1
|
Fortuna MA. The phenotypic plasticity of an evolving digital organism. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220852. [PMID: 36117864 PMCID: PMC9470259 DOI: 10.1098/rsos.220852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
Climate change will fundamentally reshape life on Earth in the coming decades. Therefore, understanding the extent to which species will cope with rising temperatures is of paramount importance. Phenotypic plasticity is the ability of an organism to change the morphological and functional traits encoded by its genome in response to the environment. I show here that plasticity pervades not only natural but also artificial systems that mimic the developmental process of biological organisms, such as self-replicating and evolving computer programs-digital organisms. Specifically, the environment can modify the sequence of instructions executed from a digital organism's genome (i.e. its transcriptome), which results in changes in its phenotype (i.e. the ability of the digital organism to perform Boolean logic operations). This genetic-based pathway for plasticity comes at a fitness cost to an organism's viability and generation time: the longer the transcriptome (higher fitness cost), the more chances for the environment to modify the genetic execution flow control, and the higher the likelihood for the genome to encode novel phenotypes. By studying to what extent a digital organism's phenotype is influenced by both its genome and the environment, I make a parallelism between natural and artificial evolving systems on how natural selection might slide trait regulation anywhere along a continuum from total environmental control to total genomic control, which harbours lessons not only for designing evolvable artificial systems, but also for synthetic biology.
Collapse
Affiliation(s)
- Miguel A. Fortuna
- Computational Biology Lab, Estación Biológica de Doñana (EBD), Spanish National Research Council (CSIC), Seville, Spain
| |
Collapse
|
2
|
Gamble MM, Calsbeek RG. A potential role for restricted intertactical heritability in preventing intralocus conflict. Evol Appl 2021; 14:2576-2590. [PMID: 34815740 PMCID: PMC8591329 DOI: 10.1111/eva.13292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 08/07/2021] [Accepted: 08/12/2021] [Indexed: 11/29/2022] Open
Abstract
Intralocus sexual conflict, which arises when the same trait has different fitness optima in males and females, reduces population growth rates. Recently, evolutionary biologists have recognized that intralocus conflict can occur between morphs or reproductive tactics within a sex and that intralocus tactical conflict might constrain tactical dimorphism and population growth rates just as intralocus sexual conflict constrains sexual dimorphism and population growth rates. However, research has only recently focused on sexual and tactical intralocus conflict simultaneously, and there is no formal theory connecting the two. We present a graphical model of how tactical and sexual conflict over the same trait could constrain both sexual and tactical dimorphisms. We then use Coho salmon (Oncorhynchus kisutch), an important species currently protected under the Endangered Species Act, to investigate the possibility of simultaneous sexual and tactical conflict. Larger Coho males gain access to females through fighting while smaller males are favored through sneaking tactics, and female reproductive success is positively correlated with length. We tested for antagonistic selection on length at maturity among sexes and tactics and then used parent-offspring regression to calculate sex- and tactic-specific heritabilities to determine whether and where intralocus conflict exists. Selection on length varied in intensity and form among tactics and years. Length was heritable between dams and daughters (h 2 ± 95% CI = 0.361 ± 0.252) and between fighter males and their fighter sons (0.867 ± 0.312), but no other heritabilities differed significantly from zero. The lack of intertactical heritabilities in this system, combined with similar selection on length among tactics, suggests the absence of intralocus conflict between sexes and among tactics, allowing for the evolution of sexual and tactical dimorphisms. Our results suggest that Coho salmon populations are unlikely to be constrained by intralocus conflict or artificial selection on male tactic.
Collapse
Affiliation(s)
- Madilyn M. Gamble
- Graduate Program in Ecology, Evolution, Ecosystems, and SocietyDartmouth CollegeHanoverNHUSA
| | - Ryan G. Calsbeek
- Graduate Program in Ecology, Evolution, Ecosystems, and SocietyDartmouth CollegeHanoverNHUSA
| |
Collapse
|
3
|
Lymbery SJ, Tomkins JL, Buzatto BA, Hosken DJ. Kin-mediated plasticity in alternative reproductive tactics. Proc Biol Sci 2021; 288:20211069. [PMID: 34344179 PMCID: PMC8334832 DOI: 10.1098/rspb.2021.1069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/12/2021] [Indexed: 11/12/2022] Open
Abstract
Conditional strategies occur when the relative fitness pay-off from expressing a given phenotype is contingent upon environmental circumstances. This conditional strategy model underlies cases of alternative reproductive tactics, in which individuals of one sex employ different means to obtain reproduction. How kin structure affects the expression of alternative reproductive tactics remains unexplored. We address this using the mite Rhizoglyphus echinopus, in which large males develop into aggressive 'fighters' and small males develop into non-aggressive 'scramblers.' Because only fighters kill their rivals, they should incur a greater indirect fitness cost when competing with their relatives, and thus fighter expression could be reduced in the presence of relatives. We raised mites in full-sibling or mixed-sibship groups and found that fighters were more common at higher body weights in full-sibling groups, not less common as we predicted (small individuals were almost exclusively scramblers in both treatments). This result could be explained if relatedness and cue variability are interpreted signals of population density, since fighters are more common at low densities in this species. Alternatively, our results may indicate that males compete more intensely with relatives in this species. We provide the first evidence of kin-mediated plasticity in the expression of alternative reproductive tactics.
