scholarly journals Diversification dynamics and (non-)parallel evolution along an ecological gradient in African cichlid fishes

2021 ◽  
Author(s):  
A. A.-T. Weber ◽  
J. Rajkov ◽  
K. Smailus ◽  
B. Egger ◽  
W. Salzburger
Keyword(s):  
Evolutionary Biology ◽  
Parallel Evolution ◽  
Cichlid Fish ◽  
Morphological Differentiation ◽  
Grey Zone ◽  
Ecological Gradient ◽  
Cichlid Species ◽  
Morphometric Analyses ◽  
Astatotilapia Burtoni ◽  
Parallel Axis

AbstractUnderstanding the drivers and dynamics of diversification is a central topic in evolutionary biology. Here, we investigated the dynamics of diversification in the cichlid fish Astatotilapia burtoni that diverged along a lake-stream environmental gradient. Whole-genome and morphometric analyses revealed that divergent selection was essential at the early stages of diversification, but that periods in allopatry were likely involved towards the completion of speciation. While morphological differentiation was continuous, genomic differentiation was not, as shown by two clearly separated categories of genomic differentiation. Reproductive isolation increased along a continuum of genomic divergence, with a “grey zone” of speciation at ~0.1% net nucleotide divergence. The quantification of the extent of (non-)parallelism in nine lake-stream population pairs from four cichlid species by means of multivariate analyses revealed one parallel axis of genomic and morphological differentiation among seven lake-stream systems. Finally, we found that parallelism was higher when ancestral lake populations were more similar.

scholarly journals A Genomic Cluster Containing Novel and Conserved Genes is Associated with Cichlid Fish Dental Developmental Convergence

2020 ◽  
Vol 37 (11) ◽  
pp. 3165-3174 ◽  
Author(s):  
Nidal Karagic ◽  
Ralf F Schneider ◽  
Axel Meyer ◽  
C Darrin Hulsey
Keyword(s):  
Molecular Mechanisms ◽  
Cichlid Fish ◽  
Gill Arch ◽  
Tooth Formation ◽  
Cichlid Species ◽  
Ecological Benefit ◽  
Conserved Genes ◽  
Astatotilapia Burtoni ◽  
Pharyngeal Jaws ◽  
Genomic Cluster

Abstract The two toothed jaws of cichlid fishes provide textbook examples of convergent evolution. Tooth phenotypes such as enlarged molar-like teeth used to process hard-shelled mollusks have evolved numerous times independently during cichlid diversification. Although the ecological benefit of molar-like teeth to crush prey is known, it is unclear whether the same molecular mechanisms underlie these convergent traits. To identify genes involved in the evolution and development of enlarged cichlid teeth, we performed RNA-seq on the serially homologous-toothed oral and pharyngeal jaws as well as the fourth toothless gill arch of Astatoreochromis alluaudi. We identified 27 genes that are highly upregulated on both tooth-bearing jaws compared with the toothless gill arch. Most of these genes have never been reported to play a role in tooth formation. Two of these genes (unk, rpfA) are not found in other vertebrate genomes but are present in all cichlid genomes. They also cluster genomically with two other highly expressed tooth genes (odam, scpp5) that exhibit conserved expression during vertebrate odontogenesis. Unk and rpfA were confirmed via in situ hybridization to be expressed in developing teeth of Astatotilapia burtoni. We then examined expression of the cluster’s four genes in six evolutionarily independent and phylogenetically disparate cichlid species pairs each with a large- and a small-toothed species. Odam and unk commonly and scpp5 and rpfA always showed higher expression in larger toothed cichlid jaws. Convergent trophic adaptations across cichlid diversity are associated with the repeated developmental deployment of this genomic cluster containing conserved and novel cichlid-specific genes.

scholarly journals Repeatability and Heritability of Behavioural Types in a Social Cichlid

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Noémie Chervet ◽  
Markus Zöttl ◽  
Roger Schürch ◽  
Michael Taborsky ◽  
Dik Heg
Keyword(s):  
Environmental Factors ◽  
Quantitative Genetics ◽  
Variance Components ◽  
Significant Variation ◽  
Cichlid Fish ◽  
Animal Personality ◽  
Cichlid Species ◽  
Behavioural Type ◽  
Variance Components Estimation ◽  
Behavioural Types

