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Kalirad A, Burch CL, Azevedo RBR. Genetic drift promotes and recombination hinders speciation on holey fitness landscapes. PLoS Genet 2024; 20:e1011126. [PMID: 38252672 PMCID: PMC10833538 DOI: 10.1371/journal.pgen.1011126] [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: 04/03/2023] [Revised: 02/01/2024] [Accepted: 01/06/2024] [Indexed: 01/24/2024] Open
Abstract
Dobzhansky and Muller proposed a general mechanism through which microevolution, the substitution of alleles within populations, can cause the evolution of reproductive isolation between populations and, therefore, macroevolution. As allopatric populations diverge, many combinations of alleles differing between them have not been tested by natural selection and may thus be incompatible. Such genetic incompatibilities often cause low fitness in hybrids between species. Furthermore, the number of incompatibilities grows with the genetic distance between diverging populations. However, what determines the rate and pattern of accumulation of incompatibilities remains unclear. We investigate this question by simulating evolution on holey fitness landscapes on which genetic incompatibilities can be identified unambiguously. We find that genetic incompatibilities accumulate more slowly among genetically robust populations and identify two determinants of the accumulation rate: recombination rate and population size. In large populations with abundant genetic variation, recombination selects for increased genetic robustness and, consequently, incompatibilities accumulate more slowly. In small populations, genetic drift interferes with this process and promotes the accumulation of genetic incompatibilities. Our results suggest a novel mechanism by which genetic drift promotes and recombination hinders speciation.
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Affiliation(s)
- Ata Kalirad
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Christina L. Burch
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Ricardo B. R. Azevedo
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
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Huang J, Morgan B. Evolution of adult male horn developmental phenotypes and character displacement in Xylotrupes beetles (Scarabaeidae). Ecol Evol 2021; 11:5503-5510. [PMID: 34026024 PMCID: PMC8131760 DOI: 10.1002/ece3.7448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 02/01/2021] [Accepted: 03/03/2021] [Indexed: 11/06/2022] Open
Abstract
Character displacement that leads to divergent phenotypes between sympatric species has been hypothesized to facilitate coexistence and promote the accumulation of biodiversity. However, there are alternative evolutionary mechanisms that may also lead to the evolution of phenotypic divergence between sympatric species; one of the mechanisms is evolutionary contingency. We studied the evolution of the presence and absence of a major male horn phenotype, which may have ecological implications for promoting coexistence between sympatric beetles, across geographic populations from different Xylotrupes beetles. By using a previously published phylogeny with 80 Xylotrupes taxa, we estimated the transition rates between the two phenotypic states (i.e., presence vs. absence of a major male phenotype). Based on the estimated transition rates, we then simulated possible phenotypic outcomes between sympatric species. We found that sympatric species were equally likely to evolve the same versus distinct phenotypic states based on the estimated transition rates given the phylogeny. The empirically observed number of sympatric species showing different phenotypic states can be explained by evolutionary contingency alone. We discussed the importance of applying phylogenetic comparative methods when studying phenotypic evolution and more generally to investigate the effect of stochastic processes before making deterministic inferences.
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Affiliation(s)
- Jen‐Pan Huang
- Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
| | - Brett Morgan
- Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
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Cai F, Gao R, Zhao Z, Ding M, Jiang S, Yagtu C, Zhu H, Zhang J, Ebner T, Mayrhofer-Reinhartshuber M, Kainz P, Chenthamara K, Akcapinar GB, Shen Q, Druzhinina IS. Evolutionary compromises in fungal fitness: hydrophobins can hinder the adverse dispersal of conidiospores and challenge their survival. THE ISME JOURNAL 2020; 14:2610-2624. [PMID: 32632264 PMCID: PMC7490268 DOI: 10.1038/s41396-020-0709-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 06/17/2020] [Accepted: 06/25/2020] [Indexed: 12/13/2022]
Abstract
Fungal evolutionary biology is impeded by the scarcity of fossils, irregular life cycles, immortality, and frequent asexual reproduction. Simple and diminutive bodies of fungi develop inside a substrate and have exceptional metabolic and ecological plasticity, which hinders species delimitation. However, the unique fungal traits can shed light on evolutionary forces that shape the environmental adaptations of these taxa. Higher filamentous fungi that disperse through aerial spores produce amphiphilic and highly surface-active proteins called hydrophobins (HFBs), which coat spores and mediate environmental interactions. We exploited a library of HFB-deficient mutants for two cryptic species of mycoparasitic and saprotrophic fungi from the genus Trichoderma (Hypocreales) and estimated fungal development, reproductive potential, and stress resistance. HFB4 and HFB10 were found to be relevant for Trichoderma fitness because they could impact the spore-mediated dispersal processes and control other fitness traits. An analysis in silico revealed purifying selection for all cases except for HFB4 from T. harzianum, which evolved under strong positive selection pressure. Interestingly, the deletion of the hfb4 gene in T. harzianum considerably increased its fitness-related traits. Conversely, the deletion of hfb4 in T. guizhouense led to the characteristic phenotypes associated with relatively low fitness. The net contribution of the hfb4 gene to fitness was found to result from evolutionary tradeoffs between individual traits. Our analysis of HFB-dependent fitness traits has provided an evolutionary snapshot of the selective pressures and speciation process in closely related fungal species.
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Affiliation(s)
- Feng Cai
- The Key Laboratory of Plant Immunity, Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Nanjing Agricultural University, 210095, Nanjing, China
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, A1060, Vienna, Austria
| | - Renwei Gao
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
| | - Zheng Zhao
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
| | - Mingyue Ding
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
| | - Siqi Jiang
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
| | - Civan Yagtu
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, A1060, Vienna, Austria
| | - Hong Zhu
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
| | - Jian Zhang
- The Key Laboratory of Plant Immunity, Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Nanjing Agricultural University, 210095, Nanjing, China
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China
| | | | | | | | - Komal Chenthamara
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, A1060, Vienna, Austria
| | - Günseli Bayram Akcapinar
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, A1060, Vienna, Austria
- Department of Medical Biotechnology, Institute of Health Sciences, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Qirong Shen
- The Key Laboratory of Plant Immunity, Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Nanjing Agricultural University, 210095, Nanjing, China.
| | - Irina S Druzhinina
- The Key Laboratory of Plant Immunity, Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Nanjing Agricultural University, 210095, Nanjing, China.
- Fungal Genomics Laboratory (FungiG), Nanjing Agricultural University, 210095, Nanjing, China.
- Institute of Chemical, Environmental and Bioscience Engineering (ICEBE), TU Wien, A1060, Vienna, Austria.
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Huang JP, Knowles LL. Testing the impact of oceanic barriers on population subdivision, speciation and zoogeographical community assembly in Xylotrupes beetles across the Indo-Australian Archipelago. Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Jen-Pan Huang
- Department of Ecology and Evolutionary Biology, Museum of Zoology, University of Michigan, Ann Arbor, MI, USA
| | - L Lacey Knowles
- Department of Ecology and Evolutionary Biology, Museum of Zoology, University of Michigan, Ann Arbor, MI, USA
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