The Amazon River system

Day, Jenny A.; Davies, BR; Junk, W. J.; Lowe-McConnell, R. H.

doi:10.1007/978-94-017-3290-1_8

Cited by 13 publications

(6 citation statements)

References 65 publications

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“…In the Amazon basin, on account of the enormous amount of water supply by rainfall and snow‐melt water from the Andes in the rainy season, the annual oscillation of the river water is as much as 10 to 20 m (Day & Davis 1986; Junk 1986; Piedade et al 1992). Based on our field observations and information from local people (Morishima & Martins 1994), the following characteristics of the life history of Amazonian O. glumaepatula were revealed.…”

Section: Discussionmentioning

confidence: 99%

Population genetic structure of wild rice Oryza glumaepatula distributed in the Amazon flood area influenced by its life‐history traits

1998

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Wild plant species develop their own way of living to adapt to the specific environment of their habitats. Their life‐history traits strongly affect the genetic structure of the population. The wild species Oryza glumaepatula Steud. growing in the Amazon basin seems to have characteristic life‐history traits suited for the flood condition. At the vegetative growth stage, the culms frequently break at internodes. With no roots anchoring on the ground, plant bodies floating in the water move downriver by water current and wind. To examine the association between the life‐history traits and genetic population structure of Amazonian O. glumaepatula, we analysed allozyme variability at 29 loci of 16 enzymes using 37 populations from five regions. Allozymes were not so variable (total gene diversity HE = 0.044) compared with Asian wild rice, O. rufipogon Griff. The bottleneck effect and rare opportunity of interspecies gene flow may prevent the development of allozyme variability. Population genotypes tended to be differentiated among geographically isolated regions. Observed heterozygosities were much lower than expected heterozygosities, or gene diversity (HO = 0.003 for whole population) and FIS over polymorphic loci was 0.931, indicating that O. glumaepatula has developed an inbreeding system. But, the intrapopulation gene diversity (HS) was higher than interpopulation gene diversity (DST), as generally observed in outbreeding populations. The migration ability of O. glumaepatula makes long‐distance seed dispersal possible. This might have led to frequent gene flow among populations.

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Section: Discussionmentioning

confidence: 99%

Population genetic structure of wild rice Oryza glumaepatula distributed in the Amazon flood area influenced by its life‐history traits

1998

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“…Moving up to a broader spatial scale, floodplains contain a greater variety of aquatic habitats, including ephemeral pools, permanent lagoons, and secondary channels. Even within a restricted area of the same floodplain, these habitats can be associated with very different hydrologies, soils, water qualities, and vegetation (Wissmar et al, 1981;Day & Davies, 1986). The lateral gradient of floodplain rivers presents fishes with a tremendous diversity of options for habitat selection.…”

Section: Riversmentioning

confidence: 99%

Effects of seasonality and fish movement on tropical river food webs

Winemiller

Jepsen

1998

Journal of Fish Biology

392

246

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Tropical rivers and their associated floodplain habitats are dynamic habitat mosaics to which fishes are challenged to respond in an adaptive manner. Migratory fishes create linkages among food webs that are partitioned along a nested hierarchy of spatial scales. Such linkages are examined across a hierarchy of spatio‐temporal scales, ranging from small streams to entire drainage basins, for rivers in South America and Africa. Migratory herbivorous fishes originating from eutrophic, productive ecosystems may subsidize resident predators of oligotrophic river ecosystems, which may result in cascading direct and indirect Effects on other species in local food webs. Successful management of many of the most important stocks of tropical river fishes requires conceptual models of how fish movement influences food web structure and dynamics.

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“…The present characteristics of the fluvial discharge system of the Amazon region have been the object of a large number of investigations over the last several decades (Sioli and Klinge, 1965;Sioli, 1975;Salati and Vose, 1984;Day and Davies, 1986;Jaccon and Cudo, 1987;Guimarães et al, 1993;Molinier et al, 1994;ANA, 2002ANA, , 2003Barthem et al, 2004). The main focus of investigations has been the evolution and characteristics of fluvial discharge systems at the surface.…”

Section: Introductionmentioning

confidence: 96%