Biology subjects

Acevedo-Whitehouse, K.

Publications and source records attributed to Acevedo-Whitehouse, K..

7 recordsLinked to original sources

bioRxiv2023

Guadalupe fur seal alopecia: a metabolic syndrome associated to climatic anomalies?

Alopecia is characterized by the thinning and loss of hair or fur, and has been observed in different marine carnivores. Until recently, there were no records of alopecia in marine mammals from the Northeast Pacific Ocean. However, sightings of juvenile male Guadalupe fur seals with patchy alopecia in the ventral body have been reported in the San Benito Archipelago. This is concerning given that the species is considered endangered under Mexican law and has only started to recover from near extinction less than a century ago. We captured 13 fur seals at San Benito Archipelago during the summer of 2017 and 2018 and collected fur samples for common dermatological analysis, as well as scanning electron microscopy and X-ray spectroscopy. We found marked damage to the structure of guard fur, with loss of integrity, medullary damage and perforations. Damage to secondary underfur hair was less common. We found no evidence of dermatophyte microorganisms or ectoparasites commonly associated with alopecia. We suggest that the damage is caused by metabolic alterations secondary to nutritional stress that is consequential to high sea surface temperatures that alter prey availability. This is the first study of alopecia in an otariid pinniped of the Northeast Pacific Ocean.

zoology↗

bioRxiv2022

Core respiratory microbiome of the blue whale, Balaenoptera musculus

The number of strandings and unusual mortality events that involve cetaceans may have increased, and potential pathogens of the respiratory tract have been found during the examination of individuals in many of these events. However, investigating the health of free-ranging large whales is logistically complex. Given that the core microbiome is key to understanding host-bacteria relationships and to identifying their relevance for individual and population health, we characterized the core respiratory bacteriome of the Eastern North Pacific blue whale, Balaenoptera musculus, using blow samples collected by a small quadracopter drone. 16S rRNA gene high-throughput sequencing revealed 1,326 amplicon sequence variants (ASVs), of which 11 were shared by more than 50% of all blue whales and had a relative abundance higher than 0.02%. Cutibacterium, Oceanivirga, Tenacibaculum, and Psychrobacter composed the common core respiratory bacteriome of the blue whale. Additionally, compositional analysis identified 15 bacterial classes dominated by Gammaproteobacteria (27.14%), Bacteroidea (19.83%), and Clostridia (12.89%) as the most representative classes in the respiratory tract of blue whales. However, two whales had a high abundance of bacteria with pathogenic potential, namely Mycoplasma spp. and Streptococcus spp. in their blow. Both bacterial genera have been associated with pulmonary diseases in mammals. Ours is the first study to characterize the respiratory bacteriome of apparently healthy blue whales and is a baseline for future long-term studies on blue whale health, an endangered species of conservation concern.

microbiology↗

bioRxiv2020

In vivo evaluation of the antiviral effect of ClO2 in chicken embryos inoculated with avian infectious bronchitis coronavirus

BackgroundThe need for safe and effective antiviral treatments is pressing given the number of viral infections that are prevalent in animal and human populations, often causing devastating economic losses and mortality. Informal accounts of anecdotal use of chlorine dioxide (ClO2), a well-known disinfectant and antiseptic, in COVID-19 patients has raised concern about potential toxicity, but also raises the question that ClO2 might elicit antiviral effects, a possibility that has never been examined in vivo in any animal model. Here, we challenged the hypothesis that ClO2 decreases the viral load and virus-induced mortality in a vertebrate model. For this, we determined viral load, virus-induced lesions and mortality in 10-day old chick embryos inoculated with 104 mean EID50/mL of attenuated Massachusetts and Connecticut avian coronavirus (IBV) strains. ResultsThe ClO2 treatment had a marked impact on IBV infection. Namely, viral titres were 2.4-fold lower and mortality was reduced by half in infected embryos that were treated with ClO2. Infection led to developmental abnormalities regardless of treatment. Lesions typical of IBV infections were observed in all inoculated embryos, but severity tended to be significantly lower in ClO2-treated embryos. We found no gross or microscopic evidence of toxicity caused by ClO2 at the doses used herein. ConclusionsOur study shows that ClO2 could be a safe and viable way of treating and mitigating the effects of avian coronavirus infections, and raises the possibility that similar effects could be observed in other organisms. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/336768v3_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@7eb076org.highwire.dtl.DTLVardef@1733722org.highwire.dtl.DTLVardef@128ad69org.highwire.dtl.DTLVardef@19108b0_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

Gene-tree Species-tree Discordance in the Eared Seals is best explained by Incomplete Lineage Sorting following Explosive Radiation in the Southern Hemisphere

