The Radiation of Darwin's Giant Daisies in the Galápagos Islands.
Curr Biol
; 30(24): 4989-4998.e7, 2020 12 21.
Article
in En
| MEDLINE
| ID: mdl-33007244
ABSTRACT
Evolutionary radiations on oceanic islands have fascinated biologists since Darwin's exploration of the Galápagos archipelago [1, 2]. Island radiations can provide key insights for understanding rapid speciation, including evolutionary patterns and the processes behind them. However, lack of resolution of species relationships has historically hindered their investigation, particularly in the plant kingdom [3-5]. Here, we report a time-calibrated phylogenomic analysis based on genotyping-by-sequencing data [6] of the 15 species of Scalesia (Darwin's giant daisies), an iconic and understudied plant radiation endemic to the Galápagos Islands and considered the plant counterpart to Darwin's finches [1, 7-9]. Results support a Pliocene to early Pleistocene divergence between Scalesia and the closest South American relatives, and rapid diversification of extant Scalesia species from a common ancestor dated to the Middle Pleistocene. Major evolutionary patterns in Scalesia include the following (1) lack of compliance with the "progression rule" hypothesis, in which earlier diverging lineages are expected to occupy older islands; (2) a predominance of within-island speciation over between-island speciation; and (3) repeated convergent evolution of potentially adaptive traits and habitat preferences on different islands during the course of diversification. Massive sequencing provided the essential framework for investigating evolutionary and ecological processes in the complex natural laboratory of the Galápagos, thereby advancing our understanding of island plant radiations.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Asteraceae
/
Genetic Speciation
/
Plant Dispersal
Country/Region as subject:
America do sul
/
Ecuador
Language:
En
Journal:
Curr Biol
Journal subject:
BIOLOGIA
Year:
2020
Document type:
Article