How Many Eggs Are Too Many? Utilizing an Under-Dispersed Count Data Model to Gain Insights Into Evolutionary Productivity Constraints on Bird Species

IF 1.7 3区 环境科学与生态学 Q4 ENVIRONMENTAL SCIENCES
Environmetrics Pub Date : 2025-07-30 DOI:10.1002/env.70032
James A. Clarke, Jeremy A. Smith, Ellie Leech, Philipp H. Boersch-Supan, Robert A. Robinson
{"title":"How Many Eggs Are Too Many? Utilizing an Under-Dispersed Count Data Model to Gain Insights Into Evolutionary Productivity Constraints on Bird Species","authors":"James A. Clarke,&nbsp;Jeremy A. Smith,&nbsp;Ellie Leech,&nbsp;Philipp H. Boersch-Supan,&nbsp;Robert A. Robinson","doi":"10.1002/env.70032","DOIUrl":null,"url":null,"abstract":"<div>\n \n <p>Changes in productivity are primary mechanisms via which bird populations change and understanding how these processes operate is key to monitoring their populations in a changing environment. A major component of productivity is fecundity, the number of propagules produced, which for birds is the number of eggs laid (clutch size) and chicks that hatch from these (brood size). There are evolutionary constraints on the size of these fecundity measures and, therefore, variation tends to be smaller than other forms of count data. Using data on clutch and brood sizes for 55 and 52 UK bird species respectively we show these are consistently under-dispersed with respect to the standard Poisson model, which is often used to fit such data. A three-parameter exponentially weighted Poisson (EWP<sub>3</sub>) model fits substantively better than either a Poisson or under-dispersed variants. We provide an R package to enable easy fitting of such models. The EWP<sub>3</sub> is characterized by two dispersion parameters, <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>β</mi>\n <mn>1</mn>\n </msub>\n </mrow>\n <annotation>$$ {\\beta}_1 $$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>β</mi>\n <mn>2</mn>\n </msub>\n </mrow>\n <annotation>$$ {\\beta}_2 $$</annotation>\n </semantics></math>, and we suggest that these can quantify evolutionary constraints on incubation. We show that <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>β</mi>\n <mn>2</mn>\n </msub>\n </mrow>\n <annotation>$$ {\\beta}_2 $$</annotation>\n </semantics></math> is generally greater than <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mi>β</mi>\n <mn>1</mn>\n </msub>\n </mrow>\n <annotation>$$ {\\beta}_1 $$</annotation>\n </semantics></math>, indicating a greater compression at the right hand end of the distribution. This suggests that the cost of having an extra egg or chick is higher than the cost of having one too few. Although we consider avian reproduction this method should be suitable for any species which has a small number of offspring in each reproductive event.</p>\n </div>","PeriodicalId":50512,"journal":{"name":"Environmetrics","volume":"36 6","pages":""},"PeriodicalIF":1.7000,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Environmetrics","FirstCategoryId":"93","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/env.70032","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0

Abstract

Changes in productivity are primary mechanisms via which bird populations change and understanding how these processes operate is key to monitoring their populations in a changing environment. A major component of productivity is fecundity, the number of propagules produced, which for birds is the number of eggs laid (clutch size) and chicks that hatch from these (brood size). There are evolutionary constraints on the size of these fecundity measures and, therefore, variation tends to be smaller than other forms of count data. Using data on clutch and brood sizes for 55 and 52 UK bird species respectively we show these are consistently under-dispersed with respect to the standard Poisson model, which is often used to fit such data. A three-parameter exponentially weighted Poisson (EWP3) model fits substantively better than either a Poisson or under-dispersed variants. We provide an R package to enable easy fitting of such models. The EWP3 is characterized by two dispersion parameters, β 1 $$ {\beta}_1 $$ and β 2 $$ {\beta}_2 $$ , and we suggest that these can quantify evolutionary constraints on incubation. We show that β 2 $$ {\beta}_2 $$ is generally greater than β 1 $$ {\beta}_1 $$ , indicating a greater compression at the right hand end of the distribution. This suggests that the cost of having an extra egg or chick is higher than the cost of having one too few. Although we consider avian reproduction this method should be suitable for any species which has a small number of offspring in each reproductive event.

多少个鸡蛋算多?利用欠分散计数数据模型深入了解鸟类物种的进化生产力约束
生产力的变化是鸟类种群变化的主要机制,了解这些过程如何运作是在不断变化的环境中监测鸟类种群的关键。生产力的一个主要组成部分是繁殖力,繁殖体的数量,对鸟类来说是产卵的数量(窝大小)和从这些蛋中孵出的小鸡(窝大小)。这些繁殖力测量的大小受到进化的限制,因此,变异往往比其他形式的计数数据要小。通过对55种和52种英国鸟类的孵蛋和育雏大小的数据,我们发现,相对于标准泊松模型(通常用于拟合此类数据),这些物种的分布一直不足。三参数指数加权泊松(EWP3)模型拟合实质上优于泊松模型或欠分散模型。我们提供了一个R包来方便地拟合这些模型。EWP3具有两个分散参数,β 1 $$ {\beta}_1 $$和β 2 $$ {\beta}_2 $$,我们认为这些参数可以量化孵化的进化约束。我们发现β 2 $$ {\beta}_2 $$一般大于β 1 $$ {\beta}_1 $$,表明在分布的右端有更大的压缩。这表明多生一个蛋或小鸡的成本要高于少生一个的成本。虽然我们考虑鸟类繁殖,但这种方法应该适用于任何在每次繁殖事件中只有少量后代的物种。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
Environmetrics
Environmetrics 环境科学-环境科学
CiteScore
2.90
自引率
17.60%
发文量
67
审稿时长
18-36 weeks
期刊介绍: Environmetrics, the official journal of The International Environmetrics Society (TIES), an Association of the International Statistical Institute, is devoted to the dissemination of high-quality quantitative research in the environmental sciences. The journal welcomes pertinent and innovative submissions from quantitative disciplines developing new statistical and mathematical techniques, methods, and theories that solve modern environmental problems. Articles must proffer substantive, new statistical or mathematical advances to answer important scientific questions in the environmental sciences, or must develop novel or enhanced statistical methodology with clear applications to environmental science. New methods should be illustrated with recent environmental data.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:604180095
Book学术官方微信