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Freedman AH, Harrigan RJ, Zhen Y, Hamilton AM, Smith TB. Evidence for ecotone speciation across an African rainforest-savanna gradient. Mol Ecol 2023; 32:2287-2300. [PMID: 36718952 DOI: 10.1111/mec.16867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 11/07/2022] [Accepted: 01/16/2023] [Indexed: 02/01/2023]
Abstract
Accelerating climate change and habitat loss make it imperative that plans to conserve biodiversity consider species' ability to adapt to changing environments. However, in biomes where biodiversity is highest, the evolutionary mechanisms responsible for generating adaptative variation and, ultimately, new species are frequently poorly understood. African rainforests represent one such biome, as decadal debates continue concerning the mechanisms generating African rainforest biodiversity. These debates hinge on the relative importance of geographic isolation versus divergent natural selection across environmental gradients. Hindering progress is a lack of robust tests of these competing hypotheses. Because African rainforests are severely at-risk due to climate change and other anthropogenic activities, addressing this long-standing debate is critical for making informed conservation decisions. We use demographic inference and allele frequency-environment relationships to investigate mechanisms of diversification in an African rainforest skink, Trachylepis affinis, a species inhabiting the gradient between rainforest and rainforest-savanna mosaic (ecotone). We provide compelling evidence of ecotone speciation, in which gene flow has all but ceased between rainforest and ecotone populations, at a level consistent with infrequent hybridization between sister species. Parallel patterns of genomic, morphological, and physiological divergence across this environmental gradient and pronounced allele frequency-environment correlation indicate speciation is mostly probably driven by ecological divergence, supporting a central role for divergent natural selection. Our results provide strong evidence for the importance of ecological gradients in African rainforest speciation and inform conservation strategies that preserve the processes that produce and maintain biodiversity.
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Affiliation(s)
- Adam H Freedman
- Faculty of Arts and Sciences Informatics Group, Harvard University, Cambridge, Massachusetts, USA
| | - Ryan J Harrigan
- Centre for Tropical Research and Institute of the Environment and Sustainability, University of California, Los Angeles, California, USA
| | - Ying Zhen
- Centre for Tropical Research and Institute of the Environment and Sustainability, University of California, Los Angeles, California, USA
- School of Life Sciences, Westlake University, Hangzhou, China
| | - Alison M Hamilton
- Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, Massachusetts, USA
| | - Thomas B Smith
- Centre for Tropical Research and Institute of the Environment and Sustainability, University of California, Los Angeles, California, USA
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA
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2
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Shaffer HB, Toffelmier E, Corbett-Detig RB, Escalona M, Erickson B, Fiedler P, Gold M, Harrigan RJ, Hodges S, Luckau TK, Miller C, Oliveira DR, Shaffer KE, Shapiro B, Sork VL, Wang IJ. Landscape Genomics to Enable Conservation Actions: The California Conservation Genomics Project. J Hered 2022; 113:577-588. [PMID: 35395669 DOI: 10.1093/jhered/esac020] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 07/04/2022] [Indexed: 12/16/2022] Open
Abstract
The California Conservation Genomics Project (CCGP) is a unique, critically important step forward in the use of comprehensive landscape genetic data to modernize natural resource management at a regional scale. We describe the CCGP, including all aspects of project administration, data collection, current progress, and future challenges. The CCGP will generate, analyze, and curate a single high-quality reference genome and 100-150 resequenced genomes for each of 153 species projects (representing 235 individual species) that span the ecological and phylogenetic breadth of California's marine, freshwater, and terrestrial ecosystems. The resulting portfolio of roughly 20 000 resequenced genomes will be analyzed with identical informatic and landscape genomic pipelines, providing a comprehensive overview of hotspots of within-species genomic diversity, potential and realized corridors connecting these hotspots, regions of reduced diversity requiring genetic rescue, and the distribution of variation critical for rapid climate adaptation. After 2 years of concerted effort, full funding ($12M USD) has been secured, species identified, and funds distributed to 68 laboratories and 114 investigators drawn from all 10 University of California campuses. The remaining phases of the CCGP include completion of data collection and analyses, and delivery of the resulting genomic data and inferences to state and federal regulatory agencies to help stabilize species declines. The aspirational goals of the CCGP are to identify geographic regions that are critical to long-term preservation of California biodiversity, prioritize those regions based on defensible genomic criteria, and provide foundational knowledge that informs management strategies at both the individual species and ecosystem levels.
