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Exceptions from dioecy and sex lability in genus Salix

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Mirski P.

Dendrobiology

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2014

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tom 71

Bisexualism (and its derivatives) is a rare exception in species which already acquired the dioecious breeding system. Although it occurs in some tree species, it is still rather uncommon, except for willows, in which bisexualism occurs in at least 18 species. In most willows such unusual individuals are subdioecious, hermaphroditic or monoecious, or produce intersexes (staminate flowers transform into pistillate flowers or the other way round). The frequency of non-dioecy can vary from a single individual to whole populations, but is in principle rare. Its possible causes are both environmental and genetic. In Salix sex lability is known to be affected by parasites and anthropogenic habitat change. In interspecific willow crosses there are numerous exceptions from dioecy that are mostly caused by polyploidization. Since sex determination in willows is genetic, environmental factors are expected to determine exclusively phenotypic sex traits.

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Polygamic system of the Great white pelican (Pelecanus onocrotalus L.) in the Poznan Zoological Garden

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Cwiertnia P., Bereszynski A.

Animal Science. Scientific Papers of Agricultural University of Poznan

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2003

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tom 05

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Are hermaphrodites better adapted to the colonization process in trioecious populations of Salix myrsinifolia?

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Mirski P., Brzosko E.

Acta Societatis Botanicorum Poloniae

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2015

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tom 84

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nr 2

In trioecious plant populations, the role of hermaphroditism is often uncertain. We investigated the advantages of hermaphroditism in the dioecious shrub Salix myrsinifolia. The sex ratio of 30 S. myrsinifolia populations in northeastern Poland (secondary range) and Lithuania (primary range) was investigated in 2010-2011. Measures of reproductive (number of catkins, number of flowers in catkins) and vegetative traits (height, diameter, number of shoots, vitality) were taken and compared among sexual morphs. In two populations, measurements collected 14 years prior on marked individuals were used to determine the rate of changes in height, crown diameter and survivorship rates. We found trioecy mostly in the secondary part of the range with an average share of hermaphrodites reaching 21% in the trioecious populations. The sex ratio varied between populations, but tended mostly towards female domination. Several traits differed significantly among sexes. The characteristics of hermaphrodites were often intermediate between males and females and provided no evidence for the higher competitive abilities of hermaphrodites. We concluded that the possible gain of hermaphroditism in the colonization process is restricted to reproduction. We consider hermaphroditism in S. myrsinifolia as an equilibrium between the allocation of resources for growth and reproduction in unstable conditions on the margins of the range.

Ograniczanie wyników

1 Acta Societatis Botanicorum Poloniae

1 Animal Science. Scientific Papers of Agricultural University of Poznan

1 Dendrobiology

2 Mirski P.

1 Bereszynski A.

1 Brzosko E.

1 Cwiertnia P.

1 2015

1 2014

1 2003

Exceptions from dioecy and sex lability in genus Salix

Polygamic system of the Great white pelican (Pelecanus onocrotalus L.) in the Poznan Zoological Garden

Are hermaphrodites better adapted to the colonization process in trioecious populations of Salix myrsinifolia?