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Palominos MF, Muhl V, Richards EJ, Miller CT, Martin CH. Jaw size variation is associated with a novel craniofacial function for galanin receptor 2 in an adaptive radiation of pupfishes. Proc Biol Sci 2023; 290:20231686. [PMID: 37876194 PMCID: PMC10598438 DOI: 10.1098/rspb.2023.1686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/02/2023] [Indexed: 10/26/2023] Open
Abstract
Understanding the genetic basis of novel adaptations in new species is a fundamental question in biology. Here we demonstrate a new role for galr2 in vertebrate craniofacial development using an adaptive radiation of trophic specialist pupfishes endemic to San Salvador Island, Bahamas. We confirmed the loss of a putative Sry transcription factor binding site upstream of galr2 in scale-eating pupfish and found significant spatial differences in galr2 expression among pupfish species in Meckel's cartilage using in situ hybridization chain reaction (HCR). We then experimentally demonstrated a novel role for Galr2 in craniofacial development by exposing embryos to Garl2-inhibiting drugs. Galr2-inhibition reduced Meckel's cartilage length and increased chondrocyte density in both trophic specialists but not in the generalist genetic background. We propose a mechanism for jaw elongation in scale-eaters based on the reduced expression of galr2 due to the loss of a putative Sry binding site. Fewer Galr2 receptors in the scale-eater Meckel's cartilage may result in their enlarged jaw lengths as adults by limiting opportunities for a circulating Galr2 agonist to bind to these receptors during development. Our findings illustrate the growing utility of linking candidate adaptive SNPs in non-model systems with highly divergent phenotypes to novel vertebrate gene functions.
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Affiliation(s)
- M. Fernanda Palominos
- Department of Integrative Biology, University of California, 3101 Valley Life Sciences Building, Berkeley, CA 94720, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
| | - Vanessa Muhl
- Department of Integrative Biology, University of California, 3101 Valley Life Sciences Building, Berkeley, CA 94720, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
| | - Emilie J. Richards
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Minneapolis, MN, USA
| | - Craig T. Miller
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA
| | - Christopher H. Martin
- Department of Integrative Biology, University of California, 3101 Valley Life Sciences Building, Berkeley, CA 94720, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
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Palominos MF, Muhl V, Richards EJ, Miller CT, Martin CH. Jaw size variation is associated with a novel craniofacial function for galanin receptor 2 in an adaptive radiation of pupfishes. bioRxiv 2023:2023.06.02.543513. [PMID: 37333213 PMCID: PMC10274624 DOI: 10.1101/2023.06.02.543513] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Understanding the genetic basis of novel adaptations in new species is a fundamental question in biology that also provides an opportunity to uncover new genes and regulatory networks with potential clinical relevance. Here we demonstrate a new role for galr2 in vertebrate craniofacial development using an adaptive radiation of trophic specialist pupfishes endemic to San Salvador Island in the Bahamas. We confirmed the loss of a putative Sry transcription factor binding site in the upstream region of galr2 in scale-eating pupfish and found significant spatial differences in galr2 expression among pupfish species in Meckel's cartilage and premaxilla using in situ hybridization chain reaction (HCR). We then experimentally demonstrated a novel function for Galr2 in craniofacial development and jaw elongation by exposing embryos to drugs that inhibit Galr2 activity. Galr2-inhibition reduced Meckel's cartilage length and increased chondrocyte density in both trophic specialists but not in the generalist genetic background. We propose a mechanism for jaw elongation in scale-eaters based on the reduced expression of galr2 due to the loss of a putative Sry binding site. Fewer Galr2 receptors in the scale-eater Meckel's cartilage may result in their enlarged jaw lengths as adults by limiting opportunities for a postulated Galr2 agonist to bind to these receptors during development. Our findings illustrate the growing utility of linking candidate adaptive SNPs in non-model systems with highly divergent phenotypes to novel vertebrate gene functions.
