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Advisor(s)
Abstract(s)
The rich endemic flora of the Macaronesian Islands places these oceanic archipelagos
among the top biodiversity hotspots worldwide. The radiations that have determined the
evolution of many of these insular lineages resulted in a wealth of endemic species, many
of which occur in a wide range of ecological niches, but show small distribution areas in
each of them. Aeonium (Crassulaceae) is the most speciose lineage in the Canary Islands
(ca. 40 taxa), and as such can be considered a good model system to understand the
diversification dynamics of oceanic endemic floras. The present study aims to assess the
genome size variation within Aeonium distribution, i.e., the Macaronesian archipelagos
of Madeira, Canaries and Cabo Verde, and analyse it together with information
on distribution (i.e., geography and conservation status), taxonomy (i.e., sections),
morphological traits (i.e., growth-form), geological data (i.e., island’s geological age),
and environmental variables (i.e., altitude, annual mean temperature, and precipitation).
Based on extensive fieldwork, a cytogeographic screening of 24 Aeonium species was
performed. The conservation status of these species was assessed based on IUCN
criteria. 61% of the taxa were found to be threatened (4% Endangered and 57%
Vulnerable). For the first time, the genome size of a comprehensive sample of Aeonium
across the Macaronesian archipelagos was estimated, and considerable differences in
Cx-values were found, ranging from0.984 pg (A. dodrantale) to 2.768 pg (A. gorgoneum).
An overall positive correlation between genome size and conservation status was found,
with the more endangered species having the larger genomes on average. However,
only slight relationships were found between genome size, morphological traits, and environmental variables. These results underscore the importance of characterizing the
cytogenomic diversity and conservation status of endemic plants found in Macaronesian
Islands, providing, therefore, new data to establish conservation priorities.
Description
Keywords
conservation cytogenomics DNA flow cytometry flora endemic species oceanic islands RAMAS Red List threatened species
Pedagogical Context
Citation
Brilhante M, Roxo G, Catarino S, dos Santos P, Reyes-Betancort JA, Caujapé-Castells J, Sequeira MM, Talhinhas P and Romeiras MM (2021) Diversification of Aeonium Species Across Macaronesian Archipelagos: Correlations Between Genome-Size Variation and Their Conservation Status. Front. Ecol. Evol. 9:607338. doi: 10.3389/fevo.2021.607338
Publisher
Frontiers