Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1111/1365-2745.12670
Title (Primary) Invasion success in polyploids: the role of inbreeding in the contrasting colonization abilities of diploid versus tetraploid populations of Centaurea stoebe s.l.
Author Rosche, C.; Hensen, I.; Mráz, P.; Durka, W. ORCID logo ; Hartmann, M.; Lachmuth, S.
Source Titel Journal of Ecology
Year 2017
Department BZF; iDiv
Volume 105
Issue 2
Page From 425
Page To 435
Language englisch
Keywords coefficient of relationship; founder effects; genetic bottleneck; geo-cytotype; inbreeding depression; invasion ecology; purging; sporophytic self-incompatibility; S-alleles; spotted knapweed
UFZ wide themes RU1;

1.As a consequence of founder effects, inbreeding can hamper colonization success: Firstly, in species with self-incompatibility controlled by an S-locus, inbreeding may decrease cross-compatibility, mainly due to the sharing of identical S-alleles between closely related mating partners. Secondly, inbreeding can reduce fitness of inbred relative to outbred offspring (i.e. inbreeding depression). Polyploids often show reduced inbreeding depression compared to diploids, which may contribute to the overrepresentation of polyploids among invasive species. This is the first study that tests how the effects of inbreeding differ between geo-cytotypes (i.e. ploidy levels within a given range).

2.Our model organism, Centaurea stoebe, is strictly self-incompatible and comprises three geo-cytotypes: diploids are more frequent than tetraploids in the native range, while only tetraploids occur in the invasive range. We conducted a breeding experiment (sib-mating vs. outcrossing) with 14 native diploid, 13 native tetraploid and 15 invasive tetraploid populations. We recorded cross-compatibility and estimated a cumulative index for offspring fitness. Since frequent inbreeding can result in purging of genetic load responsible for inbreeding depression, our analyses included a metric for within-population relatedness, based on eight microsatellite markers, to assess the effect of purging.

3. Inbreeding was found to reduce cross-compatibility, which was similarly pronounced in diploids and tetraploids. It also caused inbreeding depression in cumulative fitness, which was significant in diploids but not in tetraploids. No evidence of purging was observed as inbred fitness was not affected by within-population relatedness.

4.Synthesis. Our results provide new insights into the contrasting invasion success of the cytotypes of C. stoebe. As the effects of cross-compatibility and purging were comparable between cytotypes, both processes can be ruled out to affect the colonization success of diploids vs. tetraploids. Our findings are consistent with the hypothesis that polyploidy increases the masking of recessive mutations, which maintains high fitness in inbred tetraploids and may thus facilitate colonization of new ranges. We highlight that reduced inbreeding depression may add to previously acknowledged advantages of polyploids in range expansions, a mechanism that may hitherto have been underestimated due to a lack of data on variation in inbreeding depression across geo-cytotypes.

Persistent UFZ Identifier
Rosche, C., Hensen, I., Mráz, P., Durka, W., Hartmann, M., Lachmuth, S. (2017):
Invasion success in polyploids: the role of inbreeding in the contrasting colonization abilities of diploid versus tetraploid populations of Centaurea stoebe s.l.
J. Ecol. 105 (2), 425 - 435 10.1111/1365-2745.12670