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Affiliation(s)
- M Fernanda Palominos
- Department of Integrative Biology, University of California, Berkeley
- Museum of Vertebrate Zoology, University of California, Berkeley
| | - Vanessa Muhl
- Department of Integrative Biology, University of California, Berkeley
- Museum of Vertebrate Zoology, University of California, Berkeley
| | - Emilie J Richards
- Department of Ecology, Evolution, and Behavior, University of Minnesota
| | - Craig T Miller
- Department of Molecular & Cell Biology, University of California, Berkeley
| | - Christopher H Martin
- Department of Integrative Biology, University of California, Berkeley
- Museum of Vertebrate Zoology, University of California, Berkeley
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Olvera-Ríos YN, González-Díaz AA, Soria-Barreto M, Castillo-Uscanga MM, Cazzanelli M. Comparative analysis of cranial morphology in Middle-American heroine cichlids (Actinopterygii: Cichliformes). J Morphol 2023; 284:e21571. [PMID: 36802087 DOI: 10.1002/jmor.21571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 02/21/2023]
Abstract
Heroine cichlids are characterized by high morphological diversity, mainly in structures related to the capture and processing of food. The existence of ecomorphological groups has been proposed based on feeding behavior, where it is common for some phylogenetically unrelated species to show evolutionary convergence. Using geometric morphometrics and comparative phylogenetic methods, the variation in cranial morphology was evaluated for 17 species of heroine cichlids representing 5 ecomorphs. Cranial ecomorphs were recovered and significant differences were determined. Morphological variation of the ecomorphs was mainly explained by two axes: (1) the position of the mouth determined by the shape of the bones of the oral jaw and (2) the height of the head, defined by the size and position of the supraoccipital crest and the distance to the interopercle-subopercle junction. Cranial variation among species was related to phylogeny. To better understand the evolution of cranial morphology, it is necessary to evaluate the morphofunctional relationship of other anatomical structures related to feeding, as well as to increase the number of study species in each ecomorph by including other lineages.
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Affiliation(s)
- Yuriria Noemy Olvera-Ríos
- Maestría en Ciencias en Recursos Naturales y Desarrollo Rural, El Colegio de la Frontera Sur, San Cristóbal de Las Casas, Chiapas, México
| | - Alfonso A González-Díaz
- Departamento Conservación de la Biodiversidad, El Colegio de la Frontera Sur, San Cristóbal de Las Casas, Chiapas, México
| | - Miriam Soria-Barreto
- Departamento Conservación de la Biodiversidad, El Colegio de la Frontera Sur, San Cristóbal de Las Casas, Chiapas, México
| | | | - Matteo Cazzanelli
- Departamento de Conservación de la Biodiversidad, CONACYT-El Colegio de la Frontera Sur, San Cristóbal de Las Casas, Chiapas, México
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Munyandamutsa PS, Jere WL, Kassam D, Mtethiwa A. Trophic divergence of Lake Kivu cichlid fishes along a pelagic versus littoral habitat axis. Ecol Evol 2021; 11:1570-1585. [PMID: 33613990 PMCID: PMC7882941 DOI: 10.1002/ece3.7117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 11/05/2020] [Accepted: 11/06/2020] [Indexed: 01/16/2023] Open
Abstract
Local adaptation to the littoral and pelagic zones in two cichlid haplochromine fish species from Lake Kivu was investigated using morphometrics. Cranial variation and inferred jaw mechanics in both sexes of the two species across the two habitat types were quantified and compared. Comparisons of littoral versus pelagic populations revealed habitat-specific differences in the shape of the feeding apparatus. Also, kinematic transmission of the anterior jaw four-bar linkage that promotes greater jaw protrusion was higher in the pelagic zone than in the littoral zone for both species. Inferred bite force was likewise higher in pelagic zone fish. There were also sex-specific differences in craniofacial morphology as males exhibited longer heads than females in both habitats. As has been described for other cichlids in the East African Great Lakes, local adaptation to trophic resources in the littoral and pelagic habitats characterizes these two Lake Kivu cichlids. Similar studies involving other types of the Lake Kivu fishes are recommended to test the evidence of the observed trophic patterns and their genetic basis of divergences.
