Behavioral Genetics of Aggression of Canis lupus in Yellowstone National Park

Abstract

Little is known about the mechanisms underlying aggressive behavior in the gray wolf (Canis lupus) compared to other species such as the domestic dog (Canis familiaris). In this study I sought to learn more about what underlies aggressive behavior in gray wolves in Yellowstone National Park (YNP) by taking the candidate gene approach to examine the association of certain variants of single nucleotide polymorphisms (SNP) with aggressive behavior, as well as by examining yearly trends in aggressive behavior for wolves of different sex, coat color, and breeding status in YNP from 1995-2009. Aggression scores were collected using the IAS Individual Aggression Score (IAS) system, and 208 individuals had multiple observations over the period of the study. Sixty-eight of these individuals also had tissue samples, and as such, DNA from these individuals was used in a high resolution melting analysis to examine the association of certain SNP variants of candidate genes with aggression. Regression analysis was conducted to assess this association along with the relationship between aggression scores in parents and their offspring. Breeding individuals (IAS\(_{breeding}\)=5.2) were found to be significantly more aggressive than non-breeding (IASA\(_{non-breeding}\)=4.5) individuals (p=0.008). No other significant differences were found between sex-specific or coat-color associated aggression. No definitive conclusions could be drawn in terms of SNP genotypes and aggressive behavior due to low sample size (n=68) and little genetic diversity. There was no significant relationship between the aggression scores of parents and their offspring (p=0.234). Further work must be done with larger sample size to determine if these candidate genes are in fact associated with aggressive behavior in wolves as they are in the domestic dog.