Skip to main content
Log in

Quantitative genetics of growth and cryptic evolution of body size in an island population

  • Original Paper
  • Published:
Evolutionary Ecology Aims and scope Submit manuscript

Abstract

While evolution occurs when selection acts on a heritable trait, empirical studies of natural systems have frequently reported phenotypic stasis under these conditions. We performed quantitative genetic analyses of weight and hindleg length in a free-living population of Soay sheep (Ovis aries) to test whether genetic constraints can explain previously reported stasis in body size despite evidence for strong positive directional selection. Genetic, maternal and environmental covariance structures were estimated across ontogeny using random regression animal models. Heritability increased with age for weight and hindleg length, though both measures of size were highly heritable across ontogeny. Genetic correlations among ages were generally strong and uniformly positive, and the covariance structures were also highly integrated across ontogeny. Consequently, we found no constraint to the evolution of larger size itself. Rather we expect size at all ages to increase in response to positive selection acting at any age. Consistent with expectation, predicted breeding values for age-specific size traits have increased over a twenty-year period, while maternal performance for offspring size has declined. Re-examination of the phenotypic data confirmed that sheep are not getting larger, but also showed that there are significant negative trends in size at all ages. The genetic evolution is therefore cryptic, with the response to selection presumably being masked at the phenotypic level by a plastic response to changing environmental conditions. Density-dependence, coupled with systematically increasing population size, may contribute to declining body size but is insufficient to completely explain it. Our results demonstrate that an increased understanding of the genetic basis of quantitative traits, and of how plasticity and microevolution can occur simultaneously, is necessary for developing predictive models of phenotypic change in nature.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2

Similar content being viewed by others

References

  • Arnold SJ (1992) Constraints on phenotypic evolution. Am Nat 140:S85–S107

    Article  PubMed  Google Scholar 

  • Badyaev AV, Martin TE (2000) Individual variation in growth trajectories: phenotypic and genetic correlations in ontogeny of the house finch (Carpodacus mexicanus). J Evol Biol 13:290–301

    Article  Google Scholar 

  • Björklund M (1997) Variation in growth in the blue tit (Parus caeruleus). J Evol Biol 10:139–155

    Article  Google Scholar 

  • Blanckenhorn WU (2000) The evolution of body size: what keeps organisms small? Q Rev Biol 75:385–407

    Article  PubMed  CAS  Google Scholar 

  • Blows MW, Hoffman AA (2005) A reassessment of genetic limits to evolutionary change. Ecology 86:1371–1384

    Google Scholar 

  • Charmantier A, Garant D (2005) Environmental quality and evolutionary potential: lessons from wild populations. Proc R Soc Lond B Bio 272:1415–1425

    Article  Google Scholar 

  • Cheverud JM, Leamy LJ, Atchley WR, Rutledge JJ (1983a) Quantitative genetics and the evolution of ontogeny. I. Ontogenetic changes in quantitative genetic variance components in randombred mice. Genet Res 42:65–75

    Article  Google Scholar 

  • Cheverud JM, Rutledge JJ, Atchley WR (1983b) Quantitative genetics of development—genetic correlations among age-specific trait values and the evolution of ontogeny. Evolution 37:895–905

    Article  Google Scholar 

  • Clutton-Brock TH, Price OF, Albon SD, Jewell PA (1992) Early development and population fluctuations in Soay sheep. J Anim Ecol 61:381–396

    Article  Google Scholar 

  • Clutton-Brock TH, Pemberton JM (2004) Soay sheep: Dynamics and selection in an island population. Cambridge University Press, Cambridge, 383pp

    Google Scholar 

  • Coltman DW, Smith JA, Bancroft DR, Pilkington J, MacColl ADC, Clutton-Brock TH, Pemberton JM (1999) Density-dependent variation in lifetime breeding success and natural and sexual selection in Soay rams. Am Nat 154:730–746

    Article  PubMed  Google Scholar 

  • Coltman DW, Pilkington J, Kruuk LE, Wilson K, Pemberton JM (2001) Positive genetic correlation between parasite resistance and body size in a free-living ungulate population. Evolution 55:2116–2125

    PubMed  CAS  Google Scholar 

  • Coltman DW, O’Donoghue P, Hogg JT, Festa-Bianchet M (2005) Selection and genetic (co)variance in bighorn sheep. Evolution 59:1372–1382

    PubMed  Google Scholar 

  • Coulson T, Catchpole EA, Albon SD, Morgan BJT, Pemberton JM, Clutton-Brock TH, Crawley MJ, Grenfell BT (2001) Age, sex, density, winter weather, and population crashes in Soay sheep. Science 292:1528–1531

    Article  PubMed  CAS  Google Scholar 

  • Coulson T, Benton TG, Lundberg P, Dall SRX, Kendall BE, Gaillard J-M (2006) Estimating individual contributions to population growth: evolutionary fitness in ecological time. Proc R Soc Lond B Bio 273:547–556

