Tropical dry forests are highly vulnerable to fire due to their environmental and climatic conditions. In Madagascar, significant fire events occur every year and threaten its unique ecosystems and biodiversity. Its dry forests are particularly affected, yet knowledge about vegetation responses to fire remains limited. This study investigates how fires influenced vegetation structure, tree species diversity as well as seedling and sapling density in a dry deciduous forest. Vegetation and soil data were collected across 18 sites in Ankarafantsika National Park (ANP), the largest remnant of dry deciduous forest in the northwest of the island. Fire variables included frequency (0–6 fires) and time since last fire (1–37 years). Using generalized linear mixed models, tree diversity indices, parameters of vegetation structure (density in height classes and basal area), and seedling and sapling density were modeled as functions of fire history. Fire frequency and the time since the last fire affected the density of medium-sized (5–7.5 m height), tall (7.5–10 m height), and very tall trees (>10 m height) as well as basal area, whereas the density of smaller trees (2.5–5 m) was least affected by these fire-related variables. Tree species diversity, seedling and sapling density also declined with increasing fire frequency and recovered only slowly after fires indicating limited fire resilience of many tree species. Full recovery of forest structure, tree species diversity, and regeneration potential were achieved only after at least 27 fire-free years. These findings indicate a moderate recovery capacity under prolonged fire-free intervals.

Habitat quality is a key determinant of wildlife distribution. Fire degrades forests by increasing canopy openness and eliminating even large trees, providing shelter and necessary resources for many species. In Madagascar, fires are prominent, yet the mechanisms linking fire disturbance to lemur habitat occupation remain poorly understood. We conducted a study inside Ankarafantsika National Park during the dry seasons of 2022 and 2023, collecting data along paired burnt-unburnt transects in 18 sites containing burnt partitions with a 1-35-year fire age. Using Generalized Linear Mixed Models, we assessed the effects of forest humidity, temperature, vegetation structure, and woody species richness on lemur occurrence, and evaluated the impact of fire parameters on significant abiotic and vegetation parameters. Lemur responses varied by body size and ecological specialization. Eulemur fulvus most likely occurred in humid habitats with high floristic diversity. Floristic diversity also explained best the presence of Avahi occidentalis and Cheirogaleus medius, while Lepilemur edwardsi was rather connected to dense multi-layered canopies. Small-bodied Microcebus species displayed structural and floristic tolerance. Woody species richness declined in the burnt forest and was highest in the unburnt forest. Fires impacted vegetation structure, increasing openness and understory density, while old burnt and unburnt forests maintained complex vertical layering. Woody species richness emerged as the strongest predictor of lemur species richness. These results indicate that fire primarily affects lemurs through floristic and structural pathways, emphasizing the need to preserve intact forest refugia to sustain lemur diversity under increasing fire pressure in dry forest landscapes of Madagascar.

Madagascar's lemurs are globally unique primates, yet many nocturnal taxa remain poorly studied. Among them, the eastern woolly lemur (Avahi laniger) is widespread across the island's northern and central-eastern rainforests, but little is known about its ecology outside protected areas. We surveyed 18 unprotected forests, representing about one third of the species' range, to evaluate its occurrence, population density, habitat use, and interactions with local communities. Using 97 nocturnal line transects (291.8 km of survey effort) combined with vegetation assessments and 208 interviews, we found A. laniger at all study sites. Estimated population density was 41.3 individuals/km2, which is at the lower margin of reported values for the genus. Encounter rates did not differ significantly along a gradient of forest degradation (undisturbed to highly logged primary forest), suggesting some tolerance to structural degradation. However, use of fallow-derived habitats was restricted to sites with the early successional tree Harungana madagascariensis, highlighting the importance of vertical structures and specific food plants. Morphological measurements showed no evidence of reduced body condition compared to populations in protected areas. Interviews revealed broad local knowledge of the species (73% recognition), occasional and opportunistic hunting, and low prevalence of taboos against consumption. Notably, hunting could be linked to locally reduced abundances. We demonstrate that A. laniger persists across a gradient of human-modified landscapes, if vertical forest structures and food resources remain available. Conservation strategies should therefore include forested areas not generally considered suitable for lemurs (e.g., agroforests), while strictly preventing hunting to ensure population viability under ongoing habitat fragmentation.

