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Yeager J, Penacchio O. Outcomes of multifarious selection on the evolution of visual signals. Proc Biol Sci 2023; 290:20230327. [PMID: 37040810 PMCID: PMC10089717 DOI: 10.1098/rspb.2023.0327] [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: 10/05/2022] [Accepted: 03/17/2023] [Indexed: 04/13/2023] Open
Abstract
Multifarious sources of selection shape visual signals and can produce phenotypic divergence. Theory predicts that variance in warning signals should be minimal due to purifying selection, yet polymorphism is abundant. While in some instances divergent signals can evolve into discrete morphs, continuously variable phenotypes are also encountered in natural populations. Notwithstanding, we currently have an incomplete understanding of how combinations of selection shape fitness landscapes, particularly those which produce polymorphism. We modelled how combinations of natural and sexual selection act on aposematic traits within a single population to gain insights into what combinations of selection favours the evolution and maintenance of phenotypic variation. With a rich foundation of studies on selection and phenotypic divergence, we reference the poison frog genus Oophaga to model signal evolution. Multifarious selection on aposematic traits created the topology of our model's fitness landscape by approximating different scenarios found in natural populations. Combined, the model produced all types of phenotypic variation found in frog populations, namely monomorphism, continuous variation and discrete polymorphism. Our results afford advances into how multifarious selection shapes phenotypic divergence, which, along with additional modelling enhancements, will allow us to further our understanding of visual signal evolution.
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Affiliation(s)
- Justin Yeager
- Grupo de Investigación en Biodiversidad, Medio Ambiente y Salud (BIOMAS), Facultad de Ingenierías y Ciencas Aplicadas, Universidad de Las Américas, Ecuador
| | - Olivier Penacchio
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife KY16 9JP, UK
- Computer Vision Center, Computer Science Department, Universitat Autònoma de Barcelona, Bellaterra, Barcelona 08193, Spain
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Barzaghi B, Melotto A, Cogliati P, Manenti R, Ficetola GF. Factors determining the dorsal coloration pattern of aposematic salamanders. Sci Rep 2022; 12:17090. [PMID: 36224211 PMCID: PMC9556531 DOI: 10.1038/s41598-022-19466-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/30/2022] [Indexed: 01/04/2023] Open
Abstract
Aposematic bright colors have a key role for animal defense and can be expressed through metabolic production or by acquiring pigments from diet. Aposematic coloration can be related to both local adaptations and availability of trophic resources. The European fire salamander (Salamandra salamandra) shows significant color variability and occurs across a broad range of habitats. Here we combined field observations with common rearing experiments to disentangle the role of environmental conditions and local adaptations in determining aposematic coloration of salamander populations. We assessed color variation and measured habitat features and food availability in adults from 25 populations. Furthermore, we reared newborn larvae from 10 populations under different food availability and analyzed color of metamorphs. To assess color pattern, we measured the percentage of yellow covering the body, and the Hue, Saturation and Value of yellow coloration. Adult showed strong variation of color pattern; variation was strongly related to the individual's size, to habitat productivity and to food availability. Under common garden conditions, differences between populations were not anymore evident, and coloration was only affected by resource availability during larval development. Our results suggest that environmental conditions and food availability are more important than local adaptations in determining differences in aposematic color pattern.