Collapse
Affiliation(s)
- Samuel J. Lymbery
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9EZ, Cornwall, UK
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Joseph L. Tomkins
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Bruno A. Buzatto
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Western Australia, Australia
- Department of Biological Sciences (E8C 209), Macquarie University, Sydney 2109, New South Wales, Australia
| | - David J. Hosken
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9EZ, Cornwall, UK
| |
Collapse
|
4
|
Liotta MN, Abbott JK, Morris MR, Rios‐Cardenas O. Antagonistic selection on body size and sword length in a wild population of the swordtail fish, Xiphophorus multilineatus: Potential for intralocus tactical conflict. Ecol Evol 2021; 11:3941-3955. [PMID: 33976786 PMCID: PMC8093718 DOI: 10.1002/ece3.7288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/08/2021] [Accepted: 01/18/2021] [Indexed: 11/06/2022] Open
Abstract
Alternative reproductive tactics (ARTs) have provided valuable insights into how sexual selection and life history trade-offs can lead to variation within a sex. However, the possibility that tactics may constrain evolution through intralocus tactical conflict (IATC) is rarely considered. In addition, when IATC has been considered, the focus has often been on the genetic correlations between the ARTs, while evidence that the ARTs have different optima for associated traits and that at least one of the tactics is not at its optimum is often missing. Here, we investigate selection on three traits associated with the ARTs in the swordtail fish Xiphophorus multilineatus; body size, body shape, and the sexually selected trait for which these fishes were named, sword length (elongation of the caudal fin). All three traits are tactically dimorphic, with courter males being larger, deeper bodied and having longer swords, and the sneaker males being smaller, more fusiform and having shorter swords. Using measures of reproductive success in a wild population we calculated selection differentials, as well as linear and quadratic gradients. We demonstrated that the tactics have different optima and at least one of the tactics is not at its optimum for body size and sword length. Our results provide the first evidence of selection in the wild on the sword, an iconic trait for sexual selection. In addition, given the high probability that these traits are genetically correlated to some extent between the two tactics, our study suggests that IATC is constraining both body size and the sword from reaching their phenotypic optima. We discuss the importance of considering the role of IATC in the evolution of tactical dimorphism, how this conflict can be present despite tactical dimorphism, and how it is important to consider this conflict when explaining not only variation within a species but differences across species as well.
Collapse
Affiliation(s)
- Melissa N. Liotta
- Department of Biological SciencesThe Ohio Center for Ecological and Evolutionary StudiesOhio UniversityAthensOHUSA
| | | | - Molly R. Morris
- Department of Biological SciencesThe Ohio Center for Ecological and Evolutionary StudiesOhio UniversityAthensOHUSA
| | | |
Collapse
|
5
|
Buzatto BA, Clark HL. Selection for Male Weapons Boosts Female Fecundity, Eliminating Sexual Conflict in the Bulb Mite. Sci Rep 2020; 10:2311. [PMID: 32047190 PMCID: PMC7012872 DOI: 10.1038/s41598-020-59254-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 01/07/2020] [Indexed: 11/25/2022] Open
Abstract
Extreme differences between the sexes are usually explained by intense sexual selection on male weapons or ornaments. Sexually antagonistic genes, with a positive effect on male traits but a negative effect on female fitness, create a negative inter-sexual correlation for fitness (sexual conflict). However, such antagonism might not be apparent if sexually selected male traits are condition-dependent, and condition elevates female fitness. Here we reveal a surprising positive genetic correlation between male weaponry and female fecundity. Using mite lines that had previously been through 13 generations of selection on male weapons (fighting legs), we investigated correlated evolution in female fecundity. Females from lines under positive selection for weapons (up lines) evolved higher fecundity, despite evolving costly, thicker legs. This is likely because male mites have condition-dependent weaponry that increases our ability to indirectly select on male condition. Alleles with positive effects on condition in both sexes could have generated this correlation because: the up lines evolved a higher proportion of fighters and there were positive correlations between weapon size and the male morph and sex ratios of the offspring. This positive inter-sexual genetic correlation should boost the evolution of male weapons and extreme sex differences.
