Habitat specialization drives differential responses to habitat loss and fragmentation across multiple spatial scales in sympatric lizards

• Habitat loss negatively impacts the specialist lizard Liolaemus multimaculatus . • Specialist lizard abundance responds to landscape composition at multiple scales. • The generalist lizard Liolaemus wiegmannii shows tolerance to fragmented habitats. • Small-scale patch complexity drives generalist lizard abundance. • Exotic tree encroachment degrades specialist lizard habitat quality. Anthropogenic landscape change involves habitat loss and shifts in configuration, often increasing patch number and isolation. Ecological specialization is hypothesized to mediate species vulnerability, with specialists sensitive to habitat amount and generalists potentially utilizing structural heterogeneity. We tested this scale-dependent differential response across seven Pampean coastal dune sites in Argentina, focusing on two sympatric lizards: the endangered habitat specialist Liolaemus multimaculatus and the habitat generalist Liolaemus wiegmannii . We assessed relative lizard abundance using fixed-route visual encounter transects and modeled species abundance association with landscape metrics using Generalized Linear Mixed Models across three nested spatial scales (100-m, 300-m, and 500-m). Results revealed a clear dichotomy driven by specialization. The specialist L. multimaculatus 's abundance was explained exclusively by habitat composition metrics, showing a strong positive association with the total area of active dune habitat (500-m scale) and a consistent negative relationship with the total area of low-quality habitats (exotic forestation, semi-fixed dune, and beach) across all three scales. This indicates its vulnerability stems primarily from habitat loss. In contrast, the generalist L. wiegmannii 's abundance was explained exclusively by configuration metrics at the smallest scale (100-m), showing a positive association with the number and complexity of semi-fixed dune patches. This suggests the generalist benefits from fragmentation-induced heterogeneity. Our findings confirm that ecological specialization critically dictates species vulnerability and scale-dependent responses to landscape change. Conservation efforts for the vulnerable L. multimaculatus must prioritize maintaining the amount of core active dune habitat.