Made available in DSpace on 2014-06-12T15:05:19Z (GMT). No. of bitstreams: 2 arquivo1782_1.pdf: 1276117 bytes, checksum: 49861d6348f90df10798520fba0137ab (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2007 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Hermodice carunculata é considerado um importante predador de cnidários, alimentando-se de zooantideos, anêmonas, gorgônias, hidrocorais e corais escleractíneos. A predação é um importante agente estruturador das comunidades, podendo diminuir ou aumentar a diversidade. O objetivo desse trabalho foi identificar a dieta de H. carunculata nos bancos de Carijoa riisei na praia de Proto de Galinhas-PE e descrever o comportamento alimentar e estratégias de predação de H. carunculata. Foram coletados exemplares de H. carunculata nos ambientes recifais da Praia de Porto de Galinhas, para observação das estratégias alimentares. Foram avaliadas 1442 horas/indivíduo de observação em cinco experimentos. Nos experimentos de predação realizados com C. riisei, foram observadas duas estratégias de predação denominadas quebra e raspagem, sendo que o primeiro comportamento foi mais comum. Os poliquetas preferiram Protopalythoa variabilis a Millepora alcicornis; e preferiram Bunodosoma cangicum às especies acima. Em bancos de C. riisei, H. carunculata preferiu este octocoral como item alimentar e demonstrou preferência por animais mortos quando estes estão disponíveis. H. carunculata é um predador oportunista que se alimenta das presas mais acessíveis, utilizando para isso estratégias de ingestão diferentes que variam conforme a estrutura física de cada tipo de presa ou item alimentar

Mate choice plays an important role in sexual selection and speciation. The evolution of mate choice is intriguing in cases where choosy individuals gain little except for genetic material from the mate and where the trait used as a criterion for the choice is costly to its bearer. The sensory exploitation hypothesis is an interesting idea that applies to such cases because it suggests that sexual preferences may arise as side-effects of preferences that are under selection in other contexts. The role of mate choice in speciation is strong but is debated because the reasons for population divergence in mate preferences and sexual traits are sometimes hard to explain. Also in this context sensory exploitation offers a potential explanation in that a link between natural and sexual selection may result in divergence in sexual selection whenever populations differ in natural selection. In this thesis, I test several aspects of this hypothesis in a species of fish, the swordtail characin (Corynopoma riisei). In this species males display a flag-like ornament that grows from the operculum. Because females respond to this ornament by biting at it, it has been proposed to act as a food-mimic. By manipulating female food type and quantity, and testing the resulting female preference for the male ornament, I find support for the theory that the preference has evolved through sensory exploitation and that females indeed appear to relate the ornament to a food item. Furthermore, I show that sensory exploitation can lead to morphological divergence among natural populations in this species. Apart from the flag-ornament, other courtship signals are also investigated. The results show that the relative importance of different signals may vary depending on receiver motivation. This suggests that various aspects of both male courtship signals and the conditions during which they are being signalled should be considered to gain a full understanding of mate choice and its role in sexual selection and speciation.