Fitness consequence of female-female aggression in lizard
Female-female competition and its influence on fitness are poorly understood. Furthermore, there is a taxonomic bias in studies of female aggression and some groups, such as lizards, are particularly pending further study. The Qinghai toad-headed agama Phrynocephalus vlangalii provides a good model system for studying female-female aggression because females (and males) have high levels of aggression during and out of the mating season. Under the support of one grant from National Natural Science Foundation of China, we systematically tested several hypotheses concerned with adaptation of female-female aggression, including mate limitation, resource limitation and mate defense. The results shown that resource competition and mate defense were the main reason of female-female aggression in lizard P. vlangalii. Higher levels of female-female aggression reduced female mass in year one but increased female mass in year two, and this relationship was quadratic, and not linear, as expected. Offspring growth rate, body condition and overwinter survival were negatively associated with female-female aggression. The above results have been presented as two papers prepared for Behavioral Ecology and Animal Behaviour. This project was mostly carried out by our Ph.D candidate Yayong Wu at Zoige field station.
Motion signals of lizards in genus Phrynocephalus
Species of genus Phrynocephalus distributes widely across central Asian deserts, such as Iran, Kazakhstan, Turkmenistan, Uzbekistan, Pakistan, Afghanistan, China et al. At the best of our knowledge, each Phrynocephalus species uses complex tail motions during male-male competition, female-female competition, male-female courtship and female-male resistance. Furthermore, their habitats vary obviously from sand to gobi desert with elevation ranges from 500 meters to 5000 meters, and their morphology also vary intensively even among different populations of same species. The motion signals play similar roles during social communication as human body language. We eager to answer the following questions in coming few years: 1) Is tail motion adaptive or personality associated? 2) What is the meaning of tail motion in male and female lizards? Does tail motion function in male coercion? 3) What factors have driven the variation of tail motion structure? Phylogeny or local adaptation? 4) The genetic and physiological mechanism manipulating the expression of motion signal? 5) How does the receiver recognize tail motions from sender? We have established a standard 3-D method for lizard body language digitizing, and being able to animate each language element and use playback to verify the function. This project is at the support of one grant from National Natural Science Foundation of China, and many students would anticipate, including Xia Qiu, Yusong Lin and one post-doctor Yayong Wu.
Personality and cognition in lizards
Animal personality, defined as consistent individual difference in exploration and boldness maintained across time and/or context, while cognition refers to acquiring, processing, storing and acting on information from the environment. They are all important factors for animals adapting to local environment. One recent theory proposed that variation of cognition and personality may be correlated through the shared risk-reward trade-off between fast-slow behavioral traits and speed-accuracy cognitive styles, which means we can know personality from cognition or vice versa. Nevertheless, the reasons for personality and cognition consistency are poorly understood. We have done three small projects around this topic: 1) maternal effect on consistency of offspring personality and cognition; 2) relationships between lizard personality and energy metabolism; 3) relationships between spatial, instrumental and associative learning. The results shown that the consistency of offspring personality and cognition was based on maternal effect, when females experienced high food availability during pregnancy, the offspring would be bolder, more explosive and can learn very well. In addition, maintaining of personality needs high level of energy metabolism. We also found that lizard spatial learning could not be regarded as predictor of animal general learning ability, because it was confined to spatial learning domain. The above experiments were completed by Dr.Yin Qi, Yayong Wu and Jingfeng Chen.