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birds incubator. 一段，不长，但是3个问题，一个主旨，两个inference都是关于不同情况下鸟类的策略 or vice versa, 有combination of 情况，有点绕 。作者没有观点，就是讲两种不同情况下鸟类会用不同策略
大意是male get food for female is known, the problem is the rate of which female should go foraging. 提出两个理论，Hypo1是说有突发环境变化的情况，应该male尽量拿全部食物。Hypo2是如果有predator, 反复往返窝会引起predator注意，所以雌性应该尽量在外面喂自己。
这是我第一个阅读，大概是第三道题，incubator又不认识，当时就蒙圈了，浪费了一些时间。其实文章不难，看好每种hypo，看好inference的选项。
是原文吗？
JOURNAL ARTICLE
Males Feeding Females during Incubation. I. Required by Microclimate or Constrained by Nest Predation?
Thomas E. Martin and Cameron K. Ghalambor
The American Naturalist
Vol. 153, No. 1 (January 1999), pp. 131-139
Published by: The University of Chicago Press for The American Society of Naturalists
DOI: 10.1086/303153
https://www.jstor.org/stable/10.1086/303153
Page Count: 9
Abstract
Nest attentiveness (percentage of time spent on the nest) during incubation represents a parent‐offspring conflict; incubating birds must balance a trade‐off between caring for embryos by staying on the nest versus caring for themselves by getting off the nest to forage. For species in which females are the sole incubator, males can potentially affect this trade‐off and increase nest attentiveness by feeding incubating females on the nest (incubation feeding). Increased nest attentiveness may be required when local microclimate conditions are harsh and thereby require greater incubation feeding (microclimate hypothesis). Alternatively, incubation feeding may be constrained by risk of attracting nest predators (nest predation hypothesis), which in turn may constrain female nest attentiveness because of energy limitation. We show that incubation feeding rates are much greater among cavity‐nesting than among coexisting open‐nesting birds. Under the microclimate hypothesis, the greater incubation feeding rates of cavity‐nesting birds generate the prediction that microclimate should be harsher than for open‐nesting birds. Our results reject this hypothesis because we found the opposite pattern; cavity‐nesting birds experienced more moderate (less variable) microclimates that were less often below temperatures (i.e., 16°C) that can negatively impact eggs compared with open‐nesting species. In contrast, incubation feeding rates were highly negatively correlated with nest predation both within and between the two nest types, supporting the nest predation hypothesis. Incubation feeding in turn was positively correlated with nest attentiveness. Thus, nest predation may indirectly affect female incubation behavior by directly affecting incubation feeding by the male.
Avian embryos can suffer fitness costs such as increased mortality and reduced developmental rate with decreasing nest attentiveness (percentage of time that a parent sits on the nest) during incubation. Thus, high attentiveness should be a preferred state, possibly being somewhat relaxed in species with well-insulated nests. However, incubating birds are often constrained in their nest attentiveness because of limited energy resources. Indeed, many birds require short recesses from the nest to obtain exogenous food resources to allow continued incubation. In the many species in which females incubate alone, males may reduce recesses and increase attentiveness by bringing food to incubating females and supplementing their energy resources. Such incubation feeding has been reported in a wide diversity of bird intraspecific studies have been shown that greater incubation feeding can yield increased attentiveness. Yet the influence of incubation feeding on nest attentiveness across species is unexamined despite the fact that incubation feeding rates and nest attentiveness vary extensively across species.
Given the fitness benefits of being attentive and the potential ability of incubation feeding centers on why species vary in their rate of incubation feeding is required in harsher microclimates to allow increased attentiveness because the fitness costs of leaving eggs unattended is greater. Under this microclimate hypothesis, nest attentiveness and incubation feeding rates should be highest in species using nest sites that are exposed to extreme temperatures that can threaten embryo survival or reduce embryo development rates. An optimal temperature for embryo development is near 37oC for passerines, but they may tolerate short exposures to temperatures between 16oC and 41oC, whereas temperatures outside this range affect embryo development and survival. Indeed, Lyon and Montgomerie decreased nest attentiveness in female snow buntings by removing male incubation feeding, which caused longer developmental (incubation) periods and increased mortality in an arctic environment where air temperatures often fell below 16oC. Similarly, both Haftorn and Nilsson and Smith found reduced developmental rate and increased mortality when air temperatures fell below 16oC. Thus, both incubation feeding and nest attentiveness should increase in species with nest sites where ambient temperatures increasingly fall outside of the 16oC—41oC range.
An alternative hypothesis is that incubation feeding is always advantageous but that it is constrained by nest predation; increased trips to the nest are hypothesized to attract attention of predators and increase predation risk for species that are more vulnerable to predation. Females can obtain more foods in one foraging trip off the nest than a male can bring in one trip, so number of trips to the nest can be reduced by the female largely obtaining food herself. Under nest predation hypothesis, species with higher risk of nest predation should show increased foraging by females and lower rates of incubation feeding by males.
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发表于 2018-10-23 11:48:56
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