Negative effects of urbanisation on the physical condition of an endemic dung beetle from a neotropical hotspot

Abstract

1. Urbanisation causes important losses in biodiversity and ecosystem of animals. To test whether these negative effects are preceded by unhealthy individuals in urban populations, we evaluated the effects of urbanisation on the abundance and physical condition of the dung beetle Dichotomius guaribensis, an endemic species of the Brazilian Atlantic Forest.2. We sampled beetles in nine forest fragments with different urbanisation degrees, embedded in the urban matrix of the city of João Pessoa. Besides testing the abundance in each fragment, we quantified four indicators of physical condition in males and females: body size, body mass, energetic condition, and mite load.3. Females tended to be larger, and to have less lipid mass and more mites than males. Urbanisation had no effect on beetle abundance, but it negatively affected body mass and lipid content in males, but not females, revealing different sensitivities for both sexes. Body size and mite load were not affected by urbanisation in males or females. Fragment size had no effect on beetle abundance and physical condition in both sexes, suggesting that urbanisation has a greater impact than fragment size on beetle individual condition.4. In this study, we show that individual deterioration precedes population declines in disturbed environments, and our study opens new insights into the proximate causes that leads to the loss of biodiversity and ecosystem services in urbanised regions.

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

“…Sex and age shape dung beetle responses to biotic and abiotic conditions (e.g. Salomão et al ., 2020, 2021), as with food choice, suggesting a scenario in which it is crucial to understand how populations respond to environmental conditions. Moreover, due to the current changes of quality and quantity of food in the Anthropocene (Birnie‐Gauvin et al ., 2017; Kehoe et al ., 2020) it is critical to understand how individuals respond and species persist in different scenarios of food availability.…”

“…Although dung beetle assemblages from Atlantic Forest are diverse, many of its species have a relatively low abundance or are attracted exclusively to human feces or carrion (e.g. Canthon nigripennis Lansberge and Coprophanaeus acrisius Olsoufieff, see Iannuzzi et al ., 2016; Salomão et al ., 2020), thus using other species was an unfeasible option.…”

“…Regarding resource attraction among dung beetles, there is evidence suggesting that food choice may depend on the sexual maturity of adult beetles (Hanski & Cambefort, 1991). Although individual sex is also determinant for dung beetle habitat selection (Salomão et al ., 2020, 2021), to our knowledge there is no information about how sex affects resource attraction in dung beetles. Due to the intense competition for food resources in tropical dung beetles (Hanski & Cambefort, 1991), we could expect that intraspecific segregation could facilitate the establishment of beetle populations in the environments.…”

The conversion of native savannah into pasturelands does not affect exclusively species diversity: Effects on physiological condition of a highly abundant dung beetle species

“…We measured physiological condition and body traits in 30 individuals per sex (female and male) in each habitat type (totaling 120 studied individuals). Although there is not an ideal number proposed for studies of body physiological conditions in dung beetles, previous studies in tropical ecosystems used 30–40 individuals per treatment (e.g., França, Barlow, et al., 2016; França, Louzada, et al., 2016; Salomão et al., 2020). A sampling effort of n = 60 is the minimum threshold recommended for ensuring an accurate estimation of dung beetle mean trait values (Griffiths et al., 2016).…”

“…Most ecological studies assess the effect of environmental quality and anthropogenic landscapes on dung beetle assemblages, presenting a trend of decreases of diversity in less conserved sites (Halffter & Favila, 1993; López‐Bedoya et al., 2022; Nichols et al., 2007). However, few studies have analyzed dung beetle physiology, demonstrating a general negative response in individuals' physiological conditions when subjected to environmental disturbances in tropical forests, such as selective logging (França, Barlow, et al., 2016), fragmentation (Salomão et al., 2018), and urbanization (Salomão et al., 2020). To the date, these studies are exclusively focused on tropical rainforests, and no study evaluated how the land use changes affect the dung beetles' physiological condition in other tropical ecosystems.…”