Exploration of sexual dimorphism of Taxus baccata L. needles in natural populations

Key message Multivariate morphometric analyses were used for the first time to examine sexual dimorphism and shape variability of needles in natural populations of relict species Taxus baccata L. Abstract Needle morphology and intraspecific variability of Taxus baccata L. were examined for the first time in Serbian natural populations (in the central Balkans). A geometric morphometric approach was used to assess size and shape variation of needles and to address questions of sexual dimorphism and phenotypic plasticity. Population-specific sexual size dimorphism was found. In the Tara population, females had larger needles than males and this was in accordance with earlier reports on T. baccata dimorphism. We found it unusual that in the other two populations, Kopaonik and Malinik, sexual size dimorphism was constrained and the sexes had needles of equal size. Multivariate analysis of needle shape revealed that the Tara population differed from the other two populations and was characterized by straighter, more symmetric needles. The absence of sexual size dimorphism and the less symmetrical shape of needles could be signs of a deviation from optimal conditions for yew in the Kopaonik and Malinik populations as regards mean annual temperature, precipitation, humidity and soil quality. There is also an indication that sexual size dimorphism in needles arises from a modification in female morphology and that female yews carry more information about climate. However, the conclusions presented in this study have certain limitations because of the small number of individuals in the Tara population (only 3 female and 4 male plants) that represent the quasi-total of adult yews at this site.