A Combined Molecular and Morphological Approach to the Taxonomically Intricate European Mountain Plant Papaver Alpinum S.L
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Schönswetter & al. • Papaver alpinum s.l.—taxa or informal groups? TAXON 58 (4) • November 2009: 1326–1343 A combined molecular and morphological approach to the taxonomically intricate European mountain plant Papaver alpinum s.l. (Papaveraceae) — taxa or informal phylogeographical groups? Peter Schönswetter1*, Heidi Solstad2,3*, Pedro Escobar García1 & Reidar Elven2 1 Department of Biogeography and Botanical Garden, University of Vienna, Rennweg 14, 1030 Vienna, Austria 2 National Centre for Biosystematics, Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, 0318 Oslo, Norway 3 Icelandic Institute of Natural History, P.O. Box 180, 602 Akureyri, Iceland. [email protected] (author for correspondence) * These authors contributed equally to the manuscript. Papaver alpinum s.l. is an extraordinarily polymorphic taxon distributed throughout southern and central European mountain ranges. We tested previous hypotheses about relationships and taxonomical status of the numerous described taxa within this species or species group by applying different molecular approaches. In addition we re-evaluated morphological characters used in previous taxonomic treatments in the light of the mo- lecular results. The ancestral sequence haplotypes were widespread and dominant throughout the Alps, whereas peripheral populations in other mountain ranges were often characterised by haplotypes directly derived from the central haplotypes involving one or two mutational steps. The AFLP data corroborated the pattern of a ‘centrifugal radiation’ and additionally showed that most populations were genetically distinct, presumably due to the effect of genetic drift in small and isolated populations. The morphological data did not reveal clear patterns of variation; only the Pyrenean and Sierra Nevada populations differed in two non-overlapping and presumably independent characters. Altogether, our study implies that most previous taxonomic concepts of P. alpinum s.l. were highly artificial, and that either nearly all populations have to be raised to some taxonomic rank or that, preferably, no infraspecific taxa should be recognised at all. The only segregate possibly deserving taxonomic rank, based on both morphology and genetics, is the Iberian P. alpinum subsp. lapeyrousianum. KEYWORDS: AFLPs, central and southern European mountain ranges, low-copy nuclear region RPA2, morphology, Papaver alpinum s.l., phylogeography, plastid region psbE-petL, taxonomy Scandinavia and the western Eurasian Arctic (P. dahlia- INTRODUCTION num Nordh., P. lapponicum (Tolm.) Nordh., P. radicatum The Alpine poppy, Papaver alpinum L., belongs to Rottb.), all being high polyploids. There is a large gap to the monophyletic P. sect. Meconella Spach, which is the temperate relatives in the alpine belt of Asian Pamir sister to the Himalayan representatives of Meconopsis and Tian-Shan (mainly P. croceum Ledeb. s.l. and P. nu- Vig. (Carolan & al., 2006). Papaver sect. Meconella has dicaule L. s.l.) and further east. The morphologically most a circumpolar arctic distribution, but also occurs in the similar species has been suggested to be the northeastern alpine and subalpine belts of several temperate mountain Asian P. nivale Tolm. (Rändel, 1974). ranges, as well as in steppes and river valleys of Central Analyses of DNA sequences (plastid, nuclear ribo- and northern Asia (e.g., Rändel, 1974; Hultén & Fries, somal, low-copy nuclear; Solstad & al., unpub.) show 1986; Peschkova, 1994). The section is absent from the that P. alpinum is monophyletic. Establishment of sister- western Asian mountains and the Caucasus. Whereas the group relationships is more complicated as even analyses arctic distribution is nearly continuous, the temperate taxa including only the diploid species of P. sect. Meconella often occupy disjunct ranges in mountain areas, as is the revealed incongruent phylogenies for the different DNA case for the central and southern European P. alpinum. regions. They were, however, congruent in indicating Papaver alpinum is diploid (summarised in Jalas & that the closest relatives are Asian low-ploid taxa. AFLP Suominen, 1991), a ploidy level documented in other spe- data (Solstad & al., unpub.) indicate that P. alpinum s.l. is cies from Central Asia, Siberia, Beringia and the central distantly related to the northern European polyploid spe- Rocky Mountains (e.g., Hanelt, 1969; Rändel, 1974; Pesch- cies and rather connects to low-ploid northeastern Asian kova, 1994; Kiger & Murray, 1997; Petrovsky, 1999). The and amphi-Pacific/Beringian species (P. nivale was not geographically closest relatives of P. alpinum are found in included). 1326 TAXON 58 (4) • November 2009: 1326–1343 Schönswetter & al. • Papaver alpinum s.l.