Benefits of the destinations, not costs of the journeys, shape partial migration patterns.

摘要: Summary The reasons that lead some animals to seasonally migrate, and others remain in the same area year-round, are poorly understood. Associations between traits, such as body size, migration provide clues. For example, larger species individuals more likely migrate. One explanation for this size bias is capable of moving faster (movement hypothesis). However, linked many other biological processes. instance, energetic balances generally sensitive variation food density because effects on foraging metabolism sensitivity could drive migratory decisions (forage hypothesis). Identifying primary selective forces ultimately requires quantifying fitness impacts over full annual cycle. Here, we develop a cycle model from metabolic theory compare importance forage movement hypotheses. We parameterize Galapagos tortoises, which were recently discovered be size-dependent altitudinal migrants. The predicts phenomena not included development including maximum sizes, at begin seasonal timing these predictions agree with available data. Scenarios strongly support hypothesis hypothesis. Furthermore, male tortoises Santa Cruz Island would unable grow their enormous sizes without access both highlands lowlands. Whereas recent research has focused links traits phases cycle, find non-migratory far important determinants propensity migrate. Larger changing conditions than smaller implications maintenance face environmental change.