Biology subjects

Bornschein, M. R.

Publications and source records attributed to Bornschein, M. R..

4 recordsLinked to original sources

bioRxiv2023

Population of the Parana Antwren Formicivora acutirostris reassessed as being 64% smaller: Revision of its conservation status and assessment of its Green Status, with management proposals

Assessing the conservation status of a species is important for designing effective conservation measures. Consequently, it is often vital to review it to update biodiversity management. Formicivora acutirostris is a bird from coastal marshes and related habitats of Brazils southern flood plains. It is considered endangered in Brazil but near threatened globally. In 2007, its area of occupancy (AOO) and population size were estimated based on assessment of aerial photographs from 1978 and 1980. Since the species is threatened and occupies a small area scattered across a coastal pressured region, we aimed to reassess its conservation status and assess its Green Status. We compiled new records, conducted new density estimates, and compared the previous mapping with orbital imagery to estimate the current AOO, habitat loss, population size, and review its conservation status based on the International Union for Conservation of Nature criteria. The species is distributed across 10 populations, including two new populations from the southern coast of Santa Catarina to the northern coast of Rio Grande do Sul. We estimated the AOO at 4,102 ha and the population as 6,284 mature territorial individuals. The previously mapped AOO has decreased by 1,535 ha due to ecological succession. The loss of habitat due to invasion by exotic grasses is the main anthropogenic impact. We recommend that the species be considered vulnerable. The Green Status indicates that the Conservation Legacy of actions taken thus far and the Conservation Dependence of ongoing actions are null, but it highlights the importance of future actions for species conservation. We propose the establishment of exotic-free zones as small geographic areas with a significant amount of minimally invaded environments, which we suggest as priority areas for the conservation of the species due to their cost-effective management potential. We also propose assisted colonization to enhance its long-term conservation.

ecology↗

bioRxiv2023

Brood division in a marsh-dwelling bird and its relation with the increase in offspring survival, acceleration of renest, and reduced competition for food resources

Parental care involves strategies that increase the offsprings survival. In some birds, each adult only feeds one young (brood division). Six hypotheses explain the functions of brood division: 1) reduced predation; 2) selection of a young by the parents; 3) selection of an adult by the young; 4) reduction of offspring competition; 5) efficiency improvement in parent-offspring interactions; and 6) social specialization. We studied the reproductive behavior and nestling morphology of the species to evaluate the possible functions associated with the brood division in Formicivora acutirostris, a bird of tidal marshes of southern Brazil. Females lay two eggs, but nests with one nestling may occur. We monitored 899 nests, nestlings, and parental care of young until they reached independence. Brood division occurred when the fledglings left the nest and continued until their independence. We did not observe a difference in the frequency with which sex feed single fledglings clutches. The fledglings remain in separated areas (pro hypothesis #1). There is a sex bias in the division (pro hypothesis #2). Adults fed the siblings equally (contra hypothesis #3). There is no aggression between siblings (contra hypothesis #4). Each fledgling remained close to their adult and responds only to it (pro hypotheses #5 and #6). We propose that brood division in the species may 7) reduce drowning of fledglings, 8) spatially divide food consumption, and 9) allow concomitant reproduction. We emphasize flooding as a structuring force for F. acutirostris, which raises concerns about the effects of climate change on this species.

animal behavior and cognition↗

bioRxiv2017

Phylogenomics of montane frogs of the Brazilian Atlantic Forest supports a scenario of isolation in sky islands followed by relative climatic stability

Despite encompassing a relatively small geographical area, montane regions harbor disproportionately high levels of species diversity and endemism. Yet, relatively little is known about the evolutionary mechanisms ultimately leading to montane diversity. In this study, we use target capture of ultraconserved elements to investigate the phylogenetic relationships and diversification patterns of Melanophryniscus (Bufonidae) and Brachycephalus (Brachycephalidae), two frog genera that occur in sky islands of the southern Atlantic Forest of Brazil. Specifically, we test whether diversification of montane species in these genera can be explained by a single climatic shift leading to isolation in sky islands, followed by relative climatic stability that maintained populations in allopatry. In both genera, the topologies inferred using concatenation and coalescent-based methods were concordant and had strong nodal support, except for a few recent splits. These recent splits tended to be supported by more informative loci (those with higher average bootstrap support), suggesting that, while individual trees may be well resolved, the relationships they recover are being obscured by non-informative data. Divergence dating of a combined dataset using both genera is consistent with concordant timing of their diversification. These results support the scenario of diversification-by-isolation in sky islands, and suggest that allopatry due to climatic gradients in montane regions are an important mechanism for generating species diversity and endemism in these regions.

evolutionary biology↗

bioRxiv2017

Phylogenomic Species Delimitation In Microendemic Frogs Of The Brazilian Atlantic Forest

The advent of next-generation sequencing allows researchers to use large-scale datasets for species delimitation analyses, yet one can envision an inflection point where the added accuracy of including more loci does not offset the increased computational burden. One alternative to including all loci could be to prioritize the analysis of loci for which there is an expectation of high informativeness, such as those with higher numbers of parsimony-informative sites. Here, we explore the issue of species delimitation and locus selection with species from two anuran genera: Melanophryniscus (Bufonidae) and Brachycephalus (Brachycephalidae). Montane species in these genera have been isolated in sky islands across the southern Brazilian Atlantic Forest, which led to the formation of a number of microendemic species. To delimit species, we obtained genetic data using target enrichment of ultraconserved elements from 32 populations (13 for Melanophryniscus and 19 for Brachycephalus), and we were able to create datasets that included over 800 loci with no missing data. We ranked loci according to their corresponding number of parsimony-informative sites, and we performed species delimitation analyses using BPP in each genus based on the top 10, 20, 40, 80, 160, 320, and 640 loci. We also conducted several additional analyses using 10 randomly sampled datasets containing the same numbers of loci to discriminate the relative contribution of increasing the number of loci from prioritizing those with higher informativeness. We identified three types of node: nodes with either consistently high or low support regardless of the number of loci or their informativeness, and nodes that were initially poorly supported, but their support became stronger with more data. Adding more loci had a stronger impact on model support than prioritizing loci for their informativeness, but this effect was less apparent in datasets with more than 160 loci. When viewed across all sensitivity analyses, our results suggest that the current species richness in both genera might have been underestimated. In addition, our results provide useful guidelines to the use of different sampling strategies to carry out species delimitation with phylogenomic datasets.

evolutionary biology↗