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Protecting lemurs: Response

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... It is clear, however, that anthropogenic activities-slash-and-burn agriculture, charcoal production, fires for zebu cattle pasture, logging and, to a lesser extent, mining-are regarded as the major recent causes for forest loss and fragmentation. Accordingly, it has been shown that forest cover in Madagscar decreased by 50% over 60 years from 1950 to 2010 (Harper et al. 2007;ONE 2013;Schwitzer et al. 2014aSchwitzer et al. , 2014b. ...
... The lemurs are prominent among Malagasy endemics, with 110 species and subspecies currently recognized *Shared first co-authors, ‡ Shared last co-authors (Mittermeier et al. 2010;Schwitzer et al. 2013) 1 , and, as a group, they are among the most threatened vertebrates in the world (Schwitzer et al. 2014a(Schwitzer et al. , 2014b. Four of the nine species of sifaka (Propithecus: Indriiidae) are Critically Endangered (CR)-P. ...
... This suggests that crowned sifakas were recently and may still be able to move between neighboring forest fragments and, potentially, across grassland. However, since sifakas may have a long generation time and the landscape has been particularly impacted in the last 60 years (Harper et al. 2007;ONE 2013;Schwitzer et al. 2014aSchwitzer et al. , 2014b, it is difficult to determine when or if the dispersal stopped between forest fragments. ...
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Propithecus coronatus is an endangered, diurnal forest-dwelling lemur of northwestern Madagascar. We conducted the first extensive population genetic study for this species. We designed new primers to amplify and sequence the mitochondrial D-loop of 125 individuals from 14 localities in the northern part of the species' distribution. Our aim was to assess the genetic variability and differentiation of this species in a fragmented landscape. Compared to other lemurs, crowned sifakas have a moderate level of haplotype diversity (0.853) and a low nucleotide diversity (1.21%). Despite the considerable forest fragmentation in the region surveyed, the species does not show strong signals of genetic structure as shown by the Φ ST estimates, the network of haplotypes, and the limited correlation between genetic and geographic distance. The current mtDNA estimated effective population size was relatively large (median: 11,262; 95% HPD: 5,107−20,083), in agreement with recent census estimates, suggesting that a large number of individuals is still present across the species range. Using the Extended Bayesian Skyline Plot (EBSP) approach to reconstruct the demographic history of the species, we did not detect any genetic signal of change in population size. Despite the ongoing loss and fragmentation of their habitat, the population still harbors subtantial genetic diversity, likely as a partial consequence of a taboo against hunting the crowned sifaka among the Sakalava ethnic group inhabiting the area.
... Endemic to Madagascar, lemurs are the most endangered mammal group in the world, 94% of lemur species are threatened with extinction [1] of the forests in Madagascar [2]. While there is some disagreement on precisely how much forest has been lost in Madagascar [3], researchers estimate that between 40 and 52 percent of the forest cover has been converted to non-forested habitat between the 1950s and 2010 [2][3][4]. The processes of habitat loss and fragmentation create landscapes with discrete fragments of habitat [5]. ...
... Endemic to Madagascar, lemurs are the most endangered mammal group in the world, 94% of lemur species are threatened with extinction [1] of the forests in Madagascar [2]. While there is some disagreement on precisely how much forest has been lost in Madagascar [3], researchers estimate that between 40 and 52 percent of the forest cover has been converted to non-forested habitat between the 1950s and 2010 [2][3][4]. The processes of habitat loss and fragmentation create landscapes with discrete fragments of habitat [5]. ...
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Determining what factors affect species occurrence is vital to the study of primate biogeography. We investigated the metapopulation dynamics of a lemur community consisting of eight species (Avahi occidentalis, Propithecus coquereli, Microcebus murinus, Microcebus ravelobensis, Lepilemur edwardsi, Cheirogaleus medius, Eulemur mongoz, and Eulemur fulvus) within fragmented tropical dry deciduous forest habitat in Ankarafantsika National Park, Madagascar. We measured fragment size and isolation of 42 fragments of forest ranging in size from 0.23 to 117.7 ha adjacent to continuous forest. Between June and November 2011, we conducted 1218 surveys and observed six of eight lemur species (M. murinus, M. ravelobensis, C. medius, E. fulvus, P. coquereli, and L. edwardsi) in the 42 fragments. We applied among patch incidence function models (IFMs) with various measures of dispersal and a mainland-island IFM to lemur species occurrence, with the aim of answering the following questions: 1) Do lemur species in dry deciduous forest fragments form metapopulations? 2) What are the separate effects of area (extinction risk) and connectivity/isolation (colonization potential) within a lemur metapopulation? 3) Within simulated metapopulations over time, how do area and connectivity/isolation affect occurrence? and 4) What are the conservation implications of our findings? We found that M. murinus formed either a mainland-island or an among patch metapopulation, M. ravelobensis formed a mainland-island metapopulation, C. medius and E. fulvus formed among patch metapopulations, and neither P. coquereli or L. edwardsi formed a metapopulation. Metapopulation dynamics and simulations suggest that area was a more consistent positive factor determining lemur species occurrence than fragment isolation and is crucial to the maintenance of lemur populations within this fragmented landscape. Using a metapopulation approach to lemur biogeography is critical for understanding how lemur species respond to forest loss and fragmentation.
