Effects of gut passage on the germination of seeds ingested by didelphid marsupials in a neotropical savanna

Abstract

We analyzed the effects that passage through the guts of seven didelphid species had on the seed germination of 10 plant species. This study was conducted in an area of riparian woodland in a cerrado (savanna) reserve in southeastern Brazil. We found seeds of 23 angiosperm species in 427 fecal samples obtained from seven didelphid species. The plant families most often represented by the seeds found in the fecal samples were Melastomataceae (5 species) and Rubiaceae (4 species) . Most gut-passed seeds showed no significant difference in germinability when compared with the hand-extracted seeds. Among the ingested seeds, only those of Clidemia urceolata DC. (Melastomataceae) and Myrcia sp. (Myrtaceae) showed an increase in germinability (final proportion of germinated seeds), indicating that didelphid gut passage does not always benefit seed germination. The average germination time of consumed seeds ranged from 12 days (Cipocereus minensis (Werderm.) Ritter) to 171 days (Cordiera sessilis (Vell.) Kuntze). The small number of seeds destroyed after gut passage and the results obtained during the germination experiments underscore the importance of didelphid marsupials to the dynamics of plant reproduction, especially those of small--seeded cerrado species.

Key factors affecting seed germination of Copaifera langsdorffii, a Neotropical tree

“…The treatments that simulated the effects of a disperser increased germination by about 50%. These results are in accordance with other studies (Leal & Oliveira 1998;Robertson et al 2006;Christianini et al 2007;Lessa et al 2013;Lima et al 2013), and demonstrate the potential benefits of the seed dispersal process on seed germination (Lima et al 2013). These results suggest that dispersers, in addition to transporting seeds away from the mother plant and thus avoiding intraspecific competition and decreasing the likelihood of an attack by predators (Janzen 1970;Swamy et al 2011), are essential in the germination success of C. langsdorffii.…”

“…Zoochorous seeds have fleshy structures that attract and reward their dispersers (Christianini et al 2007) and often have substances that inhibit germination (Cipollini & Levey 1997;Yagihashi & Miyamoto 1998;Robertson et al 2006). Thus, in addition to transporting seeds away from the mother plant, seed dispersers can be important to the successful germination of some species by removing compounds that inhibit germination (Robertson et al 2006;Silveira et al 2012;Lessa et al 2013). Birds and ants are important groups that mutually interact as seed dispersers and can remove inhibitors, thus promoting germination (Meyer & Witmer 1998;Christianini & Oliveira 2010;Guerta et al 2011;Lima et al 2013), however, this influence is not uniform among zoochorous species (Barnea et al 1991;Figueroa & Castro 2002).…”

Food habits and endozoochorous seed dispersal by small rodents (Cricetidae and Echimyidae) in a riparian forest in southeastern Brazil

“…Endozoochorous seed dispersal results from a mutualistic interaction between plants and the animals that feed on ripe and nutritious fleshy fruits containing one or several seeds (Howe and Smallwood 1982;Lessa et al 2013). Therefore, the role of small mammals as potential seed dispersers is usually related to the consumption of a wide variety of fruits and the presence of intact seeds in their feces, with generally increased germinability (Magnusson and Sanaiotti 1987;Vieira et al 2006;Lessa and Costa 2009;Lessa et al 2013).…”

“…Endozoochorous seed dispersal results from a mutualistic interaction between plants and the animals that feed on ripe and nutritious fleshy fruits containing one or several seeds (Howe and Smallwood 1982;Lessa et al 2013). Therefore, the role of small mammals as potential seed dispersers is usually related to the consumption of a wide variety of fruits and the presence of intact seeds in their feces, with generally increased germinability (Magnusson and Sanaiotti 1987;Vieira et al 2006;Lessa and Costa 2009;Lessa et al 2013). However, the process of gut scarification of the seed coat by passage through the digestive tract of small mammals (rodents and marsupials) does not always have positive effects on the germinability of the ingested seeds (see Traveset 1998;Lessa and Costa 2009;Cantor et al 2010;Lessa et al 2013;Sahley et al 2016).…”

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

“…Ingestion by frugivores may increase, decrease, or have no effect on seed germination success of different plant species (Samuels and Levey 2005;Jordaan et al 2012;Spotswood et al 2012;Wilson and Downs 2012;Lessa et al 2013). Many studies show that germination is more successful after seeds pass through the digestive tract of frugivores (Traveset 1998;Yagihashi et al 1999;Traveset et al 2001;Paulsen and Hogstedt 2002;LaFleur et al 2009;D'Avila et al 2010;Reid and Armesto 2011;Jordaan et al 2011a).…”