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Gut bacteria help dung beetles metabolize nutrients contained and synthesize those unavailable in their food, depending on the ecological scenario in which they develop. However, less is known about the influence of environmental and behavioral factors on the taxonomic composition of bacterial gut communities in Scarabaeinae beetles. To address this research topic, we analyzed 13 tropical dung beetle species in the Los Tuxtlas Biosphere Reserve, Mexico, to understand how the beetle tribe, habitat, food preference, food relocation, and parental care influence the composition of gut bacterial communities. We found that the beetle tribe is the primary factor impacting the taxonomic composition of gut bacterial communities. Among them, Deltochilini displayed the highest variability in diversity due to the different combinations of habitat and food preferences among its species. On the other hand, the other tribes studied did not exhibit such variable combinations. Habitat emerged as the second most influential factor, with forest-dwelling beetles displaying higher diversity. This can be attributed to the heterogeneous environments within tropical forests, which offer a greater diversity of food resources. In contrast, grassland beetles, living in more homogeneous environments and relying on cow feces as their main food source, exhibited lower diversity. Our findings suggest a correlation between bacterial diversity and food resource availability in complex habitats, such as tropical forests, which offer a wider array of food sources compared to simpler environments like grasslands. [ABSTRACT FROM AUTHOR]

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We analysed the genetic divergence and morphology of the aedeagus (i.e. phallobase and parameres) in Canthon cyanellus at different geographical levels. The results from both approaches were compared with the current taxonomic assignment of the C. cyanellus complex, which includes three subspecies. We found a high variation in all the morphological characters of the aedeagus in the populations analysed; the morphometric variation was not geographically structured, either by population or by region. The genealogical analysis indicates a significant genetic structure that does not match either the morphological variation in the male genitalia or the previous subspecific taxonomic classification. Our results suggest that the morphological variation of the aedeagus is seemingly not an isolating reproductive barrier and that the intra- and interpopulation morphological variability of the aedeagus in the C. cyanellus complex does not permit the division into several species. We suggest that other evolutionary forces, such as genetic drift and sexual selection, have influenced the evolution of the male genitalia and the incipient differentiation of this species complex. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We analyzed mate recognition and the cooperative behavior of male-female pairs in Canthon cyanellus cyanellus LeConte (Coleoptera: Scarabaeidae), a carrion-feeding scarab, during food ball rolling among five populations found in tropical forest fragments on the eastern coastal plains of Mexico. Sexual recognition in this species is mostly mediated by chemical cues. Intrapopulation and male-female pairs formed with individual from populations <400 km apart showed cooperative behavior (joint rolling of the food ball by both members). However, male-female pairs from populations <400 km apart showed no cooperative behavior (individual food ball rolling by one of the partners and fights), although they also rolled food balls together. In male-female pairs from the more distant populations (≥600 km apart), >50% fought for food balls. Brood ball production by females and the number of eclosed beetles from the northern population and from the crosses between individuals from the most distant populations were lower than those of other intra- or interpopulation combinations. Gas chromatograph mass spectroscopy of cuticular extract showed that the southern population had 48 surface compounds, 18 of them not present in the northern or intermediate populations. The intermediate population had 41 compounds, 11 of them exclusive. However, the northern population had 24 compounds and only one was exclusive. The lack of cooperative interaction among male-female pairs from distant populations, along with their reduced reproductive success and the differences in cuticular composition between populations, suggest that extreme populations of Canthon c. cyanellus are in a process of incipient speciation. [ABSTRACT FROM AUTHOR]

We analyzed the role of cuticular compounds in sexual recognition of the carrion ball-roller scarab, Canthon cyanellus cyanellus (LeConte) (Coleoptera: Scarabaeidae). Males rolled food balls with freeze-killed females on them as though the females were alive. Acceptance of female cadavers was low when they were washed with solvents and increased significantly when the solvent extract was reapplied to the cadavers. Acceptance of female cadavers by males was significantly higher than that of male cadavers by females. Male cadavers washed with solvent and impregnated with female cuticular compounds were accepted by males as though they were frozen or living females. Similarly, extracted female cadavers impregnated with male cuticular compounds were accepted by females. These results suggest that C. c. cyanellus males recognize females by their cuticular compounds, whereas females use a combination of cuticular compounds and other unknown cues to recognize males. [ABSTRACT FROM AUTHOR]