Aim. The quantitative genetics underlying correlated behavioural traits (‘‘animal personality’’) have hitherto been studied mainly in domesticated animals. Here we report the repeatability () and heritability () of behavioural types in the highly social cichlid fish Neolamprologus pulcher. Methods. We tested 1779 individuals repeatedly and calculated the of behavioural types by variance components estimation (GLMM REML), using 1327 offspring from 162 broods from 74 pairs. Results. Repeatability of behavioural types was significant and considerable (0.546), but declined from 0.83 between tests conducted on the same day, to 0.19 on tests conducted up to 1201 days apart. All estimates were significant but low (e.g., pair identity SE). Additionally, we found significant variation between broods nested within the parent(s), but these were not related to several environmental factors tested. Conclusions. We conclude that despite a considerable , in this cichlid species is low, and variability in behavioural type appears to be strongly affected by other (non)genetic effects.

Social Status and Arginine Vasotocin Neuronal Phenotypes in a Cichlid Fish

2015 ◽  
Vol 85 (3) ◽  
pp. 203-213 ◽  
Author(s):  
Olinda Almeida ◽  
Rui F. Oliveira
Keyword(s):  
Social Status ◽  
Social Behaviour ◽  
Cichlid Fish ◽  
Brain Regions ◽  
Cell Number ◽  
Arginine Vasotocin ◽  
Cichlid Species ◽  
Neuronal Populations ◽  
Soma Size ◽  
Species Specific

The nonapeptide arginine vasotocin (AVT) and its mammalian homologue arginine vasopressin play a key role in the regulation of social behaviour across vertebrates. In teleost fishes, three AVT neuronal populations have been described in the preoptic area (POA): the parvocellular (pPOA), the magnocellular (mPOA) and the gigantocellular (gPOA). Neurons from each of these areas project both to the pituitary and to other brain regions, where AVT is supposed to regulate neural circuits underlying social behaviour. However, in the fish species studied so far, there is considerable variation in which AVT neuronal populations are involved in behavioural modulation and in the direction of the effect. In this study, the association between AVT neuronal phenotypes and social status was investigated in the Mozambique tilapia (Oreochromis mossambicus). This species is an African female mouth-brooding cichlid fish in which males form breeding aggregations in which dominant males establish territories and subordinate males to act as floaters. With respect to sex differences in AVT neuronal phenotypes, females have a larger number of AVT neurons in the pPOA and mPOA. Within males, AVT appeared associated with social subordination, as indicated by the larger cell body areas of AVT neurons in mPOA and gPOA nuclei of non-territorial males. There were also positive correlations between submissive behaviour and the soma size of AVT cells in all three nuclei and AVT cell number in the mPOA. In summary, the results provide evidence for an involvement of AVT in the modulation of social behaviour in tilapia, but it was not possible to identify specific roles for specific AVT neuronal populations. The results presented here also contrast with those previously published for another cichlid species with a similar mating system, which highlights the species-specific nature of the pattern of association between AVT and social behaviour even within the same taxonomic family.

scholarly journals Interspecific hybridization can generate functional novelty in cichlid fish

2019 ◽  
Vol 286 (1913) ◽  
pp. 20191621 ◽  
Author(s):  
O. M. Selz ◽  
O. Seehausen
Keyword(s):  
Interspecific Hybridization ◽  
First Generation ◽  
Parental Species ◽  
Cichlid Fish ◽  
Context Dependency ◽  
Functional Variation ◽  
Generate Functional ◽  
Cichlid Species ◽  
Evolutionary Consequences ◽  
African Cichlids

