Ellen Ketterson

Publications (91) View all

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  Available from: Ellen Ketterson

  Chapter: Hormones and the evolution of behavior and other complex phenotypes

  E. D. Ketterson, J. W. Atwell, J. W. McGlothlin
  01/2012;
• Source

  Available from: Kristal Cain

  Article: Two sides of the same coin? Consistency in aggression to conspecifics and predators in a female songbird.

  K E Cain, M S Rich, K Ainsworth, E D Ketterson
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  ABSTRACT: Different forms of aggression have traditionally been treated separately according to function or context (e.g. aggression towards a conspecific versus a predator). However, recent work on individual consistency in behavior predicts that different forms of aggression may be correlated across contexts, suggesting a lack of independence. For nesting birds, aggression towards both conspecifics and nest predators can affect reproductive success, yet the relationship between these behaviors, especially in females, is not known. Here we examine free-living female dark-eyed juncos (Junco hyemalis) and compare their aggressive responses towards three types of simulated intruders near the nest: a same-sex conspecific, an opposite-sex conspecific, and a nest predator. We also examine differences in the strength of response that might relate to the immediacy of the perceived threat the intruder poses for the female or her offspring. We found greater aggression directed towards a predator than a same-sex intruder, and towards a same-sex than an opposite-sex intruder, consistent with a predator being a more immediate threat than a same-sex intruder, followed by an opposite-sex intruder. We also found positive relationships across individuals between responses to a same-sex intruder and a simulated predator, and between responses to a same-sex and an opposite-sex intruder, indicating that individual females are consistent in their relative level of aggression across contexts. If correlated behaviors are mediated by related mechanisms, then different forms of aggression may be expressions of the same behavioral tendency and constrained from evolving independently.
  Ethology 09/2011; 117(9):786-795. · 2.01 Impact Factor
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  Available from: Joel W. McGlothlin

  Article: Hormones and honest signals: males with larger ornaments elevate testosterone more when challenged.

  J W McGlothlin, J M Jawor, T J Greives, J M Casto, J L Phillips, E D Ketterson
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  ABSTRACT: When male investment in mating varies with quality, reliable sexual signals may evolve. In many songbirds, testosterone mediates mating investment, suggesting that signals should be linked to testosterone production. However, because testosterone may change rapidly during behaviour such as territorial aggression and courtship, efforts to establish such a relationship have proved challenging. In a population of dark-eyed juncos, we measured individual variation in the production of short-term testosterone increases by injecting gonadotropin-releasing hormone (GnRH). We found a positive correlation between the magnitude of these increases and the size of a plumage ornament ('tail white') previously shown to be important for female choice and male-male competition. We then measured naturally elevated testosterone levels produced during male-male competition and found that they covaried with those induced by GnRH. We suggest that the association between tail white and testosterone increases may allow conspecifics to assess potential mates and competitors reliably using tail white.
  Journal of Evolutionary Biology 02/2008; 21(1):39-48. · 3.28 Impact Factor
• Article: Diet quality affects feather growth rate and an attractive white plumage pattern in dark-eyed juncos (Junco hyemalis)

  J. W. McGlothlin, D. L. Duffy, J. L. Henry-Freeman, E. D. Ketterson
  Behavioral Ecology and Sociobiology 01/2007; 61:1391-1399. · 3.18 Impact Factor
• Article: Testosterone and immune function inversely co-vary in a wild population of breeding Dark-eyed Juncos (Junco hyemalis)

  T. J. Greives, J. W. McGlothlin, J. M. Jawor, G. E. Demas, E. D. Ketterson
  Functional Ecology. 01/2007; 20:812-818.