AO_SCPLOWBSTRACTC_SCPLOWThe phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance because of strong gene-tree species tree discordance. Divergence times estimates in the group also vary largely between studies. These uncertainties impeded the understanding of the biogeographical history of the group, such as when and how trans-equatorial dispersal and subsequent speciation events occurred. Here we used high-coverage genome-wide sequencing for 14 of the 15 species of Otariidae to elucidate the phylogeny of the family and its bearing on the taxonomy and biogeographical history. Despite extreme topological discordance among gene trees, we found a fully supported species tree that agrees with the few well-accepted relationships and establishes monophyly of the genus Arctocephalus. Our data support a relatively recent trans-hemispheric dispersal at the base of a southern clade, which rapidly diversified into six major lineages between 3 to 2.5 Ma. Otaria diverged first, followed by Phocarctos and then four major lineages within Arctocephalus. However, we found Zalophus to be non-monophyletic, with California (Z. californianus) and Steller sea lions (Eumetopias jubatus) grouping closer than the Galapagos sea lion (Z. wollebaeki) with evidence for introgression between the two genera. Overall, the high degree of genealogical discordance was best explained by incomplete lineage sorting resulting from quasi-simultaneous speciation within the southern clade with introgresssion playing a subordinate role in explaining the incongruence among and within prior phylogenetic studies of the family.

evolutionary biology↗

bioRxiv2020

The demographic decline of a sea lion population followed multi-decadal sea surface warming

BackgroundThe population growth of top predators depends largely on environmental conditions suitable for aggregating sufficient and high-quality prey. We reconstructed numerically the population size dynamics of a resident population of California sea lions in the Gulf of California during 1978 - 2019, and its relation with the gulfs multi-decadal sea surface temperature trend. This are the first long-term insights to the oceanic environment of the Gulf of California and to the population trend of one of its major predators. ResultsOur results indicate that a three-decade sustained warming explains statistically the populations trend, including a [~]65% decline between 1991 - 2019, accounting for 92% of the variance. Long-term warming conditions started in the late 80s, followed by the populations decline, from a peak of 43,834 animals (range: 34,080 - 58,274) in 1991 to only 15,291 (range: range: 11,861 - 20,316) in 2019. The models suggested a century-scale optimum sea surface habitat for the population occurring in mildly temperate waters, from 0.18 to 0.39{degrees}C above the 100- year mean of 22.24{degrees}C. ConclusionsThe negative relation of the population size with warming sea surface conditions was evident, and the predictability of the former from the sea surface temperature 100-year anomalies was high. The mechanistic links of this relation are still untested, but an apparent diversification of pelagic fish catches suggests a reduction of high quality prey. We propose that this sea lion population should be considered as vulnerable to any disturbance that could add to the negative effects of the current sea surface warming conditions in the Gulf of California.

ecology↗

bioRxiv2019

Early sexual dimorphism in the developing gut microbiome of northern elephant seals

The gut microbiome is an integral part of a species ecology, but we know little about how host characteristics impact its development in wild populations. Here, we explored the role of such intrinsic factors in shaping the gut microbiome of northern elephant seals during a critical developmental window of six weeks after weaning, when the pups stay ashore without feeding. We show that the early-life gut microbiome is already substantially different in male and female pups, even though males and females cannot yet be distinguished morphologically. Sex and age both explain around 15% of the variation in gut microbial beta diversity, while microbial communities sampled from the same individual show high levels of similarity across time, explaining another 40% of the variation. Only a small proportion of the variation in beta diversity is explained by health status, but healthy individuals have a greater microbial alpha diversity than their non-healthy peers. Across the post-weaning period, the elephant seal gut microbiome is highly dynamic. We found evidence for several colonisation and extinction events as well as a decline in Bacteriodes and an increase in Prevotella, a pattern that has previously been associated with the transition from nursing to solid food. Lastly, we show that genetic relatedness is correlated with gut microbiome similarity in males but not females, again reflecting substantial early sex-differences. Our study represents a naturally diet-controlled and longitudinal investigation of how intrinsic factors shape the early gut microbiome in a species with extreme sex differences in morphology and life history.

molecular biology↗

bioRxiv2018

Recent demographic histories and genetic diversity across pinnipeds are shaped by anthropogenic interactions and mediated by ecology and life-history

A central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and negatively impact population viability and adaptive potential. In an era of unprecedented biodiversity loss and climate change, understanding both the determinants and consequences of bottlenecks in wild populations is therefore an increasingly important challenge. However, as most studies have focused on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we used a comparative approach by integrating genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to elucidate the consequences of large-scale commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong genetic signatures of recent population declines, with estimated bottleneck effective population sizes reflecting just a few tens of surviving individuals in the most extreme cases. Bottleneck strength was strongly associated with both breeding habitat and mating system variation, and together with global abundance explained a large proportion of the variation in genetic diversity across species. Overall, there was no relationship between bottleneck intensity and IUCN status, although three of the four most heavily bottlenecked species are currently endangered. Our study reveals an unforeseen interplay between anthropogenic exploitation, ecology, life history and demographic declines, sheds new light on the determinants of genetic diversity, and is consistent with the notion that both genetic and demographic factors influence population viability.

evolutionary biology↗