Ferguson Steven H, Higdon Jeff W, Schmidt Chloe, Pomerleau Corinne, Matthews Cory J D
Fisheries & Oceans Canada, 501 University Crescent, Winnipeg, MB R3T 1M6 Canada.
Higdon Wildlife Consulting, 912 Ashburn Street, Winnipeg, MB R3G 3C9 Canada.
Evol Biol. 2023;50(3):300-317. doi: 10.1007/s11692-023-09605-4. Epub 2023 May 23.
A widespread pattern in vertebrate life-history evolution is for species to evolve towards either fast or slow life histories; however, the underlying causes of this pattern remain unclear. Toothed whales (Odontoceti) are a diverse group with a range of body sizes and life histories, making them an ideal model to investigate potential drivers of this dichotomy. Using ancestral reconstruction, we identified that certain groups of odontocetes evolved more-streamlined, presumably faster, body shapes around the same time that killer whales () evolved into whale predators approximately 1 Mya during the Pleistocene. This suggests that the evolution of a streamlined body shape may have been an adaptation to escape killer whale predation, leading to longer life-history events. To test this hypothesis, we performed a cluster analysis of odontocete whales and confirmed the dual pattern of life-history traits, with one group referred to as 'reproducers' characterized by early age of maturity, short gestation, short interbirth interval, and short lifespan, and the other group referred to as 'bet-hedgers' exhibiting the opposite pattern. However, we found that life history grouping was relatively unrelated to whale shape (i.e., more streamlined or less streamlined). Therefore, we incorporated principal component results into mixed effects models, and the model results indicated that body shape was positively related to neonate length (a measure of investment in progeny), but not significantly related to the temporal life-history traits. Thus, whale body shape is not a sufficient explanation for the evolution of fast-slow life histories in odontocete whales.
The online version contains supplementary material available at 10.1007/s11692-023-09605-4.
脊椎动物生活史进化中的一个普遍模式是物种朝着快速或缓慢的生活史进化；然而，这种模式的潜在原因仍不清楚。齿鲸（鲸目齿鲸亚目）是一个多样化的群体，具有一系列体型和生活史，使其成为研究这种二分法潜在驱动因素的理想模型。通过祖先重建，我们发现某些齿鲸群体在大约100万年前的更新世虎鲸进化成为鲸鱼捕食者的同时，进化出了更流线型、可能更快的体型。这表明流线型体型的进化可能是为了逃避虎鲸的捕食，从而导致更长的生活史事件。为了验证这一假设，我们对齿鲸进行了聚类分析，并确认了生活史特征的双重模式，一组被称为“繁殖者”，其特征是成熟年龄早、妊娠期短、产仔间隔短和寿命短，另一组被称为“风险对冲者”，表现出相反的模式。然而，我们发现生活史分组与鲸鱼体型（即更流线型或不太流线型）相对无关。因此，我们将主成分结果纳入混合效应模型，模型结果表明体型与新生儿长度（衡量对后代投资的指标）呈正相关，但与时间生活史特征无显著相关。因此鲸鱼体型并不能充分解释齿鲸快速 - 缓慢生活史的进化。
在线版本包含可在10.1007/s11692-023-09605-4获取的补充材料。
