Meeting Abstract
Movement patterns in animals suggest an impressive ability to navigate and have fueled considerable interest in possible sensory mechanisms. Accumulating evidence indicates that diverse animals use information from the Earth’s magnetic field for navigation over a wide range of spatial scales. In particular, a large-scale “magnetic map” from which animals derive positional information may underpin the life-history characteristic of many marine migrants: transiting between disparate oceanic regions and ontogenetic shifts in habitat utilization. However, there are several complications for such a navigational strategy. Due to high-frequency (e.g., weather) and longer-term (e.g., El Nino) processes, ocean currents experienced by individuals may vary substantially from what is “average”, as will the optimal swimming trajectory. Thus the precision by which natural selection pairs geomagnetic information with meaningful orientation responses at particular locations, in the context of the ocean conditions encountered by individuals, may be limited. The challenge for animals is even greater given that the “map” they are attempting to overlay upon a variable ocean surface is, itself, gradually shifting across the globe and is prone to dramatic excursions and reversals every several hundred thousand years. The complex interplay between ocean circulation and geomagnetic dynamics offers a unique conceptual setting to test hypotheses for how animals deal with environmental change and the ecological and evolutionary implications of behavior. Moreover, recent work in salmon and sea turtles suggests that considering geomagnetic change is essential to mechanistically predict spatiotemporal variation in animal movement patterns and manage migratory species in the face of global climate change and widespread habitat alterations.
