Library:The genomic footprint of whaling and isolation in fin whale populations
The genomic footprint of whaling and isolation in fin whale populations is an article published in Nature Communications in July 2023.
The article reports a study that used whole-genome sequencing data to investigate the demographic history and genetic effects of natural and human-induced bottlenecks in fin whale populations. Fin whales are the second-largest whale species and the most impacted by industrial whaling worldwide. The authors compared two populations with contrasting histories: one in the Eastern North Pacific that was large, interconnected, and overexploited by whalers; and another in the Gulf of California that was small, isolated, and never targeted by whaling.
To conduct this study, high-coverage whole-genome sequence data from 50 fin whale samples collected between 1995 and 2017 were analysed. Thirty of these samples were from regions in the Eastern North Pacific that had survived intensive whaling pressure, while the remaining 20 samples belonged to a naturally small population in the Gulf of California which had maintained a low population size for thousands of years.
The results revealed stark differences in the genomic diversity between these populations. The Eastern North Pacific population exhibited higher genetic diversity, suggesting a historically larger and less isolated population. In contrast, the Gulf of California population showed signs of reduced genetic variation and higher levels of inbreeding, consistent with its small and isolated nature.
One of the significant findings of the study was the impact of whaling on the Eastern North Pacific population. The research indicated that the Eastern North Pacific population had experienced a severe decline within the last two generations, reducing its effective population size by about 99%. This decline was traced back to the intense whaling period between 1954 and 1980.
Understanding the genetic consequences of such population reductions is crucial for conservation efforts, especially in the face of current and future threats from whaling and environmental changes. These findings provide valuable insights into the complex interplay between demographic and evolutionary factors in shaping the genetic diversity of fin whale populations and offer important considerations for their conservation.
Main findings
- The Eastern North Pacific and Gulf of California populations diverged about 16,000 years ago, after which the Eastern North Pacific population expanded and then suffered a 99% reduction in effective size during the whaling period. The Gulf of California population remained small and isolated, receiving less than one migrant per generation.
- The Gulf of California population had lower genome-wide diversity and higher inbreeding than the Eastern North Pacific population, but also maintained moderate levels of variation compared with other endangered cetaceans. This suggests that low levels of migration have been crucial for maintaining its viability.
- The Eastern North Pacific population had higher genome-wide diversity and lower inbreeding than expected from its recent bottleneck, indicating a rapid recovery after the end of whaling. However, it also accumulated more deleterious mutations than the Gulf of California population, especially in homozygous state, which could reduce its fitness and adaptive potential.
- The study demonstrates the use of genome-based analyses and simulations to inform conservation strategies for fin whales and other threatened species. It also exposes the severity of whaling, emphasises the importance of migration, and highlights the genomic consequences of contrasting population reductions.
See also
External links
- https://doi.org/10.1038/s41467-023-40052-z Full Article