51
|
Gudbrandsson J, Ahi EP, Franzdottir SR, Kapralova KH, Kristjansson BK, Steinhaeuser SS, Maier VH, Johannesson IM, Snorrason SS, Jonsson ZO, Palsson A. The developmental transcriptome of contrasting Arctic charr (Salvelinus alpinus) morphs. F1000Res 2015; 4:136. [PMID: 27635217 PMCID: PMC5007756 DOI: 10.12688/f1000research.6402.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/10/2024] Open
Abstract
Species and populations with parallel evolution of specific traits can help illuminate how predictable adaptations and divergence are at the molecular and developmental level. Following the last glacial period, dwarfism and specialized bottom feeding morphology evolved rapidly in several landlocked Arctic charrSalvelinus alpinuspopulations in Iceland. To study the genetic divergence between small benthic morphs and limnetic morphs, we conducted RNA-sequencing charr embryos at four stages in early development. We studied two stocks with contrasting morphologies: the small benthic (SB) charr from Lake Thingvallavatn and Holar aquaculture (AC) charr.The data reveal significant differences in expression of several biological pathways during charr development. There was also an expression difference between SB- and AC-charr in genes involved in energy metabolism and blood coagulation genes. We confirmed differing expression of five genes in whole embryos with qPCR, includinglysozymeandnatterin-likewhich was previously identified as a fish-toxin of a lectin family that may be a putative immunopeptide. We also verified differential expression of 7 genes in the developing head that associated consistently with benthic v.s.limnetic morphology (studied in 4 morphs). Comparison of single nucleotide polymorphism (SNP) frequencies reveals extensive genetic differentiation between the SB and AC-charr (~1300 with more than 50% frequency difference). Curiously, three derived alleles in the otherwise conserved 12s and 16s mitochondrial ribosomal RNA genes are found in benthic charr.The data implicate multiple genes and molecular pathways in divergence of small benthic charr and/or the response of aquaculture charr to domestication. Functional, genetic and population genetic studies on more freshwater and anadromous populations are needed to confirm the specific loci and mutations relating to specific ecological traits in Arctic charr.
Collapse
|
52
|
Gudbrandsson J, Ahi EP, Franzdottir SR, Kapralova KH, Kristjansson BK, Steinhaeuser SS, Maier VH, Johannesson IM, Snorrason SS, Jonsson ZO, Palsson A. The developmental transcriptome of contrasting Arctic charr ( Salvelinus alpinus) morphs. F1000Res 2015; 4:136. [PMID: 27635217 PMCID: PMC5007756 DOI: 10.12688/f1000research.6402.2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/05/2016] [Indexed: 12/23/2022] Open
Abstract
Species and populations with parallel evolution of specific traits can help illuminate how predictable adaptations and divergence are at the molecular and developmental level. Following the last glacial period, dwarfism and specialized bottom feeding morphology evolved rapidly in several landlocked Arctic charr
Salvelinus alpinus populations in Iceland. To study the genetic divergence between small benthic morphs and limnetic morphs, we conducted RNA-sequencing charr embryos at four stages in early development. We studied two stocks with contrasting morphologies: the small benthic (SB) charr from Lake Thingvallavatn and Holar aquaculture (AC) charr. The data reveal significant differences in expression of several biological pathways during charr development. There was also an expression difference between SB- and AC-charr in genes involved in energy metabolism and blood coagulation genes. We confirmed differing expression of five genes in whole embryos with qPCR, including
lysozyme and
natterin-like which was previously identified as a fish-toxin of a lectin family that may be a putative immunopeptide. We also verified differential expression of 7 genes in the developing head that associated consistently with benthic v.s.limnetic morphology (studied in 4 morphs). Comparison of single nucleotide polymorphism (SNP) frequencies reveals extensive genetic differentiation between the SB and AC-charr (~1300 with more than 50% frequency difference). Curiously, three derived alleles in the otherwise conserved 12s and 16s mitochondrial ribosomal RNA genes are found in benthic charr. The data implicate multiple genes and molecular pathways in divergence of small benthic charr and/or the response of aquaculture charr to domestication. Functional, genetic and population genetic studies on more freshwater and anadromous populations are needed to confirm the specific loci and mutations relating to specific ecological traits in Arctic charr.
Collapse
Affiliation(s)
- Johannes Gudbrandsson
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Ehsan P Ahi
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Sigridur R Franzdottir
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Kalina H Kapralova
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | | | - S Sophie Steinhaeuser
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Valerie H Maier
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Isak M Johannesson
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Sigurdur S Snorrason
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Zophonias O Jonsson
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| | - Arnar Palsson
- Institute of Life and Environmental Sciences, University of Iceland, Reykjavik, 101, Iceland
| |
Collapse
|
53
|
Smith AJ, Nelson-Maney N, Parsons KJ, James Cooper W, Craig Albertson R. Body Shape Evolution in Sunfishes: Divergent Paths to Accelerated Rates of Speciation in the Centrarchidae. Evol Biol 2015. [DOI: 10.1007/s11692-015-9322-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
54
|
Santos‐Santos JH, Audenaert L, Verheyen E, Adriaens D. Divergent ontogenies of trophic morphology in two closely related haplochromine cichlids. J Morphol 2015; 276:860-71. [DOI: 10.1002/jmor.20385] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 02/15/2015] [Accepted: 02/17/2015] [Indexed: 12/18/2022]
Affiliation(s)
- Javier H. Santos‐Santos
- Evolutionary Morphology of Vertebrates, Department of BiologyGhent UniversityK.L. Ledeganckstraat 35B‐9000Gent Belgium
- Integrative Biogeography and Global Change DepartmentMuseo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (MNCN‐CSIC)28006Madrid Spain
| | - Leen Audenaert
- Operational Direction, Taxonomy, and Phylogeny VertebratesRoyal Belgian Institute of Natural SciencesVautierstraat 29B‐1000Brussels Belgium
| | - Erik Verheyen
- Operational Direction, Taxonomy, and Phylogeny VertebratesRoyal Belgian Institute of Natural SciencesVautierstraat 29B‐1000Brussels Belgium
- Evolutionary Ecology Group, Biology DepartmentUniversity of Antwerp Belgium
| | - Dominique Adriaens
- Evolutionary Morphology of Vertebrates, Department of BiologyGhent UniversityK.L. Ledeganckstraat 35B‐9000Gent Belgium
| |
Collapse
|
55
|
|
56
|
Ahi EP, Kapralova KH, Pálsson A, Maier VH, Gudbrandsson J, Snorrason SS, Jónsson ZO, Franzdóttir SR. Transcriptional dynamics of a conserved gene expression network associated with craniofacial divergence in Arctic charr. EvoDevo 2014; 5:40. [PMID: 25419450 PMCID: PMC4240837 DOI: 10.1186/2041-9139-5-40] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/17/2014] [Indexed: 12/30/2022] Open
Abstract
Background Understanding the molecular basis of craniofacial variation can provide insights into key developmental mechanisms of adaptive changes and their role in trophic divergence and speciation. Arctic charr (Salvelinus alpinus) is a polymorphic fish species, and, in Lake Thingvallavatn in Iceland, four sympatric morphs have evolved distinct craniofacial structures. We conducted a gene expression study on candidates from a conserved gene coexpression network, focusing on the development of craniofacial elements in embryos of two contrasting Arctic charr morphotypes (benthic and limnetic). Results Four Arctic charr morphs were studied: one limnetic and two benthic morphs from Lake Thingvallavatn and a limnetic reference aquaculture morph. The presence of morphological differences at developmental stages before the onset of feeding was verified by morphometric analysis. Following up on our previous findings that Mmp2 and Sparc were differentially expressed between morphotypes, we identified a network of genes with conserved coexpression across diverse vertebrate species. A comparative expression study of candidates from this network in developing heads of the four Arctic charr morphs verified the coexpression relationship of these genes and revealed distinct transcriptional dynamics strongly correlated with contrasting craniofacial morphologies (benthic versus limnetic). A literature review and Gene Ontology analysis indicated that a significant proportion of the network genes play a role in extracellular matrix organization and skeletogenesis, and motif enrichment analysis of conserved noncoding regions of network candidates predicted a handful of transcription factors, including Ap1 and Ets2, as potential regulators of the gene network. The expression of Ets2 itself was also found to associate with network gene expression. Genes linked to glucocorticoid signalling were also studied, as both Mmp2 and Sparc are responsive to this pathway. Among those, several transcriptional targets and upstream regulators showed differential expression between the contrasting morphotypes. Interestingly, although selected network genes showed overlapping expression patterns in situ and no morph differences, Timp2 expression patterns differed between morphs. Conclusion Our comparative study of transcriptional dynamics in divergent craniofacial morphologies of Arctic charr revealed a conserved network of coexpressed genes sharing functional roles in structural morphogenesis. We also implicate transcriptional regulators of the network as targets for future functional studies. Electronic supplementary material The online version of this article (doi:10.1186/2041-9139-5-40) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Ehsan Pashay Ahi
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland
| | - Kalina Hristova Kapralova
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland
| | - Arnar Pálsson
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland ; Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavik, Iceland
| | - Valerie Helene Maier
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland
| | - Jóhannes Gudbrandsson
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland
| | - Sigurdur S Snorrason
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland
| | - Zophonías O Jónsson
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland ; Biomedical Center, University of Iceland, Vatnsmýrarvegur 16, 101 Reykjavik, Iceland
| | - Sigrídur Rut Franzdóttir
- Institute of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland
| |
Collapse
|
57
|
Powder KE, Cousin H, McLinden GP, Craig Albertson R. A nonsynonymous mutation in the transcriptional regulator lbh is associated with cichlid craniofacial adaptation and neural crest cell development. Mol Biol Evol 2014; 31:3113-24. [PMID: 25234704 DOI: 10.1093/molbev/msu267] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Since the time of Darwin, biologists have sought to understand the origins and maintenance of life's diversity of form. However, the nature of the exact DNA mutations and molecular mechanisms that result in morphological differences between species remains unclear. Here, we characterize a nonsynonymous mutation in a transcriptional coactivator, limb bud and heart homolog (lbh), which is associated with adaptive variation in the lower jaw of cichlid fishes. Using both zebrafish and Xenopus, we demonstrate that lbh mediates migration of cranial neural crest cells, the cellular source of the craniofacial skeleton. A single amino acid change that is alternatively fixed in cichlids with differing facial morphologies results in discrete shifts in migration patterns of this multipotent cell type that are consistent with both embryological and adult craniofacial phenotypes. Among animals, this polymorphism in lbh represents a rare example of a coding change that is associated with continuous morphological variation. This work offers novel insights into the development and evolution of the craniofacial skeleton, underscores the evolutionary potential of neural crest cells, and extends our understanding of the genetic nature of mutations that underlie divergence in complex phenotypes.