ABSTRACT Species distributions are shaped by complex biotic and abiotic interactions, which are often not fully understood. We investigated the ecological basis of co‐occurrence and distribution of four partially sympatric and allopatric cryptic mouse lemur species ( Microcebus spp.) in the Ambatosoa and Analanjirofo region of northeastern Madagascar. Using structural habitat characteristics, adaptability to habitat degradation, bioclimatic niches, and morphology (incl. body mass variability), we estimated n ‐dimensional hypervolumes of niche sizes and overlaps. M. jonahi and M. simmonsi were found almost equally often in forest‐ and fallow‐derived habitats (52% and 58%, respectively), while M. lehilahytsara predominantly occupied fallow habitats (71%) that result from shifting cultivation practice. M. lehilahytsara exhibited the largest niche and range size, followed by M. jonahi and M . simmonsi . M . jonahi and M . simmonsi displayed significant fat deposition before the austral winter, indicating heterothermy as an adaptation to unpredictable environmental conditions. These two species were only found in allopatry, likely due to competition for critical resources like sleeping sites. The smaller M . lehilahytsara co‐occurred with M . jonahi and M . macarthurii potentially by adjusting its niche to avoid competition with these larger‐bodied species. We hypothesize that heterothermy allowed M . jonahi and M . simmonsi to persist in lowland habitats during cold phases of the Pleistocene but that it did not promote co‐occurrence. In contrast, M . lehilahytsara may have lost lowland distributions due to a lower capacity to deposit fat. Our findings require further testing but provide a plausible explanation for a complex distributional pattern of sympatric and allopatric occurrences in northeastern Madagascar.

The extent of fires in tropical ecosystems is highly dynamic, and responses of tropical dry forests to fire seem to vary and are not well understood. This study reconstructs a 35-year long fire history of the dry forests in the Ankarafantsika National Park (ANP) in Madagascar. In recent years, forest fires have been reported in this region, potentially threatening habitat integrity and connectivity inside ANP. We assessed the fire dynamics with yearly Landsat satellite images from 1988 to 2023 (Landsat 4-5, Landsat 7, Landsat 8-9) by means of the Normalized Burn Ratio (NBR) and the differenced NBR (dNBR) with a 30m resolution. To validate the fire classification in addition to exemplary ground truthing, 350 random points were selected across ANP and visually classified based on yearly Red Green Blue false-color composites and their corresponding dNBR images. Inside ANP, 70 % of the vegetation burnt at least once, while 18 % burnt even more than three times. Fire distribution was heterogenous with fires being more frequent in the north than in the south of ANP. The extent of burnt areas fluctuated over the years peaking in 2016 with 229 km2 (22 % of the park vegetation). Fires recurred after 1-34 years, but more frequently than expected after 3-5 years. Areas requiring urgent conservation attention are highlighted and a baseline for developing fire management strategies is provided. Finally, this study demonstrates that ground truthing is essential to implement an analytical pipeline to correctly infer burnt and unburnt vegetation parts from series of satellite pictures.

Madagascar is a megadiverse island with exceptionally high levels of endemism, which resulted mainly from allopatric speciation promoted by the island’s complex physical geography and paleoclimatic cycles. Northeastern Madagascar is uniquely suited to test the relative importance of river barriers, topography and climatic conditions for lemur genetic differentiation. Based on restriction site-associated DNA sequences, we inferred phylogeny, population structure, genetic diversity and rates of gene flow in four mouse lemur (genus Microcebus ) and two woolly lemur (genus Avahi ) species. In addition, we employed isolation-by-resistance models to test the importance of topography, river barriers, climate and forest cover in restricting intraspecific gene flow. Our results show that significant differences in genetic diversity and connectivity can be explained by varying responses to landscape features and species-specific phylogeographic histories. Rivers present a general barrier to gene flow, and dispersal between inter-river systems is predominantly mediated through high-elevation headwater regions. While this led to high connectivity and genetic diversity in M. lehilahytsara and A. laniger , gene flow among M. jonahi populations is limited by low climatic niche suitability at higher elevations. In addition, topographic complexity promotes connectivity among Microcebus populations, potentially by buffering impacts of seasonal or historic changes in climatic conditions. Finally, the more restricted distributions of M. macarthurii , A. mooreorum and, to some extent, M. simmonsi likely resulted from refugial dynamics and sea level fluctuations which led to geographic isolation, microendemism and secondary contact zones. Our findings generated informed hypotheses regarding the colonization history of the studied species while also having important implications for their conservation. ### Competing Interest Statement The authors have declared no competing interest. Deutsche Forschungsgemeinschaft, DFG Ra 502/23-1 Society for Tropical Ecology Houston Zoo, Inc. Bauer Foundation, T237/22985/2012/kg Zemplin Foundation, T0214/32083/2018/sm German National High Performance Computing Alliance NHR{at}Göttingen, nib00015

