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Evolutionary origin of the latitudinal diversity gradient in liverworts.
Mol Phylogenet Evol. 2018 10; 127:606-612.MP

Abstract

A latitudinal diversity gradient towards the tropics appears as one most recurrent patterns in ecology, but the mechanisms underlying this pattern remain an area of controversy. In angiosperms, the tropical conservatism hypothesis proposes that most groups originated in the tropics and are adapted to a tropical climatic regime, and that relatively few species have evolved physiological adaptations to cold, dry or unpredictable climates. This mechanism is, however, unlikely to apply across land plants, and in particular, to liverworts, a group of about 7500 species, whose ability to withstand cold much better than their tracheophyte counterparts is at odds with the tropical conservatism hypothesis. Molecular dating, diversification rate analyses and ancestral area reconstructions were employed to explore the evolutionary mechanisms that account for the latitudinal diversity gradient in liverworts. As opposed to angiosperms, tropical liverwort genera are not older than their extra-tropical counterparts (median stem age of tropical and extra-tropical liverwort genera of 24.35 ± 39.65 Ma and 39.57 ± 49.07 Ma, respectively), weakening the 'time for speciation hypothesis'. Models of ancestral area reconstructions with equal migration rates between tropical and extra-tropical regions outperformed models with asymmetrical migration rates in either direction. The symmetry and intensity of migrations between tropical and extra-tropical regions suggested by the lack of resolution in ancestral area reconstructions towards the deepest nodes are at odds with the tropical niche conservatism hypothesis. In turn, tropical genera exhibited significantly higher net diversification rates than extra-tropical ones, suggesting that the observed latitudinal diversity gradient results from either higher extinction rates in extra-tropical lineages or higher speciation rates in the tropics. We discuss a series of experiments to help deciphering the underlying evolutionary mechanisms.

Authors+Show Affiliations

Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden.Island Ecology and Evolution Research Group, Instituto de Productos Naturales and Agrobiología (IPNA-CSIC), La Laguna, Tenerife, Spain; Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA.Department of Botany, The Field Museum, Chicago, USA.Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden.Bryology Laboratory, School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.Department of Biology, Duke University, Durham, NC 27708, USA.Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA.National Fund for Scientific Research at University of Liege, Institute of Botany, Belgium. Electronic address: a.vanderpoorten@uliege.be.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29890223

Citation

Laenen, Benjamin, et al. "Evolutionary Origin of the Latitudinal Diversity Gradient in Liverworts." Molecular Phylogenetics and Evolution, vol. 127, 2018, pp. 606-612.
Laenen B, Patiño J, Hagborg A, et al. Evolutionary origin of the latitudinal diversity gradient in liverworts. Mol Phylogenet Evol. 2018;127:606-612.
Laenen, B., Patiño, J., Hagborg, A., Désamoré, A., Wang, J., Shaw, A. J., Goffinet, B., & Vanderpoorten, A. (2018). Evolutionary origin of the latitudinal diversity gradient in liverworts. Molecular Phylogenetics and Evolution, 127, 606-612. https://doi.org/10.1016/j.ympev.2018.06.007
Laenen B, et al. Evolutionary Origin of the Latitudinal Diversity Gradient in Liverworts. Mol Phylogenet Evol. 2018;127:606-612. PubMed PMID: 29890223.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evolutionary origin of the latitudinal diversity gradient in liverworts. AU - Laenen,Benjamin, AU - Patiño,Jairo, AU - Hagborg,Anders, AU - Désamoré,Aurélie, AU - Wang,Jian, AU - Shaw,A Jonathan, AU - Goffinet,Bernard, AU - Vanderpoorten,Alain, Y1 - 2018/06/08/ PY - 2017/11/23/received PY - 2018/06/02/revised PY - 2018/06/04/accepted PY - 2018/6/12/pubmed PY - 2019/2/9/medline PY - 2018/6/12/entrez KW - Bryophytes KW - Diversification KW - Latitudinal diversity gradient KW - Macroclimatic niche conservatism KW - Tropics SP - 606 EP - 612 JF - Molecular phylogenetics and evolution JO - Mol. Phylogenet. Evol. VL - 127 N2 - A latitudinal diversity gradient towards the tropics appears as one most recurrent patterns in ecology, but the mechanisms underlying this pattern remain an area of controversy. In angiosperms, the tropical conservatism hypothesis proposes that most groups originated in the tropics and are adapted to a tropical climatic regime, and that relatively few species have evolved physiological adaptations to cold, dry or unpredictable climates. This mechanism is, however, unlikely to apply across land plants, and in particular, to liverworts, a group of about 7500 species, whose ability to withstand cold much better than their tracheophyte counterparts is at odds with the tropical conservatism hypothesis. Molecular dating, diversification rate analyses and ancestral area reconstructions were employed to explore the evolutionary mechanisms that account for the latitudinal diversity gradient in liverworts. As opposed to angiosperms, tropical liverwort genera are not older than their extra-tropical counterparts (median stem age of tropical and extra-tropical liverwort genera of 24.35 ± 39.65 Ma and 39.57 ± 49.07 Ma, respectively), weakening the 'time for speciation hypothesis'. Models of ancestral area reconstructions with equal migration rates between tropical and extra-tropical regions outperformed models with asymmetrical migration rates in either direction. The symmetry and intensity of migrations between tropical and extra-tropical regions suggested by the lack of resolution in ancestral area reconstructions towards the deepest nodes are at odds with the tropical niche conservatism hypothesis. In turn, tropical genera exhibited significantly higher net diversification rates than extra-tropical ones, suggesting that the observed latitudinal diversity gradient results from either higher extinction rates in extra-tropical lineages or higher speciation rates in the tropics. We discuss a series of experiments to help deciphering the underlying evolutionary mechanisms. SN - 1095-9513 UR - https://www.unboundmedicine.com/medline/citation/29890223/Evolutionary_origin_of_the_latitudinal_diversity_gradient_in_liverworts_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1055-7903(17)30854-0 DB - PRIME DP - Unbound Medicine ER -