Domingues, M. | bioRxiv Science

bioRxiv2022

A de novo transcriptome assembly of the annelid worm Hediste diversicolor

The development of Next-Generation Sequencing (NGS) technologies has revolutionized multiple fields of Biology. The ability to sequence DNA and RNA in an automated, parallel and low-cost approach, was key to boost the applicability and acquisition efficiency of omics resources. In this context, the availability of these tools has become indispensable towards our understanding of biodiversity, deepening our knowledge on the distinct complexity levels, from cells to ecosystems. In this study we comprehensively characterised and annotated a whole-body transcriptome of Hediste diversicolor. This annelid worm species belongs to the family Nereididae and inhabits estuarine and lagoon areas on the Atlantic coasts of Europe and North America. Ecologically, this species plays an important role in benthic food webs. The ability of rework sediments through bioturbation activity makes this species essential to the estuarine mechanisms. Here, we used Illumina next-generation sequencing technology, to sequence a total 105 million (M) paired-end (PE) raw reads and produce the first multi-tissue transcriptome assembly of an adult of H. diversicolor. This transcriptome contains 69,335 transcripts with a N50 transcript length of 2,313 bp and a BUSCO gene completeness of 97.7% and 96% (S: 88.2%; D: 7.8%) in Eukaryota and Metazoa lineage-specific profile libraries. Our findings offer a valuable resource for multiple biological studies using this species.

genomics↗

bioRxiv2021

A genome assembly of the Atlantic chub mackerel (Scomber colias): a valuable teleost fishing resource

The Atlantic chub mackerel, Scomber colias Gmelin, 1789, is a medium-size pelagic fish with substantial importance in the fisheries of the Atlantic Ocean and the Mediterranean Sea. Over the past decade, this species has gained special relevance being one of the main targets of pelagic fisheries in the NE Atlantic. Here, we sequenced and annotated the first high-quality draft genome assembly of S. colias, produced with Pacbio HiFi long reads and Illumina Paired-End short reads. The estimated genome size is 814 Mb distributed into 2,028 scaffolds and 2,093 contigs with an N50 length of 4,19 and 3,34 Mb, respectively. We annotated 27,675 protein-coding genes and the BUSCO analyses indicated high completeness, with 97.3 % of the single-copy orthologs in the Actinopterygii library profile. The present genome assembly represents a valuable resource to address the biology and management of this relevant fishery. Finally, this is the fourth high-quality genome assembly within the Order Scombriformes and the first in the genus Scomber.

genomics↗

bioRxiv2021

Does genetic differentiation underlie behavioral divergence in response tomigration barriers in sticklebacks? A common garden experiment

Water management measures in the 1970s in the Netherlands have produced a large number of resident populations of three-spined sticklebacks that are no longer able to migrate to the sea. This may be viewed as a replicated field experiment, allowing us to study how the resident populations are coping with human-induced barriers to migration. We have previously shown that residents are smaller, bolder, more exploratory, more active, more aggressive, exhibited lower shoaling and lower migratory tendencies compared to their ancestral migrant counterparts. However, it is not clear if these differences in wild-caught residents and migrants reflect genetic differentiation, rather than different developmental conditions. To investigate this, we raised offspring of four crosses (migrant [male] x migrant [female], resident [male] x resident [female], migrant [male] x resident [female], resident [male] x migrant [female]) under similar controlled conditions and tested for differences in morphology and behavior as adults. We found that lab-raised resident sticklebacks exhibited lower shoaling and migratory tendencies as compared to lab-raised migrants, retaining the differences in their wild-caught parents. This indicates genetic differentiation of these traits. For all other traits, the lab-raised sticklebacks of the various crosses did not differ significantly, suggesting that the earlier-found contrast between wild-caught fish reflect differences in their environment. Our study shows that barriers to migration can lead to rapid differentiation in behavioral tendencies over contemporary timescales ([~]50 generations), and that part of these differences reflects genetic differentiation. Significance statementMany organisms face changes to their habitats due to human activities. Much research is therefore dedicated to the question whether and how organisms are able to adapt to novel conditions. We address this question in three-spined sticklebacks, where water management measures cut off some populations, prohibiting their seasonal migration to the North Sea. In a previous study, we showed that wild-caught resident fish exhibited markedly different behavior than migrants. To disentangle whether these differences reflect genetic differentiation or differences in the conditions under which the wild-caught fish grew up, we conducted crosses, raising the F1 offspring under identical conditions. As their wild-caught parents, the F1 of resident x resident crosses exhibited lower migratory and shoaling tendencies than the F1 of migrant x migrant crosses, while the F1 of hybrid crosses were intermediate. This suggests that [~]50 years of isolation are sufficient to induce behaviorally relevant genetic differentiation.

evolutionary biology↗