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Affiliation(s)
- Benedetta Barzaghi
- grid.4708.b0000 0004 1757 2822Department of Environmental Science and Policy, University of Milano, Milan, Italy
| | - Andrea Melotto
- grid.11956.3a0000 0001 2214 904XCentre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, 7600 South Africa
| | - Paola Cogliati
- grid.4708.b0000 0004 1757 2822Department of Environmental Science and Policy, University of Milano, Milan, Italy
| | - Raoul Manenti
- grid.4708.b0000 0004 1757 2822Department of Environmental Science and Policy, University of Milano, Milan, Italy
| | - Gentile Francesco Ficetola
- grid.4708.b0000 0004 1757 2822Department of Environmental Science and Policy, University of Milano, Milan, Italy ,grid.11956.3a0000 0001 2214 904XCentre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, 7600 South Africa ,grid.450307.50000 0001 0944 2786Laboratoire D’Ecologie Alpine (LECA), CNRS, Univ. Grenoble Alpes, Grenoble, France
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Almeida DA, Mappes J, Gordon S. Predator-Induced Plasticity on Warning Signal and Larval Life-History Traits of the Aposematic Wood Tiger Moth, Arctia plantaginis. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.658177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Predator-induced plasticity in life-history and antipredator traits during the larval period has been extensively studied in organisms with complex life-histories. However, it is unclear whether different levels of predation could induce warning signals in aposematic organisms. Here, we investigated whether predator-simulated handling affects warning coloration and life-history traits in the aposematic wood tiger moth larva, Arctia plantaginis. As juveniles, a larger orange patch on an otherwise black body signifies a more efficient warning signal against predators but this comes at the costs of conspicuousness and thermoregulation. Given this, one would expect that an increase in predation risk would induce flexible expression of the orange patch. Prior research in this system points to plastic effects being important as a response to environmental changes for life history traits, but we had yet to assess whether this was the case for predation risk, a key driver of this species evolution. Using a full-sib rearing design, in which individuals were reared in the presence and absence of a non-lethal simulated bird attack, we evaluated flexible responses of warning signal size (number of orange segments), growth, molting events, and development time in wood tiger moths. All measured traits except development time showed a significant response to predation. Larvae from the predation treatment developed a more melanized warning signal (smaller orange patch), reached a smaller body size, and molted more often. Our results suggest plasticity is indeed important in aposematic organisms, but in this case may be complicated by the trade-off between costly pigmentation and other life-history traits.
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Galarza JA. Comparative transcriptomics of albino and warningly-coloured caterpillars. Ecol Evol 2021; 11:7507-7517. [PMID: 34188830 PMCID: PMC8216890 DOI: 10.1002/ece3.7581] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 03/29/2021] [Accepted: 04/01/2021] [Indexed: 12/23/2022] Open
Abstract
Coloration is perhaps one of the most prominent adaptations for survival and reproduction of many taxa. Coloration is of particular importance for aposematic species, which rely on their coloring and patterning acting as a warning signal to deter predators. Most research has focused on the evolution of warning coloration by natural selection. However, little information is available for color mutants of aposematic species, particularly at the genomic level. Here, I compare the transcriptomes of albino mutant caterpillars of the aposematic wood tiger moth (Arctia plantaginis) to those of their full sibs having their distinctive orange-black warning coloration. The results showed >290 differentially expressed genes genome-wide. Genes involved in the immune system, structural constituents of cuticular, and immunity were mostly downregulated in the albino caterpillars. Surprisingly, higher expression was observed in core melanin genes from albino caterpillars, suggesting that melanin synthesis may be disrupted in terminal ends of the pathway during its final conversion. Taken together, these results suggest that caterpillar albinism may not be due to a depletion of melanin precursor genes. In contrast, the albino condition may result from the combination of faulty melanin conversion late in its synthesis and structural deficiencies in the cuticular preventing its deposition. The results are discussed in the context of how albinism may impact individuals of aposematic species in the wild.