IntroductionLocal ecological knowledge (LEK) offers valuable insights into human-wildlife relationships and bears the potential to improve the conservation of controversial species. The Endangered and elusive Aye-aye (Daubentonia madagascariensis) is commonly associated with superstition and negative perceptions that lead to targeted killings, but has recently been related to agricultural benefits. This study explores how knowledge about ecological interactions in clove agroforestry underlies this benefit perception.MethodsThrough surveys (n = 392) and expert interviews (n = 6) across 21 village communities, we assessed Aye-aye-related LEK among clove farmers in northeastern Madagascar. Survey analysis employed a Random Forest model and expert interviews were analyzed using qualitative content analysis.ResultsClove farming experts emphasized the beneficial effect that an Aye-aye has by suppressing invertebrate pest species on clove trees. About 44% of the survey participants related the Aye-aye to pest control and knowledge of its insectivory was identified as a critical factor influencing this benefit knowledge. Diverse levels of LEK about the Aye-aye were recorded and were influenced by gender, socio-economic activities, and geographic location. DiscussionThe results underscore the importance of ecological knowledge as a condition for benefit perception and demonstrate how assessing LEK can provide insights into the perception of cryptic wildlife species. This study illustrates the necessity for targeted conservation actions, sensitive to socio-ecological contexts. Conservation practitioners should employ benefit-based narratives if available and consider local knowledge transmission channels to address negative perceptions of wildlife."

AimThe riverine barrier hypothesis is often tested as a driver for allopatric speciation. Rivers are usually treated as static landscape features characterised by their width and elevation of their headwaters. We aim to investigate the role of rivers as barriers using a comprehensive database of geomorphological characteristics by assessing their influence on species turnover rates.LocationEastern Madagascar.TaxonSixty-two taxa from 11 genera of lemurs, amphibians and reptiles.MethodsWe compiled 21 geomorphological variables for 45 major rivers, estimated species turnover rates from species assemblages on either side and modelled the influence of river characteristics on species diversity. Topographic depressions, identified from longitudinal river profiles, and landscape heterogeneity were further analysed as potential palaeoclimatic refugia and alternative speciation drivers.ResultsA total of 24 rivers acted as species barriers. Three of these had disproportionately high species turnover rates and shared a set of distinct geomorphological features like the maximum elevation of the watershed, high flow accumulation values at the outlet and at an elevation of 800 m and a high concavity of the longitudinal river profile. Other variables like landscape heterogeneity along the main river channel and length of the coastal plain further helped to differentiate between rivers with intermediate turnover rates. Species richness peaked in northeastern Madagascar, a region with the highest abundance of topographic depressions and inferred palaeo-wetlands.Main ConclusionsGeomorphological river characteristics effectively explained variations in species turnover rates. However, it remains uncertain whether rivers functioned as secondary dispersal barriers and thereby maintainers of species diversity, rather than as primary drivers of allopatric speciation. Additionally, we emphasise the role of refugia during palaeoclimatic oscillations, which are often associated with topographic depressions. Overall, integrating rivers as dynamic fluvial systems through space and time into biogeographic studies offers valuable insights into speciation, dispersal and the persistence of taxa.

River barriers have long played a central role in diversification models of tropical regions, including the exceptionally biodiverse island Madagascar. Although their role is best understood by integrating additional factors such as elevation and the ecological niche of a species, empirical studies integrating these variables remain rare. We used restriction site-associated DNA sequencing to assess the combined effect of rivers, topography, climate and forest cover on the distributions and diversity of four Microcebus and two Avahi species (Primates, Lemuriformes) in northeastern Madagascar. We inferred population structure, gene flow and genetic diversity, and assessed the association of these ecogeographic variables and genetic differentiation using isolation-by-resistance models. Our results show that significant differences in genetic diversity and connectivity among species can be explained by species-specific responses to landscape features and phylogeographic histories. Specifically, rivers present general barriers to gene flow, but dispersal between inter-river systems is possible via high-elevation headwater regions. While this led to high connectivity and genetic diversity in M. lehilahytsara and A. laniger, gene flow among M. jonahi populations is limited by low climatic niche suitability at higher elevations. Moreover, the more restricted distributions of M. macarthurii, M. simmonsi and A. mooreorum likely resulted from refugial dynamics and sea level fluctuations leading to allopatric divergence and microendemism. Together, the findings illustrate how ecological differences among species and temporal landscape dynamics mediate the role of rivers as dispersal barriers. They also highlight the importance of prioritising river headwaters and topographically complex regions, which were shown to promote connectivity, in conservation efforts.