Collapse
Affiliation(s)
- Bruno A Buzatto
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, 6009, WA, Australia. .,Department of Biological Sciences (E8C 209), Macquarie University, Eastern Road, Sydney, 2109, NSW, Australia.
| | - Huon L Clark
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, 6009, WA, Australia
| |
Collapse
|
6
|
Abbott J, Rios‐Cardenas O, Morris MR. Insights from intralocus tactical conflict: adaptive states, interactions with ecology and population divergence. OIKOS 2019. [DOI: 10.1111/oik.06264] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Jessica Abbott
- Section for Evolutionary Ecology, Dept of Biology, Univ. Of Lund Sölvegatan 37 SE‐223 62 Lund Swede
| | | | | |
Collapse
|
7
|
Liotta MN, Abbott JK, Rios-Cardenas O, Morris MR. Tactical dimorphism: the interplay between body shape and mating behaviour in the swordtail Xiphophorus multilineatus (Cyprinodontiformes: Poeciliidae). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz053] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Melissa N Liotta
- Department of Biological Sciences, The Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA
| | | | - Oscar Rios-Cardenas
- Instituto de Ecología A.C., Red de Biología Evolutiva, Xalapa, Veracruz, México
| | - Molly R Morris
- Department of Biological Sciences, The Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA
| |
Collapse
|
8
|
Buzatto BA, Clark HL, Tomkins JL. Morph-specific artificial selection reveals a constraint on the evolution of polyphenisms. Proc Biol Sci 2019; 285:rspb.2018.0335. [PMID: 29794046 DOI: 10.1098/rspb.2018.0335] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 04/23/2018] [Indexed: 11/12/2022] Open
Abstract
Theory predicts that the evolution of polyphenic variation is facilitated where morphs are genetically uncoupled and free to evolve towards their phenotypic optima. However, the assumption that developmentally plastic morphs can evolve independently has not been tested directly. Using morph-specific artificial selection, we investigated correlated evolution between the sexes and male morphs of the bulb mite Rhizoglyphus echinopus Large 'fighter' males have a thick and sharply terminating pair of legs used to kill rival males, while small 'scrambler' males have unmodified legs, and search for unguarded females, avoiding fights. We selected on the relative leg width of only the fighter male morph, tracked the evolutionary responses in fighters and the correlated evolutionary responses in scramblers and females that were untouched by direct selection. Fighters diverged in relative leg thickness after six generations; assaying scramblers and females at the ninth generation we observed correlated responses in relative leg width in both. Our results represent strong evidence for the evolution of intraspecific phenotypic diversity despite correlated evolution between morphs and sexes, challenging the idea that male morphs are genetically uncoupled and free to independently respond to selection. We therefore question the perceived necessity for genetic independence in traits with extreme phenotypic plasticity.
Collapse
Affiliation(s)
- Bruno A Buzatto
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia .,Department of Biological Sciences (E8C 209), Macquarie University, 6 Wally's Walk, Sydney 2109, New South Wales, Australia
| | - Huon L Clark
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Joseph L Tomkins
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| |
Collapse
|
9
|
Van den Beuken TPG, Smallegange IM. Life-history consequences of bidirectional selection for male morph in a male-dimorphic bulb mite. EXPERIMENTAL & APPLIED ACAROLOGY 2018; 76:435-452. [PMID: 30421131 PMCID: PMC6280856 DOI: 10.1007/s10493-018-0320-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/18/2018] [Indexed: 06/09/2023]
Abstract
Intralocus sexual conflict (IASC) arises when males and females have different trait optima. Some males pursue different alternative reproductive tactics (ARTs) with different trait optima, resulting in different strengths of IASC. Consequently, for instance daughter fitness is differentially affected by her sire's morph. We tested if-and which-other life-history traits correlatively change in bidirectional, artificial selection experiments for ARTs. We used the male-dimorphic bulb mite Rhizoglyphus robini, the males of which are high-fitness 'fighters' or low-fitness 'scramblers'. Twice in each of the five generations of selection, we assessed clutch composition (number of mites of the various life stages present) and size (total number of offspring). Furthermore, we tracked offspring from egg to adulthood in the first and final generation to detect differences between selection lines in the size and duration of stages, and in maturation time. We found that selection for male morph increased the frequency of that morph. Furthermore, compared to fighter lines, scrambler lines produced more females, which laid larger eggs (in the final generations), and maintained a higher egg-laying rate for longer. Otherwise, our results showed no consistent differences between the selection lines in clutch size and composition, life stage size or duration, or maturation time. Though we found few correlated life-history trait changes in response to selection on male morph, the differences in egg laying rate and egg size suggest that IASC between fighters is costlier to females than IASC with scramblers. We hypothesize that these differences in reproductive traits allow fighter-offspring to perform better in small, declining populations but scrambler-offspring to perform better in large, growing populations.
Collapse
Affiliation(s)
- Tom P G Van den Beuken
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands.
| | - Isabel M Smallegange
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands
| |
Collapse
|