Tropical-zone highlands are always colder than lowlands; temperatures do not change across seasons the way they do in temperate-zone highlands. As a result, tropical montane organisms may be adapted to narrow temperature ranges and thus physiologically incapable of moving up or down mountains. In contrast temperate montane organisms are probably adapted to wider temperature ranges due to seasonal cycles, making them more likely to move between elevations. This prediction, called the Janzen Effect, explains why in tropical regions different elevations hold different species whereas in temperate regions a given species can live at a range of altitudes. Very few tests of the Janzen Effect exist. This research will determine if the Janzen Effect occurs in Andean frog species. In other words, do frog species in the tropical Andes move up or down the mountains less often than species in the temperate Andes? Movement rates will be estimated using genetic techniques. This study will help to understand the mechanisms of diversification of tropical animals.
The implications of this project extend to all ectotherms ("cold blooded animals"), because their physiology is directly affected by the external environment. This study will produce predictions about whether some populations of organisms might be more resilient to montane climate variation resulting from global warming. Students from small towns in the Andes will actively participate in scientific discussions with the Co-PI about the origin and diversification of their own Andean flora and fauna and will have direct contact with current field techniques and procedures in molecular evolution.