... Habitat loss and fragmentation are widely recognised as the main threat to the survival of lemurs (Ganzhorn et al., 2001;Schwitzer et al., 2014), and indeed to that of primates worldwide (Estrada et al., 2017). The littoral forests of Madagascar represent one of the island's most impacted and threatened ecosystems, and the remaining habitat is severely fragmented and limited in extent (de Gouvenain and Silander, 2003;Bollen and Donati, 2006;Consiglio et al., 2006). ...
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The biologically rich littoral forests of Sainte Luce support an isolated sub-population of Endangered red-collared brown lemur (Eulemur collaris). The area encompasses 17 disconnected forest fragments, separated by a matrix of eri-caceous heath, grasslands, swamps and watercourses. Since the earliest faunal studies in the late 1980s, this species has only been recorded within four forest patches. We detail this lemur's recent re-colonisation of a protected fragment and consider its broader implications for future conservation initiatives. This observation highlights the value of small, seemingly unimportant patches of forest and the importance of maintaining functional habitat connectivity. Our observations also provide insight into the conditions that likely led to the current distribution of this species in Sainte Luce.
... Madagascar itself is characterized by an extensive history of habitat loss and continuing deforestation and fragmentation (Brinkmann, Noromiarilanto, Ratovonamana, & Buerkert, 2014;Harper, Steininger, Tucker, Juhn, & Hawkins, 2007; review of debate regarding deforestation patterns: Schwitzer, Chikhi, et al., 2014), having lost an estimated 44% of its forest cover from 1953 to 2014 and with 54% of its forest within 100 m of the edge by 2014 (Vieilledent et al., 2018). While the anthropogenic processes driving fragmentation in Madagascar have been extensively documented (De Haulleville et al., 2018;Urech, Felber, & Sorg, 2012), Madagascar may have additionally experienced natural fragmentation driven by climate change (in southeastern littoral forests: Virah-Sawmy, Gillson, & Willis, 2009), potentially resulting in selection for species resilience within heterogeneous landscapes. ...
Article
The rise in research investigating fragmentation and its impact on primates and other taxa reflects the growing presence of fragmented landscapes themselves. Although numerous studies report the negative effects of fragmentation on biodiversity, it is difficult to generalize responses to fragmentation for specific taxonomic groups, such as non-human primates, when studies have not employed a definitive concept of fragmentation or fragments themselves. Madagascar's high degree of fragmentation, wealth of endemic taxa, and extensive history of ecological research provide the opportunity to compare fragmentation studies across similar contexts. We conducted a literature search of peer-reviewed articles on fragmentation in Madagascar to characterize its trends. A total of 70 articles, 46 of which concentrated on lemurs, tested the impacts of fragmentation on Malagasy taxa, while additional sources conducted research in one or more fragments without testing its effects (n = 112 total, 79 on lemurs). Studies on lemurs most frequently tested fragmentation's impacts on genetics and biodiversity metrics (n = 16 and 15 studies, respectively), although health, modeling, behavioral, and cross-disciplinary techniques were also reported. Responses to fragmentation were reported for 49 lemur species, with most studies concentrated in eastern Madagascar (87%). Although there was variation in the metrics reported in studies testing the effects of fragmentation on Malagasy species, the most common measures were fragment area, isolation, or comparison to a control site. Landscape-scale approaches and examination of fragmentation per se were rarely employed. Characterizing trends of fragmentation research in Madagascar emphasizes the challenges of documenting fragmentation's effects while highlighting the benefits of research within fragmented landscapes, particularly when combined with consideration for how the matrix within human-modified landscapes may impact primate populations.
... It is, however, undisputed that recent decades have brought significant human-mediated HL&F. Conservative estimates show that at least 52% of the forest cover was lost since the 1950s ( Harper, Steininger, Tucker, Juhn, & Hawkins, 2007;ONE 2013;Schwitzer et al., 2014), from the use of fire, slash-and-burn cultivation ("tavy"), cattle raising, logging ( Minten, Randrianarisoa, Randrianarison, & Food, 2003) and mining activities. ...
