Dung beetle activity had no positive effect on nutrient concentration or performance of established rainforest seedlings

1. Traits are key for understanding the environmental responses and ecological roles of organisms. Trait approaches to functional ecology are well established for plants, whereas consistent frameworks for animal groups are less developed.Here we suggest a framework for the study of the functional ecology of animals from a trait-based response-effect approach, using dung beetles as model system. Dung beetles are a key group of decomposers that are important for many ecosystem processes. The lack of a trait-based framework tailored to this group has limited the use of traits in dung beetle functional ecology.2. We review which dung beetle traits respond to the environment and affect ecosystem processes, covering the wide range of spatial, temporal and biological scales at which they are involved. Dung beetles show trait-based responses to variation in temperature, water, soil properties, trophic resources, light, vegetation structure, competition, predation and parasitism. Dung beetles' influence on ecosystem processes includes trait-mediated effects on nutrient cycling, bioturbation, plant growth, seed dispersal, other dung-based organisms and parasite transmission, as well as some cases of pollination and predation.3. We identify 66 dung beetle traits that are either response or effect traits, or both, pertaining to six main categories: morphology, feeding, reproduction, physiology, activity and movement. Several traits pertain to more than one category, in

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“…; but see Urrea-Galeano,Andresen, Coates, Mora Ardila, Diaz Rojas, et al, 2019;Urrea-Galeano et al, 2021).…”

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A trait‐based framework for dung beetle functional ecology

deCastro-Arrazola

Andrew

Berg

et al. 2022

Journal of Animal Ecology

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“…These studies gave us the first data suggesting that dung beetle activity might change the soil environment in a way that favors nutrient uptake and survival of seedlings established in the tropical forest understory. To gather more evidence, a third study in a different Mexican rainforest assessed the effects of dung beetle activity for the seedlings of six plant species, measuring foliar nutrients, growth, and survival (Urrea-Galeano et al, 2021). However, contrary to the previous results, no positive effect of dung beetle activity was detected for any of the variables in any of the seedling species.…”

Section: Plant Performancementioning

confidence: 84%

“…Whether dung beetle activity, through soil fertilization and/or bioturbation, has positive effects on the performance of tropical forest plants remains an unanswered question. At this point, to guide future studies, we can only summarize some recommendations that have been previously voiced by us or others (Nichols et al, 2008;Griffiths et al, 2016;Santos-Heredia et al, 2016;Urrea-Galeano et al, 2021): (i) to avoid extrapolating into natural conditions of tropical forests, results obtained in other study systems and regions; (ii) to carry out field experiments in tropical forest that would allow us to distinguish the effects that dung beetle activity has through fertilization vs. bioturbation on plant performance; (iii) to empirically measure the changes that feces burial by beetles causes in the tropical forest soil (i.e., physical, chemical, and biological changes) to better understand the mechanisms driving plant responses; (iv) to measure other responses in plants, such as herbivory and pathogen attack, since these plant antagonists are known to prefer plants with higher nutrient content; (v) to replicate these studies in forests that vary in soil characteristics (e.g., soil fertility, soil compaction, texture), and with plant species that differ in their functional traits (e.g., seed reserves, shade tolerance). There is much work to be done here.…”

Section: Plant Performancementioning

confidence: 99%

“…The lack of empirical evidence often leads to the assumption that effects of dung beetles measured in other study systems (e.g., greenhouse experiment on temperate grasses) can be extrapolated to natural conditions in tropical forests. However, such an assumption is not justified because the effects of dung beetle activity on plants are context dependent (Slade et al, 2011;Griffiths et al, 2016;Urrea-Galeano et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Effects of dung beetle activity on tropical forest plants

Urrea‐Galeano¹

2022

Front. Ecol. Evol.

