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Sex chromatin and Y chromosomes in dioecious species, Rumex acetosa L.

100%

Mosiolek M. , Pedrosa-Harand A. , Schweizer D. , Joachimiak A. J.

tom 47

nr 1

Natural regeneration and gender-specific spatial pattern of Taxus baccata in an old-growth population in Foresta Umbra (Italy)

84%

Vessella F. , Salis A. , Scire M. , Piovesan G. , Schirone B.

tom 73

English yew is rare and endangered dioecious species. Research on regeneration processes of endangered taxa is important to understand the mechanisms allowing a species to survive under several ecological scenarios, to predict future distribution shifts, to achieve best management practices and conservation policies. Our investigation was focusing on one of the oldest yew population in Europe, in Foresta Umbra in Italy. The main aim of this study was to understand spatial regeneration processes and dynamics related with parent trees’ sex distribution. Geostatistical analysis showed that seedlings occur in patches avoiding direct competition with adult yews. Negative relationship between regeneration and yew density and basal area was found. A general model for the reproductive ecology is proposed: females are less competitive and more environmentally demanding than males, because of their reproductive effort. Indeed, male and female fitness responds differently across environmental gradients, thus favouring spatial segregation of seedlings. Understanding the yew’s adaptive effectiveness is essential to ensure the conservation of existing populations, and encourage the species’ resilience into areas where yew is endangered.

Variation in sex expression in Polish and Ukrainian populations of Taxus baccata L.

84%

Iszkulo G. , Jasinska A. K.

tom 52

29-32

The aim of the present study was to analyse the occurrence of monoecious individuals in selected populations of Taxus baccata in Poland and Ukraine. The investigation showed the monoecy in Taxus baccata to be extremely rare phenomenon. Only four cosexual individuals were found in three by seven populations examines and the frequency of monoecy was 0.13% on average among 2986 trees verified. Isolated seeds were found on individuals with large number of male flowers. Only one tree was found with numerous macro- and microstrobiles.