1
|
Garner AG, Goulet-Scott BE, Hopkins R. Phylogenomic analyses re-examine the evolution of reinforcement and hypothesized hybrid speciation in Phlox wildflowers. THE NEW PHYTOLOGIST 2024; 243:451-465. [PMID: 38764373 DOI: 10.1111/nph.19802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 03/22/2024] [Indexed: 05/21/2024]
Abstract
The tree of life is riddled with reticulate evolutionary histories, and some clades, such as the eastern standing Phlox, appear to be hotspots of hybridization. In this group, there are two cases of reinforcement and nine hypothesized hybrid species. Given their historical importance in our understanding of plant speciation, the relationships between these taxa and the role of hybridization in their diversification require genomic validation. Using phylogenomic analyses, we resolve the evolutionary relationships of the eastern standing Phlox and evaluate hypotheses about whether and how hybridization and gene flow played a role in their diversification. Our results provide novel resolution of the phylogenetic relationships in this group, including paraphyly across some taxa. We identify gene flow during one case of reinforcement and find genomic support for a hybrid lineage underlying one of the five hypothesized homoploid hybrid speciation events. Additionally, we estimate the ancestries of four allotetraploid hybrid species. Our results are consistent with hybridization contributing to diverse evolutionary outcomes within this group; although, not as extensively as previously hypothesized. This study demonstrates the importance of phylogenomics in evaluating hypothesized evolutionary histories of non-model systems and adds to the growing support of interspecific genetic exchange in the generation of biodiversity.
Collapse
Affiliation(s)
- Austin G Garner
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, Boston, MA, 02131, USA
| | - Benjamin E Goulet-Scott
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, Boston, MA, 02131, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, Boston, MA, 02131, USA
| |
Collapse
|
2
|
Goulet-Scott BE, Farnitano MC, Brown ALM, Hale CO, Blumstein M, Hopkins R. A multidimensional selective landscape drives adaptive divergence between and within closely related Phlox species. Nat Commun 2024; 15:4661. [PMID: 38821972 PMCID: PMC11143288 DOI: 10.1038/s41467-024-49075-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 05/20/2024] [Indexed: 06/02/2024] Open
Abstract
Selection causes local adaptation across populations within species and simultaneously divergence between species. However, it is unclear if either the force of or the response to selection is similar across these scales. We show that natural selection drives divergence between closely related species in a pattern that is distinct from local adaptation within species. We use reciprocal transplant experiments across three species of Phlox wildflowers to characterize widespread adaptive divergence. Using provenance trials, we also find strong local adaptation between populations within a species. Comparing divergence and selection between these two scales of diversity we discover that one suite of traits predicts fitness differences between species and that an independent suite of traits predicts fitness variation within species. Selection drives divergence between species, contributing to speciation, while simultaneously favoring extensive diversity that is maintained across populations within a species. Our work demonstrates how the selection landscape is complex and multidimensional.
Collapse
Affiliation(s)
- Benjamin E Goulet-Scott
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Harvard Forest, Harvard University, Petersham, MA, 01366, USA
| | - Matthew C Farnitano
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA
| | - Andrea L M Brown
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Charles O Hale
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Institute for Genomic Diversity, Cornell University, Ithaca, NY, 14853, USA
| | - Meghan Blumstein
- Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.
- Arnold Arboretum of Harvard University, Boston, MA, 02131, USA.
| |
Collapse
|
3
|
Long Z, Rieseberg LH. Documenting homoploid hybrid speciation. Mol Ecol 2024:e17412. [PMID: 38780141 DOI: 10.1111/mec.17412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/11/2024] [Accepted: 04/30/2024] [Indexed: 05/25/2024]
Abstract
Homoploid hybrid speciation is challenging to document because hybridization can lead to outcomes other than speciation. Thus, some authors have argued that establishment of homoploid hybrid speciation should include evidence that reproductive barriers isolating the hybrid neo-species from its parental species were derived from hybridization. While this criterion is difficult to satisfy, several recent papers have successfully employed a common pipeline to identify candidate genes underlying such barriers and (in one case) to validate their function. We describe this pipeline, its application to several plant and animal species and what we have learned about homoploid hybrid speciation as a consequence. We argue that - given the ubiquity of admixture and the polygenic basis of reproductive isolation - homoploid hybrid speciation could be much more common and more protracted than suggested by earlier conceptual arguments and theoretical studies.
Collapse
Affiliation(s)
- Zhiqin Long
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
4
|
Bock DG, Cai Z, Elphinstone C, González-Segovia E, Hirabayashi K, Huang K, Keais GL, Kim A, Owens GL, Rieseberg LH. Genomics of plant speciation. PLANT COMMUNICATIONS 2023; 4:100599. [PMID: 37050879 PMCID: PMC10504567 DOI: 10.1016/j.xplc.2023.100599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/21/2023] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
Studies of plants have been instrumental for revealing how new species originate. For several decades, botanical research has complemented and, in some cases, challenged concepts on speciation developed via the study of other organisms while also revealing additional ways in which species can form. Now, the ability to sequence genomes at an unprecedented pace and scale has allowed biologists to settle decades-long debates and tackle other emerging challenges in speciation research. Here, we review these recent genome-enabled developments in plant speciation. We discuss complications related to identification of reproductive isolation (RI) loci using analyses of the landscape of genomic divergence and highlight the important role that structural variants have in speciation, as increasingly revealed by new sequencing technologies. Further, we review how genomics has advanced what we know of some routes to new species formation, like hybridization or whole-genome duplication, while casting doubt on others, like population bottlenecks and genetic drift. While genomics can fast-track identification of genes and mutations that confer RI, we emphasize that follow-up molecular and field experiments remain critical. Nonetheless, genomics has clarified the outsized role of ancient variants rather than new mutations, particularly early during speciation. We conclude by highlighting promising avenues of future study. These include expanding what we know so far about the role of epigenetic and structural changes during speciation, broadening the scope and taxonomic breadth of plant speciation genomics studies, and synthesizing information from extensive genomic data that have already been generated by the plant speciation community.
Collapse
Affiliation(s)
- Dan G Bock
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Zhe Cai
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Cassandra Elphinstone
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Eric González-Segovia
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | | | - Kaichi Huang
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Graeme L Keais
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Amy Kim
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Gregory L Owens
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.
| |
Collapse
|
5
|
Noguerales V. Digest: Revisiting morphology-derived hypotheses of hybridization in the light of genomics. Evolution 2021; 75:3216-3218. [PMID: 34569622 DOI: 10.1111/evo.14362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 08/31/2021] [Indexed: 11/30/2022]
Abstract
Genetic exchange between independently evolving lineages may give rise to the formation of new taxa, and hypotheses for this have been derived from species with intermediate phenotypes, when compared to potential parental species. Goulet-Scott and collaborators (2021) evaluate such a hypothesis in a wildflower species complex by integrating genomic and trait information. They find no support for hybrid speciation, despite detecting signatures of genetic admixture in some individuals resulting from interspecific gene flow in a hybrid zone.
Collapse
Affiliation(s)
- Víctor Noguerales
- Island Ecology and Evolution Research Group, Institute of Natural Products and Agrobiology (IPNA-CSIC), C/ Astrofísico Francisco Sánchez 3, 38206, San Cristóbal de La Laguna, Tenerife, Canary Islands, Spain
| |
Collapse
|