| Pfeiffer, T; Harter, D; Formella, N; Schnittler, M: Reproductive isolation vs. interbreeding between Gagea lutea (L.) Ker Gawl. and G. pratensis (Pers.) Dumort. (Liliaceae) and their putative hybrids in Mecklenburg-Western Pomerania (Germany), Plant Species Biology (2012) doi:10.1111/j.1442-1984.2012.00377.x | |
| Abstract: Mecklenburg-Western Pomerania is the main range of two hybridogeneous Gagea taxa, G. megapolitana Henker and G. pomeranica Ruthe, which have the same two parental species, G. lutea (L.) Ker. Gawl. and G. pratensis (Pers.) Dumort. We assessed the degree of reproductive isolation vs. interbreeding between these taxa using data from field observations, crossing experiments and pollen characteristics for nine hybrid, four G. lutea and five G. pratensis populations. Pollen viability was highest in 6x G. lutea and lowest in G. pratensis (most probably 5x), with intermediate figures for the studied hybrids (5x–7x). Despite the assumed anorthoploid states, sexual reproduction (though sometimes very rare) was recorded for all populations in the field and/or in experiments. The crossing experiments revealed that all taxa are also able to hybridize. However, there were differences in the directions (i.e. role as maternal vs. paternal parent) as well as the success of the crossings: the primary hybridization G. lutea x G. pratensis resulted in more seeds than the reverse combination (17.5 vs. 3.3%), but the seed set was highest in backcrosses of the hybrids with G. lutea pollen (41.2%). These differences can be explained by overlap of flowering times, and reduced fertilities due to ploidy levels. The study showed that the taxa of the G. lutea-pratensis hybrid complex are not yet reproductively isolated but can interbreed and will generate hybrids of higher ranks, forming a hybrid swarm, most probably leading to introgression via backcrosses with G. lutea. |
