“Coastal” versus “inland” shorebird species: interlinked fundamental dichotomies between their life- and demographic histories?

In this contribution I present an extended but testable hypothesis (or “evolutionary scenario”) to explain how and why many life-history features of latitudinal migrant shorebirds, basically characterised by the correlation between habitat choice in the winter and the breeding season, may be functionally and causally intertwined. The most novel (and contentious) aspect of the hypothesis is that historical restrictions in suitable habitat may generate further restriction of suitable habitat with the causal chain consisting of population bottlenecks, leading to reduced adaptive genetic variation, leading to reduced ability to fight diseases, thus affecting potential habitat choice.

Phenotypic flexibility and the evolution of organismal design

Evolutionary biologists often use phenotypic differences between species and between individuals to gain an understanding of organismal design. The focus of much recent attention has been on developmental plasticity – the environmentally induced variability during development within a single genotype. The phenotypic variation expressed by single reproductively mature organisms throughout their life, traditionally the subject of many physiological studies, has remained underexploited in evolutionary biology. Phenotypic flexibility, the reversible within-individual variation, is a function of environmental conditions varying predictably (e.g. with season), or of more stochastic fluctuations in the environment. Here, we provide a common framework to bring the different categories of phenotypic plasticity together, and emphasize perspectives on adaptation that reversible types of plasticity might provide. We argue that better recognition and use of the various levels of phenotypic variation will increase the scope for phenotypic experimentation, comparison and integration.

Migration in the balance:tight ecological margins and the changing fortunes of shorebird populations

Dependent as they are on rare and remote open habitats for breeding and survival, shorebirds connect continents and hemispheres with their individual movements. Although many of the wetland systems on which shorebirds rely, especially in the rich West, have now some form of protection, two case studies on man-induced declines of Red Knots Calidris canutus in The Netherlands and the USA demonstrate that despite the legislation in these countries, the responsible authorities have tragically failed to provide the necessary safeguards. At the same time, these examples indicate how instructive shorebirds can be in elucidating ecosystem changes at local, and at global, scales. I advocate continued close scientific scrutiny of complementary sets of shorebird species so that we can be informed about their fate, and about the fate of ecosystems world-wide that are so effectively connected by their movements