Microsatellite markers and cytoplasmic sequences reveal contrasting pattern of spatial genetic structure in the red algae species complex Mazzaella laminarioides.
Mazzaella laminarioides is a common haploid-diploid red alga that forms dense beds. This alga has a wide distributional range, covering 3,500 km of the Chilean coast, but is restricted to high rocky intertidal zones. Recently, the existence of three highly divergent genetic lineages was demonstrated for this taxon, and two cytoplasmic markers were used to determine that these lineages are distributed in strict parapatry. Here, using 454 next-generation sequencing, we developed polymorphic microsatellite loci that cross amplify in all three cytoplasmic lineages. Six sites (i.e., two sites within each lineage) were analyzed using nine microsatellite loci. Our work shows that, although substantial cytoplasmic differentiation occurs within M. laminarioides, the microsatellite loci did not retrieve three nuclear genetic clusters as expected. Indeed, while the northernmost and southernmost cytoplasmic lineages form two strongly divergent nuclear groups characterized by diagnostic alleles, the third cytoplasmic lineage did not form a third nuclear independent group. It is possible that inter-lineage gene exchange has occurred, particularly at sites along the contact zone between the different cytoplasmic lineages. This nuclear-cytoplasmic incongruence in M. laminarioides could be explained by incomplete lineage sorting of the nuclear genes or asymmetric introgressive hybridization between the lineages. Finally, highly significant heterozygote deficiencies (suggesting occurrence of intergametophytic selfing) were observed in the three small northernmost sites while the large southernmost sites generally approached panmixia.
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.|CNRS, Sorbonne Universités, UPMC University Paris VI, UMI 3614, Evolutionary Biology and Ecology of Algae, Station Biologique de Roscoff, CS 90074, Place G. Tessier, 296888, Roscoff, France.
Marie-Laure
ML
Guillemin
CNRS, Sorbonne Universités, UPMC University Paris VI, UMI 3614, Evolutionary Biology and Ecology of Algae, Station Biologique de Roscoff, CS 90074, Place G. Tessier, 296888, Roscoff, France.
Myriam
M
Valero
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
Kennia
K
Morales Collio
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
Ramona
R
Pinochet Sanchez
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
Miguel
M
Henríquez Espinosa
AUSTRAL-omics, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
Andrea X
AX
Silva
D002677:Chile; D048028:DNA, Algal / Q000235:genetics; D005819:Genetic Markers; D014644:Genetic Variation; D018895:Microsatellite Repeats; D000461:Rhodophyta / Q000235:genetics*; D017422:Sequence Analysis, DNA
D048028:DNA, Algal; D005819:Genetic Markers
Chile; Rhodophyta; gene flow; intergametophytic selfing; microsatellites; species complex