Wildfires significantly threaten biodiversity, especially in tropical regions like Madagascar, where unique ecosystems face ongoing habitat loss and degradation. This study investigated the effects of forest fires on lemur encounter rates, species richness, and their ability to recolonize burnt areas in Ankarafantsika National Park (ANP), the largest protected dry deciduous forest in northwestern Madagascar. ANP hosts eight lemur species with one diurnal (Propithecus coquereli), two cathemeral (Eulemur mongoz, E. fulvus), and five nocturnal species (Avahi occidentalis, Lepilemur edwardsi, Cheirogaleus medius, Microcebus murinus, and M. ravelobensis). Eighteen sites with varying fire histories (1 to > 35 years post-fire) and adjacent unburnt forest parts were surveyed using diurnal and nocturnal transect surveys. Transects included burnt (700 m) and unburnt (500 m) sections. We used Generalized linear mixed effect models (GLMMs) to assess the effect of fire variables such as time since the last fire, number of fires, intervals between fires, and fire severity on lemur encounter rate and species richness. A full lemur community was observed only in unburnt forests and areas with extended post-fire recovery (≥ 23 years). Frequent fires negatively impacted the encounter rates of E. fulvus and L. edwardsi, while they did not significantly affect the encounter rates of small nocturnal species (C. medius, Microcebus spp.). Lemur species richness was higher in unburnt zones and decreased with an increasing number of fires. These findings reveal the need for long recovery periods for lemur communities post-fire, suggest species-specific fire vulnerabilities, and demonstrate significant faunal impacts of this destructive driver of landscape transformation.

Global biodiversity is under accelerating threats, and species are succumbing to extinction before being described. Madagascar’s biota represents an extreme example of this scenario, with the added complication that much of its endemic biodiversity is cryptic. Here we illustrate best practices for clarifying cryptic diversification processes by presenting an integrative framework that leverages multiple lines of evidence and taxon-informed cut-offs for species delimitation, while placing special emphasis on identifying patterns of isolation by distance. We systematically apply this framework to an entire taxonomically controversial primate clade, the mouse lemurs (genus Microcebus, family Cheirogaleidae). We demonstrate that species diversity has been overestimated primarily due to the interpretation of geographic variation as speciation, potentially biasing inference of the underlying processes of evolutionary diversification. Following a revised classification, we find that crypsis within the genus is best explained by a model of morphological stasis imposed by stabilizing selection and a neutral process of niche diversification. Finally, by clarifying species limits and defining evolutionarily significant units, we provide new conservation priorities, bridging fundamental and applied objectives in a generalizable framework. A spatial taxonomic framework integrating genomic, morphological, ecological, life history and acoustic data is used to clarify the cryptic evolution of the taxonomically controversial mouse lemur complex, with a view to aiding future conservation of this and other similarly cryptic clades.

Accurate information on the location and density of people living at the forest frontier is vital for effective and equitable forest conservation. We compare the location of settlements and estimated population density from three global-scale, remote-sensed datasets (World Settlement Footprint 2015, Open Buildings, WorldPop) with a fine-scale, manually-derived dataset of 3,136 human settlements, of which 95% had fewer than 150 households. The study region is located in north-eastern Madagascar, contains three protected areas and the largest unprotected block of humid forest of the island. The Open Buildings dataset detected a much higher proportion (94%) of settlements than did World Settlement Footprint (15%). Population density from WorldPop matches poorly with that estimated from our manually-derived dataset. The accuracy of all three datasets is worse in more remote, forested areas, further away from basic infrastructure. Open Buildings appears to best reveal the distribution of low density scattered populations in forested areas. However, further testing in other climatic regions is still needed. Making good use of appropriate remote-sensed data could revolutionize the inclusion of local communities in conservation policy and practice, improve the quality of inference in conservation research, particularly in times of a planned expansion of the global protected area network. ### Competing Interest Statement The authors have declared no competing interest.

