Range size heritability and diversification patterns in the liverwort genus Radula.
Why some species exhibit larger geographical ranges than others, and to what extent does variation in range size affect diversification rates, remains a fundamental, but largely unanswered question in ecology and evolution. Here, we implement phylogenetic comparative analyses and ancestral area estimations in Radula, a liverwort genus of Cretaceous origin, to investigate the mechanisms that explain differences in geographical range size and diversification rates among lineages. Range size was phylogenetically constrained in the two sub-genera characterized by their almost complete Australasian and Neotropical endemicity, respectively. The congruence between the divergence time of these lineages and continental split suggests that plate tectonics could have played a major role in their present distribution, suggesting that a strong imprint of vicariance can still be found in extant distribution patterns in these highly mobile organisms. Amentuloradula, Volutoradula and Metaradula species did not appear to exhibit losses of dispersal capacities in terms of dispersal life-history traits, but evidence for significant phylogenetic signal in macroecological niche traits suggests that niche conservatism accounts for their restricted geographic ranges. Despite their greatly restricted distribution to Australasia and Neotropics respectively, Amentuloradula and Volutoradula did not exhibit significantly lower diversification rates than more widespread lineages, in contrast with the hypothesis that the probability of speciation increases with range size by promoting geographic isolation and increasing the rate at which novel habitats are encountered. We suggest that stochastic long-distance dispersal events may balance allele frequencies across large spatial scales, leading to low genetic structure among geographically distant areas or even continents, ultimately decreasing the diversification rates in highly mobile, widespread lineages.
Island Ecology and Evolution Research Group, Instituto de Productos Naturales y Agrobiología (IPNA-CSIC), Astrofísico Francisco Sánchez 3, La Laguna, Tenerife, Canary Islands 38206, Spain; Department of Biology, Ecology and Evolution, Institute of Botany, University of Liège, Liège, Belgium; Azorean Biodiversity Group (GBA, CITA-A) and Platform for Enhancing Ecological Research & Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Açores, Portugal. Electronic address: jpatino.llorente@gmail.com.
Jairo
J
Patiño
Bryology Laboratory, School of Life Sciences, East China Normal University, Shanghai 200241, China.
Jian
J
Wang
National Herbarium of New South Wales, Royal Botanic Gardens Sydney, Mrs Macquaries Road, Sydney, NSW 2000, Australia.
Matt A M
MAM
Renner
Département de Systématique et Evolution, Museum National d' Histoire Naturelle, Paris, France.
S Robbert
SR
Gradstein
ScienceLifeLab, Stockholm University, Solna, Sweden.
Benjamin
B
Laenen
Department of Biology, Duke University, Durham, NC, USA.
Nicolas
N
Devos
Department of Biology, Duke University, Durham, NC, USA.
A Jonathan
AJ
Shaw
Department of Biology, Ecology and Evolution, Institute of Botany, University of Liège, Liège, Belgium; Azorean Biodiversity Group (GBA, CITA-A) and Platform for Enhancing Ecological Research & Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Açores, Portugal.
Alain
A
Vanderpoorten
D044822:Biodiversity; D005075:Biological Evolution; D017753:Ecosystem; D035926:Hepatophyta / Q000145:classification*; D010641:Phenotype; D010802:Phylogeny; D058974:Phylogeography
Diversification rates; Liverworts; Long-distance dispersal; Niche conservatism; Radula; Range size