a) Within-clutch food competition


Siblings can compete strongly for food resources, and often grow at very different rates.  Renee Rosier, a graduate student in the lab, is examining the causes and consequences of within-clutch variation in growth rates.  Renee aims to understand how traits such as increased competitive ability and boldness relate to differences in growth rate, and the fitness consequences in terms of both survival and reproduction.  See Renee’s page for more detail.



b) Competition for limited retreat sites


Competition for optimal shelter sites can be significant in cases where these are limited.  I studied competition for limited thermally suitable retreat-sites in a guild of 5 montane (cold-climate) scincid lizards.  These species do not appear to reduce competition by partitioning these resources (using different parts of the habitat or different types of shelters), and there are intense agonistic interactions both within and between these species for preferred shelter-sites. Surprisingly, however, I found little direct fitness cost of exclusion from optimal retreat sites for pregnant female lizards. A long history of co-evolution in sympatry may have allowed these species to evolve behavioral traits that minimize the impact of aggressive interactions. 


Relevant publications:


Langkilde T., O’Connor D. and Shine R. 2007. The benefits of parental care: do juvenile lizards obtain better-quality habitat by remaining with their parents? Austral Ecology 32: 950-954


Langkilde T. and Shine R. 2007.  Interspecific conflict in lizards: social dominance depends upon an individual's species not its body size.  Austral Ecology 32: 869-877


Langkilde T., Lance V.A. and Shine R. 2005. Ecological consequences of agonistic interactions in lizards. Ecology 86: 1650-1659


Langkilde T. and Shine R. 2005. How do water skinks avoid shelters already occupied by other lizards? Behaviour 142: 203-216


Langkilde T. and Shine R. 2004. Competing for crevices: interspecific conflict influences retreat-site selection in montane lizards. Oecologia 140: 684-691


Langkilde T., O’Connor D. and Shine R. 2003. Shelter-site use by five species of montane scincid lizards in south-eastern Australia. Australian Journal of Zoology 51:175-186



Individuals interact in a myriad of ways with both individuals of the same and different species.  Some of these interactions occur over limiting resources, such as food, shelter, and mates. Resource competition is likely to be most intense between ecologically similar organisms, and can influence biologically significant behaviors including feeding, habitat use and thermoregulation.  Extrapolating these effects to the ecological consequences of these interactions for the species involved remains a major challenge.  We largely presume that the “losers” of competitive encounters will suffer fitness costs, but this link is often weak or absent.  In addition, evolution should favor strategies that reduce the costs of competition.  Our research addresses the mechanisms and consequences of competition within and between species.



The Role of Competition in Structuring Communities









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