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Affiliation(s)
- Juan A. Galarza
- Dpartment of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
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Motyka M, Kusy D, Masek M, Bocek M, Li Y, Bilkova R, Kapitán J, Yagi T, Bocak L. Conspicuousness, phylogenetic structure, and origins of Müllerian mimicry in 4000 lycid beetles from all zoogeographic regions. Sci Rep 2021; 11:5961. [PMID: 33727670 PMCID: PMC7971032 DOI: 10.1038/s41598-021-85567-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 02/22/2021] [Indexed: 01/31/2023] Open
Abstract
Biologists have reported on the chemical defences and the phenetic similarity of net-winged beetles (Coleoptera: Lycidae) and their co-mimics. Nevertheless, our knowledge has remained fragmental, and the evolution of mimetic patterns has not been studied in the phylogenetic context. We illustrate the general appearance of ~ 600 lycid species and ~ 200 co-mimics and their distribution. Further, we assemble the phylogeny using the transcriptomic backbone and ~ 570 species. Using phylogenetic information, we closely scrutinise the relationships among aposematically coloured species, the worldwide diversity, and the distribution of aposematic patterns. The emitted visual signals differ in conspicuousness. The uniform coloured dorsum is ancestral and was followed by the evolution of bicoloured forms. The mottled patterns, i.e. fasciate, striate, punctate, and reticulate, originated later in the course of evolution. The highest number of sympatrically occurring patterns was recovered in New Guinea and the Andean mountain ecosystems (the areas of the highest abundance), and in continental South East Asia (an area of moderate abundance but high in phylogenetic diversity). Consequently, a large number of co-existing aposematic patterns in a single region and/or locality is the rule, in contrast with the theoretical prediction, and predators do not face a simple model-like choice but cope with complex mimetic communities. Lycids display an ancestral aposematic signal even though they sympatrically occur with differently coloured unprofitable relatives. We show that the highly conspicuous patterns evolve within communities predominantly formed by less conspicuous Müllerian mimics and, and often only a single species displays a novel pattern. Our work is a forerunner to the detailed research into the aposematic signalling of net-winged beetles.
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Affiliation(s)
- Michal Motyka
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
| | - Dominik Kusy
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
| | - Michal Masek
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
| | - Matej Bocek
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
| | - Yun Li
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
| | - R. Bilkova
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
| | - Josef Kapitán
- grid.10979.360000 0001 1245 3953Department of Optics, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Takashi Yagi
- grid.261455.10000 0001 0676 0594Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 Japan
| | - Ladislav Bocak
- grid.10979.360000 0001 1245 3953Laboratory of Diversity and Molecular Evolution, CATRIN-CRH, Palacky University, 17. listopadu 50, 771 46 Olomouc, Czech Republic
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Nielsen ME, Mappes J. Out in the open: behavior's effect on predation risk and thermoregulation by aposematic caterpillars. Behav Ecol 2020; 31:1031-1039. [PMID: 32760178 PMCID: PMC7390994 DOI: 10.1093/beheco/araa048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 03/31/2020] [Accepted: 05/06/2020] [Indexed: 11/14/2022] Open
Abstract
Warning coloration should be under strong stabilizing selection but often displays considerable intraspecific variation. Opposing selection on color by predators and temperature is one potential explanation for this seeming paradox. Despite the importance of behavior for both predator avoidance and thermoregulation, its role in mediating selection by predators and temperature on warning coloration has received little attention. Wood tiger moth caterpillars, Arctia plantaginis, have aposematic coloration, an orange patch on the black body. The size of the orange patch varies considerably: individuals with larger patches are safer from predators, but having a small patch is beneficial in cool environments. We investigated microhabitat preference by these caterpillars and how it interacted with their coloration. We expected caterpillar behavior to reflect a balance between spending time exposed to maximize basking and spending time concealed to avoid detection by predators. Instead, we found that caterpillars preferred exposed locations regardless of their coloration. Whether caterpillars were exposed or concealed had a strong effect on both temperature and predation risk, but caterpillars in exposed locations were both much warmer and less likely to be attacked by a bird predator (great tits, Parus major). This shared optimum may explain why we observed so little variation in caterpillar behavior and demonstrates the important effects of behavior on multiple functions of coloration.
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Affiliation(s)
- Matthew E Nielsen
- Department of Biological and Environmental Sciences, University of Jyväskylä, Survontie 9 C, Jyväskylä, Finland
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, Stockholm, Sweden
| | - Johanna Mappes
- Department of Biological and Environmental Sciences, University of Jyväskylä, Survontie 9 C, Jyväskylä, Finland
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