Padrões de diversidade e estrutura de taxocenoses de anfíbios anuros: análise em multi-escala espacial
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Data
2008-07-01
Autores
Nomura, Fausto [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
No presente estudo, procurou-se investigar a relação entre os diferentes níveis de diversidade (alfa, beta e gama) de taxocenoses de anuros com a qualidade da cobertura vegetal e com padrões de diversidade morfológica. A diversidade alfa e gama apresentaram as mesmas repostas em função do gradiente de cobertura vegetal, sendo maior a influência de fatores estruturais em condições de maior cobertura e maior a influência de fatores climáticos em condições de menor cobertura. Em condições de maior cobertura vegetal foi encontrado um maior número de espécies arborícolas. Já espécies terrícolas vão se tornando mais comuns à medida que a cobertura vegetal vai sendo degradada. Entretanto, uma maior quantidade de espécies arborícolas não aumenta a diversidade morfológica da taxocenose. Espécies terrícolas, em função dos diferentes tipos do comportamento de escavação e divergências quanto ao hábito alimentar, proporcionam uma maior diversificação de estratégias para exploração do ambiente. Independente do grau de cobertura vegetal, a partilha do espaço acústico em taxocenoses de anuros ocorre entre três guildasdefinidas em função de características espectrais do canto de anúncio. Adicionlamente parece não haver influência de fatores ecológicos na relação entre o comprimento rostro-cloacal e a freqüência dominante do canto de anúncio. Em um extremo da relação entre o tamanho corporal e a freqüência dominante do canto de anúncio (espécies grandes – cantos graves) parece não haver a influência de fatores ecológicos, já que não houve tendência de espécies de maior porte a emitirem sons mais graves do que o esperado pelos modelos nulos. Entretanto, no outro extremo da relação (espécies pequenas – cantos agudos) foi encontrada uma tendência a espécies de pequeno porte a produzirem sons de freqüência mais alta do que o esperado...
In the present study, we investigate the relationship between the different levels of diversity (alfa, beta and gamma) in anuran assemblages with a continuum in the vegetation cover. Strucutural factors were important for the determination of the alfa and gamma diversities for the maximum vegetational cover condition and climatic factors were important for the determination of these same diversities for the minimum vegetational cover condition. A similar response was obtained when the relationship between morphological diversity and the vegetational gradient was investigated. Arboreal anurans were commom in the maximum vegetational cover condition, whereas terrestrial anurans were commom in the minimum vegetational cover condition. However, the arboreal habit appears to be limited to a fewer morphological types than the terrestrial habit. Terrestrial forms could present a diversity of burrowing and feeding strategies that promote a divesification in the morphological types associated to the terrestrial habit. Additionally, we investigated the possible existence of ecological constraints in the relationship between the rostro-cloacal length and the dominant frequency, generally associated only to morphological constraints and considered a important signal for female choice. Independently of the degree of vegetational cover, the acoustic space was shared by three anurans guilds define by spectral properties of the call. The relationship between the rostro-cloacal length and the dominant frequency was investigated with a null model approach. A ecological constraint was detected only for the smallest species of anurans. Small anurans calls in higher frequencies when compared to the randomized data sets being more efficient in short distance communication. Small anurans have grater abundance during reproductive periods than large anurans. Calls of high frequency could allow that small anurans to select the calling sites closer to other calling anurans.
In the present study, we investigate the relationship between the different levels of diversity (alfa, beta and gamma) in anuran assemblages with a continuum in the vegetation cover. Strucutural factors were important for the determination of the alfa and gamma diversities for the maximum vegetational cover condition and climatic factors were important for the determination of these same diversities for the minimum vegetational cover condition. A similar response was obtained when the relationship between morphological diversity and the vegetational gradient was investigated. Arboreal anurans were commom in the maximum vegetational cover condition, whereas terrestrial anurans were commom in the minimum vegetational cover condition. However, the arboreal habit appears to be limited to a fewer morphological types than the terrestrial habit. Terrestrial forms could present a diversity of burrowing and feeding strategies that promote a divesification in the morphological types associated to the terrestrial habit. Additionally, we investigated the possible existence of ecological constraints in the relationship between the rostro-cloacal length and the dominant frequency, generally associated only to morphological constraints and considered a important signal for female choice. Independently of the degree of vegetational cover, the acoustic space was shared by three anurans guilds define by spectral properties of the call. The relationship between the rostro-cloacal length and the dominant frequency was investigated with a null model approach. A ecological constraint was detected only for the smallest species of anurans. Small anurans calls in higher frequencies when compared to the randomized data sets being more efficient in short distance communication. Small anurans have grater abundance during reproductive periods than large anurans. Calls of high frequency could allow that small anurans to select the calling sites closer to other calling anurans.
Descrição
Palavras-chave
Anuro, Taxocenose, Anura
Como citar
NOMURA, Fausto. Padrões de diversidade e estrutura de taxocenoses de anfíbios anuros: análise em multi-escala espacial. 2008. 109 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências de Rio Claro, 2008.