Phylogeny strongly drives seed dormancy and quality in a climatically buffered hotspot for plant endemism

• Published in: Annals of botany Vol. 119; no. 2; pp. 267 - 277
• Main Authors: Dayrell, Roberta L. C., Garcia, Queila S., Negreiros, Daniel, Baskin, Carol C., Baskin, Jerry M., Silveira, Fernando A. O.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.01.2017
• Subjects: Angiospermae; biodiversity; Brazil; Ecology; evolutionarily stable strategy; ex situ conservation; germination; grasslands; indigenous species; life history; Magnoliopsida - physiology; Original; PART OF A SPECIAL ISSUE ON ENDEMISM HOTSPOTS; Phylogeny; Plant Dormancy - physiology; prediction; quantitative analysis; seed dormancy; seeds; Seeds - physiology; viability; Brazil; P-deficient soils; rupestrian grassland; Campo rupestre; ecophylogenetics; OCBIL; Cerrado; community; regeneration ecology; seed viability; embryoless seeds; evolutionarily stable strategy; refugia
• ISSN: 0305-7364; 1095-8290; 1095-8290
• DOI: 10.1093/aob/mcw163

Models of costs and benefits of dormancy (D) predict that the evolutionarily stable strategy in long-term stable environments is for non-dormancy (ND), but this prediction remains to be tested empirically. We reviewed seed traits of species in the climatically buffered, geologically stable and nutrient-impoverished campo rupestre grasslands in Brazil to test the hypothesis that ND is favoured over D. We examined the relative importance of life-history traits and phylogeny in driving the evolution of D and assessed seed viability at the community level. Germination and viability data were retrieved from 67 publications and ND/D was determined for 168 species in 25 angiosperm families. We also obtained the percentage of embryoless, viable and dormant seeds for 74 species. Frequencies of species with dormant and non-dormant seeds were compared with global databases of dormancy distribution. The majority of campo rupestre taxa (62·5 %) had non-dormant seeds, and the ND/D ratio was the highest for any vegetation type on Earth. Dormancy was unrelated to other species life-history traits, suggesting that contemporary factors are poor predictors of D. We found a significant phylogenetic structure in the dormancy categorical trait. Dormancy diversity was highly skewed towards the root of the phylogenetic tree and there was a strong phylogenetic signal in the data, suggesting a major role of phylogeny in determining the evolution of D versus ND and seed viability. Quantitative analysis of the data revealed that at least half of the seeds produced by 46 % of the surveyed populations were embryoless and/or otherwise non-viable. Our results support the view that long-term climatic and geological stability favour ND. Seed viability data show that campo rupestre species have a markedly low investment in regeneration from seeds, highlighting the need for specific in situ and ex situ conservation strategies to avoid loss of biodiversity.