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Embryonic and larval development in the Midas cichlid fish species flock (Amphilophus spp.): a new evo-devo model for the investigation of adaptive novelties and species differences.

Kratochwil CF, Sefton MM, Meyer A - BMC Dev. Biol. (2015)

Bottom Line: Key morphological differences between the embryos of Midas cichlids and other teleosts are highlighted and discussed, including the presence of adhesive glands and different early chromatophore patterns, as well as variation in developmental timing.In the past, the species flocks of the African Great Lakes have received the most attention from researchers, but some lineages of the 300-400 species of Central American lakes are fascinating model systems for adaptive radiation and rapid phenotypic evolution.The availability of genetic resources, their status as a model system for evolutionary research, and the possibility to perform functional experiments including transgenesis makes the Midas cichlid complex a very attractive model for evolutionary-developmental research.

View Article: PubMed Central - PubMed

Affiliation: Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany. claudius.kratochwil@uni-konstanz.de.

ABSTRACT

Background: Central American crater lake cichlid fish of the Midas species complex (Amphilophus spp.) are a model system for sympatric speciation and fast ecological diversification and specialization. Midas cichlids have been intensively analyzed from an ecological and morphological perspective. Genomic resources such as transcriptomic and genomic data sets, and a high-quality draft genome are available now. Many ecologically relevant species-specific traits and differences such as pigmentation and cranial morphology arise during development. Detailed descriptions of the early development of the Midas cichlid in particular, will help to investigate the ontogeny of species differences and adaptations.

Results: We describe the embryonic and larval development of the crater lake cichlid, Amphilophus xiloaensis, until seven days after fertilization. Similar to previous studies on teleost development, we describe six periods of embryogenesis - the zygote, cleavage, blastula, gastrula, segmentation, and post-hatching period. Furthermore, we define homologous stages to well-described teleost models such as medaka and zebrafish, as well as other cichlid species such as the Nile tilapia and the South American cichlid Cichlasoma dimerus. Key morphological differences between the embryos of Midas cichlids and other teleosts are highlighted and discussed, including the presence of adhesive glands and different early chromatophore patterns, as well as variation in developmental timing.

Conclusions: The developmental staging of the Midas cichlid will aid researchers in the comparative investigation of teleost ontogenies. It will facilitate comparative developmental biological studies of Neotropical and African cichlid fish in particular. In the past, the species flocks of the African Great Lakes have received the most attention from researchers, but some lineages of the 300-400 species of Central American lakes are fascinating model systems for adaptive radiation and rapid phenotypic evolution. The availability of genetic resources, their status as a model system for evolutionary research, and the possibility to perform functional experiments including transgenesis makes the Midas cichlid complex a very attractive model for evolutionary-developmental research.

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Range and prominent phenotypic differences of members of the Midas cichlid species complex. (A) Map of the Pacific coast of Nicaragua in Central America. Besides the large Nicaraguan lakes (Managua and Nicaragua), multiple crater lakes (Asososca Leon, Apoyeque, Xiloá, Asosoca Managua, Masaya and Apoyo) have appeared in the course of the last 25,000 years. These crater lakes have been colonized by Midas cichlids from the large lakes, resulting in new species. (B) Midas cichlids from Lake Xiloá, Amphilophus xiloaensis, the focal species of this study. (C) Three selected traits that are interesting from an evolutionary-developmental angle. In the large lakes and in many crater lakes, cichlid species and morphs show differences in coloration, body shape and lip shape.
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Fig1: Range and prominent phenotypic differences of members of the Midas cichlid species complex. (A) Map of the Pacific coast of Nicaragua in Central America. Besides the large Nicaraguan lakes (Managua and Nicaragua), multiple crater lakes (Asososca Leon, Apoyeque, Xiloá, Asosoca Managua, Masaya and Apoyo) have appeared in the course of the last 25,000 years. These crater lakes have been colonized by Midas cichlids from the large lakes, resulting in new species. (B) Midas cichlids from Lake Xiloá, Amphilophus xiloaensis, the focal species of this study. (C) Three selected traits that are interesting from an evolutionary-developmental angle. In the large lakes and in many crater lakes, cichlid species and morphs show differences in coloration, body shape and lip shape.

Mentions: Cichlids are famous for their astonishing rate of phenotypic diversification and speciation. With over 2000 described species, cichlid fish form one of the most diverse and species-rich groups of animals [1]. Lacustrine cichlids in Africa and in the Neotropics are well-known examples of adaptive radiations [2-4]. In particular, the cichlid radiations in Nicaraguan crater lakes (Figure 1, Table 1) provide a promising opportunity to study the early stages of speciation and diversification. This is because members of the Midas cichlid species complex (Amphilophus spp. or Amphilophus citrinellus spp.) have diverged repeatedly in several crater lakes, both sympatrically and allopatrically, often within a few thousand years [2,5-7]. Little is known so far about the molecular and developmental mechanisms that drive the observed phenotypic diversity between recently diverged species. The Midas cichlid complex underwent a rapid diversification within very short time spans (between 2000 and 25,000 years) and, interestingly, repeatedly evolved several adaptive traits (hypertrophied lips, elongated body shapes, dental innovations) in parallel in multiple crater lakes (Figure 1, Table 1). Therefore, Midas cichlids are an excellent model system for the comparative study of the phenotype-genotype relationship.Figure 1


Embryonic and larval development in the Midas cichlid fish species flock (Amphilophus spp.): a new evo-devo model for the investigation of adaptive novelties and species differences.