Collapse
Affiliation(s)
- Kara E Powder
- Department of Biology, University of Massachusetts, Amherst
| | - Hélène Cousin
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst
| | - Gretchen P McLinden
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst
| | | |
Collapse
|
58
|
Henning F, Meyer A. The evolutionary genomics of cichlid fishes: explosive speciation and adaptation in the postgenomic era. Annu Rev Genomics Hum Genet 2014; 15:417-41. [PMID: 24898042 DOI: 10.1146/annurev-genom-090413-025412] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
With more than 1,500 species, cichlid fishes provide textbook examples of recent and diverse adaptive radiations, rapid rates of speciation, and the parallel evolution of adaptive phenotypes among both recently and distantly related lineages. This extraordinary diversity has attracted considerable interest from researchers across several biological disciplines. Their broad phenotypic variation coupled with recent divergence makes cichlids an ideal model system for understanding speciation, adaptation, and phenotypic diversification. Genetic mapping, genome-wide analyses, and genome projects have flourished in the past decade and have added new insights on the question of why there are so many cichlids. These recent findings also show that the sharing of older DNA polymorphisms is extensive and suggest that linage sorting is incomplete and that adaptive introgression played a role in the African radiation. Here, we review the results of genetic and genomic research on cichlids in the past decade and suggest some potential avenues to further exploit the potential of the cichlid model system to provide a better understanding of the genomics of adaptation and speciation.
Collapse
Affiliation(s)
- Frederico Henning
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany;
| | | |
Collapse
|
59
|
Machado-Schiaffino G, Henning F, Meyer A. Species-specific differences in adaptive phenotypic plasticity in an ecologically relevant trophic trait: hypertrophic lips in Midas cichlid fishes. Evolution 2014; 68:2086-91. [PMID: 24475874 DOI: 10.1111/evo.12367] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/14/2014] [Indexed: 12/28/2022]
Abstract
The spectacular species richness of cichlids and their diversity in morphology, coloration, and behavior have made them an ideal model for the study of speciation and adaptive evolution. Hypertrophic lips evolved repeatedly and independently in African and Neotropical cichlid radiations. Cichlids with hypertrophic lips forage predominantly in rocky crevices and it has been hypothesized that mechanical stress caused by friction could result in larger lips through phenotypic plasticity. To test the influence of the environment on the size and development of lips, we conducted a series of breeding and feeding experiments on Midas cichlids. Full-sibs of Amphilophus labiatus (thick-lipped) and Amphilophus citrinellus (thin-lipped) each were split into a control group which was fed food from the water column and a treatment group whose food was fixed to substrates. We found strong evidence for phenotypic plasticity on lip area in the thick-lipped species, but not in the thin-lipped species. Intermediate phenotypic values were observed in hybrids from thick- and thin-lipped species reared under "control" conditions. Thus, both a genetic, but also a phenotypic plastic component is involved in the development of hypertrophic lips in Neotropical cichlids. Moreover, species-specific adaptive phenotypic plasticity was found, suggesting that plasticity is selected for in recent thick-lipped species.
Collapse
Affiliation(s)
- Gonzalo Machado-Schiaffino
- Chair of Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Universitaetsstrasse 10, 78457, Konstanz, Germany
| | | | | |
Collapse
|
60
|
Gunter HM, Koppermann C, Meyer A. Revisiting de Beer's textbook example of heterochrony and jaw elongation in fish: calmodulin expression reflects heterochronic growth, and underlies morphological innovation in the jaws of belonoid fishes. EvoDevo 2014; 5:8. [PMID: 24499543 PMCID: PMC3927394 DOI: 10.1186/2041-9139-5-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/12/2013] [Indexed: 01/08/2023] Open
Abstract
Background Heterochronic shifts during ontogeny can result in adaptively important innovations and might be initiated by simple developmental switches. Understanding the nature of these developmental events can provide insights into fundamental molecular mechanisms of evolutionary change. Fishes from the Suborder Belonoidei display a vast array of extreme craniofacial morphologies that appear to have arisen through a series of heterochronic shifts. We performed a molecular heterochrony study, comparing postembryonic jaw development in representatives of the Suborder Belonoidei, the halfbeak Dermogenys pusilla (where the lower jaw is considerably elongated compared to the upper jaw) and the needlefish Belone belone (where both jaws are elongated), to a representative of their sister group the Suborder Adrianichthyoidei, the medaka Oryzias latipes, which has retained the ancestral morphology. Results Early in development, the lower jaw displays accelerated growth both in needlefish and halfbeak compared to medaka, and secondary acceleration of the upper jaw is seen in needlefish later in their development, representing a case of mosaic heterochrony. We identified toothless extensions of the dentaries as innovations of Belonoid fishes and the source of heterochronic growth. The molecular basis of growth heterochronies in the Belonoidei was examined through comparing expression of skeletogenic genes during development of halfbeak and medaka. The calmodulin paralogue calm1 was identified as a potential regulator of jaw length in halfbeak as its expression gradually increases in the lower jaw, but not the upper jaw, in a pattern that matches its outgrowth. Moreover, medaka displays equal expression of calm1 in the upper and lower jaws, consistent with the lack of jaw outgrowth in this species. Conclusions Heterochronic shifts in jaw growth have occurred repeatedly during the evolution of Belonoid fishes and we identify toothless extensions of the dentaries as an important innovation of this group. Our results suggest that calm1 contributes to jaw heterochrony in halfbeak, potentially driving further heterochronic shifts in jaw growth across the Suborder Belonoidei, such as the upper jaw acceleration observed in needlefish.
Collapse
Affiliation(s)
| | | | - Axel Meyer
- Department of Biology, Lehrstuhl für Zoologie und Evolutionsbiologie, University of Konstanz, Universitätstrasse 10, 78457 Constance, Germany.
| |
Collapse
|
61
|
Complex craniofacial changes in blind cave-dwelling fish are mediated by genetically symmetric and asymmetric loci. Genetics 2014; 196:1303-19. [PMID: 24496009 DOI: 10.1534/genetics.114.161661] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The genetic regulators of regressive craniofacial morphologies are poorly understood. To shed light on this problem, we examined the freshwater fish Astyanax mexicanus, a species with surface-dwelling and multiple independent eyeless cave-dwelling forms. Changes affecting the skull in cavefish include morphological alterations to the intramembranous circumorbital bones encircling the eye. Many of these modifications, however, have evolved separately from eye loss, such as fragmentation of the third suborbital bone. To understand the genetic architecture of these eye-independent craniofacial alterations, we developed and scored 33 phenotypes in the context of an F2 hybrid mapping pedigree bred from Pachón cavefish and surface fish. We discovered several individuals exhibiting dramatic left-right differences in bone formation, such as extensive fragmentation on the right side only. This observation, along with well-known eye size asymmetry in natural cave-dwelling animals, led us to further evaluate left-right genetic differences for the craniofacial complex. We discovered three phenotypes, inclusive of bone fragmentation and fusion, which demonstrated a directional heritable basis only on one side. Interestingly, the overall areas of affected bones were genetically symmetric. Phenotypic effect plots of these novel craniofacial QTL revealed that cave alleles are associated with abnormal conditions such as bony fusion and fragmentation. Moreover, many linked loci overlapped with other cave-associated traits, suggesting regressive craniofacial changes may evolve through linkage or as antagonistic pleiotropic consequences of cave-associated adaptations. These novel findings illuminate significant craniofacial changes accompanying evolution in complete darkness and reveal complex changes to the skull differentially influenced by genetic changes affecting the left and right sides.
