Research Works
chemical cues associated with queen genotype recognition
After receiving my doctoral diploma, I joined Dr. John Wang's lab at Academia Sinica, Taiwan. John used the invasive fire ant Solenopsis invicta as a model organism to study evolutionary genetics of societies. Solenopsis invicta possesses two types of social organization: (1) the ‘monogyne’ colony in which only a single reproductive queen is present and (2) the ‘polygyne’ colony where 2-200 reproductive queens co-exist. This social polymorphism has a strong genetic basis that marked by the gene Gp-9 located inside a supergene. The supergene has two major alleles, SB and Sb. The queen and workers in a monogyne colony are all homozygous SB/SB individuals. While a polygyne colony has both SB/SB and SB/Sb workers, all the reproductive queens are restricted to be SB/Sb individuals. Monogyne workers execute any other reproductive queens entering the established colony regardless of their genotypes; polygyne workers accept queens with a b allele copy, while a BB queen will still be killed. It has therefore been suggested that the Sb allele is a selfish, green-beard allele, and the queen genotype recognition should be rooted on robust chemical cues. My works here attempts to use chromatography technique and paper surrogate-based behavioral assay to identify critical cues in this genotype recognition system. Current results indicated unsaturated hydrocarbons may be critical for facilitating retrieving behavior of polygyne workers.
Animal Personality in the cities and the Integrated Traits
My dissertation research focused on the difference of animal personality between urban and rural populations of Northern cardinals (the middle picture above). Next to the climate change, the United Nations considers urbanization the biggest environmental challenge of our time (United Nations Secretariat, 2012). Investigating how organisms cope with such environmental challenges can provide insights for possible evolutionary changes in the future which can be important for managements. I took an integrative approach to consider not only behavioral shifts but also stress hormone variation in an attempt to fully elucidate the impact of urbanization. My results revealed that urban birds were significantly more neophilic (approaching novel object to investigate sooner) and less neophobic (being less influence by the presence of unfamiliar object when feeding) than rural birds. Significant relationships between Individual’s personality trait and its stress hormone (corticosterone) levels were also found; suggesting some underlying physiological mechanisms for rural-urban variation is highly possible. I also examined the integrated relationship among personality, hormonal and melanic morphological traits given the pleiotropic network through melanocortin system proposed by Ducrest et al. (2008). I did observed phenotypic integration among melanic face mask, baseline corticosterone level and neophilia score in males, but not any kind of integrated relationship in females. This indicated that possibly due to different life history challenges, the two sexes face with different selection forces and thus result in such a varied level of phenotypic integration.
Species-specific personality and heterospecific information use
For my Master's thesis, I examined exploration (a common personality trait) of six forest bird species to investigate whether their responses toward a novel environment differ with their natural history characteristics (i.e. foraging guilds or social structure). Our results suggest that species-specific exploration exist and the variation across species is strongly associated with flock participation. Since this finding implies that interspecific associations may constrain spatial behavior and exploratory acquisition of information, I also tested whether Northern cardinals adjust their behavior based on the information provided by tufted titmouse (the left second picture above). The results suggest cardinals interpret the anti-predator signals encoded in titmouse vocalization correctly and responded accordingly, adjusting their activities to potentially reduce rick by decreasing their movements and increasing vigilance. Detailed of those works can be found in my published articles.