Parental care in Darwin's finches

Selection should act on parental care and favour parental investment decisions that optimise the number of offspring produced. Such predictions have been robustly tested in predation risk contexts, but little is known about parental care investment trade-offs under conditions of parasitism. The avian vampire fly, Philornis downsi (Diptera: Muscidae), is a myasis-causing ectoparasite accidentally introduced to the Galápagos Islands, and one of the major causes of failure in Darwin’s finch nests. With an 11-year dataset spanning 21 years, we examine the relationship between parental care behaviours and the number of fly larvae and pupae in Darwin’s finch nests. We do so across three host species (Camarhynchus parvulus, C. pauper, Geospiza fuliginosa) and one hybrid Camarhynchus group. Nests with longer female brooding duration had fewer parasites, and this effect intensified with higher male food delivery to chicks. Neither male age nor number of nest provisioning visits alone were direct...自然选择应作用于亲本抚育行为，并青睐能够最大化子代产出的亲本投资决策。此类预测已在捕食风险情境中得到了稳健的实证检验，但学界对寄生条件下的亲本抚育投资权衡机制尚缺乏深入认知。吸血鸟蝇（*Philornis downsi*，双翅目（Diptera）蝇科（Muscidae））是一种可引发蝇蛆病的体外寄生虫，经人为意外引入加拉帕戈斯群岛，亦是导致达尔文雀巢穴繁殖失败的主要诱因之一。本研究依托一套覆盖21年时长、历时11年采集的数据集，探究了达尔文雀巢穴内的亲本抚育行为与蝇类幼虫、蛹数量之间的关联，研究涵盖3种宿主物种（小地雀*Camarhynchus parvulus*、*C. pauper*、勇地雀*Geospiza fuliginosa*）以及1个卡梅隆雀（*Camarhynchus*）杂交类群。研究结果显示，雌性亲鸟育雏时长更长的巢穴，寄生虫数量更少；且雄性亲鸟向雏鸟的食物投喂频次越高，这一抑制效应越显著。雄性亲鸟的年龄，抑或是单次巢穴投喂次数，均无法单独构成直接……