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Affiliation(s)
- Philippe S. Munyandamutsa
- Africa Centre of Excellence in Aquaculture and Fisheries ScienceDepartment of Aquaculture and Fisheries ScienceBunda CollegeLilongwe University of Agriculture and Natural ResourcesLilongweCentreMalawi
- Department of Animal ProductionCollege of Agriculture, Animal Sciences and Veterinary MedicineUniversity of RwandaKK 737MusanzeNorthRwanda
| | - Wilson L. Jere
- Africa Centre of Excellence in Aquaculture and Fisheries ScienceDepartment of Aquaculture and Fisheries ScienceBunda CollegeLilongwe University of Agriculture and Natural ResourcesLilongweCentreMalawi
| | - Daud Kassam
- Africa Centre of Excellence in Aquaculture and Fisheries ScienceDepartment of Aquaculture and Fisheries ScienceBunda CollegeLilongwe University of Agriculture and Natural ResourcesLilongweCentreMalawi
| | - Austin Mtethiwa
- Africa Centre of Excellence in Aquaculture and Fisheries ScienceDepartment of Aquaculture and Fisheries ScienceBunda CollegeLilongwe University of Agriculture and Natural ResourcesLilongweCentreMalawi
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Abstract
An individual's morphology is shaped by the environmental pressures it experiences, and the resulting morphological response is the culmination of both genetic factors and environmental (non-genetic) conditions experienced early in its life (i.e. phenotypic plasticity). The role that phenotypic plasticity plays in shaping phenotypes is important, but evidence for its influence is often mixed. We exposed female neonate diamond-backed watersnakes (Nerodia rhombifer) from populations experiencing different prey-size regimes to different feeding treatments to test the influence of phenotypic plasticity in shaping trophic morphology. We found that snakes in a large-prey treatment from a population frequently encountering large prey exhibited a higher growth rate in body size than individuals in a small-prey treatment from the same population. This pattern was not observed in snakes from a population that regularly encounters small prey. We also found that regardless of treatment, snakes from the small-prey population were smaller at birth than snakes from the large-prey population and remained so throughout the study. These results suggest that the ability to plastically respond to environmental pressures may be population-specific. These results also indicate a genetic predisposition towards larger body sizes in a population where large prey items are more common.
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Affiliation(s)
- Ian T Clifton
- Department of Biology, University of Central Arkansas, Conway, Arkansas, USA.,Department of Environmental Sciences, University of Toledo, Toledo, Ohio, USA
| | | | - Matthew E Gifford
- Department of Biology, University of Central Arkansas, Conway, Arkansas, USA
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Abstract
Although sexual dimorphism is widespread in nature, its evolutionary causes often remain elusive. Here we report a case where a sex-specific conflicting functional demand related to parental care, but not to sexual selection, explains sexual dimorphism in a primarily trophic structure, the gill rakers of cichlid fishes. More specifically, we examined gill raker length in a representative set of cichlid fish species from Lake Tanganyika featuring three different parental care strategies: (i) uni-parental mouthbrooding, whereby only one parental sex incubates the eggs in the buccal cavity; (ii) bi-parental mouthbrooding, whereby both parents participate in mouthbrooding; and (iii) nest guarding without any mouthbrooding involved. As predicted from these different parental care strategies, we find sexual dimorphism in gill raker length to be present only in uni-parental mouthbrooders, but not in bi-parental mouthbrooders nor in nest guarders. Moreover, variation in the extent of sexual dimorphism among uni-parental mouthbrooders appears to be related to trophic ecology. Overall, we present a previously unrecognized scenario for the evolution of sexual dimorphism that is not related to sexual selection or initial niche divergence between sexes. Instead, sexual dimorphism in gill raker length in uni-parental mouthbrooding cichlid fish appears to be the consequence of a sex-specific functional trade-off between a trophic function present in both sexes and a reproductive function present only in the brooding sex.