    CAS  Google Scholar 

  • Falconer DS, Mackay TFC (1996) Introduction to quantitative genetics. Longman, Essex

    Google Scholar 

  • Fischer TM, Gilmour AR, Van der Werf JHJ (2004) Computing approximate standard errors for genetic parameters derived from random regression models fitted by average information REML. Gen Sel Evol 36:363–369

    Article  Google Scholar 

  • Foster J (1964) The evolution of mammals on islands. Nature 202:234–235

    Article  Google Scholar 

  • Gaillard JM, Festa-Bianchet M, Delorme D, Jorgenson J (2000) Body mass and individual fitness in female ungulates: bigger is not always better. Proc R Soc Lond Ser B-Biol Sci 267:471–477

    Article  CAS  Google Scholar 

  • Garant D, Kruuk LEB, McCleery RH, Sheldon BC (2004) Evolution in a changing environment: a case study with great tit fledging mass. Am Nat 164:E115–E129

    Article  PubMed  Google Scholar 

  • Guinness FE, Clutton-Brock TH, Albon SD (1978) Factors affecting calf mortality in red deer (Cervus elaphus). J Anim Ecol 47:817–832

    Article  Google Scholar 

  • Houle D (1992) Comparing evolvability and variability of quantitative traits. Genetics 130:195–204

    PubMed  CAS  Google Scholar 

  • Kirkpatrick M, Lofsvold D, Bulmer M (1990) Analysis of the inheritance, selection and evolution of growth trajectories. Genetics 124:979–993

    PubMed  CAS  Google Scholar 

  • Kirkpatrick M, Lofsvold D (1992) Measuring selection and constraint in the evolution of growth. Evolution 46:954–971

    Article  Google Scholar 

  • Kruuk LEB, Merilä J, Sheldon BC (2001) Phenotypic selection on a heritable size trait revisited. Am Nat 158:557–571

    Article  CAS  PubMed  Google Scholar 

  • Kruuk LEB, Slate J, Pemberton JM, Brotherstone S, Guinness F, Clutton-Brock T (2002) Antler size in red deer: heritability and selection but no evolution. Evolution 56:1683–1695

    PubMed  CAS  Google Scholar 

  • Kruuk LEB (2004) Estimating genetic parameters in natural populations using the ‘animal model’. Philos T Roy Soc B 359:873–890

    Article  Google Scholar 

  • Lomolino M (2005) Body size evolution in insular vertebrates: generality of the island rule. J Biogeogr 32:1683–1699

    Article  Google Scholar 

  • Lynch M, Walsh B (1998) Genetics and analysis of quantitative traits. Sinauer Associates, Inc., Sunderland

    Google Scholar 

  • Marshall TC, Slate J, Kruuk LE, Pemberton JM (1998) Statistical confidence for likelihood-based paternity inference in natural populations. Mol Ecol 7:639–655

    Article  PubMed  CAS  Google Scholar 

  • Merilä J, Kruuk LEB, Sheldon BC (2001a) Cryptic evolution in a wild bird population. Nature 412:76–79

    Article  Google Scholar 

  • Merilä J, Sheldon BC, Kruuk LEB (2001b) Explaining stasis: microevolutionary studies in natural populations. Genetica 112–113:199–222

    Article  Google Scholar 

  • Meyer K (1992) Variance components due to direct and maternal effects for growth traits of Australian beef cattle. Livest Prod Sci 31:179–204

    Article  Google Scholar 

  • Meyer K (1998) Estimating covariance functions for longitudinal data using a random regression model. Gen Sel Evol 30:221–240

    Google Scholar 

  • Milner JM, Albon SD, Illius AW, Pemberton JM, Clutton-Brock TH (1999) Repeated selection of morphometric traits in the Soay sheep on St Kilda. J Anim Ecol 68:472–488

    Article  Google Scholar 

  • Milner JM, Pemberton JM, Brotherstone S, Albon SD (2000) Estimating variance components and heritabilities in the wild: a case study using the ‘animal model’ approach. J Evol Biol 13:804–813

    Article  Google Scholar 

  • Nussey DH, Clutton-Brock TH, Albon SD, Pemberton JM, Kruuk LEB (2005a) Constraints on plastic responses to climate variation in red deer. Biol Lett 1:457–460

    Article  Google Scholar 

  • Nussey DH, Clutton-Brock TH, Elston DA, Albon SD, Kruuk LEB (2005b) Phenotypic plasticity in a maternal trait in red deer. J Anim Ecol 74:387–396

    Article  Google Scholar 

  • Nussey DH, Postma E, Gienapp P, Visser ME (2005c) Selection on heritable phenotypic plasticity in a wild bird population. Science 310:304–306

