The impact of hybridization on long-term persistence of polyploid Dactylorhiza species

Genetic Variability in Balkan Paleoendemic Resurrection Plants Ramonda serbica and R. nathaliae Across Their Range and in the Zone of Sympatry

The genus Ramonda includes three Paleoendemic and Tertiary relict species that survived in refugial habitats of the Balkan Peninsula (R. nathaliae and R. serbica) and the Iberian Peninsula (R. myconi). They are all "resurrection plants," a rare phenomenon among flowering plants in Europe. Ramonda myconi and R. nathaliae are diploids (2n = 2x = 48), while R. serbica is a hexaploid (2n = 6x = 144). The two Balkan species occur in sympatry in only two localities in eastern Serbia, where tetraploid potential hybrids (2n = 4x = 96) were found. This observation raised questions about the existence of gene flow between the two species and, more generally, about the evolutionary processes shaping their genetic diversity. To address this question, genetic markers (AFLP) and an estimate of genome size variation were used in a much larger sample and at a larger geographic scale than previously. The combination of AFLP markers and genome size results suggested ongoing processes of interspecific and interploidy hybridization in the two sites of sympatry. The data also showed that interspecific gene flow was strictly confined to sympatry. Elsewhere, both Ramonda species were characterized by low genetic diversity within populations and high population differentiation. This is consistent with the fact that the two species are highly fragmented into small and isolated populations, likely a consequence of their postglacial history. Within sympatry, enormous variability in cytotypes was observed, exceeding most reported cases of mixed ploidy in complex plant species (from 2x to >8x). The AFLP profiles of non-canonical ploidy levels indicated a diversity of origin pathways and that backcrosses probably occur between tetraploid interspecific hybrids and parental species. The question arises whether this diversity of cytotypes corresponds to a transient situation. If not, the question arises as to the genetic and ecological mechanisms that allow this diversity to be maintained over time.

The Epipactis helleborine Group (Orchidaceae): An Overview of Recent Taxonomic Changes, with an Updated List of Currently Accepted Taxa

The Epipactis helleborine (L.) Crantz group is one of the most taxonomically challenging species complexes within the genus Epipactis. Because of the exceptionally high levels of morphological variability and the ability to readily cross with other species, ninety different taxa at various taxonomic ranks have already been described within its nominative subspecies, but the taxonomic status of most of them is uncertain, widely disputed, and sometimes even irrelevant. The present review is based on results of the most recent research devoted to the E. helleborine group taxonomy. In addition, we analysed data about taxa belonging to this group presented in some research articles and monographs devoted directly to the genus Epipactis or to orchids in certain area(s). Based on the reviewed literature and data collected in four taxonomic databases available online, we propose an updated list of the 10 currently accepted taxa in the E. helleborine group (two species, six subspecies, and two varieties), which includes E. helleborine (L.) Crantz subsp. helleborine; E. helleborine subsp. bithynica (Robatsch) Kreutz; E. helleborine subsp. distans (Arv.-Touv.) R.Engel and P.Quentin; E. helleborine subsp. neerlandica (Verm.) Buttler; E. helleborine var. tangutica (Schltr.) S.C.Chen and G.H.Zhu; E. helleborine subsp. tremolsii (Pau) E.Klein; E. helleborine subsp. voethii (Robatsch) Jakubska-Busse, Żołubak, and Łobas, stat. nov.; E. condensata Boiss. ex D.P.Young; E. condensata var. kuenkeleana (Akhalk., H.Baumann, R.Lorenz, and Mosul.) Popovich; and E. cupaniana C.Brullo, D’Emerico, and Pulv.

Morphology and genome size of Epipactis helleborine (L.) Crantz (Orchidaceae) growing in anthropogenic and natural habitats

BACKGROUND

The process of apophytism or spreading native species to human-made habitats is one of the main elements in the creation of plant cover in anthropogenic areas. Lately, an increase of anthropogenic localities with valuable flora has been observed. Apophytes are also members of the family Orchidaceae, especially from the genus Epipactis. The aim of the study was to (i) determine and compare the phenotypic variation of E. helleborine (L.) Crantz plants in anthropogenic and natural habitats, (ii) compare the genome size of plants growing in natural and anthropogenic habitats. The results reported in this study may indicate that a habitat influences morphological characteristics of plant species.

METHODS

Field studies were conducted on four native stands and four stands in anthropogenic areas of E. helleborine in Poland in years 2011-2013. Biometrical analyses were performed on shoots and flowers. The flowers were characterised by 25 biometric features and measured using a Nikon SMZ 800 binocular, microscopic Moticam-1SP cameras and the MIPlus07 programme (Conbest Co.). The nuclear DNA content was determined in fresh and young leaves of E. helleborine, collected from four natural and four anthropogenic populations.

RESULTS

We observed that in anthropogenic populations: (i) shoots were higher than shoots from natural populations, (ii) flowers differed significantly in terms of ten biometric features between habitats, (iii) the genome size of some population differed significantly between plants growing in natural and anthropogenic habitats.

DISCUSSION

According to some researchers, the presence of phenotypic variability and the occurrence of ecotypes are adaptation strategies of plants to environmental changes. In our opinion, in the case of the studied anthropogenic habitats (roadside) in which the E. helleborine populations grew, we can talk about ecofen due to the often repeated set of characteristic features, i.e., high shoots, long inflorescence and long, broad leaves. We agree, however, that it is difficult to isolate a taxonomic unit for ecofen due to the lack of experimental research.