Stuck in fragments: Population genetics of the Endangered collared brown lemur Eulemur collaris in the Malagasy littoral forest

Abstract

Medium to long-term drift and scarce gene flow is the scenario that best explains the current genetic distribution. Habitat discontinuities such as rivers and grassland between forest fragments played a major role in structuring the population. A common history of size contraction is pointed out by several genetic estimators, indicating a possible ecological crisis triggered around 1,300 years ago. The adoption of strategies aimed at facilitating gene flow and population growth appears crucial to delay further loss of genetic diversity.

Life in a fragment: Evolution of foraging strategies of translocated collared brown lemurs, Eulemur collaris, over an 18‐year period

“…This group of strepsirrhines includes either strictly or mainly arboreal species, which makes them particularly vulnerable to habitat loss and fragmentation in a country where around half of the remaining forest (46%) is <100 m away from its edge (Vieilledent et al, 2018). Over the last two decades, numerous studies have demonstrated the impact of habitat fragmentation on lemur species richness at the landscape level (Dunham, Erhart, Overdorff, & Wright, 2008; Ganzhorn & Eisenbeiß, 2001; Steffens & Lehman, 2018), their behavioral and ecological response within and between fragments (Campera et al, 2014; Donati et al, 2011; Eppley et al, 2017; Gould & Gabriel, 2015; Irwin, 2008; Irwin, Raharison, Raubenheimer, Chapman, & Rothman, 2015; Lehman, Rajaonson, & Day, 2006), and the genetic consequences of habitat fragmentation on their populations (Bertoncini et al, 2017; Quéméré, Amelot, Pierson, Crouau‐Roy, & Chikhi, 2012; Radespiel, Rakotondravony, & Chikhi, 2008; Sgarlata et al, 2018). Despite an overall negative effect of fragmentation on lemur persistence, several species have been shown to tolerate some levels of habitat degradation via shifts in activity patterns and in dietary choices (Donati et al, 2016; Irwin et al, 2010; Sato et al, 2016).…”

Trends in forest fragment research in Madagascar: Documented responses by lemurs and other taxa

“…Sixteen studies evaluated the impact of fragmentation on lemur genetics. Lower genetic diversity and/or allelic richness with decreasing fragment size was reported for the following species: collared brown lemur ( E. collaris : for total area available per site, Bertoncini et al, 2017), black‐and‐white ruffed lemur ( Varecia variegata : Holmes et al, 2013), and gray mouse lemur ( M. murinus : Schad, Sommer, & Ganzhorn, 2004). Two studies additionally report lower genetic diversity for Milne‐Edwards’ sportive lemur ( Lepilemur edwardsi ; Craul et al, 2009) and golden‐brown mouse lemur ( Microcebus ravelobensis : Guschanski, Olivieri, Funk, & Radespiel, 2007) in forest fragments than in Ankarafantsika National Park but do not explicitly link these findings to fragment size.…”

Early Human Colonization, Climate Change and Megafaunal Extinction in Madagascar: The Contribution of Genetics in a Framework of Reciprocal Causations

“…For example, although the population size and range distribution of the extant large lemur Propithecus tattersalli is decreasing today, Quéméré et al (2012) revealed, via bottleneck modeling, a population collapse much older than the likely arrival of humans in their current range (northern Madagascar). Similarly, Bertoncini et al (2017) inferred habitat shifts from the genetic diversity of a medium-sized lemur (Eulemur collaris) living in south-eastern Madagascar (Rakotoarisoa, 1997;Virah-Sawmy et al, 2010). Genetic estimates of N e and mitochondrial coalescence times depict a scenario of strong demographic contraction for Eulemur groups now separated by extended strips of grasslands and swamps.…”