Fine-scale effects of habitat loss and fragmentation despite large-scale gene flow for some regionally declining woodland bird species

摘要: Habitat loss and associated fragmentation effects are well-recognised threats to biodiversity. Loss of functional connectivity (mobility, gene flow demographic continuity) could result in population decline altered habitat, because smaller, isolated populations more vulnerable extinction. We tested whether substantial habitat reduction plus is with reduced three ‘decliner’ woodland-dependent bird species (eastern yellow robin, weebill spotted pardalote) identified earlier work have declined disproportionately heavily fragmented landscapes the Box-Ironbark forest region north-central Victoria, Australia. For these decliners, one ‘tolerant’ (striated pardalote), we compared patterns genetic diversity, relatedness, effective size, sex-ratios genic (allele frequency) differentiation among different total tree cover, subdivision at regional scale, explored fine-scale genotypic (individual-based signature) structure. Unexpectedly high across study was detected for species. Power analysis simulations suggest that moderate reductions should been detectable. However, there evidence local negative extent structural connectivity: slightly lower sizes, higher within-site relatedness (for eastern robin) 10 × 10 km ‘landscapes’ low vegetation cover. conclude ecosystem may still allow sufficient avoid harmful inbreeding our Although be consequences connectivity, mobile this system suggests reconnecting patches less important than increasing and/or quality if need traded off.