1
|
Barrett LH, Fraga D, Lehtinen RM. The Genetic Basis of Melanism in Abert's Squirrel ( Sciurus aberti). Animals (Basel) 2024; 14:648. [PMID: 38396615 PMCID: PMC10885973 DOI: 10.3390/ani14040648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/14/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024] Open
Abstract
Melanism is widespread in different taxa and has been hypothesized to provide adaptive benefits in certain environments. Melanism is typically caused by mutations in one of two regulatory genes: the Melanocortin 1 Receptor (MC1R) or the Agouti Signaling Protein (ASIP). Melanism has repeatedly evolved among tree squirrels and their relatives (tribe Sciurini) in at least 12 different species based on our review of the literature. The causal mutations for melanism have been characterized in two species so far. This study examines Abert's Squirrel (Sciurus aberti), which has a melanistic morph whose genetic basis has not yet been established. We sequenced the MC1R and ASIP genes for five wild-type and seven melanistic S. aberti individuals to search for melanism-associated mutations. A novel single base pair mutation in the ASIP gene, unique to S. aberti, was found to be associated with melanism in the species, indicating that melanism in S. aberti evolved independently from other tree squirrels and thus represents an example of convergent evolution. The independent evolution of melanism in this species suggests that there is an adaptive advantage to the melanistic phenotype. The geographic range and habitat of S. aberti suggest possible benefits associated with thermoregulation, post-forest-fire camouflage, or other untested hypotheses.
Collapse
Affiliation(s)
| | | | - Richard M. Lehtinen
- Biology Department, 931 College Mall, The College of Wooster, Wooster, OH 44691, USA; (L.H.B.); (D.F.)
| |
Collapse
|
2
|
Elkin J, Martin A, Courtier-Orgogozo V, Santos ME. Analysis of the genetic loci of pigment pattern evolution in vertebrates. Biol Rev Camb Philos Soc 2023; 98:1250-1277. [PMID: 37017088 DOI: 10.1111/brv.12952] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 04/06/2023]
Abstract
Vertebrate pigmentation patterns are amongst the best characterised model systems for studying the genetic basis of adaptive evolution. The wealth of available data on the genetic basis for pigmentation evolution allows for analysis of trends and quantitative testing of evolutionary hypotheses. We employed Gephebase, a database of genetic variants associated with natural and domesticated trait variation, to examine trends in how cis-regulatory and coding mutations contribute to vertebrate pigmentation phenotypes, as well as factors that favour one mutation type over the other. We found that studies with lower ascertainment bias identified higher proportions of cis-regulatory mutations, and that cis-regulatory mutations were more common amongst animals harbouring a higher number of pigment cell classes. We classified pigmentation traits firstly according to their physiological basis and secondly according to whether they affect colour or pattern, and identified that carotenoid-based pigmentation and variation in pattern boundaries are preferentially associated with cis-regulatory change. We also classified genes according to their developmental, cellular, and molecular functions. We found a greater proportion of cis-regulatory mutations in genes implicated in upstream developmental processes compared to those involved in downstream cellular functions, and that ligands were associated with a higher proportion of cis-regulatory mutations than their respective receptors. Based on these trends, we discuss future directions for research in vertebrate pigmentation evolution.
