UMA REVISÃO SOBRE A SELEÇÃO SEXUAL EM PLANTAS
DOI:
https://doi.org/10.4257/oeco.2020.2401.03Palavras-chave:
Bateman’s principle, female choice, pollen competition, reproductive success, selective abortionResumo
A seleção sexual em plantas é um assunto que tem sido discutido recentemente na literatura, considerando que a origem do termo foi proposta por Darwin em 1871. A seleção sexual pode ser entendida como um mecanismo que age no sentido de conferir sucesso reprodutivo aos diferentes indivíduos envolvidos. Nestes casos, as principais relações envolvidas na seleção sexual em plantas incluem: (1) competição intrasexual por polinização e fertilização; (2) escolha da função feminina para que os melhores gametas masculinos tenham acesso aos óvulos e (3) aborto seletivo de sementes para garantir que embriões de qualidade se desenvolvam. De acordo com os resultados aqui apresentados, foi possível identificar mais de 161 espécies vegetais em que processos relacionados à seleção sexual foram demonstrados. A grande maioria dos trabalhos foi conduzida a partir de experimentos comparativos de remoção e deposição de pólen e produção de sementes com os atrativos florais, sendo embasados por testes estatísticos, mas um número considerável deles foi feito com base em experimentos genéticos e químicos, e alguns ainda com base exclusivamente teórica. A seleção sexual também tem sido entendida como um dos mecanismos responsáveis por mudanças evolutivas nas plantas, tais como a morfologia floral (e.g., tamanho das inflorescências, comprimento do estilete, receptividade do estigma) e evolução de sistemas sexuais (e.g., dioicia). Para estudos futuros, ressalta-se a necessidade de incluir uma variedade maior de grupos taxonômicos em trabalhos de seleção sexual, além de buscar entender como os mecanismos de aptidão dos grãos de pólen e escolha da fêmea funcionam em escala molecular. Este trabalho de revisão objetiva apresentar como a seleção sexual ocorre nas plantas e como os experimentos sobre esta temática têm sido conduzidos.
A REVISION OF SEXUAL SELECTION IN PLANTS. Sexual selection in plants has been discussed only recently in the literature, considering that the term was originally proposed by Darwin in 1871. Sexual selection can be understood as a mechanism that acts in order to ensure reproductive success to different individuals. In these cases, the main relations involved in the sexual selection in plants are: (1) intrasexual competition for pollination and fertilization; (2) female choice to guarantee that more vigorous male gametophytes fertilize the ovules; and (3) selective abortion of seeds so that only high-quality embryos develop. According to our revision, we found more than 161 plant species in which events related to sexual selection were identified. Most of these works have been conducted base on comparative experiments of pollen removal and deposition and seed production with floral attractiveness, corroborated by statistical tests, although a considerable number of studies has used genetic and chemical approaches, and a few are exclusively theoretical. Sexual selection has also been considered as one of the mechanisms that has driven evolutionary changes in plants, such as floral morphology (e.g., inflorescence size, style length, stigma receptivity) and the evolution of sexual systems (e.g., dioecy). For future studies, we stress the necessity to include more taxonomic groups in sexual selection experiments, as well as understand how the mechanisms of pollen ability and female choice operate in molecular scale. This revision aims to present how sexual selection occurs in plants and how experiments on this subject have been conducted.
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