No abstract

Quaternary climatic oscillations have been considered decisive in shaping much of the phylogeographic structure around the Mediterranean Basin. Within this paradigm, peripheral islands are usually considered as the endpoints of the colonization processes. Here, we use nuclear and mitochondrial markers to investigate the phylogeography of the blue tit complex (blue tit Cyanistes caeruleus, Canary blue tit C. teneriffae and azure tit C. cyanus), and assess the role of the Canary Islands for the geographic structuring of genetic variation. The Canary blue tit exhibits strong genetic differentiation within the Canary Islands and, in combination with other related continental species, provides an ideal model in which to examine recent differentiation within a closely related group of continental and oceanic island avian species. We analysed DNA sequences from 51 breeding populations and more than 400 individuals in the blue tit complex. Discrepancies in the nuclear and mitochondrial gene trees provided evidence of a complex evolutionary process around the Mediterranean Basin. Coalescent analyses revealed gene flow between C. caeruleus and C. teneriffae suggesting a dynamic process with multiple phases of colonization and geographic overlapping ranges. Microsatellite data indicated strong genetic differentiation among the Canary Islands and between the Canary archipelago and the close continental areas, indicating limited contemporary gene flow. Diversification of the blue tit complex is estimated to have started during the early Pliocene (≈ 5 Ma), coincident with the end of Messinian salinity crisis. Phylogenetic analyses indicated that the North African blue tit is derived from the Canary blue tits, a pattern is avian 'back colonization' that contrasts with more traditionally held views of islands being sinks rather than sources.

Summary 1.Basal metabolic rate (BMR) is the most widely used standard measurement of the cost of living. Despite the acknowledged phenotypic flexibility of BMR, little is known about the patterns of variation in wild animal populations. 2. We studied the sources of variation in BMR of great tit Parus major (L.) among individuals from two wild populations: Oulu (northern Finland) and Lund (southern Sweden) during six consecutive years. 3. By means of a multivariate approach, we found year, locality, date, previous week average minimum temperature, age, body mass, and the interaction between locality and year were the factors retained in the final model, together explaining 71·1% of the total variation in BMR. 4. Birds from Oulu ( n = 168) had a higher BMR than Lund birds ( n = 156), and their BMR varied more between years than that of Lund birds. The two populations reacted in the same way to the other sources of variation examined. 5. Great tits from both populations showed a positive relationship between BMR and body mass and a negative relationship between BMR and date, previous week average minimum temperature and age. 6. This study highlights the need to standardize BMR measurements when testing predictions about metabolic rates from individuals of wild populations.

Summary 1.We studied the resting metabolic rate (MR) from two great tit Parus major (Linnaeus) populations living in different winter regimes. Birds from the two different localities were exposed individually to +25 °C, 0 °C and −10 °C for the night in three consecutive sessions in random order. 2. Birds from Lund (Sweden) had a lower basal MR, as measured at thermoneutrality (+25 °C), than had birds from Oulu (Finland). Nevertheless, below thermoneutrality, birds from Oulu spent relatively more energy, especially at −10 °C. 3. Although the energy needed for thermoregulation decreased with increasing basal MR this relation is at a higher metabolic cost for birds in Oulu than for birds in Lund. 4. The higher basal MR in Oulu is probably a consequence of a higher maximal MR needed in the severe cold. Further, the observed MRs below thermoneutrality are lower than expected from published data. This suggests that all birds were probably hypothermic at −10 °C, particularly Lund birds, and that the use of controlled hypothermia in great tits may be more common than thought previously. Great tits seem to rely primarily on metabolic adjustment to cope with the harsh climatic conditions in the northernmost parts of its distribution.

We investigated the physiological and behavioral consequences for prey breeding at different distances from a nesting predator. In a natural setting, Pied Flycatchers (Ficedula hypoleuca) made territory location decisions relative to established Sparrowhawk (Accipiter nisus) nests. From female flycatchers attending nests at different distances from Sparrowhawk nests, we measured body mass, blood stress protein (HSP60 and HSP70), and plasma immunoglobulin levels at the beginning (initial) and end (final) of the flycatcher breeding cycle, and provisioning rates during the nestling phase. We found that individuals breeding in closer proximity to Sparrowhawk nests, under higher perceived predation risk, showed significantly lower body mass, higher stress protein and immunoglobulin levels, and higher nestling provisioning rates compared to those individuals breeding farther away. Across the range of distances investigated (30-610 m), final stress protein levels decreased linearly with distance, whereas the final measures of the other variables showed unimodal trends, increasing or decreasing until an intermediate distance (approximately 350 m) and reversing the direction of the trend. Within 300 m, however, all measures showed significant linear associations with distance from the Sparrowhawk nest. Body mass and stress protein associations with distance from Sparrowhawk nests were only present during late breeding, and not in early incubation. Spatial proximity to Sparrowhawk nests consistently explained significant variation in both physiological and behavioral measures, despite the multitude of potential sources of variation for these measures in a natural setting. This suggests that predictable spatial patterns in these measures in avian communities are determined by the sites of breeding predators. Habitat selection decisions of migrant prey that vary only slightly spatially have consequences even at the cellular level, which plausibly have impacts on individual survival. In addition, this study suggests that predation risk is an important factor affecting physiological condition of prey, including stress protein induction in terrestrial vertebrates.