—taxa or informal groups? Papaver alpinum is distributed throughout most of Table 1. Morphological characters studied in Papaver al- the major mountain areas of southern and Central Europe pinum s.l. (Markgraf, 1958a; Jalas & Suominen, 1991; Bittkau & Char. Kadereit, 2003; Aeschimann & al., 2004). The distribution No. Character is relatively continuous in the Alps (France, Switzerland, 1 Leaf sheath tunica: lax (1); medium (2); firm (3) Germany, Italy, Austria, Slovenia); most populations and 2 Blade colour: green (1); slightly glaucous (2); population groups are, however, more or less isolated due strongly glaucous (3) to preference for sparsely vegetated, mostly calcareous 3 Blade indumentum: glabrous or subglabrous (1); scree of varying degree of mobility. Geographically iso- sparse (2); moderate or dense (3) lated population groups are found in the Sierra Nevada 4 Blade dissection: number of times divided (1; 2; 3) (southern Spain), the Pyrenees (Spain, France), the Apen- 5 Main segment attachment: opposite (1); subopposite nines (the Gran Sasso area in Abruzzo, central Italy), the (2); alternate (3) Tatras in the Western Carpathians (Poland, Slovakia), the Southern and Eastern Carpathians (Romania), the Pirin 6 Terminal segment shape: linear or strap-shaped (1); (ob)lanceolate (2); (ob)ovate (3) (Bulgaria), and the southern Dinaric Mountains (Bosnia and Hercegovina, Montenegro). 7 Terminal segment symmetry: symmetrical (1); slightly asymmetrical, broader on proximal side of Papaver alpinum is extraordinarily polymorphic with midvein (2); distincly asymmetrical, much broader on respect to vegetative, floral and fruit characters. Variation proximal side of midvein (3) can be encountered in, e.g., firmness of the basal tunica; 8 Terminal segment direction: divergent from main axis leaf glaucescence and dissection; shape and symmetry of of main segment (1); straight (2); convergent towards terminal leaf segments; presence and density of leaf indu- main axis of main segment (3) mentum; orientation and density of scape indumentum; 9 Scape hair density: sparse (1); moderate, hairs slightly colour and length of hairs on buds; petal colour, shape and overlapping (2); dense, hairs strongly overlapping (3) degree of overlap; length of stamens relative to gynoe- 10 Scape hair direction: subappressed (1); ascending to cium; shape of capsule and stigmatic disc; and number of subpatent (2); patent (3) stigmatic rays as well as degree of their decurrence. As 11 Bud shape: globular or subglobular (1); ovoid (2); easily observed morphological differences show some ellipsoid (3) geographical pattern, they were early assigned taxonomic 12 Bud indumentum colour: pale, not contrasting with importance. Examples of characters used as diagnostic scape (1); medium, some contrast with scape (2); in previous treatments (e.g., Markgraf, 1958a; Mowat & dark, strong contrast with scape (3) Walters, 1964) are given in Table 1. In the last 250 years, 13 Petal length (broadest pair), mm numerous names at specific or subspecific levels have been coined for the different populations (summary in 14 Petal width (broadest pair), mm Markgraf, 1958a). Thirteen of these represent combined 15 Petal overlap: none (1); contiguous or overlapping (2) morphological and geographical entities that have been 16 Petal colour: white (1); yellow (2) assigned specific or subspecific rank in recent accounts 17 Stamens compared with ovary: shorter (1); equal (2); (Appendix 1*; for keys, description and more informa- longer (3) tion, see especially Markgraf 1958a). Here we apply the 18 Capsule widest part: at middle (1); between middle names without ranks in the geographical meanings given and upper third (2); within uppermost third (3) in Appendix 2. 19 Capsule length (below stigmatic disc): broad towards Studies of P. alpinum in the last 50 years have reached top (1); slightly constricted (2); strongly constricted strikingly different conclusions as regards subdivision of (3) the complex and taxonomic ranks of the entities. Six spe- 20 Capsule (without stigmatic disc), mm cies and several subspecies were accepted by Mowat & Walters (1964) in the first edition of Flora Europaea, and 21 Capsule maximum width, mm they informally commented on some additional subspe- 22 Capsule setae density: sparse, < 10 per valve (1); mod- cies. Two species were accepted by Markgraf (1958a), an erate, 10–20 per valve (2); dense, > 20 per valve (3) Iberian species as P. suaveolens Lapeyr., and P. alpinum 23 Stigmatic disc shape: broad and convex (1); broad with eight subspecies, six of them in the Alps (Markgraf, and slightly peaked (2); narrow and strongly peaked (3) 1958a). This approach was followed by Jalas & Suom- inen (1991) in Atlas Florae Europaeae with only small 24 Decurrence of stigmatic rays on capsule; decurrence: