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As such we still do not know whether migratory lifestyles in birds consistently places them toward the slow or fast end of the life-history continuum 26. The causes of such contrasting results might be partly explained by differences in taxonomic coverage (e.g., tropical taxa have slower life histories than temperate irrespective of migratory tendency). A study of North American and European land bird species found that migrants have smaller clutches than residents 27, whereas a recent and more comprehensive study of bird species across the entire globe found the opposite 28. Perhaps not surprisingly, comparative studies of the links between migration and annual reproductive outcomes have produced similarly contradictory results 27, 28. Yet the patterns across studies are inconsistent, with some studies reporting reduced lifespan in migratory birds, owing to elevated (direct) mortality during migration 23, 24, 25, and others suggesting high rates of survival throughout the annual cycle, including during migration 26. The ubiquity of migration suggests that it must bring benefits and thus natural selection should favour the evolution of behavioural and physiological mechanisms that minimise the types of cost outlined above. However, despite intensive comparative research, there is little consensus on the traits and life histories that might be associated with migration-either as pre-adaptations or evolutionary consequences. A range of extrinsic factors have been suggested to be important in this respect, including seasonality 18, 19, 20, competition, predation 21 and escape from disease 22. Based on standard life history theory 16, 17, these assume that the external context of the organism drives the evolutionary optimisation of traits that shape migratory behaviour via natural selection 8. A major challenge, in this respect, is to gain a better understanding of the associations between migratory behaviour, geographic range and life history traits, among species.Ī first set of hypotheses emphasise the role of ecology and biogeography in driving the evolution of migration. Therefore, it might be expected that migratory taxa should have a different pace of life to those of similar non-migratory taxa because of the trade-off among resources allocated to migration, reproduction and self-maintenance 15. This is surprising given the sophisticated behaviours, reorganisations of internal physiology and substantial energetic outlays associated with migration in many species 14. Migration is a flexible behaviour that can respond rapidly to selection and varies markedly with respect to propensity and distances travelled 10, 11, 12, 13. A widely accepted ecological definition is bi-directional movement between at least two areas, with a period of residency in each location. Although it has attracted scientific interest for centuries, large components of this complex behavioural syndrome remain poorly understood 2, 3, 4, 5, 6 even the definition of migration is still subject to intensive debate 7, 8, 9. Martini Anthomic Vocal Remix)ġ2.Animal migration is a widespread phenomenon, having evolved independently multiple times in all major vertebrate, and a number of invertebrate, classes 1.
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Don’t Forget About Us (Ralphi Rosario & Craig J.
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Don’t Forget About Us (Quentin Radio Mix)Ġ9. Don’t Forget About Us (Quentin Shelter Anthem Mix)Ġ8. Don’t Forget About Us (Tony Moran & Warren RIgg Radio Mix)Ġ7.
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Don’t Forget About Us (Tony Moran & Warren Rigg Dance Floor Anthem)Ġ6. Don’t Forget About Us (Desert Storm Remix)Ġ3.