Sympatric divergence and clinal variation in multiple coloration traits of Ficedula flycatchers.

Geographic variation in phenotypes plays a key role in fundamental evolutionary processes such as local adaptation, population differentiation and speciation, but the selective forces behind it are rarely known. We found support for the hypothesis that geographic variation in plumage traits of the pied flycatcher Ficedula hypoleuca is explained by character displacement with the collared flycatcher Ficedula albicollis in the contact zone. The plumage traits of the pied flycatcher differed strongly from the more conspicuous collared flycatcher in a sympatric area but increased in conspicuousness with increasing distance to there. Phenotypic differentiation (PST ) was higher than that in neutral genetic markers (FST ), and the effect of geographic distance remained when statistically controlling for neutral genetic differentiation. This suggests that a cline created by character displacement and gene flow explains phenotypic variation across the distribution of this species. The different plumage traits of the pied flycatcher are strongly to moderately correlated, indicating that they evolve non-independently from each other. The flycatchers provide an example of plumage patterns diverging in two species that differ in several aspects of appearance. The divergence in sympatry and convergence in allopatry in these birds provide a possibility to study the evolutionary mechanisms behind the highly divergent avian plumage patterns.

Heterospecific female mimicry in Ficedula flycatchers.

Mimicry is a widespread phenomenon. Vertebrate visual mimicry often operates in an intraspecific sexual context, with some males resembling conspecific females. Pied flycatcher (Ficedula hypoleuca) dorsal plumage varies from the ancestral black to female-like brown. Experimental studies have shown that conspecific and heterospecific (collared flycatcher, F. albicollis) individuals of both sexes respond, at least initially, to brown individuals as if they were female. We quantified the perceptual and biochemical differences between brown feathers and found that brown pied flycatcher males are indistinguishable from heterospecific, but not from conspecific, females in both aspects. To our knowledge, this is the first evidence of a visual mimetic signalling system in a sexual context where the model is heterospecific to the mimic. By only mimicking heterospecific females, brown pied flycatcher males can establish territories next to the more dominant collared flycatcher in sympatry, suffer less aggression by darker conspecifics in allopatry and preserve within-species sexual recognition throughout the breeding range. A closer look at the evolutionary history and ecology of these two species illustrates how such a mimetic system can evolve. Although likely rare, this phenomenon might not be unique to Ficedula flycatchers.

Rapid change in host use of the common cuckoo Cuculus canorus linked to climate change.

Parasites require synchrony with their hosts so if host timing changes with climate change, some parasites may decline and eventually go extinct. Residents and short-distance migrant hosts of the brood parasitic common cuckoo, Cuculus canorus, have advanced their phenology in response to climate change more than long-distance migrants, including the cuckoo itself. Because different parts of Europe show different degrees of climate change, we predicted that use of residents or short-distance migrants as hosts should have declined in areas with greater increase in spring temperature. Comparing relative frequency of parasitism of the two host categories in 23 European countries before and after 1990, when spring temperatures in many areas had started to increase, we found that relative parasitism of residents and short-distance migrants decreased. This change in host use was positively related to increase in spring temperature, consistent with the prediction that relative change in phenology for different migrant classes drives host-use patterns. These findings are consistent with the hypothesis that climate change affects the relative abundance of different host races of the common cuckoo.

Respiratory sinus arrhythmia is reduced in adolescent major depressive disorder.

OBJECTIVE: Although the emotion regulatory difficulties in patients with major depressive disorder (MDD) are predicted to associate with impaired cardiovascular autonomic regulation, the changes of cardiac vagal regulation MDD are incompletely understood. The aim of the study was to evaluate the respiratory sinus arrhythmia (as an index of cardiac vagal regulation) using the spectral analysis in high frequency band of the heart rate variability and the indices of deep breathing test in adolescent patients with major depressive disorder. MATERIAL AND METHOD: Twenty-eight adolescent girls were examined - 14 patients with major depressive disorder without pharmacological treatment (average age: 16.4 +/- 0.2 yr) and 14 healthy probands (control group) matched for age and gender. The respiratory sinus arrhythmia was evaluated using the spectral analysis in high frequency band of the heart rate variability (HF-HRV) and the parameters of deep breathing test (I-E, I/E). In addition, mean R-R interval was calculated. RESULTS: The adolescent patients with MDD has significantly reduced spectral activity in the HF-HRV and lower I/E, I-E parameters compared to marched health subjects (P<0.05). CONCLUSIONS: We conclude that the adolescents girls with MDD have reduced respiratory sinus arrhythmia indicating cardiac vagal dysregulation. Since impaired cardiac vagal regulation is associated with increased risk of cardiovascular morbidity, this finding underscores the importance of impaired autonomic neuro-cardiac integrity already in adolescents with major depressive disorder without pharmacological treatment.

The effect of reserpine and stress on feeding behaviour in the light and dark phases of the diurnal cycle in rats.

The effect of reserpine (2.5 mg kg-1 subcutaneously) and stress (3 h restraint) on food and water consumption and body weight change in the light and dark phases of the diurnal cycle in rats was investigated. Reserpine increased water intake and body weight loss in the light phase (250 and 180% of the control, respectively). In the dark phase the reserpinized rats consumed less food and water (20 and 30% of the control, respectively) and body weight gain was reversed (-250% of the control). After stress, rats consumed more food and water (200 and 500% of the control, respectively) and their body weight loss was diminished (60% of the control) in the light phase. In the dark phase the consumption of food and water in the stressed rats was diminished (80 and 85% of the control, respectively) without any change in body weight gain. The dark/light phase ratio for food consumption, water intake and body weight change (gain/loss) was highly statistically significant in the stressed and reserpine-treated rats. The results indicate that evaluation of behaviour in animal models should be carried out during both phases of the diurnal cycle.