Collapse
|
62
|
Webb JF, Bird NC, Carter L, Dickson J. Comparative development and evolution of two lateral line phenotypes in lake Malawi cichlids. J Morphol 2014; 275:678-92, cover illustration. [PMID: 24469933 DOI: 10.1002/jmor.20247] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/20/2013] [Accepted: 12/08/2013] [Indexed: 11/05/2022]
Abstract
A comparison of the pattern and timing of development of cranial lateral line canals and canal neuromasts in three species of Lake Malawi cichlids, Labeotropheus fuelleborni and Metriaclima zebra (narrow lateral line canals), and Aulonocara baenschi (widened lateral line canals) was used to test the hypothesis that the evolution of widened canals (thought to be an adaptive phenotype in the lateral line system) from narrow canals is the result of heterochrony. Using histological analysis and scanning electron microscopy, this study has provided the first detailed and quantitative description of the development of widened lateral line canals in a teleost, and has demonstrated that: 1) canal neuromast number and the pattern of canal morphogenesis are conserved among species with different adult canal phenotypes, 2) heterochrony ("dissociated heterochrony" in particular) can explain the evolution of widened canals and variation in morphology between canals within a species with respect to canal diameter and neuromast size, and 3) the morphology of the lateral line canals and the dermal bones in which they are found (e.g., the mandibular canal the dentary and anguloarticular bones of the mandible) can evolve independently of each other, thus requiring the addition of another level of complexity to discussions of modularity and integration in the skull of bony fishes.
Collapse
Affiliation(s)
- Jacqueline F Webb
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, 02881
| | | | | | | |
Collapse
|
63
|
Abstract
In recent years, zebrafish, and to a lesser extent medaka, have become widely used small animal models for human diseases. These organisms have convincingly demonstrated the usefulness of fish for improving our understanding of the molecular and cellular mechanisms leading to pathological conditions, and for the development of new diagnostic and therapeutic tools. Despite the usefulness of zebrafish and medaka in the investigation of a wide spectrum of traits, there is evidence to suggest that other fish species could be better suited for more targeted questions. With the emergence of new, improved sequencing technologies that enable genomic resources to be generated with increasing efficiency and speed, the potential of non-mainstream fish species as disease models can now be explored. A key feature of these fish species is that the pathological condition that they model is often related to specific evolutionary adaptations. By exploring these adaptations, new disease-causing and disease-modifier genes might be identified; thus, diverse fish species could be exploited to better understand the complexity of disease processes. In addition, non-mainstream fish models could allow us to study the impact of environmental factors, as well as genetic variation, on complex disease phenotypes. This Review will discuss the opportunities that such fish models offer for current and future biomedical research.
Collapse
Affiliation(s)
- Manfred Schartl
- Department Physiological Chemistry, Biocenter, University of Würzburg, and Comprehensive Cancer Center Mainfranken, University Clinic Würzburg, 97078 Würzburg, Germany
| |
Collapse
|
64
|
Trends of karyotypical evolution in the pearl cichlid, Geophagus brasiliensis, from southern Brazil. ZOOLOGY 2013; 116:286-92. [DOI: 10.1016/j.zool.2013.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/16/2013] [Accepted: 07/25/2013] [Indexed: 11/23/2022]
|
65
|
Gillis JA, Modrell MS, Baker CVH. Developmental evidence for serial homology of the vertebrate jaw and gill arch skeleton. Nat Commun 2013; 4:1436. [PMID: 23385581 PMCID: PMC3600657 DOI: 10.1038/ncomms2429] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 01/02/2013] [Indexed: 12/02/2022] Open
Abstract
Gegenbaur’s classical hypothesis of jaw-gill arch serial homology is widely cited, but remains unsupported by either paleontological evidence (e.g. a series of fossils reflecting the stepwise transformation of a gill arch into a jaw) or developmental genetic data (e.g. shared molecular mechanisms underlying segment identity in the mandibular, hyoid and gill arch endoskeletons). Here we show that nested expression of Dlx genes – the “Dlx code” that specifies upper and lower jaw identity in mammals and teleosts – is a primitive feature of the mandibular, hyoid and gill arches of jawed vertebrates. Using fate-mapping techniques, we demonstrate that the principal dorsal and ventral endoskeletal segments of the jaw, hyoid and gill arches of the skate Leucoraja erinacea derive from molecularly equivalent mesenchymal domains of combinatorial Dlx gene expression. Our data suggest that vertebrate jaw, hyoid and gill arch cartilages are serially homologous, and were primitively patterned dorsoventrally by a common Dlx blueprint.
Collapse
Affiliation(s)
- J Andrew Gillis
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge CB2 3DY, UK.
| | | | | |
Collapse
|
66
|
Ahi EP, Guðbrandsson J, Kapralova KH, Franzdóttir SR, Snorrason SS, Maier VH, Jónsson ZO. Validation of reference genes for expression studies during craniofacial development in arctic charr. PLoS One 2013; 8:e66389. [PMID: 23785496 PMCID: PMC3681766 DOI: 10.1371/journal.pone.0066389] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/05/2013] [Indexed: 01/08/2023] Open
Abstract
Arctic charr (Salvelinus alpinus) is a highly polymorphic species and in Lake Thingvallavatn, Iceland, four phenotypic morphs have evolved. These differences in morphology, especially in craniofacial structures are already apparent during embryonic development, indicating that genes important in the formation of the craniofacial features are expressed differentially between the morphs. In order to generate tools to examine these expression differences in Arctic charr, the aim of the present study was to identify reference genes for quantitative real-time PCR (qPCR). The specific aim was to select reference genes which are able to detect very small expression differences among different morphs. We selected twelve candidate reference genes from the literature, identified corresponding charr sequences using data derived from transcriptome sequencing (RNA-seq) and examined their expression using qPCR. Many of the candidate reference genes were found to be stably expressed, yet their quality-rank as reference genes varied considerably depending on the type of analysis used. In addition to commonly used software for reference gene validation, we used classical statistics to evaluate expression profiles avoiding a bias for reference genes with similar expression patterns (co-regulation). Based on these analyses we chose three reference genes, ACTB, UB2L3 and IF5A1 for further evaluation. Their consistency was assessed in an expression study of three known craniofacially expressed genes, sparc (or osteonectin), matrix metalloprotease 2 (mmp2) and sox9 (sex-determining region Y box 9 protein) using qPCR in embryo heads derived from four charr groups at three developmental time points. The three reference genes were found to be very suitable for studying expression differences between the morphotypes, enabling robust detection of small relative expression changes during charr development. Further, the results showed that sparc and mmp2 are differentially expressed in embryos of different Arctic charr morphotypes.
Collapse
Affiliation(s)
- Ehsan Pashay Ahi
- Institute of Life- and Environmental Sciences, University of Iceland, Reykjavik, Iceland
| | - Jóhannes Guðbrandsson
- Institute of Life- and Environmental Sciences, University of Iceland, Reykjavik, Iceland
| | - Kalina H. Kapralova
- Institute of Life- and Environmental Sciences, University of Iceland, Reykjavik, Iceland
| | | | - Sigurður S. Snorrason
- Institute of Life- and Environmental Sciences, University of Iceland, Reykjavik, Iceland
| | - Valerie H. Maier
- Institute of Life- and Environmental Sciences, University of Iceland, Reykjavik, Iceland
- * E-mail:
| | - Zophonías O. Jónsson
- Institute of Life- and Environmental Sciences, University of Iceland, Reykjavik, Iceland
| |
Collapse
|
67
|
Armfield BA, Zheng Z, Bajpai S, Vinyard CJ, Thewissen J. Development and evolution of the unique cetacean dentition. PeerJ 2013; 1:e24. [PMID: 23638359 PMCID: PMC3628747 DOI: 10.7717/peerj.24] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/10/2013] [Indexed: 11/20/2022] Open
Abstract
The evolutionary success of mammals is rooted in their high metabolic rate. A high metabolic rate is sustainable thanks to efficient food processing and that in turn is facilitated by precise occlusion of the teeth and the acquisition of rhythmic mastication. These major evolutionary innovations characterize most members of the Class Mammalia. Cetaceans are one of the few groups of mammals in which precise occlusion has been secondarily lost. Most toothed whales have an increased number of simple crowned teeth that are similar along the tooth row. Evolution toward these specializations began immediately after the time cetaceans transitioned from terrestrial-to-marine environments. The fossil record documents the critical aspects of occlusal evolution of cetaceans, and allows us to pinpoint the evolutionary timing of the macroevolutionary events leading to their unusual dental morphology among mammals. The developmental controls of tooth differentiation and tooth number have been studied in a few mammalian clades, but nothing is known about how these controls differ between cetaceans and mammals that retain functional occlusion. Here we show that pigs, a cetacean relative with regionalized tooth morphology and complex tooth crowns, retain the typical mammalian gene expression patterns that control early tooth differentiation, expressing Bmp4 in the rostral (mesial, anterior) domain of the jaw, and Fgf8 caudally (distal, posterior). By contrast, dolphins have lost these regional differences in dental morphology and the Bmp4 domain is extended into the caudal region of the developing jaw. We hypothesize that the functional constraints underlying mammalian occlusion have been released in cetaceans, facilitating changes in the genetic control of early dental development. Such major developmental changes drive morphological evolution and are correlated with major shifts in diet and food processing during cetacean evolution.
