Diversity, distribution and conservation of Annonaceae (Magnoliales) in Madagascar

Madagascar is a global biodiversity hotspot with extraordinary levels of plant endemism, but its unique ecosystems are increasingly threatened by deforestation and other human-induced activities. Annonaceae is a major pantropical plant family with approximately 2500 species. Despite its ecological importance, the taxonomic diversity and distribution of the family in Madagascar have remained poorly studied, limiting conservation assessments and planning. Here, we provide a comprehensive analysis of diversity distribution patterns and undertake preliminary conservation assessments of Malagasy Annonaceae. A taxonomically verified database of 2306 specimens representing 102 native species in nine genera was used to generate species richness patterns. Preliminary conservation status assessments were conducted following IUCN Red List Criteria A and B, and species exposure to human pressure was evaluated using deforestation layers and the anthrome framework. Annonaceae species richness is concentrated within the Eastern and Sambirano domains, corresponding to warm, humid climates. These regions also emerged as major centers of endemism and conservation concern. Based on Criterion B, 53.9% of species are preliminarily classified as threatened, while 25.5% are considered potentially threatened under Criterion A. Based on Madagascar anthromes, Annonaceae species are not restricted to intact habitats but persist across a wide range of human-modified and densely populated landscapes. Our findings highlight the need to integrate both natural and anthropogenic systems into conservation planning, especially in biodiversity hotspots undergoing rapid land-use change. These results provide a baseline for future biogeographic and evolutionary studies and support targeted conservation actions to reduce extinction risk in Madagascar's most biodiverse regions.

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