Phenotypic diversity and delimitation between wild and cultivated forms of the genus <Emphasis Type="Italic">Pyrus</Emphasis> in North-eastern Spain based on morphometric analyses |
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| Authors: | Jordi Voltas Jesús Pemán Francesca Fusté |
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| Institution: | (1) Department of Crop and Forest Sciences, University of Lleida, Alcalde Rovira Roure, 191, E-25198 Lleida, Spain |
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| Abstract: | We investigated morphological evidence that might allow wild Pyrus spp. to be distinguished from cultivated material (Pyrus communis L.) in the North-eastern Iberian Peninsula. 134 pear trees were identified in the wild and characterized by 13 quantitative
and 13 qualitative leaf–shoot and fruit traits. The trees were visually classified into two preliminary groups of wild and
cultivated material and discriminant functions, based on a reference collection for allocating individuals to one of the groups,
were constructed. Both classifications were compared with a near-optimal numerical classification (the two-stage Ward-MLM
strategy) using two criteria. The visual assignment of trees allocated 60% of trees to the wild group and 40% to the cultivated
group. The overall discrepancy rate between the field classification and the discriminant analysis was low (17.4%). In general,
wild individuals had smaller leaves, shorter petioles and more rounded and smaller fruits than their cultivated counterparts.
They also had small-to-intermediate petiole widths, thorns on their shoots and straight or convex fruit profiles. However,
the Ward-MLM strategy always formed better groups, in terms of the two criteria used, in all the continuous and categorical
variables, for both leaf–shoot and fruit traits. Likewise, the agreement between classifications (discriminant analysis and
Ward-MLM strategy) was only partial, with some Ward-MLM groups composed of both wild and cultivated material in similar proportions.
This result suggests a limited success in identifying genuine wild individuals based on morphometric data, which can be ascribed
either to poor phenotypic diversity and lack of distinguishing traits among species or to widespread crossability and subsequent
development of hybrid/introgressant populations between wild and cultivated specimens. |
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| Keywords: | Discriminant analysis Genetic variation Germplasm collection Morphological traits Pyrus spp Ward-MLM strategy |
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