The effects of some ecological factors on the life-style of the subsocial necrophagous ball-roller scarab Canthon cyanellus cyanellus were evaluated by experimental analysis. Survival of offspring cared for by parents was higher than survival of offspring without parental care; the latter were immediately attacked by fungi which prevents larval development. The propensity for food to be attacked during the earlier larval stages is a selective pressure which favours parental care in C. cyanellus. Early mating increased the lifetime reproductive success of females, but decreased their longevity. Female C. cyanellus maintained high reproductive success even when resource availability was uncertain. Furthermore, the longevity of the females increased with an irregular supply of food. The reproductive success of females increased with food of high nutritional quality and decreased with food of low nutritional quality. [ABSTRACT FROM PUBLISHER]

• The creation of the Reserve allowed the recovery of beetle assemblages through time. • Species turnover is the main component that drives beta diversity in the Reserve. • Forest indicator species increased 17 years after the creation of the Reserve. Studies addressing the temporal changes of ecological communities within fragmented forests transformed into natural protected areas are urgently needed. The creation of the Los Tuxtlas Biosphere Reserve (LTBR) in 1998 stopped the deforestation process of the northernmost tropical rainforest of the Neotropical region, allowing the analysis of the long-term effects on native communities after the halting of habitat fragmentation. We compared the diversity of dung beetles in 11 forest fragments and eight pastures in the LTBR between two periods: 1999–2000, the early years after the creation of the LTBR; and 2016–2017, i.e., 17 years later. Species richness and abundance of dung beetles were similar in both periods, being higher in forest fragments than in pastures; however, the dominant species were different in each period in both forest fragments and pastures. The number of habitat indicator species increased in 2016–2017 compared to 1999–2000, with a high species diversity of forest indicators relative to pasture indicators at both periods. Alpha and gamma diversities were lower in 1999–2000 than in 2016–2017. Beta-diversity at the spatial level was strongly driven by species turnover, which was higher in pastures than in forest fragments. All functional groups (dwellers, rollers, and tunnellers) showed higher abundances in forest fragments than in pastures in both 1999–2000 and 2016–2017 periods. Our results suggest that stopping the fragmentation process in the LTBR has allowed the survival of native dung beetle assemblages, which are undergoing a recovery process of their populations and ecological functions over the years. [ABSTRACT FROM AUTHOR]

• Urbanization threatens biodiversity and ecosystem services. • Coprophagous and roller dung beetles were severely affected by urbanization. • Urban forests serve as reservoirs of dung beetles. • Urbanization drives the homogenization and impoverishment of dung beetle assemblages. The maintenance of forest fragments within urban landscapes is essential for human well-being, as the loss of biodiversity may result in a reduction of ecological services in cities. Conserving diverse functional groups within urban landscapes is essential, since it is directly related with the resilience of such ecosystems. Through the use of indicator groups, it is possible to draw predictions on how communities respond to increasing urbanization. The goal of our study was to assess how the increase of urban land cover affects the assemblage and functional groups of dung beetles (Scarabaeinae) that inhabit forest fragments in a tropical city. We sampled dung beetles in nine fragments embedded in the metropolitan region of João Pessoa, Brazil. Increasing urbanization negatively affected the abundance of coprophagous species, as well as the species richness, abundance and biomass of roller beetles. Assemblages from the most urbanized forest fragments were significantly different from the other fragments. According to the decomposition of β diversity, species turnover was the main process shaping the dung beetle assemblages in João Pessoa. In this study we provide evidence that specific functional groups of dung beetles are affected by urbanization. Furthermore, as each functional group has different strategies to occupy habitats and use resources, urbanization has contrasting effects for each group. Our results confirm that dung beetles are highly sensitive to urbanization and that protected areas within cities are fundamental to conserve biodiversity and ecosystem services. [ABSTRACT FROM AUTHOR]