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Affiliation(s)
- Fabrizia Ronco
- Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Marius Roesti
- Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland.,Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T1Z4.,Institute of Ecology and Evolution, University of Bern, Bern 3012, Switzerland
| | - Walter Salzburger
- Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
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Hundt PJ, Simons AM. Extreme dentition does not prevent diet and tooth diversification within combtooth blennies (Ovalentaria: Blenniidae). Evolution 2018; 72:930-943. [PMID: 29457222 DOI: 10.1111/evo.13453] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 01/10/2018] [Accepted: 01/30/2018] [Indexed: 11/28/2022]
Abstract
The dentition of fishes can be quite striking and is often correlated with a specific diet. Combtooth blennies have long incisiform oral teeth, unlike most actinopterygians. It has been suggested that the long tooth morphology is an adaptation for detritivory, but given the diversity of diets (detritus, coral polyps, polychaetes, and pieces of other fishes), are blenny teeth indeed monomorphic? Or does tooth variation associated with diet still exist at this extreme? To explore tooth and diet diversification, we used a new phylogenetic hypothesis of Blenniidae, measured tooth shape, number, and mode of attachment, and quantified blenniid diet. The ancestral diet of blennies contained detritus and diversified into many different diets, including almost exclusively detritivory. Our results reveal a dental cline that may be constrained by tooth shape, but has not prevented diet diversification. Ancestral state reconstruction of tooth morphologies suggests that the ancestor of blennies had many unattached teeth and featured transitions to fewer attached teeth, with several transitions back to attached or unattached teeth. The dentition of blenniids is not monotypic; rather it is diverse and small changes in tooth shape are accompanied by changes in size, number, attachment, and often diet.
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Affiliation(s)
- Peter J Hundt
- Conservation Sciences Graduate Program, University of Minnesota, St. Paul, Minnesota, 55108.,Bell Museum of Natural History, University of Minnesota, St. Paul, Minnesota, 55108.,Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, Minnesota, 55108
| | - Andrew M Simons
- Bell Museum of Natural History, University of Minnesota, St. Paul, Minnesota, 55108.,Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, Minnesota, 55108
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Recknagel H, Hooker OE, Adams CE, Elmer KR. Ecosystem size predicts eco-morphological variability in a postglacial diversification. Ecol Evol 2017; 7:5560-5570. [PMID: 28811875 PMCID: PMC5552947 DOI: 10.1002/ece3.3013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 03/08/2017] [Accepted: 03/26/2017] [Indexed: 02/03/2023] Open
Abstract
Identifying the processes by which new phenotypes and species emerge has been a long‐standing effort in evolutionary biology. Young adaptive radiations provide a model to study patterns of morphological and ecological diversification in environmental context. Here, we use the recent radiation (ca. 12k years old) of the freshwater fish Arctic charr (Salvelinus alpinus) to identify abiotic and biotic environmental factors associated with adaptive morphological variation. Arctic charr are exceptionally diverse, and in postglacial lakes there is strong evidence of repeated parallel evolution of similar morphologies associated with foraging. We measured head depth (a trait reflecting general eco‐morphology and foraging ecology) of 1,091 individuals across 30 lake populations to test whether fish morphological variation was associated with lake bathymetry and/or ecological parameters. Across populations, we found a significant relationship between the variation in head depth of the charr and abiotic environmental characteristics: positively with ecosystem size (i.e., lake volume, surface area, depth) and negatively with the amount of littoral zone. In addition, extremely robust‐headed phenotypes tended to be associated with larger and deeper lakes. We identified no influence of co‐existing biotic community on Arctic charr trophic morphology. This study evidences the role of the extrinsic environment as a facilitator of rapid eco‐morphological diversification.