Collapse
Affiliation(s)
- Brooke A Armfield
- Department of Anatomy and Neurobiology , Northeast Ohio Medical University , Rootstown, Ohio , United States ; Howard Hughes Medical Institute and Department of Molecular Genetics and Microbiology , University of Florida , Gainesville, Florida , USA
| | | | | | | | | |
Collapse
|
68
|
A hybrid genetic linkage map of two ecologically and morphologically divergent Midas cichlid fishes (Amphilophus spp.) obtained by massively parallel DNA sequencing (ddRADSeq). G3-GENES GENOMES GENETICS 2013; 3:65-74. [PMID: 23316439 PMCID: PMC3538344 DOI: 10.1534/g3.112.003897] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 11/05/2012] [Indexed: 12/30/2022]
Abstract
Cichlid fishes are an excellent model system for studying speciation and the formation of adaptive radiations because of their tremendous species richness and astonishing phenotypic diversity. Most research has focused on African rift lake fishes, although Neotropical cichlid species display much variability as well. Almost one dozen species of the Midas cichlid species complex (Amphilophus spp.) have been described so far and have formed repeated adaptive radiations in several Nicaraguan crater lakes. Here we apply double-digest restriction-site associated DNA sequencing to obtain a high-density linkage map of an interspecific cross between the benthic Amphilophus astorquii and the limnetic Amphilophus zaliosus, which are sympatric species endemic to Crater Lake Apoyo, Nicaragua. A total of 755 RAD markers were genotyped in 343 F2 hybrids. The map resolved 25 linkage groups and spans a total distance of 1427 cM with an average marker spacing distance of 1.95 cM, almost matching the total number of chromosomes (n = 24) in these species. Regions of segregation distortion were identified in five linkage groups. Based on the pedigree of parents to F2 offspring, we calculated a genome-wide mutation rate of 6.6 × 10−8 mutations per nucleotide per generation. This genetic map will facilitate the mapping of ecomorphologically relevant adaptive traits in the repeated phenotypes that evolved within the Midas cichlid lineage and, as the first linkage map of a Neotropical cichlid, facilitate comparative genomic analyses between African cichlids, Neotropical cichlids and other teleost fishes.
Collapse
|
69
|
Greenwood AK, Cech JN, Peichel CL. Molecular and developmental contributions to divergent pigment patterns in marine and freshwater sticklebacks. Evol Dev 2012; 14:351-62. [PMID: 22765206 DOI: 10.1111/j.1525-142x.2012.00553.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pigment pattern variation across species or populations offers a tractable framework in which to investigate the evolution of development. Juvenile threespine sticklebacks (Gasterosteus aculeatus) from marine and freshwater environments exhibit divergent pigment patterns that are associated with ecological differences. Juvenile marine sticklebacks have a silvery appearance, whereas sticklebacks from freshwater environments exhibit a pattern of vertical bars. We investigated both the developmental and molecular basis of this population-level variation in pigment pattern. Time course imaging during the transition from larval to juvenile stages revealed differences between marine and freshwater fish in spatial patterns of chromatophore differentiation as well as in pigment amount and dispersal. In freshwater fish, melanophores appear primarily within dark bars whereas iridophores appear within light bars. By contrast, in marine fish, these chromatophores are interspersed across the flank. In addition to spatially segregated chromatophore differentiation, pigment amount and dispersal within melanophores varies spatially across the flank of freshwater, but not marine fish. To gain insight into the molecular pathways that underlie the differences in pigment pattern development, we evaluated differential gene expression in the flanks of developing fish using high-throughput cDNA sequencing (RNA-seq) and quantitative PCR. We identified several genes that were differentially expressed across dark and light bars of freshwater fish, and between freshwater and marine fish. Together, these experiments begin to shed light on the process of pigment pattern evolution in sticklebacks.
Collapse
Affiliation(s)
- Anna K Greenwood
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | | | | |
Collapse
|
70
|
Keller I, Wagner CE, Greuter L, Mwaiko S, Selz OM, Sivasundar A, Wittwer S, Seehausen O. Population genomic signatures of divergent adaptation, gene flow and hybrid speciation in the rapid radiation of Lake Victoria cichlid fishes. Mol Ecol 2012; 22:2848-63. [DOI: 10.1111/mec.12083] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 08/29/2012] [Accepted: 09/07/2012] [Indexed: 01/07/2023]
|
71
|
Closely related bird species demonstrate flexibility between beak morphology and underlying developmental programs. Proc Natl Acad Sci U S A 2012; 109:16222-7. [PMID: 22988109 DOI: 10.1073/pnas.1206205109] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The astonishing variation in the shape and size of bird beaks reflects a wide range of dietary specializations that played an important role in avian diversification. Among Darwin's finches, ground finches (Geospiza spp.) have beaks that represent scaling variations of the same shape, which are generated by alterations in the signaling pathways that regulate growth of the two skeletal components of the beak: the prenasal cartilage (pnc) and the premaxillary bone (pmx). Whether this developmental mechanism is responsible for variation within groups of other closely related bird species, however, has remained unknown. Here, we report that the Caribbean bullfinches (Loxigilla spp.), which are closely related to Darwin's finches, have independently evolved beaks of a novel shape, different from Geospiza, but also varying from each other only in scaling. However, despite sharing the same beak shape, the signaling pathways and tissues patterning Loxigilla beaks differ among the three species. In Loxigilla noctis, as in Geospiza, the pnc develops first, shaped by Bmp4 and CaM signaling, followed by the development of the pmx, regulated by TGFβIIr, β-catenin, and Dkk3 signaling. In contrast, beak morphogenesis in Loxigilla violacea and Loxigilla portoricensis is generated almost exclusively by the pmx through a mechanism in which Ihh and Bmp4 synergize to promote expansion of bone tissue. Together, our results demonstrate high flexibility in the relationship between morphology and underlying developmental causes, where different developmental programs can generate identical shapes, and similar developmental programs can pattern different shapes.
Collapse
|
72
|
Doi H, Vander Zanden MJ, Hillebrand H. Shorter food chain length in ancient lakes: evidence from a global synthesis. PLoS One 2012; 7:e37856. [PMID: 22701583 PMCID: PMC3368915 DOI: 10.1371/journal.pone.0037856] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Accepted: 04/27/2012] [Indexed: 11/18/2022] Open
Abstract
Food webs may be affected by evolutionary processes, and effective evolutionary time ultimately affects the probability of species evolving to fill the niche space. Thus, ecosystem history may set important evolutionary constraints on community composition and food web structure. Food chain length (FCL) has long been recognized as a fundamental ecosystem attribute. We examined historical effects on FCL in large lakes spanning >6 orders of magnitude in age. We found that food chains in the world's ancient lakes (n = 8) were significantly shorter than in recently formed lakes (n = 10) and reservoirs (n = 3), despite the fact that ancient lakes harbored much higher species richness, including many endemic species. One potential factor leading to shorter FCL in ancient lakes is an increasing diversity of trophic omnivores and herbivores. Speciation could simply broaden the number of species within a trophic group, particularly at lower trophic levels and could also lead to a greater degree of trophic omnivory. Our results highlight a counter-intuitive and poorly-understood role of evolutionary history in shaping key food web properties such as FCL.