A link between the abundance of species and their degree of ecological specialization has previously been suggested within the primate order. Many species of lemurs were only recently described and even basic ecological data are not yet available for them. We investigated the habitat use, abundance, and habitat characteristics of the critically endangered Microcebus gerpi and evaluated potential impacts of vegetation structure and human disturbances on variations in its abundance. We determined abundance by systematic nocturnal surveys along 13 transects that were also used for characterizing the vegetation structure in seven study sites that were widely distributed within its range. Although M. gerpi occurred in all studied lowland rainforest and littoral forest fragments in central eastern Madagascar and therefore has a higher ecological plasticity and wider distribution than previously thought, its actual Area of Occupancy is very small (339.78 km(2)) due to an extreme degree of habitat fragmentation throughout its range. M. gerpi occurred with a mean encounter rate of 3.04 individuals/km but abundance varied substantially between sites (0.75-4.5 individuals/km). Statistical modeling revealed that the cover of small- to medium-sized trees had a positive impact on the abundance of M. gerpi, whereas a composite disturbance score (CDS), formed on the basis of information on the prominence of fires, cattle, charcoal production and wood extraction inside and around the forest, had a negative impact on abundance. These results suggest that M. gerpi is slightly less threatened than expected because of its larger geographic range, but also that it responds negatively to human disturbances. These findings raise strong conservation concerns and question the long-term viability of the remaining small and isolated populations of this arboreal solitary forager.

Ecological niche modeling (ENM) is particularly useful in the study of cryptic and elusive species that are only rarely seen, difficult to study in the wild, and simultaneously threatened by a multitude of anthropogenic factors. We collected presence records one such example, the understudied Hairy-eared Dwarf Lemur (Allocebus trichotis), from the literature and supplemented these with observations from surveys in previously unstudied areas to model its fundamental and realized niche throughout Madagascar. We further evaluated habitat characteristics at each sighting location to judge its conservation status and its adaptability toward habitat degradation. We found 31 presence localities in the literature and directly observed A. trichotis a further 23 times. According to the ENMs, precipitation of the driest quarter and maximum temperature of the warmest month mostly influenced its distribution, restricting it to the higher altitudes of the northeastern humid forests of Madagascar. Its fundamental niche, extent of occurrence, and area of occupancy were estimated as 65,819, 53,054, and 16,967 km² respectively. The latter, however, declined by 29.2% since 1990. On a habitat level, it was most often observed in primary forest habitats of different degradation stages (85.7%, n = 21). The fundamental niche of A. trichotis is most likely restricted by climatic factors. Although it can be found in moderately degraded forests, it is known to depend on the availability of tree holes and therefore old-growth forest structures. Ongoing deforestation and habitat fragmentation are likely to be the major threats to the survival of this species. Our ENMs provide evidence on where to intensify survey efforts on the elusive Hairy-eared Dwarf Lemurs of Madagascar.

Madagascar exhibits exceptionally high levels of biodiversity and endemism. Models to explain the diversification and distribution of species in Madagascar stress the importance of historical variability in climate conditions which may have led to the formation of geographic barriers by changing water and habitat availability. The relative importance of these models for the diversification of the various forest-adapted taxa of Madagascar has yet to be understood. Here, we reconstructed the phylogeographic history of Gerp's mouse lemur (Microcebus gerpi) to identify relevant mechanisms and drivers of diversification in Madagascar's humid rainforests. We used restriction site associated DNA (RAD) markers and applied population genomic and coalescent-based techniques to estimate genetic diversity, population structure, gene flow and divergence times among M. gerpi populations and its two sister species M. jollyae and M. marohita. Genomic results were complemented with ecological niche models to better understand the relative barrier function of rivers and altitude. We show that M. gerpi diversified during the late Pleistocene. The inferred ecological niche, patterns of gene flow and genetic differentiation in M. gerpi suggest that the potential for rivers to act as biogeographic barriers depended on both size and elevation of headwaters. Populations on opposite sides of the largest river in the area with headwaters that extend far into the highlands show particularly high genetic differentiation, whereas rivers with lower elevation headwaters have weaker barrier functions, indicated by higher migration rates and admixture. We conclude that M. gerpi likely diversified through repeated cycles of dispersal punctuated by isolation to refugia as a result of paleoclimatic fluctuations during the Pleistocene. We argue that this diversification scenario serves as a model of diversification for other rainforest taxa that are similarly limited by geographic factors. In addition, we highlight conservation implications for this critically endangered species, which faces extreme habitat loss and fragmentation.