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Affiliation(s)
- Hans Recknagel
- Institute of Biodiversity Animal Health & Comparative Medicine College of Medical, Veterinary & Life Sciences University of Glasgow Glasgow UK
| | - Oliver E Hooker
- Institute of Biodiversity Animal Health & Comparative Medicine College of Medical, Veterinary & Life Sciences University of Glasgow Glasgow UK.,PR Statistics Glasgow UK
| | - Colin E Adams
- Institute of Biodiversity Animal Health & Comparative Medicine College of Medical, Veterinary & Life Sciences University of Glasgow Glasgow UK
| | - Kathryn R Elmer
- Institute of Biodiversity Animal Health & Comparative Medicine College of Medical, Veterinary & Life Sciences University of Glasgow Glasgow UK
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Abstract
The genetic changes responsible for evolutionary transitions from generalist to specialist phenotypes are poorly understood. Here we examine the genetic basis of craniofacial traits enabling novel trophic specialization in a sympatric radiation of Cyprinodon pupfishes endemic to San Salvador Island, Bahamas. This recent radiation consists of a generalist species and two novel specialists: a small-jawed "snail-eater" and a large-jawed "scale-eater." We genotyped 12 million single nucleotide polymorphisms (SNPs) by whole-genome resequencing of 37 individuals of all three species from nine populations and integrated genome-wide divergence scans with association mapping to identify divergent regions containing putatively causal SNPs affecting jaw size-the most rapidly diversifying trait in this radiation. A mere 22 fixed variants accompanied extreme ecological divergence between generalist and scale-eater species. We identified 31 regions (20 kb) containing variants fixed between specialists that were significantly associated with variation in jaw size which contained 11 genes annotated for skeletal system effects and 18 novel candidate genes never previously associated with craniofacial phenotypes. Six of these 31 regions showed robust signs of hard selective sweeps after accounting for demographic history. Our data are consistent with predictions based on quantitative genetic models of adaptation, suggesting that the effect sizes of regions influencing jaw phenotypes are positively correlated with distance between fitness peaks on a complex adaptive landscape.
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Affiliation(s)
- Joseph A. McGirr
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
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Weese DJ, Ferguson MM, Robinson BW. Contemporary and historical evolutionary processes interact to shape patterns of within-lake phenotypic divergences in polyphenic pumpkinseed sunfish, Lepomis gibbosus. Ecol Evol 2012; 2:574-92. [PMID: 22822436 PMCID: PMC3399146 DOI: 10.1002/ece3.72] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 10/04/2011] [Indexed: 11/23/2022] Open
Abstract
Historical and contemporary evolutionary processes can both contribute to patterns of phenotypic variation among populations of a species. Recent studies are revealing how interactions between historical and contemporary processes better explain observed patterns of phenotypic divergence than either process alone. Here, we investigate the roles of evolutionary history and adaptation to current environmental conditions in structuring phenotypic variation among polyphenic populations of sunfish inhabiting 12 postglacial lakes in eastern North America. The pumpkinseed sunfish polyphenism includes sympatric ecomorphs specialized for littoral or pelagic lake habitats. First, we use population genetic methods to test the evolutionary independence of within-lake phenotypic divergences of ecomorphs and to describe patterns of genetic structure among lake populations that clustered into three geographical groupings. We then used multivariate analysis of covariance (MANCOVA) to partition body shape variation (quantified with geometric morphometrics) among the effects of evolutionary history (reflecting phenotypic variation among genetic clusters), the shared phenotypic response of all populations to alternate habitats within lakes (reflecting adaptation to contemporary conditions), and unique phenotypic responses to habitats within lakes nested within genetic clusters. All effects had a significant influence on body form, but the effects of history and the interaction between history and contemporary habitat were larger than contemporary processes in structuring phenotypic variation. This highlights how divergence can be better understood against a known backdrop of evolutionary history.
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Affiliation(s)
- Dylan J Weese
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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