Collapse
Affiliation(s)
- Hideyuki Doi
- Institute for Chemistry and Biology of the Marine Environment, Carl-von-Ossietzky University Oldenburg, Schleusenstrasse 1, Wilhelmshaven, Germany.
| | | | | |
Collapse
|
73
|
More than meets the eye: functionally salient changes in internal bone architecture accompany divergence in cichlid feeding mode. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:538146. [PMID: 22666625 PMCID: PMC3362014 DOI: 10.1155/2012/538146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/14/2012] [Indexed: 11/23/2022]
Abstract
African cichlids have undergone extensive and repeated adaptive radiations in foraging habitat. While the external morphology of the cichlid craniofacial skeleton has been studied extensively, biomechanically relevant changes to internal bone architecture have been largely overlooked. Here we explore two fundamental questions: (1) Do changes in the internal architecture of bone accompany shifts in foraging mode? (2) What is the genetic basis for this trait? We focus on the maxilla, which is an integral part of the feeding apparatus and an element that should be subjected to significant bending forces during biting. Analyses of μCT scans revealed clear differences between the maxilla of two species that employ alternative foraging strategies (i.e., biting versus suction feeding). Hybrids between the two species exhibit maxillary geometries that closely resemble those of the suction feeding species, consistent with a dominant mode of inheritance. This was supported by the results of a genetic mapping experiment, where suction feeding alleles were dominant to biting alleles at two loci that affect bone architecture. Overall, these data suggest that the internal structure of the cichlid maxilla has a tractable genetic basis and that discrete shifts in this trait have accompanied the evolution of alternate feeding modes.
Collapse
|
74
|
Fan S, Elmer KR, Meyer A. Genomics of adaptation and speciation in cichlid fishes: recent advances and analyses in African and Neotropical lineages. Philos Trans R Soc Lond B Biol Sci 2012; 367:385-94. [PMID: 22201168 DOI: 10.1098/rstb.2011.0247] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cichlid fishes are remarkably phenotypically diverse and species-rich. Therefore, they provide an exciting opportunity for the study of the genetics of adaptation and speciation by natural and sexual selection. Here, we review advances in the genomics and transcriptomics of cichlids, particularly regarding ecologically relevant differences in body shape, trophic apparatus, coloration and patterning, and sex determination. Research conducted so far has focused almost exclusively on African cichlids. To analyse genomic diversity and selection in a Neotropical radiation, we conducted a comparative transcriptomic analysis between sympatric, ecologically divergent crater-lake Midas cichlids (Lake Xiloá Amphilophus amarillo and Amphilophus sagittae). We pyrosequenced (Roche 454) expressed sequence tag (EST) libraries and generated more than 178 000 000 ESTs and identified nine ESTs under positive selection between these sister species (Ka/Ks > 1). None of these ESTs were found to be under selection in African cichlids. Of 11 candidate genes for ecomorphological differentiation in African cichlids, none showed signs of selection between A. amarillo and A. sagittae. Although more population-level studies are now needed to thoroughly document patterns of divergence during speciation of cichlids, available information so far suggests that adaptive phenotypic diversification in Neotropical and African cichlids may be evolving through non-parallel genetic bases.
Collapse
Affiliation(s)
- Shaohua Fan
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätstrasse 10, 78457 Konstanz, Germany
| | | | | |
Collapse
|
75
|
Akiyama T, Marqués G, Wharton KA. A large bioactive BMP ligand with distinct signaling properties is produced by alternative proconvertase processing. Sci Signal 2012; 5:ra28. [PMID: 22472650 DOI: 10.1126/scisignal.2002549] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dimers of conventional transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) ligands are composed of two 100- to 140-amino acid peptides that are produced through the proteolytic processing of a proprotein precursor by proconvertases, such as furin. We report the identification of an evolutionarily conserved furin processing site in the amino terminus (NS) of the Glass bottom boat (Gbb; the Drosophila ortholog of vertebrate BMP5, 6, and 7) proprotein that generates a 328-amino acid, active BMP ligand distinct from the conventional 130-amino acid ligand. Gbb38, the large ligand form of Gbb, exhibited greater signaling activity and a longer range than the shorter form Gbb15. The abundance of Gbb15 and Gbb38 varied among different tissues, raising the possibility that differential processing could account for tissue-specific behaviors of BMPs. In human populations, mutations that abolished the NS cleavage site in BMP4, BMP15, or anti-Müllerian hormone were associated with cleft lip with or without cleft palate (BMP4), premature ovarian failure (BMP15), and persistent Müllerian duct syndrome (anti-Müllerian hormone), suggesting the importance of NS processing during development. The identification of this large BMP ligand form and the functional differences between large and small ligands exemplifies the potential for differential proprotein processing to substantially affect BMP and TGF-β signaling output in different tissue and cellular contexts.
Collapse
Affiliation(s)
- Takuya Akiyama
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
| | | | | |
Collapse
|
76
|
Tkint T, Verheyen E, De Kegel B, Helsen P, Adriaens D. Dealing with food and eggs in mouthbrooding cichlids: structural and functional trade-offs in fitness related traits. PLoS One 2012; 7:e31117. [PMID: 22348043 PMCID: PMC3279513 DOI: 10.1371/journal.pone.0031117] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 01/03/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species. METHODOLOGY/PRINCIPAL FINDINGS Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus) and a "biter" (H. fischeri). The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs. CONCLUSIONS/SIGNIFICANCE Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two studied haplochromine cichlids, stressing the importance of including species-specific information at the gender level when addressing interspecific functional/morphological differences.
Collapse
Affiliation(s)
- Tim Tkint
- Department of Biology, Research Group Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium.
| | | | | | | | | |
Collapse
|
77
|
Diepeveen ET, Salzburger W. Molecular Characterization of Two Endothelin Pathways in East African Cichlid Fishes. J Mol Evol 2012; 73:355-68. [DOI: 10.1007/s00239-012-9483-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 01/04/2012] [Indexed: 12/21/2022]
|
78
|
Koch M, Wilson AJ, Kerschbaumer M, Wiedl T, Sturmbauer C. Additive genetic variance of quantitative traits in natural and pond-bred populations of the Lake Tanganyika cichlid Tropheus moorii. HYDROBIOLOGIA 2012; 682:131-141. [PMID: 26069346 PMCID: PMC4459473 DOI: 10.1007/s10750-011-0785-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 05/29/2011] [Indexed: 05/06/2023]
Abstract
Quantitative genetic studies in natural populations are of growing interest to speciation research since divergence is often believed to arise through micro-evolutionary change, caused by natural selection on functional morphological traits. The species flock of cichlid fishes in Africa's oldest lake, Lake Tanganyika, offers a rare opportunity to study this process. Using the cichlid species Tropheus moorii, we assessed the potential for microevolution in a set of morphological traits by estimating their quantitative genetic basis of variation. Two approaches were employed: (1) estimation of trait heritabilities (h2) in situ from a sample of wild caught fish, and (2) estimation of h2 from first generation offspring produced in a semi-natural breeding experiment. In both cases, microsatellite data were used to infer pedigree structure among the sampled individuals and estimates of h2 were made using an animal model approach. Although power was limited by the pedigree structures estimated (particularly in the wild caught sample), we nonetheless demonstrate the presence of significant additive genetic variance for aspects of morphology that, in the cichlid species Tropheus moorii, are expected to be functionally and ecologically important, and therefore likely targets of natural selection. We hypothesize that traits showing significant additive genetic variance, such as the mouth position have most likely played a key role in the adaptive evolution of the cichlid fish Tropheus moorii.
Collapse
Affiliation(s)
- Martin Koch
- Department of Zoology, University of Graz, Universitätsplatz 2, 8010 Graz, Austria
| | - Alastair J. Wilson
- Institute of Evolutionary Biology, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JT UK
| | | | - Thomas Wiedl
- Department of Zoology, University of Graz, Universitätsplatz 2, 8010 Graz, Austria
| | - Christian Sturmbauer
- Department of Zoology, University of Graz, Universitätsplatz 2, 8010 Graz, Austria
| |
Collapse
|
79
|
Brakefield PM. Evo-devo and accounting for Darwin's endless forms. Philos Trans R Soc Lond B Biol Sci 2011; 366:2069-75. [PMID: 21690125 DOI: 10.1098/rstb.2011.0007] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Evo-devo has led to dramatic advances in our understanding of how the processes of development can contribute to explaining patterns of evolutionary diversification that underlie the endless forms of animal life on the Earth. This is increasingly the case not only for the origins of evolutionary novelties that permit new functions and open up new adaptive zones, but also for the processes of evolutionary tinkering that occur within the subsequent radiations of related species. Evo-devo has time and again yielded spectacular examples of Darwin's notions of common ancestry and of descent with modification. It has also shown that the evolution of endless forms is more about the evolution of the regulatory machinery of ancient genes than the origin and elaboration of new genes. Evolvability, especially with respect to the capacity of a developmental system to evolve and to generate the variation in form for natural selection to screen, has become a pivotal focus of evo-devo. As a consequence, a balancing of the concept of endless forms in morphospace with a greater awareness of the potential for developmental constraints and bias is becoming more general. The prospect of parallel horizons opening up for the evolution of behaviour is exciting; in particular, does Sean Carroll's phrase referring to old genes learning new tricks in the evolution of endless forms apply equally as well to patterns of diversity and disparity in behavioural trait-space?
