Orientador: Paulo Sérgio Moreira Carvalho de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T09:19:12Z (GMT). No. of bitstreams: 1 Bottcher_Claudia_D.pdf: 2277526 bytes, checksum: fd9c885535eb1d45ead71daf14f43c8a (MD5) Previous issue date: 2010 / Resumo: A grande quantidade de frutos carnosos e a diversidade e abundância de formigas em ambientes tropicais faz com que a interação entre formigas e diásporos seja bastante comum. Atualmente sabe-se que estas interações envolvem dezenas de espécies de plantas e formigas em uma comunidade ecológica. Dentre as espécies da fauna de formigas que interagem com diásporos, Pachycondyla striata e Odontomachus chelifer destacam-se como dispersores de sementes caídas no solo e as características físicas e químicas de seus ninhos freqüentemente promovem o estabelecimento de plântulas. Contudo, apesar da reconhecida importância dessas formigas para algumas espécies de plantas, nada se sabe sobre a influência desses diásporos no desenvolvimento e reprodução de suas colônias. Com base nesse cenário, esta tese foi dividida em duas partes relacionadas. Na primeira parte, Capítulo I, investigamos as interações entre formigas e diásporos não-mirmecocóricos em três diferentes fisionomias florestais da Ilha do Cardoso (restinga, planície e encosta), sudeste do Brasil. Durante dois anos de amostras mensais 517 interações envolvendo 53 espécies de formigas e 48 espécies de diásporos foram observadas. A maior parte das interações ocorreu em floresta de planície (54.62%), e menos da metade ocorreu nas demais áreas, encosta (31.33%) e restinga (14.06%). Myrmicinae teve o maior número de espécies em interação (39 espécies), totalizando 436 interações (82.20%). Seis espécies da subfamília Ponerinae foram responsáveis por 33 interações (6,4%). Myrtaceae foi a família de planta mais numerosa nas interações (14 espécies). Na segunda parte da tese, capítulos II e III, foi dado ênfase às duas espécies de formigas da subfamília Ponerinae (Pachycondyla striata e Odontomachus chelifer) onde investigamos a importância dos frutos na ecologia de forrageamento e desenvolvimento das colônias. No capítulo II nós estudamos como a estrutura dos ninhos, demografia das colônias, ritmo diário de atividades, dieta e área de vida dessas espécies variam espacial e sazonalmente em restinga e planície. Operárias de O. chelifer e de P. striata caçam de modo oportunista incluindo uma ampla variedade de itens alimentares, forrageando mais intensamente no período úmido quando alados são mais abundantes e as condições ambientais são mais favoráveis. A atividade de forrageamento apresentou variação entre as espécies de formigas, o que poderia ser associada com fatores físicos e disponibilidade de alimentos, mostrando que o comportamento de forrageamento de O. chelifer e P. striata corresponde a variabilidade temporal e espacial da Mata Atlântica. Para testar a hipótese de que o consumo de diásporos não-mirmecocóricos beneficiaria colônias de formigas, no Capítulo III nós testamos o efeito do consumo de sementes de C. canjerana, com arilos ricos em lipídeos, em colônias de O. chelifer sob condições controladas em laboratório. Constatamos que larvas de formigas alimentadas com diásporos de C. canjerana foram em média maiores e se desenvolveram melhor que larvas controle. Em conclusão, os resultados desta tese reforçam a importância da dispersão secundária por formigas para sementes primariamente dispersas por vertebrados. Os dados evidenciam também a importância do estudo da ecologia de forrageamento e da influência do consumo de frutos na sobrevivência e crescimento de colônias de formigas. / Abstract: The large number of fleshy fruits and the diversity and abundance of ants in tropical environments makes the ant-diaspore interaction very common. Currently it is known that these interactions involve a large number of plants and ants species in an ecological community. Among the ant species interacting with diaspores, Pachycondyla striata and Odontomachus chelifer stand out as main dispersers of seeds encountered on the forest ground. Moreover, the physical and chemical characteristics of their nests often promote the establishment of seedlings. However, despite the recognized importance of these ants for some species of plants, nothing is known about the influence of the consumption of fleshy diaspores in the development and reproduction of the ant colonies. Based on this scenario, this thesis was divided into two related parts. In the first part, Chapter I, we investigated the interactions between ants and nonmyrmecochorous diaspores in three different physiognomic forest of Cardoso Island (sandy, lowland and hillside), southeastern Brazil. During two years of monthly samples 517 interactions involving 53 ant species and 48 species of seeds were observed. Most interactions occurred in lowland Forest (54.62%), and less than half occurred in the two other areas, hillside (31.33%) and sandy Forest (14.06%). Myrmicinae had the highest species number in interaction (39 species), totaling 436 interactions (82.20%). The six species of the Ponerinae subfamily were observed exploring diaspores accounted for 33 interactions (6.4%). Myrtaceae was the most numerous plant family in interactions (14 species). In the second part of this thesis, Chapter II and III, we emphasized two species of Ponerinae (Pachycondyla striata and Odontomachus chelifer), investigating the importance of fruits in their foraging ecology and the development of their colonies. In Chapter II we studied how nest structure, colonies demography, daily activities, diet and home range of these two species vary spatially and seasonally in sandy and lowland forest. Odontomachus chelifer and Pachycondyla striata workers hunt opportunistically including a wide variety of food items. They forage more intensively during the wet season when alates are more abundant and environmental conditions are more favorable. The foraging activity showed variation among the ant species, which could be associated with physical factors and food availability, showing that the foraging behavior of O. chelifer and P. striata correspond to temporal and spatial variability of the Atlantic Forest. To test the hypothesis that the consumption of non-myrmecochorous diaspores benefit ant colonies, in Chapter III we tested the effect of consumption of seeds of Cabralea canjerana, with lipid-rich arils, in colonies of O. chelifer under controlled laboratory conditions. We found that ant larvae fed with diaspores of C. canjerana were on average larger and grew better than control larvae. In conclusion, the data presented here reinforce the importance of secondary dispersal by ants for seeds primarily dispersed by vertebrates. Our results also indicate the importance of studying the foraging ecology and the influence of fruit consumption on survival and growth of colonies of ants. / Doutorado / Ecologia / Doutor em Ecologia

Unregulated North Swedish rivers show large seasonal variations in their physical characteristics. During winter the whole littoral zone freezes solid, and in spring the water flow increases rapidly and the same areas become flooded. The two mayflies Parameletus chelifer and P. minor are common in the North Swedish river Vindelälven. They probably pass through a dormant egg stage in its mid-stream section. The first tiny nymphs appeared in January to March, but they did not become abundant until the ice broke up in May. At this time they migrated rapidly to the flooded upper littoral, some continuing into the tributaries. During  the migration phase, both species used chemoreception to orient themselves towards the flooded areas. The shoreward migration allowed the nymphs to avoid high current velocity, and to utilize unexploited food resources. The two species differed with respect to utilization of the upper littoral. Most Parameletus chelifer nymphs colo­nized a seasonal stream, while the P. minor nymphs were equally abundant at the river margin as in a seasonal stream. Both temperature and food quality differed between the river margin and the seasonal stream. Compared to P. minor specimens, those of Parameletus chelifer showed a somewhat higher optimum tempe­rature, and they gained advantage of the higher food quality observed in the seasonal stream. Parameletus chelifer specimens colonizing a seasonal stream had higher growth rate, higher fecundity, and probably also advanced emergence as well as larger adult size compared with those remaining at the river margin. In addition mortality from fish predation may be lowered by utilizing shallow seasonal streams. Specimens of P. minor had higher growth rate, larger adult size and advanced emergence in the seasonal stream compared with those at the river margin. Nevertheless, fecundity was equal in both habitats and the mortality caused by predation seemed almost similar in both habitats. In most years Parameletus chelifer specimens utilizing the seasonal stream thus obtain a higher fitness than those utilizing the river margin. In P. minor this diffe­rence was not so pronounced. However, due to mortality risks caused by an early desiccation of the seasonal stream, the long-term reproductive output of the two species probably varies irregularly in the two habitats. / digitalisering@umu