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The relative effect of past climate fluctuations and anthropogenic activities on current biome distribution is subject to increasing attention, notably in biodiversity hotspots. In Madagascar, where humans arrived in the last ~4-5,000 years, the exact causes of the demise of large vertebrates that cohabited with humans is yet unresolved. The prevailing narrative holds that Madagascar was covered with forest before human arrival, and that the expansion of grasslands was the result of human driven deforestation. However, recent studies have shown that vegetation and fauna structure substantially fluctuated during the Holocene. Here we study the Holocene history of habitat fragmentation in the north of Madagascar using a population genetics approach. To do so we infer the demographic history of two northern Madagascar neighboring, congeneric, and critically endangered forest dwelling lemur species - Propithecus tattersalli and P. perrieri - using population genetic analyses. Our results highlight the necessity to consider population structure and changes in connectivity in demographic history inferences. We show that both species underwent demographic fluctuations which most likely occured after the mid-Holocene transition. While mid-Holocene climate change probably triggered major demographic changes in the two lemur species range and connectivity, human settlements that expanded over the last four millennia in northern Madagascar likely played a role in the loss and fragmentation of the forest cover. This article is protected by copyright. All rights reserved.
... 4000 years BP (Dewar et al. 2013;Gommery et al. 2011), and it has been suggested that a major part of Madagascar's original forest cover has been lost since humans arrived (Humbert et al. 1965), with only 10-20% of Madagascar being forested today (Moat and Smith 2007). Conservative estimates show that ≥52% of the forest cover has been lost since the 1950s (Harper et al. 2007;ONE 2013;Schwitzer et al. 2014a), from the use of fire for slash and burn cultivation and cattle raising, logging (Minten et al. 2003), and mining activities. These deforestation rates are alarming considering that >90% of the species in Madagascar (including lemurs) live exclusively in forests and woodlands (Goodman and Benstead 2005). ...
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Genetic data can be combined with ecological data to study the demographic history of a species, identify landscape features that influence migration patterns, and guide conservation efforts. Perrier ’ s sifaka (Propithecus perrieri) is a Critically Endangered, rare, and elusive social lemur living in a very restricted, fragmented landscape. To assess the effect of habitat loss and fragmentation on the genetic diversity of the Perrier ’ s sifaka population we examined 24 microsatellite markers genotyped for 67 samples corresponding to 42 individuals. Perrier ’ s sifaka shows a low current effective population size (ca. 52 – 105) and a strong heterozygosity excess, suggesting a historically large but dwindling population. Moreover, we identified a pattern of isolation by distance, typical of continuous habitat, suggesting that sifakas were still able to cross the grasslands between forest fragments in the recent past. Our study calls for a unified conservation plan covering the two protected areas where the species is still present, if not the whole area of its past distribution. Further studies inferring the past demographic history of Perrier ’ s sifaka may confirm the population decline and shed light on its potential causes.
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Madagascar is a biodiversity hotspot particularly rich in amphibian diversity and only a few charismatic Malagasy amphibians have been investigated for their population-level differentiation. The Mantella madagascariensis group is composed of two rainforest and three swamp forest species of poison frogs. We first confirm the monophyly of this clade using DNA sequences of three nuclear and four mitochondrial genes, and subsequently investigate the population genetic differentiation and demography of the swamp forest species using one mitochondrial, two nuclear and a set of nine microsatellite markers. Our results confirm the occurrence of two main mitochondrial lineages, one dominated by Mantella aurantiaca (a grouping supported also by our microsatellite-based tree) and the other by Mantella crocea + Mantella milotympanum. These two main lineages probably reflect an older divergence in swamp Mantella. Widespread mitochondrial introgression suggests a fairly common occurrence of inter-lineage gene flow. However, nuclear admixture seems to play only a limited role in this group, and the analyses of the RAG-1 marker points to a predominant incomplete lineage sorting scenario between all five species of the group, which probably diverged relatively recently. Our demographic analyses show a common, severe and recent demographic contraction, inferred to be in temporal coincidence with the massive deforestation events that took place in the past 1000 years. Current data do not allow to conclusively delimit independent evolutionary units in these frogs, and we therefore refrain to suggest any taxonomic changes.
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Objectives: The Endangered collared brown lemur (Eulemur collaris) is the largest primate living in the littoral forest of southeastern Madagascar, a top priority habitat for biodiversity conservation on the island. Because this lemur is a key seed-disperser, an evaluation of the structure and connectivity of the populations surviving in the forest fragments is urgently needed to guide conservation plans. Materials and methods: Genetic variability at autosomal microsatellites and mitochondrial DNA was investigated in a total of 49 collared brown lemurs sampled by non-invasive methods in three littoral forest fragments and in the nearby lowland humid forest. Results: The overall genetic diversity of E. collaris in the southeastern coastal region of Madagascar was lower than in other populations, as well as in other lemur species. The population appears highly structured, with less variable and more inbred groups inhabiting the littoral forest fragments compared to the inland area. Major barriers to gene flow were identified isolating littoral forest fragments from each other and from the inland lowland humid forest. Discussion: 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.
