Population studies are essential for understanding different aspects of species’ biology, estimating extinction probability, and determining evolutionary and life history. Using the mark-recapture method, we studied the abundance and population structure of dung beetle species (Deltochilum mexicanum and Dichotomius satanas) over one year in a human-modified landscape in Mexico. We captured 1960 individuals with a net recapture rate of 11%. Deltochilum mexicanum had a higher rate of recapture (14%) than Dichotomius satanas (5%). Annual variation in abundance was similar for both species, with maximum abundance occurring in summer and a marked reduction during winter. Deltochilum mexicanum was dominant inside the forest, and its abundance was influenced by vegetation cover, temperature, and humidity. Dichotomius satanas was more frequent outside the forest, and none of the considered environmental variables affected its abundance. The adult sex ratio of Deltochilum mexicanum was female-biased, whereas that of Dichotomius satanas was male-biased. The maximum estimated population size was similar for both species, but Deltochilum mexicanum had a higher number of new individuals and survival rate. Since species with different biological attributes presented a similar pattern of abundance and population structure, we conclude that environmental conditions are the main regulator of dung beetle populations in the human-modified landscape.

No abstract

Understanding how species use and persist in agricultural areas is useful for planning conservation efforts at the landscape scale. Information at the population level is scarce, even for organisms, such as dung beetles, that are traditionally used in biodiversity studies to evaluate the effects of anthropic disturbance. Based on multiple mark-recapture events, the description of movement patterns and three population parameters (population size, survival and recruitment) were compared for two dung beetle species (Dichotomius cf. alyattes and Oxysternon conspicillatum) in a fragmented Andean landscape dominated by sun-grown coffee crops. Interspecific differences were detected in movement patterns and in the minimum distance moved across the landscape, with the latter associated with wing loading and species habitat preferences. D. cf. alyattes was captured in both the forest and in sungrown coffee plots, but tended to limit its movement to patches of forest, while O. conspicillatum covered large distances in short periods of time across the sun-grown coffee crops (ca. 1.7 km/24 h). The population of each species increased during the months of greatest precipitation, prior to the recruitment of new beetles. Given their great capacity for movement, habitat preference and their differential use of the landscape, the species studied can be used as models to evaluate the functional connectivity of Andean landscapes under high anthropic demand. Our results support the idea of the differential response of species to land-use changes, an aspect that should be considered for effective biodiversity conservation and ecosystem functioning in human-dominated landscapes.

In landscapes dominated by agriculture, conspicuous edges often occur between landscape elements. However, there is disagreement about the existence and intensity of edge effects, and information about species‐specific responses remains scarce. Studying such edge effects can help elucidate functional landscape connectivity and contribute to agricultural management. We, therefore, assessed whether sun‐grown coffee represents a barrier to dung beetles in an Andean agricultural landscape. We also evaluated whether the response to edge effects differs among species. We found that diversity and abundance tend to decrease from forest to sun‐grown coffee and that there are sharp increases in species turnover at the forest–coffee edge. We detected several different species‐specific responses to the forest–coffee edge, suggesting differences in the mobility of the species (or spillover) and in the degree of penetration that takes place from forest patches to sun‐grown coffee plantations. This study demonstrates that the sun‐grown coffee matrix constitutes a barrier to forest species and suggests that the forest–coffee ecotone is more complex than expected. Our results support the notion that the conservation value of native forest patches in agricultural scenarios depends on the functional connectivity of forest units in the landscape to maximize the opportunities species have to disperse through the agricultural matrix.