Collapse
Affiliation(s)
- Joel Elkin
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, 800 22nd St. NW, Suite 6000, Washington, DC, 20052, USA
| | | | - M Emília Santos
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| |
Collapse
|
3
|
Large scale phenotypic characterisation of Hierophis viridiflavus (Squamata: Serpentes): climatic and environmental drivers suggest the role of evolutionary processes in a polymorphic species. Evol Ecol 2023. [DOI: 10.1007/s10682-023-10234-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
AbstractColour variability is largely widespread in the animal world as it is tightly associated with fitness and survivorship. Therefore, the drivers and implications of such variability have been of great interest for zoologists in the past decades. Reptiles are excellent models to investigate colour variations and expression under different conditions. Here, we focused on melanism occurrence in the two main lineages of Hierophis viridiflavus at the scale of the species distribution, by extracting available data from iNaturalist, a citizen science network, with the aim of detecting any pure effect of climate or local habitat on colour expression. Our analyses highlighted that habitat does not explain differences in phenotypes, whereas marked effects of geographic and climatic variables were detected. However, the observed climatic effects could be a proxy of the geographical distribution of the two groups, and thus the high occurrence of bright colourations in western populations of the eastern lineage could be addressed to an ongoing event of asymmetric gene flow in contact zones. The current distribution of phenotypes could be the outcome of the evolutionary history of the species combined with the geological history of the Mediterranean region. This investigation, though, is only preliminary and molecular analyses on highly variable regions of the genome are mandatory to address this issue.
Collapse
|
4
|
McDonald JMC, Reed RD. Patterns of selection across gene regulatory networks. Semin Cell Dev Biol 2022; 145:60-67. [PMID: 35474149 DOI: 10.1016/j.semcdb.2022.03.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 01/31/2022] [Accepted: 03/23/2022] [Indexed: 12/29/2022]
Abstract
Gene regulatory networks (GRNs) are the core engine of organismal development. If we would like to understand the origin and diversification of phenotypes, it is necessary to consider the structure of GRNs in order to reconstruct the links between genetic mutations and phenotypic change. Much of the progress in evolutionary developmental biology, however, has occurred without a nuanced consideration of the evolution of functional relationships between genes, especially in the context of their broader network interactions. Characterizing and comparing GRNs across traits and species in a more detailed way will allow us to determine how network position influences what genes drive adaptive evolution. In this perspective paper, we consider the architecture of developmental GRNs and how positive selection strength may vary across a GRN. We then propose several testable models for these patterns of selection and experimental approaches to test these models.
Collapse
Affiliation(s)
- Jeanne M C McDonald
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States.
| | - Robert D Reed
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States.
| |
Collapse
|
5
|
González-Guzmán S, Mellink E, Tremor S. MELANISTIC CALIFORNIA GROUND SQUIRRELS (OTOSPERMOPHILUS BEECHEYI). SOUTHWEST NAT 2022. [DOI: 10.1894/0038-4909-65.3-4.266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
| | - Eric Mellink
- Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada–Tijuana 3918, 22860 Ensenada, México (EM)
| | - Scott Tremor
- San Diego Natural History Museum, P.O. Box 121390, San Diego, CA 92112 (ST)
| |
Collapse
|
6
|
Kokita T, Ueno K, Yamasaki YY, Matsuda M, Tabata R, Nagano AJ, Mishina T, Watanabe K. Gudgeon fish with and without genetically determined countershading coexist in heterogeneous littoral environments of an ancient lake. Ecol Evol 2021; 11:13283-13294. [PMID: 34646469 PMCID: PMC8495823 DOI: 10.1002/ece3.8050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/02/2021] [Accepted: 08/09/2021] [Indexed: 11/16/2022] Open
Abstract
Countershading, characterized by a darker dorsal surface and lighter ventral surface, is common among many animals. This dorsoventral pigment polarity is often thought to be adaptive coloration for camouflage. By contrast, noncountershaded (melanistic) morphs often occur within a species due to genetic color polymorphism in terrestrial animals. However, the polymorphism with either countershaded or melanistic morphs is poorly known in wild aquatic animals. This study explored the genetic nature of diverged color morphs of a lineage of gudgeon fish (genus Sarcocheilichthys) in the ancient Lake Biwa and propose this system as a novel model for testing hypotheses of functional aspects of countershading and its loss in aquatic environments. This system harbors two color morphs that have been treated taxonomically as separate species; Sarcocheilichthys variegatus microoculus which occurs throughout the littoral zone and Sarcocheilichthys biwaensis which occurs in and around rocky areas. First, we confirmed that the divergence of dorsoventral color patterns between the two morphs is under strict genetic control at the levels of chromatophore distribution and melanin-related gene expression under common garden rearing. The former morph displayed sharp countershading coloration, whereas the latter morph exhibited a strong tendency toward its loss. The crossing results indicated that this divergence was likely controlled by a single locus in a two-allele Mendelian inheritance pattern. Furthermore, our population genomic and genome-wide association study analyses detected no genome-wide divergence between the two morphs, except for one region near a locus that may be associated with the color divergence. Thus, these morphs are either in a state of intraspecific color polymorphism or two incipient species. Evolutionary forces underlying this polymorphism appear to be associated with heterogeneous littoral environments in this lake. Future ecological genomic research will provide insight into adaptive functions of this widespread coloration, including the eco-evolutionary drivers of its loss, in the aquatic world.
