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221.
222.
Adolf Ćerný 《Development genes and evolution》1907,23(4):503-510
Ohne Zusammenfassung 相似文献
223.
The results of different photoperiodic treatments preventing flowering and representing the control vegetative treatments
in the studies of floral induction and differentiation were studied inChenopodium rubrum seedlings. A fully vegetative growth pattern of the meristem was maintained only in continuous light or after a photoperiodic
treatment which consisted in a 15 min light break of the 8 h dark periods which themselves are a threshold for flowering inChenopodium. Light breaks applied to 10 h and longer dark periods did not prevent the changes resembling the early events of transition
to flowering. Disappearance of zonal pattern, stimulation of apical growth, precocious initiation of leaf primordia and weakening
of apical dominance have been observed. Flower formation did not follow.
This work was supported by a grant from the Scientific Research Fund of SR Serbia. 相似文献
224.
The evolutionary history of aquatic invasion in birds would be incomplete without incorporation of extinct species. We show that aquatic affinities in fossil birds can be inferred by multivariate analysis of skeletal features and locomotion of 245 species of extant birds. Regularized discriminant analyses revealed that measurements of appendicular skeletons successfully separated diving birds from surface swimmers and flyers, while also discriminating among different underwater modes of swimming. The high accuracy of this method allows detection of skeletal characteristics that are indicative of aquatic locomotion and inference of such locomotion in bird species with insufficient behavioural information. Statistical predictions based on the analyses confirm qualitative assessments for both foot‐propelled (Hesperornithiformes) and wing‐propelled (Copepteryx) underwater locomotion in fossil birds. This is the first quantitative inference of underwater modes of swimming in fossil birds, enabling future studies of locomotion in extinct birds and evolutionary transitions among locomotor modes in avian lineage. 相似文献