Dung beetle trophic ecology: are we misunderstanding resources attraction?

1. Food choice may change depending on sex, age, and physiological condition due to nutritional requirements or because of mechanisms that promote food recognition. Among dung beetles, some species are attracted to both carrion and dung, but why males and females are more attracted to either resource remains unclear. This study aimed to investigate whether body size, physiological condition (body dry mass, lipid mass, muscle mass) and age (young, mature, old) affect resource attraction in males and females of two species of dung beetles, Dichotomius iannuzziae and D. gilletti. 2. This study was carried out in remnants of Atlantic Forest in Brazil. To evaluate resource attraction, pitfall traps baited with feces or carrion were installed in the remnants, and the beetles were categorized according to sex and age. Furthermore, beetles' physiological condition and body size were measured. 3. Population structure of D. iannuzziae differed according to bait type. Males of D. iannuzziae were more attracted to feces than carrion across all age classes. The same occurred among conspecific mature females, suggesting a sex‐specific reproductive preference for feces. Contrastingly, D. gilletti resource attraction did not vary with sex or age. For both species, neither body size nor physiological condition defined resource attraction, indicating that compensatory feeding due to nutrient requirements is unlikely. 4. Due to the changes in food quality and quantity as a consequence of forest loss, mammal extinction and landscape transformation, it is critical to understand how wild species respond to different scenarios of food availability.

Section: Discussionmentioning

confidence: 99%

Dung or carrion? Sex and age determine resource attraction in dung beetles

Salomão

Cerqueira

Gomes

et al. 2021

“…We used a total of 25 functional traits: 10 morphological (seven of these associated with the body and three with the mouthpieces), four ethological, and 11 physiological; morphological and physiological traits were estimated from measurements performed in this study, while ethological traits were obtained from previous studies held in the same ecosystem (Giménez G omez et al, 2020(Giménez G omez et al, , 2021Giménez G omez, Verdú, G omez-Cifuentes, et al, 2018;Hernández, 2002;Hernández et al, 2011), and from the authors' field experience. All functional traits are directly or indirectly associated with three ecological functions performed by dung beetles: nutrient cycling (Slade et al, 2007;Yamada et al, 2007), secondary seed dispersal (Gardner et al, 2008;Slade et al, 2007), and parasite control (Braga et al, 2012;Nichols & G omez, 2014).…”

Section: Functional Traits: Selection Classification and Association ...mentioning

confidence: 99%

Functional responses to anthropogenic disturbance and the importance of selected traits: A study case using dung beetles

Gómez

Verdú

Casanoves

et al. 2022

Self Cite

Functional diversity has been defined as the value, range, distribution, and relative abundance of the functional traits of individuals that belong to an ecosystem. Thus, the functional response of organisms to environmental disturbances depends largely on their functional traits. Here, we evaluated dung beetle functional diversity associated to the Atlantic Forest replacement using a matrix with 25 functional traits (10 morphological, four ethological, and 11 physiological). We compared functional diversity among native and disturbed habitats with a multi and single trait approach. Contrary to previous studies, habitats with higher disturbance (open pasture) exhibited higher functional diversity compared to native forests, which could be explained by the incorporation of physiological response traits. Species of open disturbed habitats showed extreme values of such traits, explaining the observed pattern. The inclusion of several traits that represent both species ecology and morphology, and their physiology, generates different results to those observed in previous functional studies. This highlights the importance of including a large variety of functional traits in future functional diversity studies. We propose that functional traits must (1) be carefully chosen according to their biological and functional basis; (2) represent species ecology and physiology; and (3) include both effect and response traits. In addition, we consider it is extremely relevant to include a multi and single trait approach in functional diversity studies. A combination of all these considerations will provide a more realistic and complete overview of functional diversity patterns and the potential consequences of human disturbance on ecosystem functioning.

“…However, when more dimensions of the ecological niche are involved (not only physiology), the interspecific competition can seem favoured (Feer & Pincebourde, 2005;Tokeshi, 1999). In highly diverse assemblages, dung beetle exhibit differences in several axes of the ecological niche due to the interspecific competition (Hanski & Cambefort, 1991a;Peck & Forsyth, 1982;Verdú et al, 2004), including endothermy, thermoregulation, thermal tolerance, metabolic rate (Giménez G omez et al, 2020;Verdú et al, 2006Verdú et al, , 2007Verdú et al, 2019); nesting strategies (Chao et al, 2013;Halffter & Edmonds, 1982); trophic preferences (da Silva et al, 2012;Giménez G omez et al, 2018Giménez G omez et al, , 2021Hanski & Cambefort, 1991b;Lumaret & Iborra, 1996); resource size, time of colonisation, food relocation behaviour (Hanski & Cambefort, 1991b;Noriega & Vulinec, 2021); seasonal and daily activity (Hernández, 2012;Krell-Westerwalbesloh et al, 2004;Lobo & Cuesta, 2021). The study of the interaction among species (in different ecological axes) in a community allows understanding the mechanisms of coexistence under the same environmental conditions (Sexton et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Differential ecophysiological syndromes explain the partition of the thermal niche resource in coexisting Eucraniini dung beetles

Verdú

Oliva

Gómez

et al. 2022

Self Cite

The authors investigated the role of thermoregulation mechanisms and thermal limits on thermal niche differentiation in two hierarchical similar Eucraniini dung beetle assemblages inhabiting arid environments in north‐western Argentina. Both dung beetle assemblages showed temporal and thermal niche segregation between all sympatric species, minimising overlap during their daily activity and soil temperature preferences. Thermal tolerance of Eucraniini species was partially modulated by behavioural adaptations and complementary thermoregulatory mechanisms related to eliminating the temperature excess, increasing the metabolic rate promoting an effective regulation of the excess heat that permitted a decrease in their body temperature by evaporative cooling. Based on the physiological syndromes obtained, the authors found a greatest interspecific differentiation that allows us to differentiate each species using ecophysiological traits. Interspecific body size differences in sympatric Eucraniini contributed greatly to the metabolic capacity of individuals to thermoregulate. Eucranium species, the largest species showed the lowest capacity to respond to thermal stress decreasing heat excess temperature, presenting the lowest thermal limit values coinciding with a ‘minithermy’ strategy that explains the preferred lower soil temperatures around 30°C. On the contrary, Anomiopsoides species showed a clear adaptation to being active during periods of the day in which the soil temperature reached over 50°C, adopting a strategy of ‘maxithermy’ by foraging when temperatures are closer to their thermal limits. In conclusion, it can be determined that ecophysiological syndromes related to thermal stress regulation and thermal limits allowed a displacement in thermal niche dimension, minimising interspecific competition and so allowing species coexistence in Eucraniini dung beetles.