The role of interspecific hybridization in evolution is still being debated. Interspecific hybridization has been suggested to facilitate the evolution of ecological novelty, and hence the invasion of new niches and adaptive radiation when ecological opportunity is present beyond the parental species niches. On the other hand, hybrids between two ecologically divergent species may perform less well than parental species in their respective niches because hybrids would be intermediate in performance in both niches. The evolutionary consequences of hybridization may hence be context-dependent, depending on whether ecological opportunities, beyond those of the parental species, do or do not exist. Surprisingly, these complementary predictions may never have been tested in the same experiment in animals. To do so, we investigate if hybrids between ecologically distinct cichlid species perform less well than the parental species when feeding on food either parent is adapted to, and if the same hybrids perform better than their parents when feeding on food none of the species are adapted to. We generated two first-generation hybrid crosses between species of African cichlids. In feeding efficiency experiments we measured the performance of hybrids and parental species on food types representing both parental species niches and additional ‘novel’ niches, not used by either of the parental species but by other species in the African cichlid radiations. We found that hybrids can have higher feeding efficiencies on the ‘novel’ food types but typically have lower efficiencies on parental food types when compared to parental species. This suggests that hybridization can generate functional variation that can be of ecological relevance allowing the access to resources outside of either parental species niche. Hence, we provide support for the hypothesis of ecological context-dependency of the evolutionary impact of interspecific hybridization.

scholarly journals The Adaptive Radiation of Cichlid Fish in Lake Tanganyika: A Morphological Perspective

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Tetsumi Takahashi ◽  
Stephan Koblmüller
Keyword(s):  
East Africa ◽  
Adaptive Radiation ◽  
Lake Tanganyika ◽  
Cichlid Fish ◽  
Ancient Lakes ◽  
Species Assemblage ◽  
Cichlid Species ◽  
Morphological Studies ◽  
Rapid Speciation ◽  
Explosive Speciation

Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources. To elucidate the processes and mechanisms underlying the rapid speciation and adaptive radiation of Lake Tanganyika's cichlid species assemblage it is important to integrate evidence from several lines of research. Great efforts have been, are, and certainly will be taken to solve the mystery of how so many cichlid species evolved in so little time. In the present review, we summarize morphological studies that relate to the adaptive radiation of Lake Tanganyika's cichlids and highlight their importance for understanding the process of adaptive radiation.

scholarly journals Heritability and adaptive significance of the number of egg-dummies in the cichlid fish Astatotilapia burtoni

2011 ◽  
Vol 278 (1716) ◽  
pp. 2318-2324 ◽  
Author(s):  
Topi K. Lehtonen ◽  
Axel Meyer
Keyword(s):  
Species Recognition ◽  
Cichlid Fish ◽  
Fertilization Success ◽  
Narrow Sense Heritability ◽  
Key Innovation ◽  
Bright Spots ◽  
Spot Number ◽  
Astatotilapia Burtoni ◽  
Important Trait ◽  
High Degree

Cichlid fishes are a textbook example of rapid speciation and exuberant diversity—this applies especially to haplochromines, a lineage with approximately 1800 species. Haplochromine males uniquely possess oval, bright spots on their anal fin, called ‘egg-spots’ or ‘egg-dummies’. These are presumed to be an evolutionary key innovation that contributed to the tribe's evolutionary success. Egg-spots have been proposed to mimic the ova of the mouthbrooding females of the corresponding species, contribute to fertilization success and even facilitate species recognition. Interestingly, egg-spot number varies extensively not only between species, but also within some populations. This high degree of intraspecific variation may appear to be counterintuitive since selection might be expected to act to stabilize traits that are correlated with fitness measures. We addressed this ‘paradox’ experimentally, and found that in the haplochromine cichlid Astatotilapia burtoni , the number of egg-spots was related to male age, body condition and dominance status. Intriguingly, the egg-spot number also had a high heritable component (narrow sense heritability of 0.5). These results suggest that the function of egg-spots might have less to do with fertilization success or species recognition, but rather relate to mate choice and/or male–male competition, helping to explain the high variability in this important trait.

Arginine vasotocin regulates social ascent in the African cichlid fish Astatotilapia burtoni

2015 ◽  
Vol 212 ◽  
pp. 106-113 ◽  
Author(s):  
Lin S. Huffman ◽  
Flora I. Hinz ◽  
Sophie Wojcik ◽  
Nadia Aubin-Horth ◽  
Hans A. Hofmann
Keyword(s):  
Cichlid Fish ◽  
Arginine Vasotocin ◽  
African Cichlid ◽  
Astatotilapia Burtoni
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