The ecology and evolution of the Monito del monte, a relict species from the southern South America temperate forests

Abstract

The arboreal marsupial Monito del Monte (genus Dromiciops, with two recognized species) is a paradigmatic mammal. It is the sole living representative of the order Microbiotheria, the ancestor lineage of Australian marsupials. Also, this marsupial is the unique frugivorous mammal in the temperate rainforest, being the main seed disperser of several endemic plants of this ecosystem, thus acting as keystone species. Dromiciops is also one of the few hibernating mammals in South America, spending half of the year in a physiological dormancy where metabolism is reduced to 10% of normal levels. This capacity to reduce energy expenditure in winter contrasts with the enormous energy turnover rate they experience in spring and summer. The unique life-history strategies of this living Microbiotheria, characterized by an alternation of life in the slow and fast lanes, putatively represent ancestral traits that permitted these cold-adapted mammals to survive in this environment. Here we describe the ecological role of this emblematic marsupial, summarizing the ecophysiology of hibernation and sociality, actualized phylogeographic relationships, reproductive cycle, trophic relationships, mutualisms, conservation and threats. This marsupial shows high densities, despite presenting slow reproductive rates, a paradox that is explained by the unique characteristics of its three-dimensional habitat. We finally suggest immediate actions to protect these locally abundant but globally threatened species.

Huddling nest use are the optimal strategies for heat conservation in a social marsupial: lessons from biophysical models

“…This is coincident with the previous observation, indicating that heterothermic animals do not benefit from huddling if temperatures are not extremely low. To study how these behavioral strategies vary between lowland and highland populations remains as an open important question (some high-altitudinal populations of this marsupial has sub-zero T A s for most of the winter, see Fonturbel et al, 2022; Mejias et al, 2021).…”

“…First , direct measurements of energy expenditure in clustered and isolated individuals did not produce significant differences between treatments (Franco et al, 2012). Second , monitos are one of the few marsupials with advanced levels of sociality (Fonturbel et al, 2022; Nespolo et al, 2022b; Russell, 1984). The sociality of monitos is supported by observations of long-term persistence of familiar groups and the existence of foraging groups composed of unrelated individuals, in spring and summer (Fonturbel et al, 2022; Nespolo et al, 2022b).…”

With a little help from my friends: Hyperparasitism allows a generalist mistletoe to expand habitat use

“…Although both species belong to the Loranthaceae family, T. corymbosus is capable of parasitizing at least 30 plant species (Atencio et al, 2021); D. mutabilis only parasitizes trees of the genus Nothofagus (Kuijt, 1985), which cannot be parasitized by T. corymbosus . Both mistletoes have tubular flowers pollinated by hummingbirds and insects and greenish fleshy fruits (Figure 1) mainly consumed by the arboreal marsupial Dromiciops spp., the main seed disperser agent in these forests (Fontúrbel et al, 2022). Despite these similarities, these mistletoes have three major differences: (1) T. corymbosus is an evergreen species, whereas D. mutabilis is deciduous and remains leafless during fall and winter (being a rare case of deciduous mistletoe; Glatzel et al, 2017); (2) although both species fruit during the summer (January to March, when the seed disperser agent is active; Balazote‐Oliver et al, 2017), T. corymbosus has a long flowering period (March to October), whereas D. mutabilis has a short but intense flowering period (December to January) in which its flowers are intensively visited by hummingbirds and many insect species (authors' personal observation); and (3) host range.…”

“…But how does this happen? The most likely explanation relies on the seed dispersal process, which in turn relies on the arboreal marsupial Dromiciops bozinovici (Fontúrbel et al, 2022). This relict marsupial is the most important seed disperser agent in these forests (Amico et al, 2009) and the sole disperser of green mistletoe fruits, which frugivorous birds cannot visually detect because they lack chromatic contrast against the foliage (Amico et al, 2011).…”