Article
1. The concept of biodiversity conservation relies primarily on protected areas. Yet, protected areas are influenced by the surrounding anthropogenic matrix as degradation of landscapes used by humans also has negative consequences on species within the adjacent protected, nondegraded ecosystems. Increasing the heterogeneity of the anthropogenic landscape has the potential to promote biodiversity conservation in protected and non-protected sites. 2. To find options for reconciling land use and biodiversity conservation, we evaluated reptile diversity of two areas. Both areas contained three types of habitat: cultivated areas, degraded forest and undegraded forest. In one area (Tsim), a network of hedges surrounding fields provided a variety of possible resources for reptile species. Another area (Andremba) lacked such landscape elements. 3. In 480 survey walks on 48 transects evenly distributed over two areas, we recorded a total of 24 reptile species, of which 18 occurred in both areas. 4. Perennial plant cover explained the variation in local (per transect) species richness best. Species richness was low along field margins in the cultivated area that lacked hedges and had a perennial plant cover below 20%. It was high in undegraded and degraded forest and along hedges in the cultivated area where perennial plant cover was above 40%. 5. Similarities of reptile assemblages were higher between habitat types in the area structurally enriched with hedges, than in the area lacking such enrichment. In the latter area, beta diversity was largely the result of species losses which could result from impeded movement between habitats. 6. Synthesis and applications. A continuous network of hedges and associated trees and shrubs contribute to the maintenance of reptile biodiversity in dry south-western Madagascar. When present, these interconnected landscape elements enhance habitat suitability of the agriculturally used matrix. They also provide habitat for species of conservation concern. High similarity between assemblages in the area with hedges indicated that movement between habitats was facilitated. We conclude that incorporating hedges in pastures contributes not just to the suitability of the matrix, but also enhances landscape connectivity and thus improves biodiversity conservation in the human-used landscape.
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Aim Coastal biodiversity hotspots are globally threatened by sea-level rise. As such it is important to understand how ecosystems resist, respond and adapt to sea-level rise. Using pollen, geochemistry, charcoal and diatom records in conjunction with previously published palaeoclimatic records, we investigated the mechanism, interactions and ecosystem response and resilience of Madagascar's littoral forest to late Holocene sea-level rise. Location Sediment sequences were collected along the south-east coast of Madagascar in two adjacent habitats in Mandena; the highly diverse littoral forest fragment and species-poor Erica-matrix. Methods We used a multi-proxy approach to investigate the relative influence of environmental changes on the littoral ecosystem. We reconstructed past vegetation and fire dynamics over the past 6500 years at two sites in the littoral forest using fossil pollen and macrofossil charcoal contained in sedimentary sequences. Alongside these records we reconstructed past marine transgressions from the same sedimentary sequences using geochemical analyses, and a salinity and drought index through the analysis of fossil diatoms. Results Our findings indicated that it was the synergistic effect of sea-level rise coupled with rainfall deficits that triggered a threshold event with a switch from two types of littoral forest (an open Uapaca forest and a closed littoral forest fragment) to an Erica–Myrica heath/grassland occurring in approximately less than 100 years. Resilience to sea-level rise differed in the two adjacent habitats, suggesting that the littoral forest fragment was more resilient to the impacts of sea-level change and aridity than the open Uapaca woodland. Conclusions We demonstrated that the littoral ecosystem was influenced by late Holocene sea-level rise and climatic desiccation. While climate change-integrated conservation strategies address the effects of climate change on species distribution and dispersal, our work suggests that more attention should be paid to the impacts of interactive climatic variables that affect ecosystem thresholds.
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According to a traditional but hitherto untested reconstruction of Madagascar’s Holocene environment, continuous forest preceded the monotonous grassland formations that now cover most of the island’s interior. Preliminary analyses of pollen samples collected near14C-dated horizons at Ampasambazimba (central Madagascar) indicate that a mosaic of woodlands, bushlands, and savanna existed close to this important vertebrate subfossil site around 7000–8000 BP. Although most members of Madagascar’s recently extinct “subfossil” fauna are thought to have been forest dwellers, several may have preferred a more open habitat like the one inferred for the region of Ampasambazimba. Dry savanna-woodland burns more readily than does dense forest and may have been more severely affected by the forces which transformed the Malagasy environment during the later Holocene. If so, the loss of savanna-woodland, not dense forest, may have been an important factor in the subfossil extinctions.
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