Collapse
Affiliation(s)
- Paul M Brakefield
- Department of Zoology, University Museum of Zoology Cambridge, , University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
| |
Collapse
|
80
|
Fujimura K, Kocher TD. Tol2-mediated transgenesis in tilapia (Oreochromis niloticus). AQUACULTURE (AMSTERDAM, NETHERLANDS) 2011; 319:342-346. [PMID: 21938082 PMCID: PMC3175368 DOI: 10.1016/j.aquaculture.2011.07.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Nile tilapia (Oreochromis niloticus) is an important species in aquaculture and an excellent model system for laboratory studies. Functional genetic analysis using this species has been difficult because existing methods for producing transgenics are inefficient. Here we show that the Tol2 transposon system can be used to create transgenic tilapia with high efficiency. We constructed a line that is transgenic for GFP under control of a Xenopus elongation factor 1α (EF1α) promoter. The germline transmission rate of the Tol2 construct to the first generation was about 30%, which is much higher than conventional methods. GFP expression was strong and ubiquitous in the embryos. Application of the Tol2 system for constructing transgenics in tilapia and related species will promote research in many areas, but will be especially useful for studies of evolutionary developmental biology in the cichlid fishes of East Africa.
Collapse
Affiliation(s)
- Koji Fujimura
- Department of Biology, University of Maryland, 1210 Biology/Psychology Building, University of Maryland, College Park, Maryland 20742, USA
| | - Thomas D. Kocher
- Department of Biology, University of Maryland, 1210 Biology/Psychology Building, University of Maryland, College Park, Maryland 20742, USA
| |
Collapse
|
81
|
Fan S, Elmer KR, Meyer A. Positive Darwinian selection drives the evolution of the morphology-related gene, EPCAM, in particularly species-rich lineages of African cichlid fishes. J Mol Evol 2011; 73:1-9. [PMID: 21811860 DOI: 10.1007/s00239-011-9452-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 07/07/2011] [Indexed: 12/23/2022]
Abstract
The study of genetic evolution within the context of adaptive radiations offers insights to genes and selection pressures that result in rapid morphological change. Cichlid fishes are very species-rich and variable in coloration, behavior, and morphology, and so provide a classical model system for studying the genetics of adaptive radiation. In this study, we researched the evolution of the epithelial cell adhesion molecule (EPCAM), a candidate gene for the adaptive evolution of morphology broadly, and skin development specifically, in fishes. We compared EPCAM gene sequences from a rapidly speciating African cichlid lineage (the haplochromines), a species-poor African lineage (Nile tilapia Oreochromis niloticus), and a very young adaptive radiation in the Neotropics (sympatric crater lake Midas cichlids, Amphilophus sp.). Our results, based on a hierarchy of evolutionary analyses of nucleotide substitution, demonstrate that there are different selection pressures on the EPCAM gene among the cichlid lineages. Several waves of positive natural selection were identified not only on the terminal branches, but also on ancestral branches. Interestingly, significant positive or directional selection was found in the haplochromine cichlids only but not the comparatively species-poor tilapia lineage. We hypothesize that the strong signal of selection in the ancestral African cichlid lineage coincided with the transition from riverine to lacustrine habitat. The two neotropical species for which we collected new sequence data were invariant in the EPCAM locus. Our results suggest that functional changes promoted by positive Darwinian selection are widespread in the EPCAM gene during African cichlid evolution.
Collapse
Affiliation(s)
- Shaohua Fan
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätstrasse 10, 78457 Constance, Germany
| | | | | |
Collapse
|
82
|
|
83
|
Muschick M, Barluenga M, Salzburger W, Meyer A. Adaptive phenotypic plasticity in the Midas cichlid fish pharyngeal jaw and its relevance in adaptive radiation. BMC Evol Biol 2011; 11:116. [PMID: 21529367 PMCID: PMC3103464 DOI: 10.1186/1471-2148-11-116] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 04/30/2011] [Indexed: 01/05/2023] Open
Abstract
Background Phenotypic evolution and its role in the diversification of organisms is a central topic in evolutionary biology. A neglected factor during the modern evolutionary synthesis, adaptive phenotypic plasticity, more recently attracted the attention of many evolutionary biologists and is now recognized as an important ingredient in both population persistence and diversification. The traits and directions in which an ancestral source population displays phenotypic plasticity might partly determine the trajectories in morphospace, which are accessible for an adaptive radiation, starting from the colonization of a novel environment. In the case of repeated colonizations of similar environments from the same source population this "flexible stem" hypothesis predicts similar phenotypes to arise in repeated subsequent radiations. The Midas Cichlid (Amphilophus spp.) in Nicaragua has radiated in parallel in several crater-lakes seeded by populations originating from the Nicaraguan Great Lakes. Here, we tested phenotypic plasticity in the pharyngeal jaw of Midas Cichlids. The pharyngeal jaw apparatus of cichlids, a second set of jaws functionally decoupled from the oral ones, is known to mediate ecological specialization and often differs strongly between sister-species. Results We performed a common garden experiment raising three groups of Midas cichlids on food differing in hardness and calcium content. Analyzing the lower pharyngeal jaw-bones we find significant differences between diet groups qualitatively resembling the differences found between specialized species. Observed differences in pharyngeal jaw expression between groups were attributable to the diet's mechanical resistance, whereas surplus calcium in the diet was not found to be of importance. Conclusions The pharyngeal jaw apparatus of Midas Cichlids can be expressed plastically if stimulated mechanically during feeding. Since this trait is commonly differentiated - among other traits - between Midas Cichlid species, its plasticity might be an important factor in Midas Cichlid speciation. The prevalence of pharyngeal jaw differentiation across the Cichlidae further suggests that adaptive phenotypic plasticity in this trait could play an important role in cichlid speciation in general. We discuss several possibilities how the adaptive radiation of Midas Cichlids might have been influenced in this respect.
Collapse
Affiliation(s)
- Moritz Muschick
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
| | | | | | | |
Collapse
|
84
|
Svensson O, Egger B, Gricar B, Woodhouse K, van Oosterhout C, Salzburger W, Seehausen O, Turner GF. Segregation of species-specific male attractiveness in f(2) hybrid lake Malawi cichlid fish. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2011; 2011:426179. [PMID: 21716739 PMCID: PMC3119475 DOI: 10.4061/2011/426179] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 02/14/2011] [Indexed: 11/20/2022]
Abstract
Among the huge radiations of haplochromine cichlid fish in Lakes Malawi and Victoria, closely related species are often reproductively isolated via female mate choice although viable fertile hybrids can be produced when females are confined only with heterospecific males. We generated F2 hybrid males from a cross between a pair of closely related sympatric cichlid fish from Lake Malawi. Laboratory mate choice experiments using microsatellite paternity analysis demonstrated that F2 hybrid males differed significantly in their attractiveness to females of the two parental species, indicating heritable variation in traits involved in mate choice that may contribute to reproductive isolation between these species. We found no significant correlation between male mating success and any measurement of male colour pattern. A simple quantitative genetic model of reproductive isolation suggests that there may be as few as two chromosomal regions controlling species-specific attractiveness. We propose that adaptive radiation of Lake Malawi cichlids could be facilitated by the presence of genes with major effects on mate choice and reproductive isolation.
Collapse
Affiliation(s)
- Ola Svensson
- Evolutionary Biology Group, Biological Sciences, University of Hull, Hull HU6 7RX, UK
| | | | | | | | | | | | | | | |
Collapse
|
85
|
Ancestral and derived attributes of the dlx gene repertoire, cluster structure and expression patterns in an African cichlid fish. EvoDevo 2011; 2:1. [PMID: 21205289 PMCID: PMC3024246 DOI: 10.1186/2041-9139-2-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 01/04/2011] [Indexed: 01/03/2023] Open
Abstract
Background Cichlid fishes have undergone rapid, expansive evolutionary radiations that are manifested in the diversification of their trophic morphologies, tooth patterning and coloration. Understanding the molecular mechanisms that underlie the cichlids' unique patterns of evolution requires a thorough examination of genes that pattern the neural crest, from which these diverse phenotypes are derived. Among those genes, the homeobox-containing Dlx gene family is of particular interest since it is involved in the patterning of the brain, jaws and teeth. Results In this study, we characterized the dlx genes of an African cichlid fish, Astatotilapia burtoni, to provide a baseline to later allow cross-species comparison within Cichlidae. We identified seven dlx paralogs (dlx1a, -2a, -4a, -3b, -4b, -5a and -6a), whose orthologies were validated with molecular phylogenetic trees. The intergenic regions of three dlx gene clusters (dlx1a-2a, dlx3b-4b, and dlx5a-6a) were amplified with long PCR. Intensive cross-species comparison revealed a number of conserved non-coding elements (CNEs) that are shared with other percomorph fishes. This analysis highlighted additional lineage-specific gains/losses of CNEs in different teleost fish lineages and a novel CNE that had previously not been identified. Our gene expression analyses revealed overlapping but distinct expression of dlx orthologs in the developing brain and pharyngeal arches. Notably, four of the seven A. burtoni dlx genes, dlx2a, dlx3b, dlx4a and dlx5a, were expressed in the developing pharyngeal teeth. Conclusion This comparative study of the dlx genes of A. burtoni has deepened our knowledge of the diversity of the Dlx gene family, in terms of gene repertoire, expression patterns and non-coding elements. We have identified possible cichlid lineage-specific changes, including losses of a subset of dlx expression domains in the pharyngeal teeth, which will be the targets of future functional studies.
