I received an East Asia and Pacific Summer Institutes (EAPSI) fellowship from the National Science Foundation (NSF) to study in China for the summer of 2011. NSF partnered with the Ministry of Science and Technology (MOST), the Chinese Academy of Sciences (CAS), China Science and Technology Exchange Center (CSTEC), and the National Natural Science Foundation of China (NSFC) to allow 40 graduate students from the United States to study abroad at various locations in China and promote greater scientific collaboration between the two countries. My host was Chun-Guang Zhang of the Institute of Zoology, CAS in Beijing. He researches the classification, distribution, and conservation of fishes across China. For my dissertation, I study the invasion history of mosquitofish. For the EAPSI program, I focused on collecting specimens from across China and generating genetic data to understand where the mosquitofish came from. Invasive species are important to study because they negatively impact the environment by driving native species extinct and becoming a nuisance and pest to society. The U.S. government spends over $120 billion dollars each year in controlling and repairing the damaging effects of invasive species. Thus, it is important to have accurate information regarding the invasion to help control and eradicate invasive species effectively. Mosquitofish are native to the U.S. and were introduced around the world in the early 20th century to control mosquito populations. They have since established themselves in the wild and are considered one of the worst invasive species due to their negative impacts on the environment. Basically, I wanted to use genetics to understand where the mosquitofish in China came from. Prior to the EAPSI program, I collected mosquitofish from across the native range in the U.S. and obtained a DNA sequence fragment for them. During the EAPSI program, I collected more specimens in China and obtained the same DNA sequence fragment for them for comparison. I hoped that this data would allow me to determine what part of the native range they came from. My host introduced me to his colleagues who knew where I could find mosquitofish in China. I made a couple trips to collect along the Yangtze River with these colleagues and was successful in obtaining the specimens needed. My host further helped me secure space in a lab at CAS to perform the necessary lab work. My host and I had many discussions regarding my project and invasive species in general. I found that the populations I have collected in China are all genetically similar. This suggests they ultimately came from a single location in the native range. However, there is a slight amount of variation found in China that suggests that there were multiple lineages introduced to China. The historical record mentioned introductions of mosquitofish coming directly from both Taiwan and the Philippines. Currently, I am following up what I found this summer by expanding my sampling to include Taiwan, Japan, and the Philippines. This will allow me to compare the genetic lineages and determine where the fish came from once they left the United States. My work is ongoing as I have many more genetic assays to run on my samples and some key locations still to secure. However, this information on the invasion history can provide scientists and field biologists with information that will affect how they manage mosquitofish. Furthermore, it can provide valuable insight into other regions of the world where mosquitofish have also been introduced (i.e. Europe & Australia). This work could not have been accomplished without the help of my host researcher and his Chinese colleagues. The EAPSI program facilitated this research by providing me with an opportunity to develop a relationship with them. I am eager to continue this research and know that future ventures into China will be aided by the partnerships I developed during my two months in China. Having international collaboration and partners is essential in understanding invasive species that are moving around the globe both accidentally and intentionally.