    Article  CAS  Google Scholar 

  • Overall ADJ, Byrne KA, Pilkington J, Pemberton JM (2005) Heterozygosity, inbreeding and neonatal traits in Soay sheep on St Kilda. Mol Ecol 14:3383–3393

    Article  PubMed  CAS  Google Scholar 

  • Pakkasmaa S, Merilä J, O’Hara RB (2003) Genetic and maternal effect influences on viability of common frog tadpoles under different environmental conditions. Heredity 91:117–124

    Article  PubMed  CAS  Google Scholar 

  • Pease CM, Bull JJ (1988) A critique of methods for measuring life history trade-offs. J Evol Biol 1:293–303

    Article  Google Scholar 

  • Postma E (2006) Implications of the difference between true and predicted breeding values for the study of natural selection and micro-evolution. J Evol Biol 19, Doi: 10.1111/j.1420–9101.2005.01007

  • Ragland GJ, Carter PA (2004) Genetic covariance structure of growth in the salamander Ambystoma macrodactylum. Heredity 92:569–578

    Article  PubMed  CAS  Google Scholar 

  • Réale D, Festa-Bianchet M, Jorgenson JT (1999) Heritability of body mass varies with age and season in wild bighorn sheep. Heredity 83:526–532

    Article  PubMed  Google Scholar 

  • Réale D, McAdam AG, Boutin S, Berteaux D (2003) Genetic and plastic responses of a northern mammal to climate change. Pro R Soc Lond B 270:591–596

    Article  Google Scholar 

  • Schaeffer LR (2004) Application of random regression models in animal breeding. Livest Prod Sci 86:35–45

    Article  Google Scholar 

  • Sogard SM (1997) Size-selective mortality in the juvenile stage of teleost fishes: a review. B Mar Sci 60:1129–1157

    Google Scholar 

  • Willham RL (1972) The role of maternal effects in animal breeding: III. Biometrical aspects of maternal effects in animals. J Anim Sci 35:1288–1293

    PubMed  CAS  Google Scholar 

  • Wilson AJ, Hutchings JA, Ferguson MM (2003) Selective and genetic constraints on the evolution of body size in a stream-dwelling salmonid fish. J Evol Biol 16:584–594

    Article  PubMed  CAS  Google Scholar 

  • Wilson AJ, Coltman DW, Pemberton JM, Overall ADJ, Byrne KA, Kruuk LEB (2005a) Maternal genetic effects set the potential for evolution in a free-living vertebrate population. J Evol Biol 18:405–414

    Article  CAS  Google Scholar 

  • Wilson AJ, Kruuk LEB, Coltman DW (2005b) Ontogenetic patterns in heritable variation for body size: using random regression models in a wild ungulate population. Am Nat 166:E177–E192

    Article  Google Scholar 

  • Wilson AJ, Pilkington JG, Pemberton JM, Coltman DW, Overall ADJ, Byrne KA, Kruuk LEB (2005c) Selection on mothers and offspring: whose phenotype is it and does it matter? Evolution 59:451–463

    Google Scholar 

  • Wilson AJ, Pemberton JM, Pilkington JG, Coltman DW, Mifsud DV, Clutton-Brock TH, Kruuk LEB (2006) Environmental coupling of selection and heritability limits evolution. PLoS Biol 4(7):e216

    Article  PubMed  CAS  Google Scholar 

  • Wilson AJ, Réale D (2006) Ontogeny of additive and maternal genetic effects: lessons from domestic mammals. Am Nat 167:E23–E38

    Article  PubMed  Google Scholar 

  • Wolf JB, Brodie ED, Cheverud JM, Moore AJ, Wade MJ (1998) Evolutionary consequences of indirect genetic effects. Trends Ecol Evol 13:64–69

    Article  Google Scholar 

Download references

Acknowledgements

We thank the National Trust for Scotland and Scottish Natural Heritage for permission to work on St. Kilda, the Royal Artillery Range (Hebrides) and QinetiQ and Eurest for logistic support. The long-term data collection on St. Kilda has been supported by the Natural Environment Research Council, the Wellcome Trust, the Biotechnology and Biological Sciences Research Council and the Royal Society, through grants to THCB, B.T. Grenfell, M.J. Crawley, T. Coulson, S. Albon, JMP and LEBK. The work described here was funded by a Leverhulme Trust research project grant to LEBK and D.W. Coltman. LEBK is supported by the Royal Society. We also thank the many previous members of the project (including many volunteers) who have collected field data or have contributed genotyping and paternity inference. T. Coulson and two anonymous referees provided useful comments on a previous version of this manuscript.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to A. J. Wilson.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Wilson, A.J., Pemberton, J.M., Pilkington, J.G. et al. Quantitative genetics of growth and cryptic evolution of body size in an island population. Evol Ecol 21, 337–356 (2007). https://doi.org/10.1007/s10682-006-9106-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10682-006-9106-z

Keywords

Navigation