Hunting of wild animals for meat and habitat loss are the main drivers of wildlife population decline around the world, and in tropical regions in particular. While Madagascar is a hotspot for biodiversity, hunting is widespread, mostly in form of subsistence hunting, while hunting for the pet trade is less often reported. We studied hunting of the Critically Endangered black-and-white ruffed lemur ( Varecia variegata ) in northeastern Madagascar. Using lemur surveys (102.7 km survey effort) and 54 semi-structured and seven key informant interviews, we assessed the local knowledge, hunting pressure, and the perceived and actual abundances of V. variegata in two hunting and two non-hunting villages. V. variegata was well known (> 83%) by the respondents but abundance estimates differed significantly between hunting and non-hunting villages, with 26% and 77% of respondents, respectively, estimating a high abundance of ruffed lemurs in the adjacent forests of the villages. Actual observations of V. variegata also differed strongly, in accordance to perceived abundances. Hunting was either done by trapping animals or by pursuit hunts. In both hunting villages, adult lemurs were used for direct meat consumption and juveniles for rearing for the later trade. Hand-raised V. variegata were reported to be sold for 38–71 USD on regional markets or ‘delivered’ directly to buyers. While wildlife hunting has been widely reported from all over Madagascar, commercial hunting, hand-rearing and trading adds a new dimension of threat towards these Critically Endangered lemurs. As such, the extent of the trade is a priority for future studies.

Objectives: The investigation of morphological variation in animals is widely used in taxonomy, ecology, and evolution. Using large datasets for meta-analyses has dramatically increased, raising concerns about dataset compatibilities and biases introduced by contributions of multiple researchers.Materials and Methods: We compiled morphological data on 13 variables for 3073 individual mouse lemurs (Cheirogaleidae, Microcebus spp.) from 25 taxa and 153 different sampling locations, measured by 48 different researchers. We introduced and applied a filtering pipeline and quantified improvements in data quality (Shapiro-Francia statistic, skewness, and excess kurtosis). The filtered dataset was then used to test for genus-wide sexual size dimorphism and the applicability of Rensch's, Allen's, and Bergmann's rules.Results: Our pipeline reduced inter-observer bias (i.e., increased normality of data distributions). Inter-observer reliability of measurements was notably variable, highlighting the need to reduce data collection biases. Although subtle, we found a consistent pattern of sexual size dimorphism across Microcebus, with females being the larger (but not heavier) sex. Sexual size dimorphism was isometric, providing no support for Rensch's rule. Variations in tail length but not in ear size were consistent with the predictions of Allen's rule. Body mass and length followed a pattern contrary to predictions of Bergmann's rule.Discussion: We highlighted the usefulness of large multi-researcher datasets for testing ecological hypotheses after correcting for inter-observer biases. Using genus-wide tests, we outlined generalizable patterns of morphological variability across all mouse lemurs. This new methodological toolkit aims to facilitate future large-scale morphological comparisons for a wide range of taxa and applications.

EDITORIAL article Front. For. Glob. Change, 30 May 2023Sec. Forest Management Volume 6 - 2023 | https://doi.org/10.3389/ffgc.2023.1172760

Madagascar's Central Highlands are largely composed of grasslands, interspersed with patches of forest. The historical perspective was that Madagascar's grasslands had anthropogenic origins, but emerging evidence suggests that grasslands were a component of the pre-human Central Highlands vegetation. Consequently, there is now vigorous debate regarding the extent to which these grasslands have expanded due to anthropogenic pressures. Here, we shed light on the temporal dynamics of Madagascar's vegetative composition by conducting a population genomic investigation of Goodman's mouse lemur (Microcebus lehilahytsara; Cheirogaleidae). These small-bodied primates occur both in Madagascar's eastern rainforests and in the Central Highlands, making them a valuable indicator species. Population divergences among forest-dwelling mammals will reflect changes to their habitat, including fragmentation, whereas patterns of post-divergence gene flow can reveal formerly wooded migration corridors. To explore these patterns, we used RADseq data to infer population genetic structure, demographic models of post-divergence gene flow, and population size change through time. The results offer evidence that open habitats are an ancient component of the Central Highlands, and that widespread forest fragmentation occurred naturally during a period of decreased precipitation near the last glacial maximum. Models of gene flow suggest that migration across the Central Highlands has been possible from the Pleistocene through the recent Holocene via riparian corridors. Though our findings support the hypothesis that Central Highland grasslands predate human arrival, we also find evidence for human-mediated population declines. This highlights the extent to which species imminently threatened by human-mediated deforestation may already be vulnerable from paleoclimatic conditions.