Kratochwil CF, Sefton MM, Meyer A - BMC Dev. Biol. (2015)

Range and prominent phenotypic differences of members of the Midas cichlid species complex. (A) Map of the Pacific coast of Nicaragua in Central America. Besides the large Nicaraguan lakes (Managua and Nicaragua), multiple crater lakes (Asososca Leon, Apoyeque, Xiloá, Asosoca Managua, Masaya and Apoyo) have appeared in the course of the last 25,000 years. These crater lakes have been colonized by Midas cichlids from the large lakes, resulting in new species. (B) Midas cichlids from Lake Xiloá, Amphilophus xiloaensis, the focal species of this study. (C) Three selected traits that are interesting from an evolutionary-developmental angle. In the large lakes and in many crater lakes, cichlid species and morphs show differences in coloration, body shape and lip shape.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4352272&req=5

Fig1: Range and prominent phenotypic differences of members of the Midas cichlid species complex. (A) Map of the Pacific coast of Nicaragua in Central America. Besides the large Nicaraguan lakes (Managua and Nicaragua), multiple crater lakes (Asososca Leon, Apoyeque, Xiloá, Asosoca Managua, Masaya and Apoyo) have appeared in the course of the last 25,000 years. These crater lakes have been colonized by Midas cichlids from the large lakes, resulting in new species. (B) Midas cichlids from Lake Xiloá, Amphilophus xiloaensis, the focal species of this study. (C) Three selected traits that are interesting from an evolutionary-developmental angle. In the large lakes and in many crater lakes, cichlid species and morphs show differences in coloration, body shape and lip shape.
Mentions: Cichlids are famous for their astonishing rate of phenotypic diversification and speciation. With over 2000 described species, cichlid fish form one of the most diverse and species-rich groups of animals [1]. Lacustrine cichlids in Africa and in the Neotropics are well-known examples of adaptive radiations [2-4]. In particular, the cichlid radiations in Nicaraguan crater lakes (Figure 1, Table 1) provide a promising opportunity to study the early stages of speciation and diversification. This is because members of the Midas cichlid species complex (Amphilophus spp. or Amphilophus citrinellus spp.) have diverged repeatedly in several crater lakes, both sympatrically and allopatrically, often within a few thousand years [2,5-7]. Little is known so far about the molecular and developmental mechanisms that drive the observed phenotypic diversity between recently diverged species. The Midas cichlid complex underwent a rapid diversification within very short time spans (between 2000 and 25,000 years) and, interestingly, repeatedly evolved several adaptive traits (hypertrophied lips, elongated body shapes, dental innovations) in parallel in multiple crater lakes (Figure 1, Table 1). Therefore, Midas cichlids are an excellent model system for the comparative study of the phenotype-genotype relationship.Figure 1

Bottom Line: Key morphological differences between the embryos of Midas cichlids and other teleosts are highlighted and discussed, including the presence of adhesive glands and different early chromatophore patterns, as well as variation in developmental timing.In the past, the species flocks of the African Great Lakes have received the most attention from researchers, but some lineages of the 300-400 species of Central American lakes are fascinating model systems for adaptive radiation and rapid phenotypic evolution.The availability of genetic resources, their status as a model system for evolutionary research, and the possibility to perform functional experiments including transgenesis makes the Midas cichlid complex a very attractive model for evolutionary-developmental research.

View Article: PubMed Central - PubMed

Affiliation: Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany. claudius.kratochwil@uni-konstanz.de.

ABSTRACT

Background: Central American crater lake cichlid fish of the Midas species complex (Amphilophus spp.) are a model system for sympatric speciation and fast ecological diversification and specialization. Midas cichlids have been intensively analyzed from an ecological and morphological perspective. Genomic resources such as transcriptomic and genomic data sets, and a high-quality draft genome are available now. Many ecologically relevant species-specific traits and differences such as pigmentation and cranial morphology arise during development. Detailed descriptions of the early development of the Midas cichlid in particular, will help to investigate the ontogeny of species differences and adaptations.

Results: We describe the embryonic and larval development of the crater lake cichlid, Amphilophus xiloaensis, until seven days after fertilization. Similar to previous studies on teleost development, we describe six periods of embryogenesis - the zygote, cleavage, blastula, gastrula, segmentation, and post-hatching period. Furthermore, we define homologous stages to well-described teleost models such as medaka and zebrafish, as well as other cichlid species such as the Nile tilapia and the South American cichlid Cichlasoma dimerus. Key morphological differences between the embryos of Midas cichlids and other teleosts are highlighted and discussed, including the presence of adhesive glands and different early chromatophore patterns, as well as variation in developmental timing.

Conclusions: The developmental staging of the Midas cichlid will aid researchers in the comparative investigation of teleost ontogenies. It will facilitate comparative developmental biological studies of Neotropical and African cichlid fish in particular. In the past, the species flocks of the African Great Lakes have received the most attention from researchers, but some lineages of the 300-400 species of Central American lakes are fascinating model systems for adaptive radiation and rapid phenotypic evolution. The availability of genetic resources, their status as a model system for evolutionary research, and the possibility to perform functional experiments including transgenesis makes the Midas cichlid complex a very attractive model for evolutionary-developmental research.

Show MeSH