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Affiliation(s)
- H Bradley Shaffer
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA.,California Department of Fish and Wildlife, Fisheries Branch, West Sacramento, CA 95605, USA
| | - Erin Toffelmier
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Russ B Corbett-Detig
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Merly Escalona
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Bjorn Erickson
- U.S. Fish and Wildlife Service, Sacramento, CA 95825, USA
| | - Peggy Fiedler
- Natural Reserve System, Office of the President, University of California, Oakland, CA 94607, USA
| | - Mark Gold
- California Natural Resources Agency, 1416 Ninth Street, Suite 1311, Sacramento, CA 95814, USA
| | - Ryan J Harrigan
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA.,Center for Tropical Research, Institute for Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Scott Hodges
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Tara K Luckau
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Courtney Miller
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Daniel R Oliveira
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Kevin E Shaffer
- California Department of Fish and Wildlife, Fisheries Branch, West Sacramento, CA 95605, USA
| | - Beth Shapiro
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.,Howard Hughes Medical Institute, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Victoria L Sork
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Ian J Wang
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA.,Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
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Chen Y, Jiang Z, Fan P, Ericson PGP, Song G, Luo X, Lei F, Qu Y. The combination of genomic offset and niche modelling provides insights into climate change-driven vulnerability. Nat Commun 2022; 13:4821. [PMID: 35974023 PMCID: PMC9381542 DOI: 10.1038/s41467-022-32546-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 08/01/2022] [Indexed: 11/09/2022] Open
Abstract
Global warming is increasingly exacerbating biodiversity loss. Populations locally adapted to spatially heterogeneous environments may respond differentially to climate change, but this intraspecific variation has only recently been considered when modelling vulnerability under climate change. Here, we incorporate intraspecific variation in genomic offset and ecological niche modelling to estimate climate change-driven vulnerability in two bird species in the Sino-Himalayan Mountains. We found that the cold-tolerant populations show higher genomic offset but risk less challenge for niche suitability decline under future climate than the warm-tolerant populations. Based on a genome-niche index estimated by combining genomic offset and niche suitability change, we identified the populations with the least genome-niche interruption as potential donors for evolutionary rescue, i.e., the populations tolerant to climate change. We evaluated potential rescue routes via a landscape genetic analysis. Overall, we demonstrate that the integration of genomic offset, niche suitability modelling, and landscape connectivity can improve climate change-driven vulnerability assessments and facilitate effective conservation management.
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Affiliation(s)
- Yilin Chen
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Zhiyong Jiang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ping Fan
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Per G P Ericson
- Department of Bioinformatics and Genetics, Swedish Museum of Natural History, PO Box 50007, SE-104 05, Stockholm, Sweden
| | - Gang Song
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xu Luo
- Faculty of Biodiversity and Conservation, Southwest Forestry University, Kunming, China
| | - Fumin Lei
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China. .,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China. .,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China.
| | - Yanhua Qu
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China. .,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
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Alvarado AH, Bossu CM, Harrigan RJ, Bay RA, Nelson ARP, Smith TB, Ruegg KC. Genotype‐environment associations across spatial scales reveal the importance of putative adaptive genetic variation in divergence. Evol Appl 2022; 15:1390-1407. [PMID: 36187181 PMCID: PMC9488676 DOI: 10.1111/eva.13444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 06/04/2022] [Indexed: 12/01/2022] Open
Abstract
Identifying areas of high evolutionary potential is a judicious strategy for developing conservation priorities in the face of environmental change. For wide‐ranging species occupying heterogeneous environments, the evolutionary forces that shape distinct populations can vary spatially. Here, we investigate patterns of genomic variation and genotype–environment associations in the hermit thrush (Catharus guttatus), a North American songbird, at broad (across the breeding range) and narrow spatial scales (at a hybrid zone). We begin by building a genoscape or map of genetic variation across the breeding range and find five distinct genetic clusters within the species, with the greatest variation occurring in the western portion of the range. Genotype–environment association analyses indicate higher allelic turnover in the west than in the east, with measures of temperature surfacing as key predictors of putative adaptive genomic variation rangewide. Since broad patterns detected across a species' range represent the aggregate of many locally adapted populations, we investigate whether our broadscale analysis is consistent with a finer scale analysis. We find that top rangewide temperature‐associated loci vary in their clinal patterns (e.g., steep clines vs. fixed allele frequencies) across a hybrid zone in British Columbia, suggesting that the environmental predictors and the associated candidate loci identified in the rangewide analysis are of variable importance in this particular region. However, two candidate loci exhibit strong concordance with the temperature gradient in British Columbia, suggesting a potential role for temperature‐related barriers to gene flow and/or temperature‐driven ecological selection in maintaining putative local adaptation. This study demonstrates how patterns identified at the broad (macrogeographic) scale can be validated by investigating genotype–environment correlations at the local (microgeographic) scale. Furthermore, our results highlight the importance of considering the spatial distribution of putative adaptive variation when assessing population‐level sensitivity to climate change and other stressors.
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Affiliation(s)
- Allison H. Alvarado
- Biology Department California State University Channel Islands Camarillo CA USA
| | - Christen M. Bossu
- Center for Tropical Research, Institute of Environment and Sustainability University of California Los Angeles CA USA
- Department of Biology Colorado State University Fort Collins CO USA
| | - Ryan J. Harrigan
- Center for Tropical Research, Institute of Environment and Sustainability University of California Los Angeles CA USA
| | - Rachael A. Bay
- Department of Evolution and Ecology University of California Davis CA USA
| | | | - Thomas B. Smith
- Center for Tropical Research, Institute of Environment and Sustainability University of California Los Angeles CA USA
- Department of Ecology and Evolutionary Biology University of California Los Angeles CA USA
| | - Kristen C. Ruegg
- Department of Biology Colorado State University Fort Collins CO USA
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