Abstract Detail

Floristics & Taxonomy

Vejvodova, Katerina [1], Ekrt, Libor [1], Krejčí, Joel [1], Koutecký, Petr [1], Lučanová, Magdalena [1], Hornych, Ondrej [1].

Huperzia (Huperziaceae, lycophytes) diversified in the shadow of the ice ages: The first steps to understanding the H. selago group cytotype and spore variability.

The diversification of many plant groups growing in northern temperate regions followed the climate fluctuations of the ice ages. These climate changes had the most intensive effect on plants in arctic and alpine zones, where several genera of lycophytes commonly occur. The extreme conditions associated with these areas demands specific adaptations, which may intensify speciation. In the long-term, environmental pressures could lead to an increase in genome size and convergent morphology.
In northern regions, the most abundant lycophytes belong to the Huperzia selago group. The representatives of this primitive vascular plant group are widespread in temperate mountains and north boreal to arctic regions. Although general knowledge of speciation and diversification among H. selago is still very limited, active evolution associated with limited molecular divergence, cryptic lineages, and high chromosome numbers is presumed.
Our study focused on determining the ploidy level and genome size of plants in the Huperzia selago group. We collected 2100 plants from 310 populations throughout Europe. For the sake of comparison, additional samples were obtained from North America and northern Asia. All the samples were analyzed by flow cytometry, which was calibrated by chromosome counts. We discovered five different cytotypes in the Huperzia selago group, representing ploidy levels from diploid to hexaploid. Tetraploids were the most common, occurring nearly in all examined regions. Triploids were confined to the subalpine and tundra zones of high altitudes and latitudes. Other cytotypes were very rare, found in disjunctive and extreme habitats, mostly in mixture with other cytotypes.
Spore size did not differ markedly between cytotypes. All Huperzia types produced well-developed spores, aborted spores, diplospores and undivided tetrads. A few strong trends were observed. Odd ploidy levels (3x, 5x) were characterized by higher spore abortion, indicating hybrid origin. Additionally, 5x plants produced more diplospores, compared to other cytotypes, which could be seen as an example of adaptation for the survival in more extreme habitats.
To fully understand the biology and phylogeny of this complicated group, it is also necessary to study their reproductive systems, sporogenesis, physiology and extant diversity. The results need to be calibrated with a thorough molecular study, ultimately allowing us to resolve the phylogenetic relationships and correctly assign (cyto-)types to existing or newly-described taxa.

1 - University Of South Bohemia, Faculty Of Science, Department Of Botany, Branisovska 1760, Ceske Budejovice, JC, CZ-37005, Czech Republic

Keywords:
Lycopods
Huperzia
flow cytometry
genome size
ploidy diversity
cytogeography
spores
chromosomes.

Presentation Type: Oral Paper
Number: F&T II011
Abstract ID:309
Candidate for Awards:None