What makes the structure and dynamics of coupled natural and human systems difficult to interpret in the Mediterranean is the extreme diversity in space and time of both environments and human societies. The succession of civilizations that waxed and waned in the Mediterranean Basin over several millennia has had great impacts on biota and ecosystems everywhere in the basin. A complex 'coevolution' has been claimed to shape the interactions between ecosystem components and human societies. Two opposing schools of thought traditionally have considered the consequences of human pressures on Mediterranean ecosystems. The 'Ruined Landscape' or 'Lost Eden theory' argues that human action resulted in a cumulative degradation and desertification of Mediterranean landscapes. The second school argues that humans actually contributed to keeping Mediterranean landscapes diverse since the last glacial episode. With this debate in mind, I show the following: (1) One cannot understand the components and dynamics of current biodiversity in the Mediterranean without taking into account the history of human-induced changes; (2) The various systems of land use and resource management that provided a framework for the blossoming of Mediterranean civilizations also had profound consequences on the distribution and dynamics of species, communities, and landscapes;(3) The processes of domestication of plant and animal species, which first occurred in the eastern Mediterranean area some 10,000 years ago, contributed to the increase of certain components of biodiversity at several spatial scales. Positive and negative feedback cycles between cultural practices and natural systems at the local and regional levels have kept ecosystems robust and resilient; (4) Assuming that human action can, to a certain extent, be considered a large-scale surrogate for natural sources of ecosystem disturbance, such patterns give support to the diversity-disturbance hypothesis-specifically, intermediate levels of disturbance have promoted biological diversity; (5) Intraspecific adaptive variation increased as a result of human-induced habitat changes over millennia, resulting in bursts of differentiation during the later Holocene of local ecotypes and gene pools of domesticated and wild plant and animal species, with region-specific characters fitting them to local climate and environmental conditions. High intraspecific adaptive variation also arose from Hum Ecol (2006) 34:713-729 earlier natural processes of the Pleistocene, mainly from a combination of periodic refugia formation and climate dynamics. During the Holocene, the main sources of disturbance came increasingly from humans, specifically from the coupled cultural and natural modifications of community and landscape structure. It is concluded that a high degree of resilience of Mediterranean ecosystems resulted in a dynamic coexistence of human and natural living systems, which in some cases provided stability, while fostering diversity and productivity (Blondel and Aronson, 1999). The word "d...

By advancing spring leaf flush and ensuing food availability, climatic warming results in a mismatch between the timing of peak food supply and nestling demand, shifting the optimal time for reproduction in birds. Two populations of blue tits (Parus caeruleus) that breed at different dates in similar, but spatially distinct, habitat types in Corsica and southern France provide a unique opportunity to quantify the energetic and fitness consequences when breeding is mismatched with local productivity. As food supply and demand become progressively mismatched, the increased cost of rearing young pushes the metabolic effort of adults beyond their apparent sustainable limit, drastically reducing the persistence of adults in the breeding population. We provide evidence that the economics of parental foraging and limits to sustainable metabolic effort are key selective forces underlying synchronized seasonal breeding and long-term shifts in breeding date in response to climatic change.

Although most researchers use the terms “guild” and “functional group” more or less synonymously, these two concepts bear different meanings. The guild concept refers primarily to the mechanisms of resource sharing by species in a competitive context whereas the functional groups concept is concerned with how a resource or any other ecological component is processed by different species to provide a specific ecosystem service or function. In many cases but not necessarily all, the two concepts are the two “faces” or “sides” of the same coin: the sharing by species of a similar resource is the guild facet (structural), while the ecosystem processes these species eventually perform through resource exploitation is the functional group facet. The two concepts differ in that competitive relationships within groups of species are not the focus of the functional group approach, exactly as processes or functions are not the focus of the guild approach. A group of species can be considered either as a guild or a functional group depending on the question addressed. Guild and functional group membership is independent of phylogenetic relationships but because species tend to share similar life history traits and adaptations through common evolutionary history, guild and functional group associates are often closely related. The concept of guild has had broader application in animal studies than in plant studies, whereas the reverse is true for the concept of functional group. Recent methodological advances to objectively partition species into guilds and functional groups, taking into consideration the most relevant characters or traits for delineating them, provide the means to construct an operational framework for making in situ and ex situ experiments that are urgently needed for a better understanding of the role of species in ecosystem functioning, especially in relation to global change concerns.

No abstract

No abstract

The blue tit is a highly mobile small passerine found in deciduous and evergreen oaks. In mainland populations, gene flow results in local maladaptive timing of breeding in evergreen oak forests, the rarer habitat. However, on the island of Corsica, two populations only 25 kilometers apart are highly specialized and differ between the two habitat types in breeding and morphological traits. In contrast to theoretical predictions about the homogenizing effects of gene flow, this highlights evolutionary consequences of habitat diversification and isolation at a small spatial scale in insular organisms, which should be taken into account in conservation policies.

High variation in laying date and clutch size of the blue tit between a Mediterranean mixed habitat on the mainland, southern France, and a sclerophyllous habitat on the island of Corsica is hypothesized to be related to differences in the food supply. The diet of the nestlings and feeding frequencies were studied using camera nestboxes and electronic chronographs. Food items brought to the nestlings were much more diverse on Corsica than on the mainland, including many fewer caterpillars and a wider range of taxa. However, when expressed as a volume index, prey items were on average larger on Corsica than on the mainland. Feeding frequencies were significantly lower on Corsica. A good correlation was found in both habitats between laying date and the caterpillar peak date, although both the leafing development of oaks and the peak of abundance of caterpillars occurred 3 weeks later in the Corsican sclerophyllous trees than in the mainland deciduous ones. Differences in the feeding ecology of tits between the two habitats are discussed in the light of the evergreen habit, which means that only 30% of leaves are available for phyllophagous insects instead of 100% in deciduous trees. the combination of a late and low food supply in evergreen trees is the best explanation for the differences in breeding traits betwen the two populations.

Many bird species face seasonal and spatial variation in the availability of the specific food required to rear chicks. Caterpillar availability is often identified as the most important factor determining chick quality and breeding success in forest birds, such as tits Parus spp. It is assumed that parents play an important role in mediating the effect of environment on chick development. A reduction in prey availability should therefore result in increased foraging effort to maintain the amount of food required for optimal chick development. To investigate the capacity of adults to compensate for a reduction in food supply, we compared the foraging behaviour of Blue Tits Parus caeruleus breeding in rich and poor habitats in Corsica. We monitored the foraging effort of adults using radiotelemetry. We also identified and quantified prey items provided to nestlings by using a video camera mounted on the nest. We found that the mean travelling distance of adults was twice as great in the poor habitat as it was in the rich. Despite the marked difference in foraging distance, the proportion of optimal prey (caterpillars) in the diet of the chicks and the total biomass per hour per chick did not differ between the two habitats. We argue that relationships between habitat richness, offspring quality and breeding success cannot be understood adequately without quantifying parental effort.