Ecological character displacement in the face of gene flow: Evidence from two species of nightingales

<p>Abstract</p> <p>Background</p> <p>Ecological character displacement is a process of phenotypic differentiation of sympatric populations caused by interspecific competition. Such differentiation could facilitate speciation by enhancing reproductive isolation between incipient species, although empirical evidence for it at early stages of divergence when gene flow still occurs between the species is relatively scarce. Here we studied patterns of morphological variation in sympatric and allopatric populations of two hybridizing species of birds, the Common Nightingale (<it>Luscinia megarhynchos</it>) and the Thrush Nightingale (<it>L. luscinia</it>).</p> <p>Results</p> <p>We conducted principal component (PC) analysis of morphological traits and found that nightingale species converged in overall body size (PC1) and diverged in relative bill size (PC3) in sympatry. Closer analysis of morphological variation along geographical gradients revealed that the convergence in body size can be attributed largely to increasing body size with increasing latitude, a phenomenon known as Bergmann's rule. In contrast, interspecific interactions contributed significantly to the observed divergence in relative bill size, even after controlling for the effects of geographical gradients. We suggest that the divergence in bill size most likely reflects segregation of feeding niches between the species in sympatry.</p> <p>Conclusions</p> <p>Our results suggest that interspecific competition for food resources can drive species divergence even in the face of ongoing hybridization. Such divergence may enhance reproductive isolation between the species and thus contribute to speciation.</p

Bird voices joyfully in nature-forestry education

Ptaki występują w różnych środowiskach. Stosunkowo łatwo je zauważyć, ale nie zawsze można szybko rozpoznać. Stanowią jednak wdzięczny obiekt do obserwacji. Oprócz rozmaitości upierzenia wiele ptaków odzywa się rozmaitymi głosami, dzięki którym można je wykryć w gęstwinie lasu lub w szuwarach na obrzeżach zbiorników wodnych. Często są bohaterami literatury dziecięcej i to nie tylko w bajkach dla najmłodszych.Birds live in different habitats. It is quite easy to notice them, yet it is not always easy to recognize them. They are very nice objects for observation. Apart from their visual diversity, many birds have various voices, and thanks to it they can be discovered in the forest thicket or rushes at the water. Often they are characters in the children literature, not only in fairy tales for the youngest

Tannic acid-modified silver nanoparticles for wound healing: the importance of size

Piotr Orlowski,1 Magdalena Zmigrodzka,2 Emilia Tomaszewska,3 Katarzyna Ranoszek-Soliwoda,3 Monika Czupryn,1 Malgorzata Antos-Bielska,1 Janusz Szemraj,4 Grzegorz Celichowski,3 Jaroslaw Grobelny,3 Malgorzata Krzyzowska1 1Military Institute of Hygiene and Epidemiology, Warsaw, Poland; 2Department of Pathology and Veterinary Diagnostics, Faculty of Veterinary Medicine, Warsaw University of Life Sciences (WULS-SGGW), Warsaw, Poland; 3Department of Materials Technology and Chemistry, Faculty of Chemistry, University of Lodz, Lodz, Poland; 4Bionanopark, Lodz, Poland Introduction: Silver nanoparticles (AgNPs) have been shown to promote wound healing and to exhibit antimicrobial properties against a broad range of bacteria. In our previous study, we prepared tannic acid (TA)-modified AgNPs showing a good toxicological profile and immunomodulatory properties useful for potential dermal applications.Methods: In this study, in vitro scratch assay, antimicrobial tests, modified lymph node assay as well as a mouse splint wound model were used to access the wound healing potential of TA-modified and unmodified AgNPs.Results: TA-modified but not unmodified AgNPs exhibited effective antibacterial activity against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli and stimulated migration of keratinocytes in vitro. The tests using the mouse splint wound model showed that TA-modified 33 and 46&nbsp;nm AgNPs promoted better wound closure, epithelialization, angiogenesis and formation of the granulation tissue. Additionally, AgNPs elicited expression of VEGF-&alpha;, PDGF-&beta; and TGF-&beta;1 cytokines involved in wound healing more efficiently in comparison to control and TA-treated wounds. However, both the lymph node assay and the wound model showed that TA-modified AgNPs sized 13&nbsp;nm can elicit strong inflammatory response not only during wound healing but also when applied to the damaged skin.Conclusion: TA-modified AgNPs sized &gt;26&nbsp;nm promote wound healing better than TA-modified or unmodified AgNPs. These findings suggest that TA-modified AgNPs sized &gt;26&nbsp;nm may have a promising application in wound management. Keywords: hydrolyzable tannin, split wound, silver, antimicrobials, inflammation, fibroblasts, monocyte