronei and P. transitoria.
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Avaliou-se a divergência genética entre quinze linhagens (Hav 13, Hav 14, Hav 21, Hav 22, Hav 25, Hav 38, Hav 40, Hav 41, Hav 49, Hav 53, Hav 56, Hav 64, Hav 65, Hav 67 e Hav 68) e cinco cultivares (Macarrão Favorito AG480, Macarrão Preferido AG482, Manteiga Maravilha AG481, Teresópolis AG484 e Macarrão Bragança) de feijão-vagem de crescimento indeterminado, utilizando-se vinte características agronômicas. O ensaio foi conduzido na AGENCIARURAL - EE de Anápolis, no período de 30/04 a 10/08/1998. Os dados foram submetidos às análises de variância e multivariada (distância D² de Mahalanobis e o método de agrupamento de Tocher). Houve diferenças significativas entre os genótipos para as características consideradas. Os genótipos Hav 13, Hav 49, Hav 56, Hav 64, Hav 68, Favorito AG480 e Teresópolis AG484 destacaram-se com relação ao conjunto de características favoráveis a produtores e consumidores. Houve maior freqüência de pares com maiores distâncias, quando um dos componentes era a cultivar Teresópolis AG484 ou Hav 49, e de pares com menores distâncias quando seus componentes tiveram como ancestral comum a linhagem Hab 229. Os genótipos distribuíram-se em quatro grupos, sendo um constituído exclusivamente pela linhagem Hav 49, outro englobando as cultivares Manteiga Maravilha AG481 e Teresópolis AG484. A linhagem Hav 41 e as cultivares Macarrão Favorito AG480 e Macarrão Preferido AG482 um terceiro grupo, e os demais genótipos um único grupo. As características que mais contribuíram para a divergência entre os genótipos foram o número de dias para o início de floração e o comprimento das vagens, com 58,11% do total, seguidas da porcentagem de palha na vagem seca, da largura das vagens, das alturas das plantas nas duas épocas avaliadas, do peso médio de vagem e do número de vagens por planta que, em conjunto, contribuíram com 85,73% do total.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The genus Mycetagroicus is perhaps the least known of all fungus-growing ant genera, having been first described in 2001 from museum specimens. A recent molecular phylogenetic analysis of the fungus-growing ants demonstrated that Mycetagroicus is the sister to all higher attine ants (Trachymyrmex, Sericomyrmex, Acromyrmex, Pseudoatta, and Atta), making it of extreme importance for understanding the transition between lower and higher attine agriculture. Four nests of Mycetagroicus cerradensis near Uberlandia, Minas Gerais, Brazil were excavated, and fungus chambers for one were located at a depth of 3.5 meters. Based on its lack of gongylidia (hyphal-tip swellings typical of higher attine cultivars), and a phylogenetic analysis of the ITS rDNA gene region, M. cerradensis cultivates a lower attine fungus in Clade 2 of lower attine (G3) fungi. This finding refines a previous estimate for the origin of higher attine agriculture, an event that can now be dated at approximately 21-25 mya in the ancestor of extant species of Trachymyrmex and Sericomyrmex.
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The Neotropical pitviper genus Bothrops comprises about 40 species, which occur in all main ecosystems of cis-Andean South America. We explored the relationships of body size and form (tail length and stoutness) with macrohabitat use in 20 forms of Bothrops. Sen-ii-arboreal habits appeared only in forest forms. Semi-arboreals are significantly more slender and have longer tails than terrestrials; body size is not significantly different between terrestrials and semi-arboreals. Within Bothrops, independent contrasts for macrohabitat use were significantly correlated with contrasts of tail size (positively) and stoutness (negatively); thus, the more arboreal the species, the longer its tail and the more slender its body. Contrasts of adult body size seems to remain constant over the lower range of macrohabitat use, but to decrease in species of Bothrops which are more arboreal. Reconstructions of character states indicate that: (1) the ancestor of Bothrops was a small, stout, terrestrial species; (2) semi-arboreal habits appeared one to three times in the genus; (3) a decrease in stoutness and an increase in tail length occurred along with an increase in arboreality in some clades. Although macrohabitat use seems to be important in determining body form in Bothrops, our results also indicate that tail size, stoutness and body size may also be affected by selective agents other than macrohabitat use. The selective agents responsible for the shifts in macrohabitat use in Bothrops are still uncertain, although they may have included prey availability and/or predation pressure. The plasticity of macrohabitat use, morphology and body size described in this study may have been key features that facilitated the highly successful ecological diversification of Bothrops in South America.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)