Collapse
|
86
|
Morphological distinctness despite large-scale phenotypic plasticity--analysis of wild and pond-bred juveniles of allopatric populations of Tropheus moorii. Naturwissenschaften 2010; 98:125-34. [PMID: 21161156 PMCID: PMC3029815 DOI: 10.1007/s00114-010-0751-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 11/22/2010] [Accepted: 11/24/2010] [Indexed: 10/31/2022]
Abstract
Cichlids are an excellent model to study explosive speciation and adaptive radiation. Their evolutionary success has been attributed to their ability to undergo rapid morphological changes related to diet, and their particular breeding biology. Relatively minor changes in morphology allow for exploitation of novel food resources. The importance of phenotypic plasticity and genetically based differences for diversification was long recognized, but their relationship and relative magnitude remained unclear. We compared morphology of individuals of four wild populations of the Lake Tanganyika cichlid Tropheus moorii with their pond-raised F(1) offspring. The magnitude of morphological change via phenotypic plasticity between wild and pond-bred F(1) fish exceeds pairwise population differences by a factor of 2.4 (mean Mahalanobis distances). The genetic and environmental effects responsible for among population differentiation in the wild could still be recognized in the pond-bred F(1) fish. All four pond populations showed the same trends in morphological change, mainly in mouth orientation, size and orientation of fins, and thickness of the caudal peduncle. As between population differentiation was lower in the wild than differentiation between pond-raised versus wild fish, we suggest the narrow ecological niche and intense interspecific competition in rock habitats is responsible for consistent shape similarity, even among long-term isolated populations.
Collapse
|
87
|
Klingenberg CP, Debat V, Roff DA. Quantitative genetics of shape in cricket wings: developmental integration in a functional structure. Evolution 2010; 64:2935-51. [PMID: 20482613 DOI: 10.1111/j.1558-5646.2010.01030.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The role of developmental and genetic integration for evolution is contentious. One hypothesis states that integration acts as a constraint on evolution, whereas an alternative is that developmental and genetic systems evolve to match the functional modularity of organisms. This study examined a morphological structure, the cricket wing, where developmental and functional modules are discordant, making it possible to distinguish the two alternatives. Wing shape was characterized with geometric morphometrics, quantitative genetic information was extracted using a full-sibling breeding design, and patterns of developmental integration were inferred from fluctuating asymmetry of wing shape. The patterns of genetic, phenotypic, and developmental integration were clearly similar, but not identical. Heritabilities for different shape variables varied widely, but no shape variables were devoid of genetic variation. Simulated selection for specific shape changes produced predicted responses with marked deflections due to the genetic covariance structure. Three hypotheses of modularity according to the wing structures involved in sound production were inconsistent with the genetic, phenotypic, or developmental covariance structure. Instead, there appears to be strong integration throughout the wing. The hypothesis that genetic and developmental integration evolve to match functional modularity can therefore be rejected for this example.
Collapse
Affiliation(s)
- Christian Peter Klingenberg
- Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, United Kingdom.
| | | | | |
Collapse
|
88
|
HOFMANN CHRISTOPHERM, O’QUIN KELLYE, SMITH ADAMR, CARLETON KARENL. Plasticity of opsin gene expression in cichlids from Lake Malawi. Mol Ecol 2010; 19:2064-74. [DOI: 10.1111/j.1365-294x.2010.04621.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
89
|
le Pabic P, Stellwag EJ, Scemama JL. Embryonic development and skeletogenesis of the pharyngeal jaw apparatus in the cichlid Nile tilapia (Oreochromis niloticus). Anat Rec (Hoboken) 2010; 292:1780-800. [PMID: 19718717 DOI: 10.1002/ar.20960] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The evolution of a specialized pharyngeal jaw apparatus (PJA) has been argued to be the key evolutionary innovation that allowed the explosive adaptive radiation of cichlid fishes in East African lakes. Subsequent studies together with recent molecular phylogenies have shown that similar innovations evolved independently several times within the teleosts, which poses the questions: (1) how similar are the developmental mechanisms responsible for these changes in divergent taxa and (2) how did such complex features arise independently in evolution? A detailed knowledge of PJA development in cichlids and other teleosts is needed to address these questions. Here, we provide a detailed account of the development of the PJA in one species of cichlid, the Nile tilapia (Oreochromis niloticus), from the early segmentation and patterning of its embryonic precursors - pharyngeal arches 3 to 7 - to its ossification. We find that pharyngeal segmentation occurs sequentially from anterior to posterior during early segmentation stages through the mid-pharyngula period. We show a clear combinatorial code of Hox gene expression such that each posterior arch is defined by a distinctive Hox signature. Posterior arch chondrogenesis in tilapia is essentially complete by the end of the hatching period, and most elements become ossified over the next two days. Our results reveal that both the fusion of lower jaw bones and articulation between the neurocranium and upper jaws occur during post-embryonic development.
Collapse
Affiliation(s)
- Pierre le Pabic
- Department of Biology, East Carolina University, Howell Science Complex, Greenville, NC, USA
| | | | | |
Collapse
|
90
|
Suzuki D, Brandley MC, Tokita M. The mitochondrial phylogeny of an ancient lineage of ray-finned fishes (Polypteridae) with implications for the evolution of body elongation, pelvic fin loss, and craniofacial morphology in Osteichthyes. BMC Evol Biol 2010; 10:21. [PMID: 20100320 PMCID: PMC2825197 DOI: 10.1186/1471-2148-10-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 01/25/2010] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The family Polypteridae, commonly known as "bichirs", is a lineage that diverged early in the evolutionary history of Actinopterygii (ray-finned fish), but has been the subject of far less evolutionary study than other members of that clade. Uncovering patterns of morphological change within Polypteridae provides an important opportunity to evaluate if the mechanisms underlying morphological evolution are shared among actinoptyerygians, and in fact, perhaps the entire osteichthyan (bony fish and tetrapods) tree of life. However, the greatest impediment to elucidating these patterns is the lack of a well-resolved, highly-supported phylogenetic tree of Polypteridae. In fact, the interrelationships of polypterid species have never been subject to molecular phylogenetic analysis. Here, we infer the first molecular phylogeny of bichirs, including all 12 recognized species and multiple subspecies using Bayesian analyses of 16S and cyt-b mtDNA. We use this mitochondrial phylogeny, ancestral state reconstruction, and geometric morphometrics to test whether patterns of morphological evolution, including the evolution of body elongation, pelvic fin reduction, and craniofacial morphology, are shared throughout the osteichthyan tree of life. RESULTS Our molecular phylogeny reveals 1) a basal divergence between Erpetoichthys and Polypterus, 2) polyphyly of P. endlicheri and P. palmas, and thus 3) the current taxonomy of Polypteridae masks its underlying genetic diversity. Ancestral state reconstructions suggest that pelvic fins were lost independently in Erpetoichthys, and unambiguously estimate multiple independent derivations of body elongation and shortening. Our mitochondrial phylogeny suggested species that have lower jaw protrusion and up-righted orbit are closely related to each other, indicating a single transformation of craniofacial morphology. CONCLUSION The mitochondrial phylogeny of polypterid fish provides a strongly-supported phylogenetic framework for future comparative evolutionary, physiological, ecological, and genetic analyses. Indeed, ancestral reconstruction and geometric morphometric analyses revealed that the patterns of morphological evolution in Polypteridae are similar to those seen in other osteichthyans, thus implying the underlying genetic and developmental mechanisms responsible for those patterns were established early in the evolutionary history of Osteichthyes. We propose developmental and genetic mechanisms to be tested under the light of this new phylogenetic framework.
