Abstract
In the present study, we assessed the ecomorphology of two species of Astyanax in streams with different substrates found in the Rio São Francisco Basin. The dominant substrate of each stream was defined as either "fine" (0 to 2 mm), "gravel" (2 to 250 mm), "rock" (> 250 mm), or "leaf bank". We analyzed a total of 22 ecomorphological attributes of Astyanax intermedius Eigenmann, 1908 (127 individuals) and Astyanax rivularis (Lütken, 1875) (238 individuals) adults. We detected significant ecomorphological differences between the populations of A. rivularis and A. intermedius from habitats with different types of substrates. However, the two species did not show the same morphological differences depending on the type of substrate. These results confirmed the hypothesis that individuals from environments with different characteristics may have different ecomorphological patterns. Knowing that morphology is associated with habitat use and available resources, the loss of a resource or a modification in the environment may directly affect the permanence of a species, leading to a loss of morphologic diversity.
Highlights
The relationship between the body shape of organisms and the environments they inhabit was suggested by Aristotle in the fourth century BC
Comparing the ecomorphology of populations of two species of Astyanax inhabiting streams characterized by different substrate types, this study addressed the following questions: I) are there intraspecific, differences in morphology related to the different stream substrate types?; and II) do different species show the same substrate related morphological differences?
Ecomorphology studies the relationship between morphology and ecology across individuals, populations, and communities, and it examines the evolutionary consequences of these relationships, which are primarily adaptive convergence and divergence (GATZ 1979, WINEMILLER 1991)
Summary
The relationship between the body shape of organisms and the environments they inhabit was suggested by Aristotle in the fourth century BC. It was only in 1859 with the publication of The Origin of Species by Charles Darwin that the theoretical base of this relationship was consolidated (FREIRE & AGOSTINHO 2001). Adaptation is the most important concept for understanding the relationship between morphology and ecology, and it is described as structures that increase fitness (ELDREDGE 1989). This understanding states that adaptations can be detected by relating physiology to environmental variables (PERESNETO 1999). 2014 Sociedade Brasileira de Zoologia | www.sbzoologia.org.br | www.scielo.br/zool All content of the journal, except where identified, is licensed under a Creative Commons attribution-type BY-NC
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