Are ecologists blind to small things? The missed stories on non-tropical seed predation on feces

Abstract

Seed dispersal involves several complex stages that can be affected by multiple peripheral processes. Thus, a major dispersal event can be followed by secondary dispersal, which can reduce density‐dependent mortality and consolidate the dispersal phase. But predation events can also follow, and predation of seeds in feces is particularly interesting because it can heavily alter the fate of seeds dispersed through vertebrate guts. Our review of 20 cases involving this kind of interaction found that research has chiefly been in tropical and subtropical areas (85% of cases), suggesting that it is a minor phenomenon at higher latitudes. However, the small size of both the seeds and predators involved may have caused this process to go unnoticed outside the tropics. We tested the presence of predation of seeds in feces at a temperate, semi‐arid and small‐seed dominated ecosystem and found that it can be as important as in tropical latitudes, affecting up to 80% of feces in mid‐summer. Moreover, it may influence endozoochory in a way whose significance could have been strongly underestimated, as it affects 35% of the seeds dispersed by sheep during the year. Our results may encourage scientists to pay attention to other interactions that may be widespread globally but go unnoticed. The study of seed dispersal, especially, may be suffering from the researchers’ difficulty in handling processes that are difficult to observe because of the small size of the organisms involved.

Drove roads as local biodiversity reservoirs: effects on landscape pattern and plant communities in a Mediterranean region

“…Scientific studies often suffer from bias due to the difficulty of conducting the relevant research (Manzano et al. ), and indeed one possible reason for the lack of research into drove roads is the difficulty of finding drove roads that are still functional (i.e. used for pastoralism), legally defined and easily identifiable.…”

Does Gut Passage Affect Post-dispersal Seed Fate in a Wild Chili, Capsicum annuum?

“…Furthermore, at least some observed impacts from these studies are inconsistent between seasons (Mártinez- Mota et al 2004) or within a season (Andresen 1999). For small-seeded temperate species like Bird Peppers, post-dispersal predation of defecated seeds is poorly understood; the vast majority of previous studies concern large-seeded tropical species (Manzano et al 2010). An exception is a recent study by Fricke et al (2013), which found that gut passage increased Capsicum chacoense Hunz.…”

“…As part of the Lower Suwannee National Wildlife Refuge, the island is undeveloped and retains much of its original flora and fauna. In temperate woodlands (like Seahorse Key), rodents are generally the most important granivores (Hulme 1998), but ants are usually better at locating small seeds at low densities (like those used in this study; Kaspari 1993, Manzano et al 2010), and in Bolivia, ants are post-dispersal predators of chilies (Fricke et. al.…”

“…Any advantages associated with germination, however, would be rendered irrelevant if seeds are consumed soon after dispersal. In this context, it is becoming increasingly apparent that gut treatment can change the chemical and physical structure of seeds in ways that impact post-dispersal seed predation (Andresen and Levey 2004, Fricke et al 2013, Manzano et al 2010, Mártinez-Mota et al 2004.…”

How does the seed fate of Crotalaria podocarpa DC, a highly competitive herbaceous legume in arid rangelands, contribute to its establishment probability?

“…In contrast post-dispersal seed loss is mainly affected by larger, more generalist species, such as rodents, ground-foraging birds but also by invertebrates, such as weevils and ants (Hulme and Kollmann, 2005;Kuechly et al, 2011;Mokotjomela and Hoffmann, 2013). Besides their role as predator, these animals can also act as vectors for seed dispersal by ingestion and subsequent defaecation, by deliberate removal for later recovery or by epizoochorous transport (Cousens et al, 2008;Manzano et al, 2010;Stamp and Lucas, 1990), often increasing seed availability and recruitment success at the landscape level (Münzbergová and Herben, 2005;Vander Wall et al, 2005). Seed predation and removal are often influenced by biotic conditions, e.g.…”