in "Male approach and female avoidance as mechanisms of population discrimination in sagebrush lizards", discriminatory trials were conducted to study behavioral mechanism of sagebrush lizards’ population discrimination. The questions they asked were whether population-level discrimination varies in strength in relation to geographic distance between populations, whether it is more apparent in inter or intra sexual interactions, and if it takes the form of attraction or avoidance. Through these studies, a majority of the population-level discrimination was exhibited by male lizards who preferred to associate with particular females, and female lizards who avoided certain types of males. Male attraction and female avoidance play significant roles in population discrimination, speciation, and reproductive isolation. Sagebrush lizards are involved with many forms of social interactions and they are involved with reproductive isolation. Male and female lizards defend territories and during their active seasons, they engage with a lot of social interactions. This study aimed to determine whether the sagebrush lizards from eastern Oregon could distinguish between lizards in their population and four different populations. The study showed that population discrimination mainly occurs when males are attracted to particular females, but females avoid certain males. It is not really dependent on female choice. In terms of reproductive isolation in territorial species where mate choice is interconnected with spatial relationships, male attraction and female avoidance are particularly important mechanisms. Male choice seems to play a significant role in preferences and it can significantly impact the frequency or quality of courtship and female receptivity. Other important factors are body size and color. These serve as signal traits for population-level discrimination. The males tended to associate with the larger of the females they were presented with. Since larger mass is an indicator that the female is gravid and receptive to courtship, it seems probable that males would prefer this size of lizard. Furthermore, color cues could also be a good distinguishing feature. Lastly, the study determined that the pattern of discrimination with geographic distance is quite complicated. When they performed simultaneous-choice trials, there really was no significant relationship between geographic distance and discrimination levels. The populations they compared are from similar desert habitats, but over time, they probably have gone through rapid diversification of behavioral, physiological, and morphological traits. All of these factors result in population discrimination. This study cannot conclude whether the trait differences have an environmental or evolutionary basis or if they resulted from natural selection