Collapse
Affiliation(s)
- Tomoyuki Kokita
- Faculty of Marine Science and TechnologyFukui Prefectural UniversityObamaJapan
| | - Kohtaro Ueno
- Faculty of Marine Science and TechnologyFukui Prefectural UniversityObamaJapan
| | | | | | | | - Atsushi J. Nagano
- Faculty of AgricultureRyukoku UniversityOtsuJapan
- Institute for Advanced BiosciencesKeio UniversityTsuruokaJapan
| | - Tappei Mishina
- Laboratory for Chromosome SegregationRIKEN Center for Biosystems Dynamics ResearchKobeJapan
| | | |
Collapse
|
7
|
Kang L, Michalak P, Hallerman E, Moncrief ND. A Draft Genome Assembly for the Eastern Fox Squirrel, Sciurus niger. G3-GENES GENOMES GENETICS 2021; 11:6373894. [PMID: 34550334 PMCID: PMC8664420 DOI: 10.1093/g3journal/jkab315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/27/2021] [Indexed: 11/12/2022]
Abstract
The eastern fox squirrel, Sciurus niger, exhibits marked geographic variation in size and coat color, is a model organism for studies of behavior and ecology, and a potential model for investigating physiological solutions to human porphyrias. We assembled a genome using Illumina HiSeq, PacBio SMRT, and Oxford Nanopore MinION sequencing platforms. Together, the sequencing data resulted in a draft genome of 2.99 Gb, containing 32,830 scaffolds with an average size of 90.9Kb and N50 of 183.8 Kb. Genome completeness was estimated to be 93.78%. A total of 24,443 protein-encoding genes were predicted from the assembly, and 23,079 (94.42%) were annotated. Repeat elements comprised an estimated 38.49% of the genome, with the majority being LINEs (13.92%), SINEs (6.04%), and LTR elements. The topology of the species tree reconstructed using maximum likelihood phylogenetic analysis was congruent with those of previous studies. This genome assembly can prove useful for comparative studies of genome structure and function in this rapidly diversifying lineage of mammals, for studies of population genomics and adaptation, and for biomedical research. Predicted amino acid sequence alignments for genes affecting heme biosynthesis, color vision and hibernation showed point mutations and indels that may affect protein function and ecological adaptation.
