Crossman Carla A, Hamilton Philip K, Brown Moira W, Conger Lisa A, George R Clay, Jackson Katharine A, Radvan Sonya N, Frasier Timothy R
Biology Department, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3.
Anderson Cabot Center for Ocean Life, New England Aquarium, Central Wharf, Boston, Massachusetts, USA.
R Soc Open Sci. 2024 Jul 31;11(7):240490. doi: 10.1098/rsos.240490. eCollection 2024 Jul.
Only approximately 356 North Atlantic right whales () remain. With extremely low levels of genetic diversity, limited options for mates, and variation in reproductive success across females, there is concern regarding the potential for genetic limitations of population growth from inbreeding depression. In this study, we quantified reproductive success of female North Atlantic right whales with a modified de-lifing approach using reproductive history information collected over decades of field observations. We used double-digest restriction site-associated sequencing to sequence approximately 2% of the genome of 105 female North Atlantic right whales and combined genomic inbreeding estimates with individual fecundity values to assess evidence of inbreeding depression. Inbreeding depression could not explain the variance in reproductive success of females, however we present evidence that inbreeding depression may be affecting the viability of inbred fetuses-potentially lowering the reproductive success of the species as a whole. Combined, these results allay some concerns that genetic factors are impacting species survival as genetic diversity is being retained through selection against inbred fetuses. While still far fewer calves are being born each year than expected, the small role of genetics underlying variance in female fecundity suggests that variance may be explained by external factors that can potentially be mitigated through protection measures designed to reduce serious injury and mortality from human activities.
目前仅存约356头北大西洋露脊鲸。由于遗传多样性极低、配偶选择有限以及雌性个体繁殖成功率存在差异，人们担心近亲繁殖衰退可能对种群增长造成基因限制。在本研究中，我们采用改良的去标识方法，利用数十年来实地观察收集的繁殖历史信息，对雌性北大西洋露脊鲸的繁殖成功率进行了量化。我们使用双酶切限制性位点关联测序技术，对105头雌性北大西洋露脊鲸约2%的基因组进行测序，并将基因组近交系数估计值与个体繁殖力值相结合，以评估近亲繁殖衰退的证据。近亲繁殖衰退无法解释雌性繁殖成功率的差异，然而，我们提供的证据表明，近亲繁殖衰退可能正在影响近交胎儿的生存能力，这可能会降低整个物种的繁殖成功率。综合来看，这些结果缓解了一些关于遗传因素影响物种生存的担忧，因为通过对近交胎儿的选择，遗传多样性得以保留。虽然每年出生的幼鲸数量仍远低于预期，但雌性繁殖力差异背后的遗传因素作用较小，这表明差异可能是由外部因素导致的，通过旨在减少人类活动造成的严重伤害和死亡的保护措施，这些外部因素有可能得到缓解。
