This paper explores the influence of forest structural parameters on the abundance and distribution of potential habitats for the middle spotted woodpecker (Dendrocopos medius) in three different forest landscapes in Poland. We applied predictive habitat suitability models (MaxEnt) based on forest inventory data to identify key environmental variables that affect the occurrence of the species under varying habitat conditions and the spatial configuration of suitable habitats. All models had good discriminative ability as indicated by high AUC values (> 0.75). Our results show that the species exhibited a certain degree of flexibility in habitat use, utilizing other habitats than mature oak stands commonly associated with its occurrence. In areas where old oakdominated stands are rare, alder bogs and species-rich deciduous forests containing other rough-barked tree species are important habitats. Habitat suitability models show that, besides tree species and age, an uneven stand structure was a significant predictor of the occurrence of middle spotted woodpecker. The total area of suitable habitats in the studied forests varied from 9% to 60%. Predictive habitat models identified several concentrations of suitable habitats (clusters) with the average distances between them ranging from 3.2 to 5.0 km. Although these distances lie within the species' dispersal ability, the migration of individuals between these sites might be difficult due to the necessity of travelling long distances through unsuitable forest types.

Emerging diseases, such as the crayfish plague, are a worldwide problem with serious ecological and economic impacts. Under the framework of ecological immunology, we investigated whether variation in crayfish plague resistance, the indicators of immune defence (encapsulation response, phenoloxidase and lytic activity), and the exploration behaviour among four subpopulations of noble crayfish is explained by potential local adaptation through differences in crayfish plague history, or alternatively by geographical divergence in a large watershed. We examined whether the strength of immune defence is associated with survival and exploration behaviour. Survival time after experimental crayfish plague infection and phenoloxidase activity differed among the subpopulations of the watershed but did not reveal local adaptation to the disease. Increased investment in immune defence (i.e. encapsulation response) compromised survival time after infection, suggesting the self-reactivity costs of mounting a strong immune response. Exploration behaviour was negatively associated with phenoloxidase activity before and after immune challenge.

Global climate is changing at an unprecedented rate. Adjustments to breeding phenology represent responses to current climate change, and some climatic effects have negatively affected population reproductive performances. Here we simulated the possibility that climate warming-induced changes in the timing of egg-laying may modify the phenotype composition (i.e. proportion of high- vs. low-quality phenotypes) of avian populations of single-brooded, long-lived species in northern countries (where asymmetric changes of weather conditions are more pronounced), therefore affecting the internal structure and long-term stability of populations. In northern countries, prelaying temperatures have risen and laying and hatching are expected to occur earlier. However, because post-hatching temperatures have remained stable, early chicks hatch under conditions of low temperature and great precipitation, and may face increased mortality. Because early breeders are generally high-quality individuals, their contribution to the future recruitment of the breeding population will decrease, engendering a doubly negative effect: (1) the number of offspring in a population will be lower than in the past because of higher mortality in the largest broods; and (2) the population will increasingly be composed of the offspring of low-quality individuals, which will consequently decrease fitness of the entire population.

The Eurasian minnow Phoxinus phoxinus is widely distributed across most of Europe and northern Asia. It displays considerable morphological diversity and variable colouration. Despite this it is still believed that its whole distribution holds only one monotypic species. There are no previous conclusive morphometric analyses of samples from different parts of its distribution area. This paper presents results of multidimensional analyses of morphometric characters of 14 widely scattered populations of the species. Our analyses show considerable inter-population differences. Morphometric evidence suggests that populations from the Amur River system and central Asia may represent new, distinct species or subspecies. The status of the remaining populations remains unclear.