# Chromosome-level genome provides insights into environmental adaptability and innate immunity in the common dolphin (Delphinus delphis)

## TL;DR

This paper presents the first high-quality genome of the common dolphin, revealing genes linked to adaptability and immunity, which could help in conservation efforts.

## Contribution

The study provides the first chromosome-level genome of Delphinus delphis and identifies genes related to environmental adaptability and innate immunity.

## Key findings

- The genome assembly has a size of 2.56 Gb with a contig N50 of 63.85 Mb.
- Expanded HSP70 gene family suggests strong stress-buffering capabilities in D. delphis.
- Expanded IFN-α and IFN-ω gene families and positively selected genes are linked to antiviral and anti-inflammatory mechanisms.

## Abstract

The common dolphin (Delphinus delphis) is widely distributed worldwide and well adapted to various habitats. Animal genomes store clues about their pasts, and can reveal the genes underlying their evolutionary success. Here, we report the first high-quality chromosome-level genome of D. delphis. The assembled genome size was 2.56 Gb with a contig N50 of 63.85 Mb. Phylogenetically, D. delphis was close to Tursiops truncatus and T. aduncus. The genome of D. delphis exhibited 428 expanded and 1,885 contracted gene families, and 120 genes were identified as positively selected. The expansion of the HSP70 gene family suggested that D. delphis has a powerful system for buffering stress, which might be associated with its broad adaptability, longevity, and detoxification capacity. The expanded IFN-α and IFN-ω gene families, as well as the positively selected genes encoding tripartite motif-containing protein 25, peptidyl-prolyl cis-trans isomerase NIMA-interacting 1, and p38 MAP kinase, were all involved in pathways for antiviral, anti-inflammatory, and antineoplastic mechanisms. The genome data also revealed dramatic fluctuations in the effective population size during the Pleistocene. Overall, the high-quality genome assembly and annotation represent significant molecular resources for ecological and evolutionary studies of Delphinus and help support their sustainable treatment and conservation.

The online version contains supplementary material available at 10.1186/s12864-024-10268-4.