Skip to content

Research at St Andrews

Temperature and aridity determine body size conformity to Bergmann’s rule independent of latitudinal differences in a tropical environment

Research output: Contribution to journalArticle

Abstract

Bergmann’s rule, defined as the tendency for endotherms to be larger in colder environments, is a biophysical generalization of body size variation that is frequently tested along latitudinal gradients, even though latitude is only a proxy for temperature variation. We test whether variation in temperature and aridity determine avian body size conformity to Bergmann’s rule independent of latitude differences, using the ubiquitous Common Bulbul Pycnonotus barbatus, along a West African environmental gradient. We trapped 538 birds in 22 locations between latitudes 6 and 13°N in Nigeria, and estimated average body surface area to mass ratio per location. We then modelled body surface to mass ratio using general linear models, with latitude, altitude and one of 19 bioclimatic variables extracted from http://www.worldclim.org/bioclim as predictors. We sequentially dropped latitude and altitude from each model to obtain the R2 of the resultant models. Finally, we compared the R2 of univariate models, where bioclimatic variables predicted body surface area to mass ratio significantly (14 out of 19), to multivariate models including latitude, altitude and a bioclimatic variable, using the Wilcoxon matched pairs test. We found that multivariate models did not perform better than univariate models with only bioclimatic variables. Six temperature and eight precipitation variables significantly predicted variation in body surface area to mass ratio between locations; in fact, 50% (seven out of 14) of these better explained variation in body surface area to mass ratio than the multivariate models. Birds showed a larger body surface area relative to body mass ratio in hotter environments independent of latitude or altitude, which conforms to Bergmann’s rule. Yet, a combination of morphometric analyses and controlled temperature-exposure experiments is required to prove the proposed relationship between relative body surface area and thermoregulation in endotherms.
Close

Details

Original languageEnglish
Pages (from-to)1053–1062
Number of pages10
JournalJournal of Ornithology
Volume159
Issue number4
Early online date27 Jun 2018
DOIs
Publication statusPublished - Oct 2018

    Research areas

  • Latitude, Thermoregulation, Global warming, Birds, Temperature variation, Bioclimatic variable

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Seasonal differences in baseline innate immune function are better explained by environment than annual cycle stage in a year-round breeding tropical songbird

    Nwaogu, C. J., Cresswell, W., Versteegh, M. A. & Tieleman, B. I., 6 Feb 2019, In : Journal of Animal Ecology. Early View, 17 p.

    Research output: Contribution to journalArticle

  2. Weak breeding seasonality of a songbird in a seasonally arid tropical environment arises from individual flexibility and strongly seasonal moult

    Nwaogu, C. J., Tieleman, B. I. & Cresswell, W., 22 Sep 2018, In : Ibis. Early View, 13 p.

    Research output: Contribution to journalArticle

  3. Spring migration strategies of Whinchat Saxicola rubetra when successfully crossing potential barriers of the Sahara and the Mediterranean Sea

    Blackburn, E., Burgess, M., Freeman, B., Risely, A., Izang, A., Ivande, S., Hewson, C. & Cresswell, W., 2 May 2018, In : Ibis. Early View

    Research output: Contribution to journalArticle

  4. Population consequences of migratory variability differ between flyways

    Patchett, R., Finch, T. & Cresswell, W., 23 Apr 2018, In : Current Biology. 28, 8, p. R340-R341

    Research output: Contribution to journalArticle

Related by journal

  1. Parental behaviour and family proximity as key to gosling survival in Greylag Geese (Anser anser)

    Szipl, G., Loth, A., Wascher, C. A. F., Hemetsberger, J., Kotrschal, K. & Frigerio, D., 20 Feb 2019, In : Journal of Ornithology. First Online, 11 p.

    Research output: Contribution to journalArticle

  2. Differential responses to gosling distress calls in parental and non-parental Greylag Geese

    Loth, A., Frigerio, D., Kotrschal, K. & Szipl, G., Apr 2018, In : Journal of Ornithology. 159, 2, p. 401-412 12 p.

    Research output: Contribution to journalArticle

  3. Body reserves in intra-African migrants

    Nwaogu, C. J. & Cresswell, W., Jan 2016, In : Journal of Ornithology. 157, 1, p. 125-135

    Research output: Contribution to journalArticle

Related by journal

  1. Journal of Ornithology (Journal)

    Will Cresswell (Reviewer)
    17 Jul 2018

    Activity: Publication peer-review and editorial work typesPeer review of manuscripts

ID: 253199123