Widespread forest vertebrate extinctions induced by a mega hydroelectric dam in lowland Amazonia

Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, underconstruction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments

Urban Biodiversity and Landscape Ecology: Patterns, Processes and Planning

Effective planning for biodiversity in cities and towns is increasingly important as urban areas and their human populations grow, both to achieve conservation goals and because ecological communities support services on which humans depend. Landscape ecology provides important frameworks for understanding and conserving urban biodiversity both within cities and considering whole cities in their regional context, and has played an important role in the development of a substantial and expanding body of knowledge about urban landscapes and communities. Characteristics of the whole city including size, overall amount of green space, age and regional context are important considerations for understanding and planning for biotic assemblages at the scale of entire cities, but have received relatively little research attention. Studies of biodiversity within cities are more abundant and show that longstanding principles regarding how patch size, configuration and composition influence biodiversity apply to urban areas as they do in other habitats. However, the fine spatial scales at which urban areas are fragmented and the altered temporal dynamics compared to non-urban areas indicate a need to apply hierarchical multi-scalar landscape ecology models to urban environments. Transferring results from landscape-scale urban biodiversity research into planning remains challenging, not least because of the requirements for urban green space to provide multiple functions. An increasing array of tools is available to meet this challenge and increasingly requires ecologists to work with planners to address biodiversity challenges. Biodiversity conservation and enhancement is just one strand in urban planning, but is increasingly important in a rapidly urbanising world

The influence of evolutionary distance between cross-species microsatellites and primer base-pair composition on allelic dropout rates

Allelic dropouts (ADO) are an important source of genotyping error and because of their negative impact on non-invasive sampling techniques, have become the focus of considerable attention. Previous studies have noted that ADO rates are greater with increasing allele size and in tetranucleotides. It has also been suggested, but not tested, that ADO rates may be higher in studies using crossspecies microsatellites and that mutations may play a role in ADO rates. Here we examine the relationship between ADO rates and the relationship between evolutionary distance since divergence time between species for which the microsatellite was designed for and species on which it was used (divergence times), and how this may interact with median allele size. In addition, as the adenosine (A) and thymine (T) content of the primer may increase mutation rates, we also included total % AT content of the primer in the analyses. Finally, we examined whether other commonly associated causes of ADO (i.e. repeat motif length, median allele size and allele number) co-varied. We found that ADO rates were positively associated to divergence time and median allele size. Repeat motif length, median allele size and allele number positively covaried suggesting a link between mutability and these parameters. Results from previous studies that did not correct for co-variation among these parameters may have been confounded. AT content of the primer was positively associated with ADO rates. The best linear regression model contained divergence time, median allele size and total % AT content, explaining 21% of the variation in ADO rates. The available evidence suggests that mutations partly cause ADO and that studies using cross-species microsatellites may be at higher risk of ADO. Based on our results we highlight some important considerations in the selection of microsatellites for all conservation genetic studies