Mouse Lemurs in an Assemblage of Cheirogaleid Primates in Menabe Central, Western Madagascar – Three Reasons to Coexist

Abstract

Ecological communities are structured by interactions between coexisting species that mutually influence their distribution and abundance. Ecologically similar species are expected to exclude one another from suitable habitat, so the coexistence of two mouse lemur species in an assemblage of several closely related cheirogaleid primates in the central Menabe region of Madagascar requires explanation. We assessed the occurrence of Madame Berthe’s mouse lemurs (Microcebus berthae) and Gray mouse lemurs (Microcebus murinus), and of two larger cheirogaleids, Coquerel’s giant mouse lemur (Mirza coquereli) and the western fat-tailed dwarf lemur (Cheirogaleus medius), by nocturnal line transect walks between 2003 and 2007. We explored interspecific interactions for four different scenarios with varying resource availability (degraded and non-degraded habitat in the wet and dry season), both on the regional spatial scale and on a finer local (transect) scale. We tested whether the interspecific distribution of mouse lemur individuals indicates interspecific competition and whether their regional coexistence might be stabilized by interactions with M. coquereli or C. medius. We developed the “Inter-Species Index of Attraction” (ISIA) to quantify the observed interspecific interactions within transects and determined if these were significantly different from a null model generated by a combination of randomization and bootstrapping to control for intraspecific aggregation. For the two mouse lemurs, interspecific spatial exclusion was most pronounced during the resource-poor dry season, consistent with the hypothesis of feeding competition. Seasonally varying distribution patterns indicated resource tracking in a spatio-temporally heterogeneous environment. The interspecific distribution of individuals suggested that the larger cheirogaleids benefit M. berthae at the expense of the more abundant M. murinus: spatial associations of both, M. coquereli and C. medius, with M. murinus were negative in most scenarios and across spatial scales, but neutral or even positive with M. berthae. Thus, our study revealed that coexistence among ecologically similar heterospecifics can rely on complex density-mediated interspecific processes varying with habitat quality and season. With regard to the stability of animal assemblages, this insight has major implications for biodiversity conservation.

Linking cognition to ecology in wild sympatric mouse lemur species

“…MBML occur only in a few square kilometres of seasonally dry deciduous lowland forests [ 26 ] and have an annual feeding niche breadth of 0.12 [ 23 ], qualifying them as habitat specialists. As the smallest living primates, they are also more sensitive to natural and anthropogenic habitat modifications [ 26 ], markedly decreasing their population size in recent years [ 27 ], and justifying their classification as ‘Critically Endangered’ [ 28 ].…”

Complex social and political factors threaten the world's smallest primate with extinction

“…With an adult body mass of just 30 g, this is not only the tiniest of the lemurs, but also the smallest known extant primate. After its scientific discovery and description only 30 years ago (Schmid & Kappeler, 1994), our monthly population monitoring failed to record any sightings or trappings of M. berthae in an 80 ha study area since 2018, even though they used to be common there (Schäffler et al, 2015, 2021). Because this study area is buffered from the deforestation on the forest's edge (Figure 1), still unknown factors in addition to habitat loss must have contributed to their population decline.…”

Technical and Social Approaches to Study Shoreline Change of Kuakata, Bangladesh

“…The PRA employed here relies on field observations and group meetings with communities and stakeholders, such as fisherman, farmers, small business owners, and tourism-related employees. More specifically, PRA verifies the results through a transect walk (Dooley et al, 2018;Schäffler et al, 2021), timeline (historical mapping) analysis (Mueller et al, 2010;Tomlinson et al, 2018), cause and effect diagram (Holme and Chalauisaeng, 2006;Saja et al, 2021), key informant interview (KII; Chenais et al, 2015;Balgah, 2016;Nicholson and Valentine, 2019;Dureab et al, 2021;Roothaert et al, 2021), and focus group discussion (FGD; Shamsuddin et al, 2007;Ng et al, 2021). These tools emphasize the following questions: What is the perception about shoreline change along the coast of Kuakata?…”