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Dung beetles are recognized as providers of important ecosystem functions, most of which are derived from the removal of vertebrate dung from the soil surface. These insects occur in nearly all terrestrial biomes but are most diverse in the humid tropics. Several of the ecological functions attributed to dung beetles are related to their direct and indirect interactions with plants. Among these functions, the secondary dispersal of seeds defecated by mammals has received the most attention in tropical forests. Nonetheless, while several aspects of secondary seed dispersal by dung beetles are relatively well understood, others remain understudied or have not been addressed at all. Thus, a broad generalization about the effects of secondary seed dispersal by dung beetles on plant fitness remains somewhat elusive. Furthermore, other effects of dung beetle activity on tropical plants have received very little attention. A few studies have shown that through their behaviors of dung burial and soil-excavation, dung beetles can shape seed bank structure and dynamics. Also, though numerous greenhouse studies and field experiments in agricultural lands and temperate grasslands have shown that dung beetle activity increases plant nutrient uptake and yield, it is uncertain whether such effects are common in tropical forests. Here, we review and synthesize our current knowledge on how dung beetles affect tropical forest plants by dispersing defecated seeds, shaping the structure and dynamics of seed banks, and influencing the performance of understory seedlings. We focus on the Neotropics, where most studies on the effects of dung beetles on tropical forest plants have been carried out, but we also show results from other regions and biomes, to present a more general picture of these beetle-plant interactions. Throughout the review we emphasize aspects that need more research to allow generalizations and point out those questions that remain unanswered. We hope that this review will stimulate more research about the fascinating interactions between dung beetles and plants in tropical ecosystems.

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“…Studies with other mammals have shown increased nitrogen, phosphorus, potassium, sulfur, and carbon in latrines (McGregor & Brown, 2010), with important consequences to plant diversity and composition (Shrestha & Moe, 2015). However, while recurrent defecation offers input of nutrients to the soil, it does not necessarily mean that plants will directly benefit from the extra nutrients (Urrea-Galeano et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Linking howler monkey ranging and defecation patterns to primary and secondary seed dispersal

Fuzessy

Sobral

Culot

2021

American J Primatol

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To define the chances of a dispersed seed to produce a new recruit, it is essential to consider all stages of the dispersal process. Howler monkeys are recognized to have positive impacts on forest regeneration, acting as primary dispersers. Furthermore, dung beetles attracted to their feces protect the seeds against predators, and provide a better microenvironment for germination due to the removal of fecal matter, to seed burial, and/or by reducing the spatial aggregation of seeds in fecal clumps.Despite the recognized positive effects of primary seed dispersal through defecation by howler monkeys for plant recruitment, there are some important aspects of their behavior, such as the habit of defecating in latrines, that remain to be explored.Here, we investigated the fate of Campomanesia xanthocarpa seeds defecated by brown howlers, Alouatta guariba clamitans, and the secondary seed dispersal by dung beetles, considering how this process is affected by the monkey's defecation patterns. We found that brown howler monkeys dispersed seeds from several species away from fruit-feeding trees, partly because defecation under the canopy of such trees was not very frequent. Instead, most defecations were associated with latrines under overnight sleeping trees. Despite a very similar dung beetle community attracted to howler feces in latrines and fruit-feeding sites, seeds were more likely to be buried when deposited in latrines. In addition, C. xanthocarpa seeds showed higher germination and establishment success in latrines, but this positive effect was not due to the presence of fecal matter surrounding seeds. Our results highlight that A. guariba clamitans acts as a legitimate seed disperser of C. xanthocarpa seeds in a preserved context of the Brazilian Atlantic Forest and that defecations in latrines increase the dispersal effectiveness.

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Dung beetle activity had no positive effect on nutrient concentration or performance of established rainforest seedlings

Cited by 4 publications

References 67 publications

A trait‐based framework for dung beetle functional ecology

A trait‐based framework for dung beetle functional ecology

Effects of dung beetle activity on tropical forest plants

Linking howler monkey ranging and defecation patterns to primary and secondary seed dispersal

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