Collapse
Affiliation(s)
- Lin Kang
- Edward Via College of Osteopathic Medicine, University of Louisiana Monroe, Monroe, LA 71203, USA.,Center for One Health Research, VA-MD Regional College of Veterinary Medicine, Blacksburg, VA 24060, USA
| | - Pawel Michalak
- Edward Via College of Osteopathic Medicine, University of Louisiana Monroe, Monroe, LA 71203, USA.,Center for One Health Research, VA-MD Regional College of Veterinary Medicine, Blacksburg, VA 24060, USA.,Institute of Evolution, Haifa University, Haifa 3498838, Israel
| | - Eric Hallerman
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - Nancy D Moncrief
- Virginia Museum of Natural History, 21 Starling Avenue, Martinsville, Virginia 24112, USA. 276.634.4177
| |
Collapse
|
8
|
Stothart MR, Newman AEM. Shades of grey: host phenotype dependent effect of urbanization on the bacterial microbiome of a wild mammal. Anim Microbiome 2021; 3:46. [PMID: 34225812 PMCID: PMC8256534 DOI: 10.1186/s42523-021-00105-4] [Citation(s) in RCA: 4] [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: 03/19/2021] [Accepted: 05/31/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Host-associated microbiota are integral to the ecology of their host and may help wildlife species cope with rapid environmental change. Urbanization is a globally replicated form of severe environmental change which we can leverage to better understand wildlife microbiomes. Does the colonization of separate cities result in parallel changes in the intestinal microbiome of wildlife, and if so, does within-city habitat heterogeneity matter? Using 16S rRNA gene amplicon sequencing, we quantified the effect of urbanization (across three cities) on the microbiome of eastern grey squirrels (Sciurus carolinensis). Grey squirrels are ubiquitous in rural and urban environments throughout their native range, across which they display an apparent coat colour polymorphism (agouti, black, intermediate). RESULTS Grey squirrel microbiomes differed between rural and city environments; however, comparable variation was explained by habitat heterogeneity within cities. Our analyses suggest that operational taxonomic unit (OTU) community structure was more strongly influenced by local environmental conditions (rural and city forests versus human built habitats) than urbanization of the broader landscape (city versus rural). The bacterial genera characterizing the microbiomes of built-environment squirrels are thought to specialize on host-derived products and have been linked in previous research to low fibre diets. However, despite an effect of urbanization at fine spatial scales, phylogenetic patterns in the microbiome were coat colour phenotype dependent. City and built-environment agouti squirrels displayed greater phylogenetic beta-dispersion than those in rural or forest environments, and null modelling results indicated that the phylogenetic structure of urban agouti squirrels did not differ greatly from stochastic expectations. CONCLUSIONS Squirrel microbiomes differed between city and rural environments, but differences of comparable magnitude were observed between land classes at a within-city scale. We did not observe strong evidence that inter-environmental differences were the result of disparate selective pressures. Rather, our results suggest that microbiota dispersal and ecological drift are integral to shaping the inter-environmental differences we observed. However, these processes were partly mediated by squirrel coat colour phenotype. Given a well-known urban cline in squirrel coat colour melanism, grey squirrels provide a useful free-living system with which to study how host genetics mediate environment x microbiome interactions.
Collapse
Affiliation(s)
- Mason R. Stothart
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, T2N 4Z6 Canada
| | - Amy E. M. Newman
- Department of Integrative Biology, College of Biological Sciences, University of Guelph, Guelph, N1G 2W1 Canada
| |
Collapse
|
9
|
Cronk L, Palombit R. Eastern gray squirrel (Sciurus carolinensis) color morphs do not differ in aggressiveness. Acta Ethol 2021. [DOI: 10.1007/s10211-021-00372-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
10
|
Abstract
The diversity of mammalian coat colors, and their potential adaptive significance, have long fascinated scientists as well as the general public. The recent decades have seen substantial improvement in our understanding of their genetic bases and evolutionary relevance, revealing novel insights into the complex interplay of forces that influence these phenotypes. At the same time, many aspects remain poorly known, hampering a comprehensive understanding of these phenomena. Here we review the current state of this field and indicate topics that should be the focus of additional research. We devote particular attention to two aspects of mammalian pigmentation, melanism and pattern formation, highlighting recent advances and outstanding challenges, and proposing novel syntheses of available information. For both specific areas, and for pigmentation in general, we attempt to lay out recommendations for establishing novel model systems and integrated research programs that target the genetics and evolution of these phenotypes throughout the Mammalia.