Collapse
Affiliation(s)
- Dai Suzuki
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
| | - Matthew C Brandley
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8105 USA
| | - Masayoshi Tokita
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572 Japan
| |
Collapse
|
91
|
Pfaender J, Schliewen UK, Herder F. Phenotypic traits meet patterns of resource use in the radiation of “sharpfin” sailfin silverside fish in Lake Matano. Evol Ecol 2009. [DOI: 10.1007/s10682-009-9332-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
92
|
Abstract
Absolute barriers to dispersal are not common in marine systems, and the prevalence of planktonic larvae in marine taxa provides potential for gene flow across large geographic distances. These observations raise the fundamental question in marine evolutionary biology as to whether geographic and oceanographic barriers alone can account for the high levels of species diversity observed in marine environments such as coral reefs, or whether marine speciation also operates in the presence of gene flow between diverging populations. In this respect, the ecological hypothesis of speciation, in which reproductive isolation results from divergent or disruptive natural selection, is of particular interest because it may operate in the presence of gene flow. Although important insights into the process of ecological speciation in aquatic environments have been provided by the study of freshwater fishes, comparatively little is known about the possibility of ecological speciation in marine teleosts. In this study, the evidence consistent with different aspects of the ecological hypothesis of speciation is evaluated in marine fishes. Molecular approaches have played a critical role in the development of speciation hypotheses in marine fishes, with a role of ecology suggested by the occurrence of sister clades separated by ecological factors, rapid cladogenesis or the persistence of genetically and ecologically differentiated species in the presence of gene flow. Yet, ecological speciation research in marine fishes is still largely at an exploratory stage. Cases where the major ingredients of ecological speciation, namely a source of natural divergent or disruptive selection, a mechanism of reproductive isolation and a link between the two have been explicitly documented are few. Even in these cases, specific predictions of the ecological hypothesis of speciation remain largely untested. Recent developments in the study of freshwater fishes illustrate the potential for molecular approaches to address specific questions related to the ecological hypothesis of speciation such as the nature of the genes underlying key ecological traits, the magnitude of their effect on phenotype and the mechanisms underlying their differential expression in different ecological contexts. The potential provided by molecular studies is fully realized when they are complemented with alternative (e.g. ecological, theoretical) approaches.
Collapse
Affiliation(s)
- O Puebla
- Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Balboa, Ancon, Republic of Panama.
| |
Collapse
|
93
|
Hulsey CD. Cichlid genomics and phenotypic diversity in a comparative context. Integr Comp Biol 2009; 49:618-29. [DOI: 10.1093/icb/icp071] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
94
|
Feathers with Ocular Architecture: Implications for Functional and Evolutionary Similarities of Visual Signals and Receptors. Evol Biol 2009. [DOI: 10.1007/s11692-009-9059-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
95
|
SALZBURGER WALTER. The interaction of sexually and naturally selected traits in the adaptive radiations of cichlid fishes. Mol Ecol 2009; 18:169-85. [DOI: 10.1111/j.1365-294x.2008.03981.x] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
96
|
Albertson RC. Morphological Divergence Predicts Habitat Partitioning in a Lake Malawi Cichlid Species Complex. COPEIA 2008. [DOI: 10.1643/cg-07-217] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
97
|
A microsatellite-based genetic linkage map of the cichlid fish, Astatotilapia burtoni (Teleostei): a comparison of genomic architectures among rapidly speciating cichlids. Genetics 2008; 182:387-97. [PMID: 18757932 DOI: 10.1534/genetics.108.089367] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cichlid fishes compose an astonishingly large number of species and formed species flocks in record-breaking time. To facilitate efficient genome scans and comparisons of cichlid genomes, we constructed a medium-density genetic linkage map of microsatellite markers of Astatotilapia burtoni. The mapping cross was derived from two inbred laboratory lines to obtain F(2) progeny by intercrossing. The map revealed 25 linkage groups spanning 1249.3 cM of the genome (size approximately 950 Mb) with an average marker spacing of 6.12 cM. The seven Hox clusters, ParaHox C1, and two paralogs of Pdgfrbeta were mapped to different linkage groups, thus supporting the hypothesis of a teleost-specific genome duplication. The A. burtoni linkage map was compared to the other two available maps for cichlids using shared markers that showed conservation and synteny among East African cichlid genomes. Interesting candidate genes for cichlid speciation were mapped using SNP markers.
Collapse
|
98
|
Fujimura K, Okada N. Shaping of the lower jaw bone during growth of Nile tilapia Oreochromis niloticus and a Lake Victoria cichlid Haplochromis chilotes: a geometric morphometric approach. Dev Growth Differ 2008; 50:653-63. [PMID: 18707606 DOI: 10.1111/j.1440-169x.2008.01063.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
East African cichlids have evolved feeding apparatus morphologies to adapt to diverse feeding environments. However, little is known about how the morphologies are formed during development. Here, we assessed the shape changes of the lower jaw bone during growth of the Nile tilapia Oreochromis niloticus and a Lake Victoria cichlid Haplochromis chilotes using geometric morphometric methods. 'Early Juvenile to Late Juvenile' and 'Late Juvenile to Adult' transitions of the shape change during growth of both O. niloticus and H. chilotes were detected. The 'Early Juvenile to Late Juvenile' transition of the shape change in H. chilotes occurred slightly earlier than in O. niloticus. We also compared the shape changes during growth of the two cichlids. Principal component analysis showed both commonalities and differences in the morphological changes between the cichlids. Our data suggest that most shape change may have a similar pattern during the growth of O. niloticus and H. chilotes, and that the differences in adult shapes may be due to differences arising early in development, not to the difference of shape change during growth. These data provide a basis for understanding the developmental mechanisms underlying this adaptive trait of East African cichlids.
Collapse
Affiliation(s)
- Koji Fujimura
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-21 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | | |
Collapse
|
99
|
Fujimura K, Okada N. Bone development in the jaw of Nile tilapia Oreochromis niloticus (Pisces: Cichlidae). Dev Growth Differ 2008; 50:339-55. [PMID: 18430028 DOI: 10.1111/j.1440-169x.2008.01032.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
East African cichlids have evolved feeding apparatus morphologies adapted to their diverse feeding behaviors. The evolution of the oral jaw morphologies is accomplished by the diversity of bone formation during development. To further understand this evolutionary process, we examined the skeletal elements of the jaw and their temporal and sequential emergence, categorized by developmental stages, using the Nile tilapia Oreochromis niloticus as a model cichlid. We found that chondrogenesis started in Stage 17. The deposition of osteoid for the dermal bones commenced in Stage 18. The uptake of calcium dramatically shifted from the surface of larvae to the gills in Stage 20. The bone mineralization of the skeleton began in Stage 25. These data provide important information regarding the sequential events of craniofacial development in East African cichlids and lay the groundwork for studying the molecular mechanisms underlying adaptation of jaw structure to feeding behavior.
Collapse
Affiliation(s)
- Koji Fujimura
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, B-21-4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | | |
Collapse
|
100
|
Merrill AE, Eames BF, Weston SJ, Heath T, Schneider RA. Mesenchyme-dependent BMP signaling directs the timing of mandibular osteogenesis. Development 2008; 135:1223-34. [PMID: 18287200 DOI: 10.1242/dev.015933] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
To identify molecular and cellular mechanisms that determine when bone forms, and to elucidate the role played by osteogenic mesenchyme, we employed an avian chimeric system that draws upon the divergent embryonic maturation rates of quail and duck. Pre-migratory neural crest mesenchyme destined to form bone in the mandible was transplanted from quail to duck. In resulting chimeras, quail donor mesenchyme established significantly faster molecular and histological programs for osteogenesis within the relatively slower-progressing duck host environment. To understand this phenotype, we assayed for changes in the timing of epithelial-mesenchymal interactions required for bone formation and found that such interactions were accelerated in chimeras. In situ hybridization analyses uncovered donor-dependent changes in the spatiotemporal expression of genes, including the osteo-inductive growth factor Bmp4. Mesenchymal expression of Bmp4 correlated with an ability of quail donor cells to form bone precociously without duck host epithelium, and also relied upon epithelial interactions until mesenchyme could form bone independently. Treating control mandibles with exogenous BMP4 recapitulated the capacity of chimeras to express molecular mediators of osteogenesis prematurely and led to the early differentiation of bone. Inhibiting BMP signaling delayed bone formation in a stage-dependent manner that was accelerated in chimeras. Thus, mandibular mesenchyme dictates when bone forms by temporally regulating its interactions with epithelium and its own expression of Bmp4. Our findings offer a developmental mechanism to explain how neural crest-derived mesenchyme and BMP signaling underlie the evolution of species-specific skeletal morphology.
Collapse
Affiliation(s)
- Amy E Merrill
- Department of Orthopaedic Surgery, University of California at San Francisco, 533 Parnassus Avenue, U-453, San Francisco, CA 94143-0514, USA
| | | | | | | | | |
Collapse
|