Biology subjects

Balboa, R. F.

Publications and source records attributed to Balboa, R. F..

4 recordsLinked to original sources

bioRxiv2025

Unfolding admixed ancestry and genomic diversity in zoo giraffes

A giraffe nicknamed Marius attracted international media attention and world-wide notoriety when euthanized by Copenhagen Zoo in 2014, deemed surplus to the European breeding program. This incident highlights the challenges of managing zoo populations to best contribute to species conservation amid limited resources. Here, we investigated the degree of admixture, genetic diversity and inbreeding in ex situ giraffes using whole genome sequencing data from Marius and 12 other zoo giraffes, leveraging a reference data set from 71 wild giraffes. We found that most zoo giraffes show admixed ancestries. Marius, and zoo individuals assigned to Reticulated giraffes, exhibits mosaic ancestry with 85% Reticulated and 15% Nubian origin. We further detected recent inbreeding in some of the zoo individuals, consistent with their studbook data. Runs of homozygosity revealed that Marius and three other zoo giraffes were more inbred than their wild counterparts, although their admixed ancestry compensates for the reduction in genetic diversity caused by inbreeding. Our findings highlight the dual challenges of admixture and inbreeding in ex situ populations of giraffe, emphasizing the need for balanced genetic management to mitigate inbreeding and outbreeding degression while preserving diversity reflective of wild populations. This study also reinforces the importance of studbooks and genomic tools in guiding ex situ conservation strategies.

evolutionary biology↗

bioRxiv2024

Extensive population structure highlights an apparent paradox of stasis in the impala (Aepyceros melampus)

Impalas are unusual among bovids because they have remained morphologically similar over millions of years - a phenomenon referred to as evolutionary stasis. Here, we sequenced 119 whole genomes from the two extant subspecies of impala, the common (Aepyceros melampus melampus) and black-faced (A. m. petersi) impala. We investigated the evolutionary forces working within the species to explore how they might be associated with its evolutionary stasis as a taxon. Despite being one of the most abundant bovid species, we found low genetic diversity overall, and a phylogeographic signal of spatial expansion from southern to eastern Africa. Contrary to expectations under a scenario of evolutionary stasis, we found pronounced genetic structure between and within the two subspecies with indications of ancient, but not recent, gene flow. Black-faced impala and eastern African common impala populations had more runs of homozygosity than common impala in southern Africa, and, using a proxy for genetic load, we found that natural selection is working less efficiently in these populations compared to the southern African populations. Together with the fossil record, our results are consistent with a fixed-optimum model of evolutionary stasis, in which impalas in the southern African core of the range are able to stay near their evolutionary fitness optimum as a generalist ecotone species, whereas eastern African impalas may struggle to do so due to the effects of genetic drift and reduced adaptation to the local habitat, leading to recurrent local extinction in eastern Africa and re-colonization from the South.

evolutionary biology↗

bioRxiv2023

African bush pigs exhibit porous species boundaries and appeared in Madagascar concurrently with human arrival

Several African mammals exhibit a phylogeographic pattern where closely related taxa are split between West/Central and East/Southern Africa, but their evolutionary relationships and histories remain controversial. Bushpigs (Potamochoerus larvatus) and red river hogs (P. porcus) are recognised as separate species due to morphological distinctions, a perceived lack of interbreeding at contact, and putatively old divergence times, but historically, they were considered conspecific. Moreover, the presence of Malagasy bushpigs as the sole large terrestrial mammal shared with the African mainland raises intriguing questions about its origin and arrival in Madagascar. Analyses of 67 whole genomes revealed a genetic continuum between the two species, with putative signatures of historical gene flow, variable FST values, and a recent divergence time (<500,000 years). Thus, our study challenges key arguments for splitting Potamochoerus into two species and suggests their speciation might be incomplete. Our findings also indicate that Malagasy bushpigs diverged from southern African populations and underwent a limited bottleneck 1,000-5,000 years ago, concurrent with human arrival in Madagascar. These results shed new light on the evolutionary history of an iconic and widespread African genus and provide insight into the longstanding biogeographic puzzle surrounding the bushpigs presence in Madagascar.

evolutionary biology↗

bioRxiv2020

PACIFIC: A lightweight deep-learning classifier of SARS-CoV-2 and co-infecting RNA viruses

Viral co-infections occur in COVID-19 patients, potentially impacting disease progression and severity. However, there is currently no dedicated method to identify viral co-infections in patient RNA-seq data. We developed PACIFIC, a deep-learning algorithm that accurately detects SARS-CoV-2 and other common RNA respiratory viruses from RNA-seq data. Using in silico data, PACIFIC recovers the presence and relative concentrations of viruses with >99% precision and recall. PACIFIC accurately detects SARS-CoV-2 and other viral infections in 63 independent in vitro cell culture and patient datasets. PACIFIC is an end-to-end tool that enables the systematic monitoring of viral infections in the current global pandemic.

bioinformatics↗