Egg shape in an obligate brood parasite stabilizes temperature variation during incubation.

IF 2 2区 生物学 Q2 ZOOLOGY
Current Zoology Pub Date : 2024-11-15 eCollection Date: 2025-08-01 DOI:10.1093/cz/zoae070
Francisco R Magdaleno, Lyndon R Hawkins, Isaac Quintanilla Salinas, Brian D Peer
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引用次数: 0

Abstract

The brood-parasitic brown-headed cowbird (Molothrus ater) has one of the shortest incubation periods of any bird. Brown-headed cowbird eggs, and those of other avian brood parasites, tend to be more spherical due to their greater relative width. The traditional explanation for this egg shape is that it, combined with the thicker eggshells, resists host puncture-ejection. However, very few North American hosts of the brown-headed cowbird actually engage in puncture-ejection and therefore wider eggs may instead provide greater contact with a host's brood patch during incubation, especially in large host nests. We tested whether greater egg width increased mean temperature and reduced temperature variation in brown-headed cowbirds by inserting temperature probes into brown-headed cowbird and house sparrow (Passer domesticus) eggs and placing them into red-winged blackbird (Agelaius phoeniceus) nests. House sparrow eggs are similar in appearance and in length to cowbird eggs, but are not as wide. We found no significant relationship between brown-headed cowbird egg width and mean incubation temperature. However, brown-headed cowbird eggs experienced less temperature variation than house sparrow eggs, and within brown-headed cowbird eggs, more spherical eggs experienced less temperature variation when accounting for differences in width. These results suggest that brown-headed cowbirds may have short incubation periods in part because their eggs exhibit less temperature variation over the course of incubation. The brown-headed cowbird's egg shape may contribute to its accelerated embryonic development rate relative to host eggs of similar size, which explains its ability to hatch in a variety of host nests.

Abstract Image

Abstract Image

专性寄主的卵形稳定了孵化期间的温度变化。
巢寄生褐头牛鹂(Molothrus ater)的孵化期是所有鸟类中最短的。褐头牛鹂的蛋,以及其他禽类寄生虫的蛋,由于它们的相对宽度更大,往往更呈球形。对这种蛋形的传统解释是,它与较厚的蛋壳结合在一起,可以抵抗宿主的刺射。然而,北美棕头牛鹂的宿主很少会进行刺射,因此在孵化期间,更宽的卵可能会与宿主的孵化区有更大的接触,尤其是在大型宿主巢穴中。我们通过在褐头牛鹂和家雀(Passer domesticus)的卵中插入温度探头,并将其放入红翅黑鹂(Agelaius phoeniceus)的巢中,来测试更大的卵宽是否会增加褐头牛鹂的平均温度并降低温度变化。麻雀的蛋在外形和长度上与牛鹂的蛋相似,但没有牛鹂的蛋那么宽。褐头牛鹂蛋宽与平均孵化温度无显著关系。棕头牛鹂蛋的温度变化小于家麻雀蛋,且考虑宽度差异时,棕头牛鹂蛋内球形蛋的温度变化较小。这些结果表明,棕头牛鹂的孵化期可能较短,部分原因是它们的蛋在孵化过程中温度变化较小。棕头牛鹂的蛋的形状可能有助于其相对于相似大小的寄主蛋更快的胚胎发育速度,这解释了它能够在各种寄主巢中孵化的能力。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Current Zoology
Current Zoology Agricultural and Biological Sciences-Animal Science and Zoology
CiteScore
3.20
自引率
9.10%
发文量
111
审稿时长
6 weeks
期刊介绍: About the Journal Current Zoology (formerly Acta Zoologica Sinica, founded in 1935) is an open access, bimonthly, peer-reviewed international journal of zoology. It publishes review articles and research papers in the fields of ecology, evolution and behaviour. Current Zoology is sponsored by Institute of Zoology, Chinese Academy of Sciences, along with the China Zoological Society.
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