INTRODUCTION
Resource utilization is a fundamental ecological process that mediates a variety of interactions, from mutualisms to antagonisms (Bronstein 2015). Investigating resource use patterns provides insight into the trophic niche species occupy and the functional roles they may play in an ecosystem (Elton 2001, Chase and Leibold 2009, van Leeuwen et al. 2022). Furthermore, quantifying spatiotemporal patterns in resource use can reveal the consistency of consumers in their dietary habits or shifts toward preferred food items that are limited in time and/or space (Abrahms et al. 2021). One spatiotemporally limited resource that is closely tracked by animals are fleshy fruits (Koike et al. 2008, Takahashi et al. 2008). In many ecosystems, as fleshy fruits become more abundant through time, animals shift their diet to become more frugivorous (Remis 1997, Gerardo Herrera M. et al. 2008, Robira et al. 2023).
Consequently, differences in a consumer’s strength of frugivory may influence its effectiveness as a seed disperser (Marques Dracxler and Kissling 2022, van Leeuwen et al. 2022), and since seed dispersal is a fundamental aspect in the life cycle of plants (Traveset et al. 2014), the strength of a consumer’s frugivory may have implications for plant life histories. Thus, quantifying the importance of fruit in the diet of an animal is a first step toward understanding its dispersal effectiveness (sensu Schupp 1993, Schupp et al. 2010). Identifying which fruit species are important in the consumer’s diet then opens the question about the reciprocal importance of the consumer as its disperser. While it has been demonstrated that plant dispersal syndromes are unreliable in predicting ingestion and dispersal (i.e., endozoochorous dispersal) of seeds (Green et al. 2021), an approach to quantify whether the functional role of an animal seed disperser changes as it becomes more frugivorous is to gauge if seed dispersal for species with the endozoochory syndrome (i.e., fleshy fruit) increases with frugivory.
In this study, we investigate patterns of frugivory in a population of hindgut fermenters, the gopher tortoise (Gopherus polyphemus ), and aim to address whether its functional role as a seed disperser changes as it becomes more frugivorous. Specifically, we aim to answer the following questions: (1) Are there temporal patterns of frugivory in this species? and (2) Which fleshy fruits drive frugivory? (3) Does the dispersal of species with the endozoochory syndrome increase as frugivory increases?
We hypothesize that after the seasonal precipitation begins, there will be a time lag between peak precipitation and peak frugivory in the gopher tortoise. Considering the phenology of many fleshy fruits in south Florida, coinciding with seasonal rains (Lodge 2017, Flora of North America Editorial Committee, eds. 1993+ 2023), as well as the two-to-three week gut retention time of the gopher tortoise (Bjorndal 1987), we anticipate that frugivory will increase steadily in throughout the summer with its peak in late summer/early fall. We expect that ultimately, the tortoises will disperse more fleshy-fruit species as they become more frugivorous, given the extremely broad and opportunistically frugivorous diet of this species (Ashton and Ashton 2008). This would demonstrate a shift along the mutualism-antagonism continuum by ecologically functioning as a frugivore by dispersing more species with the endozoochory syndrome as fruit consumption increases (sensu van Leeuwen et al. 2022).