Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.

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Aim: Migratory animals regularly move between often distant breeding and non-breeding ranges. Knowledge about how these ranges are linked by movements of individuals from different populations is crucial for unravelling temporal variability in population spatial structuring and for identifying environmental drivers of population dynamics acting at different spatio-temporal scales. We performed a large-scale individual-based migration tracking study of the lesser kestrel (Falco naumanni), an Afro-Palearctic migratory raptor, to determine the patterns of migratory connectivity of European breeding populations. Location: Europe, Africa. Methods: Migration data were recorded using different devices (geolocators, Argos PTTs, GPS loggers) from 87 individuals breeding in the three core European populations, located in the Iberian, Italian and Balkan peninsulas. We estimated connectivity by the Mantel correlation coefficient (rM), and computed both the degree of separation between the non-breeding areas of individuals from the same population (i.e. the population spread) and the relative size of the non-breeding range (i.e. the non-breeding range spread). Results: European lesser kestrels migrated on a broad-front across the Mediterranean Sea and Sahara Desert, with different populations using different routes. Iberian birds migrated to western Sahel (Senegal, Mauritania, western Mali), Balkan birds migrated chiefly to central-eastern Sahel (Niger, Nigeria, Chad), whereas Italian ones spread from eastern Mali to Nigeria. Spatial differentiation of non-breeding areas led to a strong migratory connectivity (rM = 0.58), associated with a relatively high population (637 km) and non-breeding range (1149 km) spread. Main conclusions: Our comprehensive analysis of the non-breeding distribution of European lesser kestrel populations revealed a strong migratory connectivity, a rare occurrence in long-distance avian migrants. The geographic conformation of the species' breeding and non-breeding ranges, together with broad-front migration across ecological barriers, promoted the differentiation of migratory routes and non-breeding areas. Strong connectivity could then arise because of both high population spread and broad non-breeding range.

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