Genetic Diversity and Phylogeography of the Relict Tree Fern Culcita macrocarpa: Influence of Clonality and Breeding System on Genetic Variation
Metadatos
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MDPI
Materia
breeding system clonality Culcita macrocarpa
Date
2024-06-07Referencia bibliográfica
Suárez Santiago, Víctor N. et. al. Plants 2024, 13, 1587. [https://doi.org/10.3390/plants13121587]
Résumé
The tree fern Culcita macrocarpa, a threatened Iberian–Macaronesian endemism, represents
the sole European species of the order Cyatheales. Considered a Tertiary relict of European
Palaeotropical flora, its evolutionary history and genetic diversity, potentially influenced by presumed
high clonal propagation, remain largely unknown. This study elucidates the phylogeographic
history of C. macrocarpa, assessing the impact of vegetative reproduction on population dynamics and
genetic variability. We provide genetic data from eight newly identified nuclear microsatellite loci
and one plastid DNA region for 17 populations spanning the species’ range, together with species
distribution modeling data. Microsatellites reveal pervasive clonality in C. macrocarpa, which has
varied among populations. We assess the impact of clonality on genetic diversity and evaluate how
estimates of intra-population genetic diversity indices and genetic structuring are affected by the
chosen definition of “individual” (focusing exclusively on genetically distinct individuals, genets, as
opposed to considering all independent clonal replicates, ramets). We identify two main population
groups, one in the northern Iberian Peninsula and the other in the Macaronesian archipelagos and
southern Iberian Peninsula. Within each group, we found relict populations (in the Azores and the
Cantabrian Cornice) as well as recent originated populations. This population structure suggests
colonization dynamics in which recent populations originated from one or a few genets of relict
populations and became established through intra-gametophytic self-fertilization and vegetative
expansion. DAPC analysis facilitated the identification of alleles that most significantly contributed
to the observed population structure. The current Andalusian populations appear to have originated
from colonization events from the Azores and the Cantabrian Cornice. Our findings suggest that C.
macrocarpa persisted through the Last GlacialMaximum in two refugia: the Azores and the Cantabrian
Cornice. Colonization into new areas occurred presumably from these refuges, generating two large
population groups with structured genetic diversity. This study underscores the significance of
clonality in establishing new populations and shaping genetic structure.