Faculty Profiles
Graduate student assistantships available
Diana K. Hews
Professor
Ph.D., University of Texas at Austin
Phone: 812-237-8352
E-mail: Diana.Hews@indstate.edu
Office: Science Building 346
Editorial Board Member, Integrative and Comparative Biology (Oxford University Press), 2008-2013
Program Officer, Animal Behavior Society (Western Hemisphere), 2006-2009
Research Interests: behavioral endocrinology; evolution of sexual dimorphism; visual and chemical signals and social communication; stress physiology; environmental endocrine disruptors.
Sexual selection is responsible for many differences between males and females (sexual dimorphism), and it also can result in relatively discrete differences among males (Alternative Reproductive Tactics) that can be as extreme as male-female differences. Research in Dr. Hews' laboratory examines sexual selection at the interface between physiology and evolution. Dr. Hews seeks to identify the sources of selection favoring the evolution of such between- and within-sex differences, and how the underlying hormonal control of such differences has been shaped by natural and sexual selection. Differences in behavior, particularly aggression and territoriality, and in related morphological traits (body size, body mass, color signals) are the focus of work in the Hews lab. Interactions and trade-offs between sexually-selected signaling traits and other physiological systems, including immunocompetence and the hypothalamic-pituitary-adrenal axis, are studied. A new focus is starting to examine the effects of environmental endocrine disrupting compounds on sexual differentiation, in vertebrates that occur in the Wabash Valley wetlands.
Males of Sceloporus virgatus are an example of a species without blue abdominal patches that most other male Sceloporus express. Sexual dimorphism is ancestral for
Sceloporus so this white abdomen represents a male loss of a secondary sexual trait.
© 2001 by David Sanders
A major area of research in Dr. Hews' lab involves the study of color signals & chemical signals used in social communication. A relatively new long-term project focuses on fence lizards (Sceloporus). Males of some Sceloporus species are "feminized": these species have evolutionarily lost the color signals that, in most Sceloporus, are expressed only in males. Males in these species are also less aggressive than males of typical species. In other species, females are "masculinized", expressing this normally "male-only" color trait and also elevated levels of aggression. Thus, Sceloporus species differ in the degree and nature of some aspects of sexual differentiation. Hormone manipulations can identify actions of early (pre-hatching and hatchling) and late (adult) differences in hormone levels in contributing to species differences in sexual differentiation. Comparing among species will identify how hormonal control mechanisms have evolved. Histological description of color signal production in several Sceloporus species have assisted in identifying cellular targets of hormone action. Current work is examining the epithelium of the vomeronasal organ (VNO), and asking if there asex and species differences in VNO size that map on to sex and species differences in the relative importance of chemicals signaling and aggression in Sceloporus.
Dr. Hews emphasizes studying animals in the wild, where the full array of social and environmental stimuli are present. Field studies or studies with captive animals in outdoor enclosures manipulate hormones, social conditions, or color signals to determine the effects on aggressive interactions, and, in longer-term studies, to document sources of selection acting on the color signals. Laboratory manipulations of hormones compliment field studies. Other major laboratory techniques include radioimmunoassay of plasma steroid hormone levels, ELISA, and immunohistochemisty. Techniques used to study immune function in wild vertebrates include WBC counts, hemagglutination assay using sRBC challenge, a delayed-type hypersensitivity assay (using injections og KLH as a antigen to cause swelling), and a bacterial killing assay (BKA) to assess innate immunity. Examples of field techniques used include staged territorial challenges to measure hormonal and behavior responses, territory mapping and focal animal observations to record rates of key behaviors.
Selected Publications
Quinn VS, Hews DK (2010) The evolutionary decoupling of behavioral and color cues in a multicomponent signal in two Sceloporus lizards. Ethology 116: 509-516
Thaker M, Lima SL, Vanak AT and Hews DK (2010) Hormonal mediation of aversive learning: attack intensity affects memory in a wild vertebrate. American Naturalist 175: 50-60 and Supplemental Online Materials.
Thaker M,
Lima SL and Hews DK (2009) Corticosterone mediation of antipredator responses in male lizards with
alternative reproductive tactics. Hormones & Behavior
56: 51–57.
Thaker, M. Lima, S.L. and Hews, D.K. (2009) Alternative antipredator tactics in tree lizard morphs: hormonal and behavioral responses to a predator encounter. Animal Behaviour 77: 395-401.
Calisi,
R.M., Malone, J.H. and Hews, D.K. (2008)
Female secondary coloration in the Mexican boulder spiny
lizard (Sceloporus pyrocephalus)
is associated with nematode load.
Journal of Zoology, London 276:
358-367.
Baird, T.A. and Hews, D.K. (2007) Plasma levels of steroid hormones in
territorial and non-territorial male collard lizards. Physiology & Behavior
92(4): 755–763.
Calisi,
R.M. and Hews, D.K. (2007) Steroid correlates of
multiple color traits in the spiny lizard, Sceloporus pyrocephalus. Journal of
Comparative Physiology Series B: Biochemical, Systemic, and Environmental
Physiology 177 (6):641-654.
Quinn, V.S. and
Hews, D.K. (2005) Detection and response to conspecific chemical cues by ornate
tree lizards (Urosaurus ornatus). Journal of Herpetology 39:
496-499.
Hews, D.K., M. Castellano, and E. Hara. 2004. Aggression in females is also lateralized: left-eye bias during aggressive courtship rejection in lizards. Animal Behaviour 68: 1201-1207.
Quinn, V. S. and D. K. Hews. 2003. Positive relationship between abdominal coloration and dermal melanin density in phrynosomatid lizards. Copeia 2003: 858-864.
Knapp, R., D. K. Hews, C. W. Thompson, L. E. Ray, and M. C. Moore. 2003. Environmental and endocrine correlates of tactic switching by nonterritorial male tree lizards (Urosaurus ornatus). Hormones and Behavior 43: 83-92.
Hews, D. K. and R. A. Worthington. 2001. Fighting from the right side of the brain: Left visual field preference during aggression in free-ranging male tree lizards (Urosaurus ornatus). Brain, Behavior and Evolution 58: 356-361.
Hews, D. K. and M. F. Benard. 2001. Negative association between conspicuous visual display and chemosensory behavior in two phrynosomatid lizards. Ethology 107: 839-850.
Quinn VS,
Klukowsky M and Hews DK (2001) Longevity of paint marks and lack of an effect on
survivorship or growth of Sceloporus
lizards. Herpetological Review
32:92-93.
Quinn, V. S. and D. K. Hews. 2000. Signals and behavioural responses are not coupled in males: aggression affected by replacement of an evolutionarily lost colour signal. Proceedings of the Royal Society of London B 267: 755-758.
In Review
Quinn VS
and Hews DK. Signal and receiver responses to a sexually dimorphic and
evolutionarily labile signaling trait.
Hara E,
Anderson M and Hews DK. Sex and species differences in brain distribution of
androgen receptor immunoreactive cells in Sceloporus lizards differing in
aggression.
Hews DK and Abell AJ.
Plasma levels of corticosterone
and androgens following acute handling stress in male and female striped plateau
lizards, Sceloporus virgatus.
Hews DK, Date P, Hara E & Castellano MJ.
Field presentation of conspecific chemicals alters social display rates in the
white-bellied Sceloporus virgatus but not in the more-visually oriented
blue-bellied Sceloporus undulatus.