Banca de QUALIFICAÇÃO: VIRGÍNIA HELEN FIGUEIREDO PAIXÃO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : VIRGÍNIA HELEN FIGUEIREDO PAIXÃO
DATE: 10/07/2025
TIME: 09:00
LOCAL: Sala de Reuniões do Decol
TITLE:

Frugivory and seed dispersal in Cactaceae Juss. (1789) and its role as a keystone resource for the
Neotropical fauna.

 

KEY WORDS:

Fruit consumption; seed germination; fruiting phenology; morphometry; nutritional content.

PAGES: 109
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Frugivory and seed dispersal are key processes for maintaining biodiversity, as they promote colonization of new areas, gene flow, and ecosystem resilience. In arid environments, cacti stand out due to their high species and life form diversity, production of zoochorous fruits, and their role as a source of water and nutrients. Therefore, the overall objective of this dissertation was to identify, at global, regional, and local scales, the main frugivores and effective seed dispersers of Cactaceae, and to describe plant and fruit traits associated with animal consumption.In the first chapter, we synthesized the existing literature on frugivory, life forms, fruit and seed traits, and seed germination in Cactaceae. We documented 630 cactus-frugivore interactions involving 255 frugivore species, distributed across 21 orders, 46 families, and 138 genera, and 94 cactus species belonging to 35 genera. Overall, birds were the most represented group with 146 species, of which 66% belonged to the order Passeriformes, accounting for 64% of the interactions. The most frequently reported cactus genera were Pilosocereus, Stenocereus, and Cereus — all columnar cacti. We found high diversity in cactus life forms and heights, as well as in fruit and seed colors and shapes. Most interactions involved Treelike cacti with fleshy dehiscent fruits containing small seeds ranging from 0.6 mm to 4 mm in length. Birds and mammals mainly consumed red fruits with white
pulp. Passage through the digestive tract of birds, particularly Passeriformes, significantly increased seed germination rates. Moreover, seeds germinated 46% faster after passing through the guts of birds, mammals, and reptiles.In the second chapter, we investigated fruiting phenology, morphometry of plants, fruits, and seeds, and the nutritional composition of fruits in three species of Mammillaria (Cactaceae) in the Tehuacán-Cuicatlán Valley, Mexico. Mammillaria produced fruits continuously throughout the study period, with fruiting peaks synchronized with peak rainfall in June. The fruits are small and red, contain between 10 and 260 small seeds, and are rich in water, carbohydrates, proteins, and lipids — making them a potentially viable food source for both humans and animals in the region. The species showed subtle but significant differences in morphological traits (plant height and width, spine length, fruit size and weight, and seed size). Despite having slightly different ecological strategies, fruit
characteristics (color, size, and shape) appear to be associated with zoochory. In the third chapter, we examined frugivory using camera traps and seed dispersal through germination tests after gut passage in three Mammillaria species in the Tehuacán-Cuicatlán Valley, Mexico—previously unexplored aspects for the genus. We recorded 93 frugivory events by 15 vertebrate species across six orders and 12 families, consuming 131 fruits directly from plants. Passeriformes was the most species-rich order. Although the Teiidae lizard Aspidoscelis sp. had the highest number of visits and fruit consumption events (N = 22), the cuculiform bird Geococcyx velox consumed a total of 43 fruits in just 12 visits, compared to 24 fruits consumed by the lizard. Overall, birds were the most effective seed removers per visit, followed by reptiles and small mammals. In germination tests, 93% of Mammillaria seeds that had passed through animal digestive tracts (birds and lizards) germinated under natural conditions, compared to 1% of seeds extracted directly from fruits and 4% of manually cleaned seeds. Additionally, seeds dispersed by animals germinated faster than those in other treatments. As a general conclusion, our results indicate that, at both global and local scales, cactus fruits are consumed by a wide range of animals and that seeds benefit from gut passage by germinating more and faster. Fruit color and shape, along with small seeds embedded in a fleshy pulp rich in water and nutrients, enhance the role of cactus species as key resources, especially in arid environments.

 

 

COMMITTEE MEMBERS:
Externa ao Programa - 1813882 - ALICE DE MORAES CALVENTE - nullInterno - 1678202 - CARLOS ROBERTO SORENSEN DUTRA DA FONSECA
Interno - 1718346 - EDUARDO MARTINS VENTICINQUE