Female sagebrush lizards with greater courtship experience are more likely to be courted by their male counterparts, according to a recent study.
The study is described by Mayte Ruiz, Zachary M. Beals, and Emilia P. Martins in the June 2010 issue of Herpetologica.
For the study, the three researchers collected 13 male and 26 female sagebrush lizards from the San Gabriel Mountains of Southern California and housed them in terraria at Indiana University, Bloomington. During a two-week test period, half of the female lizards were assigned at random to a low-courtship treatment group that received one visit from a robotic male lizard every other day, while the other female lizards were placed in a high-courtship group that saw the robotic male lizard four times daily.
The researchers wanted to see whether the amount of female courtship experience influences male sagebrush lizards' behavior. "Repeated male courtship may be beneficial to males if increasing female exposure to courtship displays advances reproductive state," the researchers write. This also may help female lizards produce more fertilized eggs and breed earlier and more often.
After the two weeks of robotic lizard visits, a live male lizard was place in each female lizard's terrarium for 30 minutes. The researchers paired each male sequentially with two females -- one from the low-courtship group and one from the high-courtship group.
"In our study, male lizards distinguished between females that had received more previous courtship and those that had received less, directing more tongue-flicks and moving more often toward females that had greater courtship experience than when placed with females that received few displays," the researchers write. "Although females did not differ in behavioral response due to display treatment, males may detect differences in physiological state of the female and respond accordingly."
They note that additional research is needed to determine physiological differences between females with varied courtship experience. The researchers also note that their study "used a robotic lizard to create differences between females that were not detectable to human observers, and an assay of male behavior to detect those differences." This shows how robotic stimuli can help manipulate animals in a controlled way for research purposes, they write.
- Ruiz et al. Male Sagebrush Lizards (Sceloporus graciosus) Increase Exploratory Behavior Toward Females with More Courtship Experience. Herpetologica, 2010; 66 (2): 142 DOI: 10.1655/09-022R2.1
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