MHC Class II Variation in Endangered Indo-Pacific Humpback Dolphins

32 Indo-Pacific humpback dolphin samples from the Pearl River Estuary, collected between 2003 and 2011, provide data on MHC class II gene expression and sequence polymorphism. The study investigates two specific genes, DQB and DRB, to evaluate the role of balancing selection in this endangered population. Analysis includes metrics like non-synonymous to synonymous substitution rates and tests for trans-species polymorphism.

Use Cases

• Analyze the ratio of non-synonymous to synonymous substitution rates in DQB and DRB gene sequences to detect signatures of balancing selection.
• Test for trans-species polymorphism (TSP) in MHC class II haplotypes to understand long-term evolutionary pressures.
• Compare heterozygosity levels at the DQB and DRB loci with microsatellite data to assess the relative impact of selection versus genetic drift.
• Examine the limited haplotype diversity (only 2 haplotypes per locus) in the context of historical population bottlenecks for conservation genetics.

Strengths

• Focuses on an endangered marine mammal species, the Indo-Pacific humpback dolphin (Sousa chinensis).
• Data spans an 8-year collection period (2003-2011) from the Pearl River Estuary.
• Analysis includes two specific immune-related genes, MHC class II DQB and DRB.
• Employs multiple analytical methods, including codon-based selection analysis and Hardy-Weinberg expectation tests.

Limitations

• Small sample size of 32 individual dolphins, limiting statistical power for population-level inferences.
• Geographic focus is restricted to the Pearl River Estuary, which may not represent the species' full genetic diversity.
• Genetic data is limited to specific MHC loci and microsatellites, providing a partial genomic picture.

Provenance

Source

Dryad digital repository, authored by Xiyang Zhang.

Collection Method

Genetic analysis of tissue samples from dolphins, investigating MHC class II gene expression and sequence polymorphism.

Time Range

Samples collected between 2003 and 2011.

Freshness

Data last updated in 2020.

Geography

Pearl River Estuary.