and Luikart, 2007). Until some years ago, biodiversity was explained in specific level only (number of species) characterizing biodiversity “hot spots” based on high numbers of species in some biomes (Myers et al., 2000). However, the use of a non-reductionist approach is increasing in studies about biodiversity and conservation mechanisms. Currently, such studies take into account the population genetics influence as well as phylogenetic and evolutionary ecology, based on technological advance in obtaining and analyzing data, explaining the evolutionary mechanisms that occur within and between species and the key role they have in the generation and structuring of biodiversity in any environment (Salducci et al., 2004).
THE AMAZON BIOME The Amazon is a complex and delicate biome resulting from high biological diversity, one of the richest on the planet. This diversity has been explained by mechanisms resulting from the combination of geological processes occurring during the formation of the basin, climatic adjustments during the process of development and ecological-genetic mechanisms that have brought a profusion of speciation processes. Many researchers include as determinant elements of this diversity the environmental heterogeneity that occurs in the Amazon, its open character (it is linked to other adjacent hydrographical basins) and its pulsing characteristic (the basin is periodically flooded with a flooding pulse every year), which favors the existence of transitional environments and the periodic occupation of new habitats. Some authors suggest that environmental fragmentation is a mechanism that promotes the allopatric speciation and therefore promotes biodiversity (Meffe and Carroll, 1997). However, the theoretical and practical population’s genetics estimates that most of the fragmentation events caused by human activities facilitates local extinction, due to environmental degradation as well as the loss of genetic variability caused by the reduction in population size (Templeton et al., 2001). Understanding how human activities affect the genetic diversity and how the adaptation to the changed environment can be used to mitigate such influence is one of the
most difficult tasks in evolutionary biology. Differentiating between anthropogenic effects and evolutionary events that occur naturally in a population is a “jigsaw puzzle”, because these two mechanisms are the main responsible for the current distribution of species in the environment. It is increasingly important to recognize the similarities between the adaptive processes of the organisms that result in the survival or extinction of species and maintenance of the ecosystem. The same mechanisms that promote the adaptation to certain environments can be used by invasive species, completely changing the evolutionary course of the species and the community of a particular ecosystem. Adaptive processes that occurred up during the evolutionary history can be harmful to species that suffer in adverse environmental changes. The Amazon basin annually experiences inundation pulses that result in flooding of large forests extension. The mechanisms to adapt to such flooding areas may represent one of the main survival strategies to changes caused by the man. Therefore, knowing such mechanisms become extremely important when seeking environmental conservation. For identifying the main inte rac tions between organism and environment as well as the chances these organisms have to survive to changes in their environments, is necessary to examine: (i) changes in the behavior of the species facing environmental changes, which constitute a species first response level and can be initially used to characterize the occurrence, type, or intensity of the environmental change; (ii) physiological adjustments that include neurological and hormonal changes, which result in short term adjustments taking place at an individual level, and determined by gene regulation mechanisms (phenotypic plasticity); (iii) metabolic adjustments, still at the individual level, provided by gene regulation being more important within medium term, that is, only if the change is environmentally durable; (iv) changes in the genotypic frequency, which will occur after changes in the mortality rate and selective fertility of a population facing the environment change; (v) changes in the genetic composition of populations, which may cause speciation events; and (vi) morphological, anatomical or innate behavioral changes that result from pressure of a long period of time
AQUATIC BIOTA ADAPTATIONS
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