Abstract. The outcome of the dispersal process in zoochorous plants is largely determined by the behavior of frugivorous animals. Recent simulation studies have found that fruit removal rates and mean dispersal distances are strongly affected by fruiting plant neighborhoods. We empirically tested the effects of conspecific fruiting plant neighborhoods, crop sizes, and plant accessibility on fruit removal rates and seed dispersal distances of a mistletoe species exclusively dispersed by an arboreal marsupial in Northern Patagonia. Moreover, in this study, we overcome technical limitations in the empirical estimation of seed dispersal by using a novel 15 N stable isotope enrichment technique together with Bayesian mixing models that allowed us to identify dispersed seeds from focal plants without the need of extensive genotyping. We found that, as predicted by theory, plants in denser neighborhoods had greater fruit removal and shorter mean dispersal distances than more isolated plants. Furthermore, the probability of dispersing seeds farther away decreased with neighborhood density. Larger crop sizes resulted in larger fruit removal rates and smaller probabilities of longer distance dispersal. The interplay between frugivore behavioral decisions and the spatial distribution of plants could have important consequences for plant spatial dynamics.

Dromiciops gliroides is an arboreal marsupial found in the temperate forests of South America (36-43 °S). This species is the sole extant representative of the order Microbiotheria, and is a key seed disperser of many native plant species, including the keystone mistletoe Tristerix corymbosus. Here, we synthesized the current knowledge on the ecological aspects of this species, and compared the available information from Argentina and Chile. Population density (23 ± 2 (mean ± SE) individual/ha) and home range (1.6 ± 0.6 ha) appear to be relatively similar across a marked ecological gradient in the mainland, but lower densities (7 ± 2 individual/ha) and smaller home ranges (0.26 ± 0.04 ha) were detected at island sites. We detected regional variation in body condition in Chile, but there were no significant differences across a wider E-W gradient. Movement patterns fit a random walk model; such behavior might have important consequences in shaping plant's spatial patterns. Although our data suggest that D. gliroides is more tolerant to habitat disturbance than previously thought, its incapability to disperse across non-forested areas suggests that the rapid rate of habitat loss and fragmentation that characterizes southern temperate forests likely poses a serious threat to this species. These ecological similarities are surprising given that forests studied receive dramatically different rainfall and correspond to distinct forest types. The evidence synthetized here dispels some of the myths about this species but also stresses the need for more comprehensive ecological studies across its distribution range.

No abstract

Protected Areas (PAs) are key to avoiding habitat destruction and biodiversity loss. Most research conducted in PAs has focused on the geological, biological or ecological aspects of sites, while few studies have examined the policymaking process. However, PA designation might reflect the political history of a country regarding environmental protection and whether PA designation is based on a strong conservation commitment or is instead propaganda yielding ‘paper parks’. Argentina, the first Latin American nation to set land aside to protect it, provides a case study of the process of constructing a PA system, and certain elements apply to other developing countries. Its first national park was created in 1922, and the first law concerning PAs was promulgated in 1934. Since then, a succession of democratic governments interrupted by military regimes has modified parks and promulgated laws changing conservation priorities. The conservation goal of PAs was not always manifest in government policies. Despite the number of PAs (48 by 2019) and area covered (14,718,420 hectares total by 2019), most of these lands face the same challenges as PAs in many other developing nations, including limited budgets, lack of field staff, absence of strategic planning, insufficient political support and corruption. Since the return to democracy in 1983, new laws have been enacted based on experience gathered in other nations. However, existence of a law does not guarantee its enforcement. Environmental NGOs, the scientific community and a growing concerned citizenry nowadays constitute the most important forces supporting the conservation function of PAs and environmental conservation in general in Argentina.