Evidence for a Role in Seed Dispersal by Two Tropical Herbivorous Turtles

Moll, Don; Jansen, Kevin P.

doi:10.2307/2388909

Cited by 82 publications

(51 citation statements)

References 30 publications

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“…Although the passage times recorded for C. denticulata are long compared to those recorded for birds and mammals, which are normally only a few hours and rarely reach a day (Holbrook and Smith 2000;Wehncke et al 2003;Link and Di Fiore 2006), germination does not seem to be affected after seeds pass through a tortoise gut, a result that has been recorded for other reptile species (Moll and Jansen 1995;Traveset 1998;Liu et al 2004). Passed seeds of two of three plant species that were tested, germinated successfully.…”

Section: Diversity Of Dispersed Seedsmentioning

confidence: 69%

Are tortoises important seed dispersers in Amazonian forests?

2009

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According to most studies on seed dispersal in tropical forests, mammals and birds are considered the main dispersal agents and the role played by other animal groups remains poorly explored. We investigate qualitative and quantitative components of the role played by the tortoise Chelonoidis denticulata in seed dispersal in southeastern Amazon, and the influence of seasonal variation in tortoise movement patterns on resulting seed shadows. Seed shadows produced by this tortoise were estimated by combining information on seed passage times through their digestive tract, which varied from 3 to 17 days, with a robust dataset on movements obtained from 18 adult C. denticulata monitored with radio transmitters and spoon-and-line tracking devices. A total of 4,206 seeds were found in 94 collected feces, belonging to 50 seed morphotypes of, at least, 25 plant genera. Very low rates of damage to the external structure of the ingested seeds were observed. Additionally, results of germination trials suggested that passage of seeds through C. denticulata's digestive tract does not seem to negatively affect seed germination. The estimated seed shadows are likely to contribute significantly to the dispersal of seeds away from parent plants. During the dry season seeds were dispersed, on average, 174.1 m away from the location of fruit ingestion; during the rainy season, this mean dispersal distance increased to 276.7 m. Our results suggest that C. denticulata plays an important role in seed dispersal in Amazonian forests and highlight the influence of seasonal changes in movements on the resulting seed shadows.

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Section: Diversity Of Dispersed Seedsmentioning

confidence: 69%

Are tortoises important seed dispersers in Amazonian forests?

2009

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“…While seed dispersal by insects, birds, and mammals is well studied (Abrahamson 1989), saurochory, the dispersal of seeds by reptiles, has received comparatively little attention (Traveset 1998) despite recognition that early reptiles were a significant selective force in the evolution of modern fruit (van der Pijl 1982;Tiffney 1986;Moll and Jansen 1995). Although many reptiles are carnivorous and therefore unlikely to ingest fruits and disperse seeds, numerous partially or wholly herbivorous species are potential seed dispersal agents (Moll and Jansen 1995).…”

Section: Introductionmentioning

confidence: 99%

Seed dispersal by the Florida box turtle ( Terrapene carolina bauri ) in pine rockland forests of the lower Florida Keys, United States

2004

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Seed dispersal by animals is one of the most important plant-animal mutualisms, but saurochory, the dispersal of seeds by reptiles, has received little attention. We investigated the role of the Florida box turtle (Terrapene carolina bauri) as a seed dispersal agent in pine rockland forests of the lower Florida Keys and examined the effect of turtle digestion on seed germination. We obtained seeds of 11 species with fleshy fruits and 2 species with non-fleshy fruits (a grass and legume) from the feces of 145 box turtles collected on Key Deer National Wildlife Refuge from 1999 to 2000. We planted the seeds of nine species and germination percentage (percentage of seeds that germinated during the experiment) varied from 10% to 80%. Comparative germination experiments were conducted with Thrinax morrissii, Serenoa repens, and Byrsonima lucida. We compared the germination percentage and germination rate (number of days from planting to seedling emergence) of seeds from three treatments (seeds recovered from feces, control seeds with pulp, and control seeds without pulp) and continued these experiments for up to 2 years. Passage through the box turtle digestive tract greatly enhanced the germination percentage and germination rate of S. repens, but decreased the germination percentage of B. lucida and T. morrissii, and decreased germination rate for T. morrissii. Subsequent destructive seed viability tests revealed that many ungerminated T. morrissii seeds remained viable, suggesting long-term seed dormancy may occur, even after passage through the turtle digestive system. In addition, the proportion of ungerminated seeds which remained viable was greater for seeds recovered from turtle feces than from control seeds with pulp. Furthermore, removal of fleshy pulp either manually or by the turtle digestive system may allow T. morrissii to escape insect predation.

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“…South American river turtles consume fruits, and these can then be dispersed along water margins (Moll and Jansen, 1995) or carried further during long-distance migrations (Kubitzki and Ziburski, 1994). Amazon giant river turtles (Podocnemis expansa, up to 55 kg; Smith, 1979) are known seed dispersers and migrate great distances between feeding and nesting grounds.…”

Section: Reptiles As Gene Transportersmentioning

confidence: 99%

The Plight of Reptiles as Ecological Actors in the Tropics

Miranda

Everton²

2017

Front. Ecol. Evol.

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Earth's tropical ecosystems have witnessed several extinctions and a dramatic reduction of the range and abundance of large reptile species, which is directly related to the rise of early and modern humans. The occurrence of such extinctions, range reduction, species loss, and the consequences for several paramount ecosystem processes are poorly documented compared to other large vertebrate species. Here, I reviewed the literature on the ecological processes performed by large tropical reptile species and their human-induced widespread demise in order to determine knowledge gaps and encourage a paradigm shift in understanding on the interactiveness of such species. The interactions and species involved indicate that large abundant reptiles in the tropics are important in ecological processes, and can consequently have an important role in ecosystem function through gene dispersal, nutrient cycling, trophic action, and ecosystem engineering. These important interactions performed by reptiles are not solely performed by few species, or geographically restricted to islands, but instead present a pattern that repeatedly occurs in large reptiles distributed over tropical ecosystems. The observed tendency of reptiles to be tightly involved in these ecological interactions has important implications for the ecology of tropical ecosystems. Lost and current ecological processes performed by large reptiles may be orders of magnitude higher than what is currently perceived, and the misleading baseline of those processes must be addressed otherwise we risk losing species and services that are dependent of such interactions. To fix this bias I suggest: (a) Increase information spreading about Pleistocene-Holocene reptile extinctions using popular media; (b) Improved exchange between the research field of megafauna effects in ecosystems and herpetologists working with large reptiles; (c) Increase research effort on anthropogenic reptile extinctions and their potential to predict future losses; (d) Address the knowledge gaps, as human-reptile conflict, chelonian seed dispersal and nutrient movement; (e) Increase quantitative research on large reptile population ecology, density, and abundance. (f) address the potentially present or lost ecosystem effects of extant and extinct reptile species. Although the importance of reptiles in most tropical ecosystems has been perceived as negligible, this study shows that this may be a misleading paradigm.

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Evidence for a Role in Seed Dispersal by Two Tropical Herbivorous Turtles

Cited by 82 publications

References 30 publications

Are tortoises important seed dispersers in Amazonian forests?

Are tortoises important seed dispersers in Amazonian forests?

Seed dispersal by the Florida box turtle ( Terrapene carolina bauri ) in pine rockland forests of the lower Florida Keys, United States

The Plight of Reptiles as Ecological Actors in the Tropics

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