Collapse
Affiliation(s)
- Eduardo Eizirik
- Laboratory of Genomics and Molecular Biology, School of Health and Life Sciences, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul 90619-900, Brazil;
| | - Fernanda J Trindade
- Laboratory of Genomics and Molecular Biology, School of Health and Life Sciences, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul 90619-900, Brazil;
| |
Collapse
|
11
|
Jamie GA, Meier JI. The Persistence of Polymorphisms across Species Radiations. Trends Ecol Evol 2020; 35:795-808. [DOI: 10.1016/j.tree.2020.04.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/08/2020] [Accepted: 04/16/2020] [Indexed: 12/12/2022]
|
12
|
Caro T, Mallarino R. Coloration in Mammals. Trends Ecol Evol 2020; 35:357-366. [PMID: 31980234 PMCID: PMC10754262 DOI: 10.1016/j.tree.2019.12.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/11/2022]
Abstract
Mammalian colors and color patterns are some of the most diverse and conspicuous traits found in nature and have been widely studied from genetic/developmental and evolutionary perspectives. In this review we first discuss the proximate causes underlying variation in pigment type (i.e., color) and pigment distribution (i.e., color pattern) and highlight both processes as having a distinct developmental basis. Then, using multiple examples, we discuss ultimate factors that have driven the evolution of coloration differences in mammals, which include background matching, intra- and interspecific signaling, and physiological influences. Throughout, we outline bridges between developmental and functional investigatory approaches that help broaden knowledge of mammals' memorable external appearances, and we point out areas for future interdisciplinary research.
Collapse
Affiliation(s)
- Tim Caro
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS81TQ, UK; Center for Population Biology, 1 Shields Avenue, University of California, Davis, CA 95616, USA.
| | - Ricardo Mallarino
- Department of Molecular Biology, Princeton University, 119 Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| |
Collapse
|
13
|
Graipel ME, Bogoni JA, Giehl ELH, Cerezer FO, Cáceres NC, Eizirik E. Melanism evolution in the cat family is influenced by intraspecific communication under low visibility. PLoS One 2019; 14:e0226136. [PMID: 31851714 PMCID: PMC6919575 DOI: 10.1371/journal.pone.0226136] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 11/20/2019] [Indexed: 11/18/2022] Open
Abstract
Melanism in the cat family has been associated with functions including camouflage, thermoregulation and parasite resistance. Here we investigate a new hypothesis proposing that the evolution of melanism in cats has additionally been influenced by communication functions of body markings. To evaluate this hypothesis, we assembled a species-level data set of morphological (body marks: white marks on the backs of ears) and ecological (circadian activity: arrhythmic/nocturnal, and environmental preference: open/closed) characteristics that could be associated with communication via body markings, and combined these data with a dated molecular phylogeny. Next, we tested the association between melanism and communication, first by relating species’ body marks with their ecological conditions, using a Bayesian implementation of the threshold model. Second, to explore the evolution of characteristics potentially influencing melanism in cat species, we modeled their evolution relative to melanism using models of coordinated vs. independent character changes. Our results suggest that white marks are associated with intraspecific communication between individuals that have non-melanistic phenotypes, as well as towards melanistic individuals (without white marks). The absence of white marks in a melanistic individual tends to be a limiting condition for intraspecific visual communication at night, resulting in an evolutionary dilemma for these species, i.e. to be almost invisible at night, but not to communicate visually. The comparative analysis of several evolutionary models indicated more support for the evolution of melanism being coordinated with the evolution of arrhythmic activity and white marks on the backs of ears.
Collapse
Affiliation(s)
- Maurício Eduardo Graipel
- Departamento de Ecologia e Zoologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
- * E-mail:
| | - Juliano André Bogoni
- Laboratório de Ecologia, Manejo e Conservação de Fauna Silvestre (LEMaC), Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, São Paulo, Brazil
| | - Eduardo Luís Hettwer Giehl
- Programa de Pós-Graduação em Ecologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Felipe O. Cerezer
- Programa de Pós-Graduação em Biodiversidade Animal, CCNE, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Nilton Carlos Cáceres
- Departamento de Ecologia e Evolução, CCNE, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Eduardo Eizirik
- Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| |
Collapse
|