Variação morfológica em girinos bentônicos e nectônicos: influência de fatores espaciais ou ambientais?
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Data
2023-03-03
Autores
Santos, Danusy Lopes
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A morfologia é um dos principais componentes do fenótipo de um organismo. Os girinos apresentam grande diversidade morfológica e comportamental, e ocupam uma ampla gama de habitats aquáticos e terrestres. Essa diversidade tem disso atribuída às características físicas do ambiente e à presença a predadores e competidores. Apesar dos girinos serem excelentes modelos para estudos morfológicos e de variação fenotípica, existe uma carência em estudos envolvendo variação morfológica, suas origens e distribuição no espaço e no tempo. Outra carência envolvendo o estudo de girinos está na relação entre as estruturas anatômicas e suas respectivas funções, e variações morfológicas apresentadas por essas estruturas. Considerando a ausência de estudos com ampla abrangência geográfica acerca das variações morfológicas, assim como sobre a organização e funcionamento de órgãos e sistemas, e se eles sofrem modificações de acordo com diferenças no uso do ambiente, nossos objetivos gerais foram: (1) determinar a variação em caracteres morfológicos externos em girinos de diferentes guildas ecomorfológicas, verificando a existência de padrõesassociados a distância espacial entre populações ao longo da distribuição geográfica das espécies alvo; (2) caracterizar o sistema nervoso de girinos de diferentes guildas ecomorfológicas, buscando correlacionar a morfologia do sistema nervoso ao ambiente utilizado. Utilizando técnicas de morfometria geométrica, além de imagens tridimensionais, nós analisamos a variação da morfologia externa. Por meio de modelos tridimensionais analisamos as variações morfológicas no cérebro de girinos de três diferentes guildas ecomorfológicas e verificamos se as variações morfológicas observadas podem estar associadas a diferenças no uso do habitat. Nossos resultados demonstram que a morfologia externa dos girinos é correlacionada com a distância espacial entre as populações de todas as espécies analisadas, com exceção de Rhinella diptycha. A morfologia do cérebro variou acima do esperado, principalmente as regiões do cerebelo, optic tectum e diencéfalo. Observamos também que essas variações estão associadas ao uso da coluna d’água e também ao tamanho do cérebro. Girinos nectônicos de D. minutus, que usam o ambiente em três dimensões, apresentaram cérebro com maior tamanho e cerebelo mais volumoso
Morphology is one of the main components of an organism's phenotype. Thus questions and hypotheses related to the origin of morphological variation and its distribution in space and time are common within biology. Tadpoles occupy a wide range of aquatic and terrestrial habitats and include a great diversity of ecomorphotypes, with diverse morphological and behavioral adaptations, differences in developmental time, size at metamorphosis and in physiological aspects, both in response to the physical characteristics of the environment and/or in response to the presence of predators and competitors, thus being excellent models for morphological and phenotypic variation studies. However, there is a lack of studies involving morphological variation, its origins and distribution in space and time using tadpoles. Another deficiency involving the study of tadpoles is the relationship between anatomical structures and their respective functions, and morphological variations presented by these structures. Considering the absence of basic information and studies with a wide geographical distribution about morphological variations, as well as about the organization and functioning of organs and systems, and how they are modified to meet the demands of different types of environment our general objective was: (1) to determine the variation in larval morphological characters in tadpoles from different ecomorphological guilds, verifying the existence of patterns, associated with distance between populations or environmental variables along the geographic distribution of the target species , (2) to characterize the nervous system of tadpoles from different ecomorphological guilds, seeking to correlate the morphology of the nervous system to the environment used. Using geometric morphometric techniques, in addition to three-dimensional images, we analyzed the variation in external morphology found in tadpole populations from different ecomorphological guilds and whether this variation is associated with the spatial distance between populations along their geographic distribution. In addition, through threedimensional models, we analyzed the morphological variations presented by the brain of tadpoles from three different guilds and whether the observed morphological variations could be associated with these guilds. Our results indicate that the external morphology of tadpoles presents a spatial correlation for all species analyzed with the exception of Rhinella diptycha. As for the brains, we observed a variation above the expected, mainly for the regions of the cerebellum, optic tectum and diencephalon. We also observed that these variations are associated with guilds and brain size.
Morphology is one of the main components of an organism's phenotype. Thus questions and hypotheses related to the origin of morphological variation and its distribution in space and time are common within biology. Tadpoles occupy a wide range of aquatic and terrestrial habitats and include a great diversity of ecomorphotypes, with diverse morphological and behavioral adaptations, differences in developmental time, size at metamorphosis and in physiological aspects, both in response to the physical characteristics of the environment and/or in response to the presence of predators and competitors, thus being excellent models for morphological and phenotypic variation studies. However, there is a lack of studies involving morphological variation, its origins and distribution in space and time using tadpoles. Another deficiency involving the study of tadpoles is the relationship between anatomical structures and their respective functions, and morphological variations presented by these structures. Considering the absence of basic information and studies with a wide geographical distribution about morphological variations, as well as about the organization and functioning of organs and systems, and how they are modified to meet the demands of different types of environment our general objective was: (1) to determine the variation in larval morphological characters in tadpoles from different ecomorphological guilds, verifying the existence of patterns, associated with distance between populations or environmental variables along the geographic distribution of the target species , (2) to characterize the nervous system of tadpoles from different ecomorphological guilds, seeking to correlate the morphology of the nervous system to the environment used. Using geometric morphometric techniques, in addition to three-dimensional images, we analyzed the variation in external morphology found in tadpole populations from different ecomorphological guilds and whether this variation is associated with the spatial distance between populations along their geographic distribution. In addition, through threedimensional models, we analyzed the morphological variations presented by the brain of tadpoles from three different guilds and whether the observed morphological variations could be associated with these guilds. Our results indicate that the external morphology of tadpoles presents a spatial correlation for all species analyzed with the exception of Rhinella diptycha. As for the brains, we observed a variation above the expected, mainly for the regions of the cerebellum, optic tectum and diencephalon. We also observed that these variations are associated with guilds and brain size.
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Palavras-chave
Girinos, Morfologia, Microtomografia computadorizada, Guildas ecomorfológicas, Padrões espaciais, Tadpoles, Morphology, Micro computed tomography (μCT), Ecomorphological guilds, Spatial patterns