Do functional traits offset the effects of fragmentation? The case of large‐bodied diurnal lemur species

Abstract

Primates worldwide are faced with increasing threats making them more vulnerable to extinction. Anthropogenic disturbances, such as habitat degradation and fragmentation, are among the main concerns, and in Madagascar, these issues have become widespread. As this situation continues to worsen, we sought to understand how fragmentation affects primate distribution throughout the island. Further, because species may exhibit different sensitivity to fragmentation, we also aimed to estimate the role of functional traits in mitigating their response. We collated data from 32 large-bodied lemur species ranges, consisting of species from the families Lemuridae (five genera) and Indriidae (two genera). We fitted Generalized Linear Models to determine the role of habitat fragmentation characteristics, for example, forest cover, patch size, edge density, and landscape configuration, as well as the protected area (PA) network, on the species relative probability of presence. We then assessed how the influence of functional traits (dietary guild, home range size) mitigate the response of species to these habitat metrics. Habitat area had a strong positive effect for many species, and there were significantly negative effects of fragmentation on the distribution of many lemur species. In addition, there was a positive influence of PAs on many lemur species' distribution. Functional trait classifications showed that lemurs of all dietary guilds are negatively affected by fragmentation; however, folivore-frugivores show greater flexibility/variability in terms of habitat area and landscape complexity compared to nearly exclusive folivores and frugivores. Furthermore, species of all home range sizes showed a negative response to fragmentation, while habitat area had an increasingly positive effect as home range increased in size. Overall, the general trends for the majority of lemur species are dire and point to the need for immediate actions on a multitude of fronts, most importantly landscape-level reforestation efforts.

Life on the edge: behavioural and physiological responses of Verreaux's sifakas (<i>Propithecus verreauxi</i>) to forest edges

“…The assay has previously been validated for monitoring glucocorticoid output in numerous species of primates (e.g. Heistermann et al, 2006), including Verreaux's sifakas (Fichtel et al, 2007). The assay was carried out as described in detail by Heistermann et al (2004).…”

“…Second, habitat fragmentation had a generally negative effect on the distribution of 32 lemur species (Eppley et al, 2020). Folivorous-frugivorous species, however, showed greater flexibility and variability in terms of habitat area and landscape complexity compared with nearly exclusively folivorous or frugivorous species, which appear to exhibit some resilience to forest fragmentation (Eppley et al, 2020). Third, population density and juvenile recruitment can depend on fragment size and the availability of key feeding trees, as shown for ring-tailed lemurs (Lemur catta; Gould and Cowen, 2020).…”

“…Hence, physiological stress responses to disturbed habitats are a major focus in conservation physiology because they provide a quantitative measure of how environmental changes impact individuals (Tarlow and Blumstein, 2007;Dantzer et al, 2014). Second, habitat fragmentation had a generally negative effect on the distribution of 32 lemur species (Eppley et al, 2020). Folivorous-frugivorous species, however, showed greater flexibility and variability in terms of habitat area and landscape complexity compared with nearly exclusively folivorous or frugivorous species, which appear to exhibit some resilience to forest fragmentation (Eppley et al, 2020).…”

“…ravelobensis (Andriatsitohaina et al, 2019), but others have been found to exhibit a neutral (Eulemur rubriventer, Hapalemur griseus, and Avahi laniger) or even positive edge response (Microcebus rufus and Propithecus edwardsi), stressing the importance of studies of individual species or populations. Among sifakas (genus Propithecus: Indridae), which are folivorous and, hence, potentially less resilient to habitat fragmentation (Eppley et al, 2020), responses to edges differ between species. Coquerel's sifakas (Propithecus coquereli) seem to avoid edge areas and do not range right on the forest edge but within 400 m of it, resulting in larger home ranges in comparison with groups occurring in the forest interior, although food quality does not differ between habitats (McGoogan et al, 2009).…”

Seasonal variability in the diet and feeding ecology of black‐and‐white ruffed lemurs (Varecia variegata) in Ranomafana National Park, southeastern Madagascar

“…Our results lend themselves to further characterizing the diet of this Critically Endangered fruit-specialist and emphasizes how flexible behavioral strategies enable species to cope with variable ecological conditions and resource availability. This is increasingly important to understand in the face of ongoing deforestation and anthropogenic disturbance to Madagascar's forests (Harper, Steininger, Tucker, Juhn, & Hawkins, 2007;Morelli et al, 2020;Vieilledent et al, 2018;, particularly given that frugivorous diets are commonly associated with high sensitivity to habitat modification (Boyle & Smith, 2010;Eppley, Santini, Tinsman, & Donati, 2020;Harcourt, 1998;Marsh, Johns, & Ayres, 1987;Richard & Sussman, 1987;Struhsaker, 1997). investigation; methodology; project administration; writing-original draft; writing-review and editing.…”