Meeting Abstract
Female Indo-Pacific bottlenose dolphins (Tursiops aduncus) are subject to high costs of reproduction, both during consortships, in which they experience allied sexual coercion from males, and during lengthy periods of gestation and lactation. Male dolphins cooperate in alliances to herd and aggress on females in order to increase mating access. Females must meet the high energetic demands of prolonged maternal investment in each offspring; gestation is one year and lactation averages 4 years. Here, we examine the effects of allied sexual coercion and maternal investment on reproductive fitness and survival in Indo-pacific bottlenose dolphins in Shark Bay, Australia. Nearly 20% of adult females in this population never successfully raise a calf to weaning. Mean age of first birth is higher for reproductively unsuccessful females (17.5 years) than for successful females (13.3 years), indicating that condition at the onset of reproduction could influence reproductive trajectory (t(36.5) = 4.5, p < 0.001). Females who are reproductively unsuccessful spend more time with adult males at the onset of sexual maturity than successful females do, suggesting that unsuccessful females may be subject to increased costs of coercion (GLMM, p < 0.001). Additionally, reproductively unsuccessful females have shorter lifespans than successful females (χ2 (1)= 16.8, p < 0.001). Taken together, these findings indicate that females who fail to raise a calf to weaning are then subject to increased risk of harassment and coercion from males, reducing their ability to recover condition and ultimately increasing their risk of mortality.
