Disturbance effects on anuran communities and relative fitness across urban-adjacent forests of Peninsular Malaysia and Malaysian Borneo

Urbanisation profoundly affects anuran biodiversity, particularly species composition and functional traits in natural vegetation contiguous to cities. We assessed anuran community structure and trait variation in two urban-adjacent forests: Ayer Hitam Forest Reserve (AHFR) in Peninsular Malaysia and Universiti Putra Malaysia Bintulu Campus (UPMBC) in Malaysian Borneo, with each system analysed independently within a shared ecological context. We examined biodiversity, abundance, and trait variation across disturbance zones and forest types, while accounting for microclimates and seasonal sampling periods. For AHFR, we integrated published checklist records from 1975 to 1999 with our multi-year monitoring data collected between 2015 and 2019. Standardised nocturnal surveys combined with historical records documented diverse anuran assemblages at both study sites, with disturbance effects most evident in the disturbed zone of AHFR, which showed the lowest rarefied species richness. Anurans in moderately disturbed and disturbed zones of AHFR were associated with variation in body size and condition, with notable responses observed in Ingerophrynus parvus and Kalophrynus palmatissimus . In UPMBC, planted forest supported relatively resilient species such as Limnonectes ibanorum , while species with narrower habitat associations, including Alcalus baluensis and Kalophrynus heterochirus , showed negative body size deviations. Differences in body size and condition between allopatric populations of L. ibanorum in AHFR and UPMBC suggested geographical influences on traits variation. Our study reveals disturbance-driven variation in anurans and conservation relevance.