Adil GÜNER, Vehbi ESER - optima

Oral Lectures
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HAVE CYTOLOGY AND MORPHOMETRICS ALREADY BEEN
ABSORBED INTO TRADITIONAL SYSTEMATICS?
Karol MARHOLD
Institute of Botany, Slovak Academy of Sciences, Bratislava, Slovakia & Department of Botany, Faculty of Science,
Charles University, Prague, Czech Republic
karol.marhold@savba.sk
Polyploidisation is undoubtedly a frequent mode of speciation in plants and recent data indicate
that most angiosperm lineages have undergone one or more episodes of genome duplication
during their evolutionary history. Therefore, at least basic knowledge about chromosome
numbers and/or ploidy levels of studied taxa is crucial for systematic studies of any group of
plant species. Acquiring such data is facilitated by the recent expansion of flow cytometry
applications that enable screening a large number of samples. These methods, however, often
reveal also differences in DNA content among close relatives of the same ploidy level, and can
identify hybrids among them. Detailed studies of cytotype distribution go hand in hand with
deeper insights into morphological variation provided by the methods of multivariate
morphometrics. This approach, as opposite to the cladistic one, is particularly useful for taxa
recognition, rather than for reconstructing phylogenetic relationships. It is most efficient in cases
where differences among taxa are based on quantitative characters with values overlapping
among related taxa. Application of morphometric methods introduced much broader population
sampling into taxonomic studies, as well as screening of numerous morphological characters.
Various approaches can be taken in morphometric studies. While the analysis of population
samples characterised by mean values of characters may reveal certain trends, the analyses of
individual plants enable to go into considerable detail. Hypotheses can be generated using
clustering and/or ordination methods, such as PCA, PCoA, and MDS, while a wide spectrum of
discriminant analyses can be used for hypothesis testing. A special case is represented
bygeometrical morphometrics dealing with the comparison of the shape rather than the size of
organisms or individual organs. Indeed, morphometric studies have shown in many cases that
identification keys and descriptions based on limited material might be seriously biased, which
underlines the need for thorough sampling in systematic studies.
Keywords: cytology, flow cytometry, morphometrics, sampling strategies
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