Variação individual de nicho em espécies que coexistem
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Data
2018-12-06
Autores
Pereira, Raul Costa [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Esta tese gravita em torno da ideia de que indivíduos de uma mesma espécie são ecologicamente diferentes. Apesar de esse fato não parecer surpreendente, a teoria ecológica tem historicamente negligenciado a variação intraespecífica em várias de suas frentes. Um exemplo claro é a teoria clássica de nicho, que implicitamente supõe que indivíduos conspecíficos utilizam exatamente os mesmos recursos. De modo similar, a teoria de comunidades considera que espécies são bem representadas em termos ecológicos pela média de atributos de seus indivíduos. Ao longo dos quatro capítulos que compõem esta tese, estudei os padrões, causas e consequências da diversidade ecológica entre indivíduos em um contexto de múltiplas espécies que coexistem. Utilizei quatro espécies de rãs do gênero Leptodactylus que coexistem em áreas do Pantanal e entorno como sistema de estudo. No Capítulo 1, mostro que diferenças de nicho trófico entre indivíduos e espécies são flexíveis e dependentes de contexto, o que pode ter implicações importantes para os padrões locais e regionais de biodiversidade. No Capítulo 2, elucido que a tremenda variação na alometria de interações tróficas entre e dentro de comunidades pode ser explicada por gradientes de limitação de presas. No Capítulo 3, estudei os nichos tróficos de espécies competidoras em uma perspectiva multidimensional, revelando interessantes mecanismos pelos quais indivíduos e espécies particionam recursos em duas dimensões tróficas. Finalmente, no Capítulo 4, ao mostrar que mudanças temporais de dieta podem aumentar o valor adaptativo de indivíduos, avanço na compreensão das ainda pouco estudadas consequências da variação individual de nicho. Em conclusão, esta tese contribui para o entendimento dos mecanismos que geram e mantêm variabilidade ecológica entre indivíduos na natureza, bem como das implicações ecológicas desse fenômeno em escalas de organização biológicas superiores.
This thesis gravitates around the idea that individuals from the same species are ecologically different. Although this fact does not seem surprising, ecological theory has historically neglected intraspecific variation. A clear instance is the classic niche theory, which implicitly assumes that conspecific individuals utilize the same resources. Accordingly, community theory considers that species are well represented by the mean of individuals’ traits. Over the four chapters of this thesis, I studied the patterns, causes, and consequences of the ecological diversity between individuals in the context of multiple coexisting species. I studied four frog species from the genus Leptodactylus that coexist in the Pantanal wetlands and surrounding areas as model organisms. In Chapter 1, I show that trophic niche differences between individuals and species are flexible and context-dependent, which may have important implications to local and regional diversity patterns. In Chapter 2, I elucidate that the tremendous variation in the allometric scaling of trophic interactions within and between natural communities is predictable, responding to gradients of prey limitation. In Chapter 3, I studied trophic niches of competing species in a multidimensional perspective, revealing interesting mechanisms by which individuals and species partition resources in two trophic dimensions. Finally, Chapter 4 advances in the understanding of the underexplored consequences of individual niche variation by showing that temporal diet changes may have major fitness implications. Altogether, these results contribute to broadening our understanding of the mechanisms generating and maintaining ecological variability between individuals in nature, as well as of the implications of this phenomenon across scales of biological organization.
This thesis gravitates around the idea that individuals from the same species are ecologically different. Although this fact does not seem surprising, ecological theory has historically neglected intraspecific variation. A clear instance is the classic niche theory, which implicitly assumes that conspecific individuals utilize the same resources. Accordingly, community theory considers that species are well represented by the mean of individuals’ traits. Over the four chapters of this thesis, I studied the patterns, causes, and consequences of the ecological diversity between individuals in the context of multiple coexisting species. I studied four frog species from the genus Leptodactylus that coexist in the Pantanal wetlands and surrounding areas as model organisms. In Chapter 1, I show that trophic niche differences between individuals and species are flexible and context-dependent, which may have important implications to local and regional diversity patterns. In Chapter 2, I elucidate that the tremendous variation in the allometric scaling of trophic interactions within and between natural communities is predictable, responding to gradients of prey limitation. In Chapter 3, I studied trophic niches of competing species in a multidimensional perspective, revealing interesting mechanisms by which individuals and species partition resources in two trophic dimensions. Finally, Chapter 4 advances in the understanding of the underexplored consequences of individual niche variation by showing that temporal diet changes may have major fitness implications. Altogether, these results contribute to broadening our understanding of the mechanisms generating and maintaining ecological variability between individuals in nature, as well as of the implications of this phenomenon across scales of biological organization.
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Palavras-chave
Isótopos estáveis, Especialização individual, Sobreposição de nicho, Dieta, Variação de nicho, Competição, , Stable isotopes, Individual specializiation, Niche overlap, Diet, Niche variation, Competition, Fitness