Abstracts (first author)

Talk 

The genetic bases of body shape architecture of two sympatric Mesoamerican cichlid species: a RAD-QTL approach

Author(s): Fruciano C, Franchini P, Jones JC, Spreitzer ML, Elmer KR, Henning F, Meyer A

Summary:

Determining the genetic bases of phenotypic adaptation and ultimately speciation is one of the major quests in evolutionary biology. Cichlid fish species flocks are a prime example of recent rapid radiations often associated with adaptive phenotypic divergence from a common ancestor in a short period of time. In these fishes divergence in eco-morphological traits, including body shape, colour, lips and jaws, are thought to underpin their diversification. The Midas cichlid species complex (Amphilophus) of Nicaragua provides one of the few known examples of sympatric speciation, where species have rapidly evolved different eco-morphologies in young crater lakes. In this study we use SNP marker genotypes generated using ddRAD sequencing and a combination of morphometric analyses to identify significant QTLs in ecologically divergent cichlid species with different body morphs: an elongated limnetic species (A. zaliosus) and a high-bodied benthic species (A. astorquii) inhabiting lake Apoyo. A total of 453 informative RAD markers were identified in 240 F2 hybrids. These markers were used to construct a genetic map for which 25 linkage groups were resolved. We found 27 segregating SNPs linked to QTLs. The QTL-linked genomic regions were annotated to identify genes that likely contribute to divergence in body shape in benthic and limnetic Midas cichlid sympatric species. These results underline the effectiveness of RAD-Seq as a tool for rapid and efficient generation of QTL-targeted and genome-wide marker data and a promising method for investigating the genomic bases of divergence in ecologically relevant traits.


Video

Poster 

A resampling-based approach to study variation in morphological modularity

PDF

Author(s): Fruciano C, Franchini P, Meyer A

Summary:

Modularity has been suggested to be connected to evolvability because an higher degree of independence among parts allows them to evolve as separate units. Recently, the Escoufier RV coefficient has been proposed as a measure of morphological modularity in multivariate morphometric datasets. However, it has been shown, using randomly simulated datasets, that the value of the RV coefficient depends on sample size. Also, so far there is no statistical test for the difference in modularity between a priori defined groups. Here we: 1. using a rarefaction analysis, show that the value of the RV Escoufier coefficient depends on sample size also in real morphometric datasets; 2. propose a permutation procedure to test for the difference in the RV coefficient between a priori defined groups; 3. show, through simulations, that such a permutation procedure has an appropriate Type I error. The permutation procedure outlined here, readily extendable to non-morphometric datasets, will allow statistically sound comparisons of the degree of modularity between a priori defined groups.



Abstracts (coauthor)

No strain no gain: genetic investigation of adaptive phenotypic plasticity in teleost jaws

Author(s): Gunter, HM, Fan S, Xiong F, Schneider RF, Franchini P, Fruciano C, Meyer A

Summary:

Through incorporating environmental signals into ontogenetic pathways, phenotypically plastic species can fine-tune their phenotypes to precisely match local environmental conditions. In spite of its importance in the generation of adaptive phenotypes, the molecular basis of phenotypic plasticity remains poorly characterised. We are establishing a new molecular model for phenotypic plasticity research: the East African cichlid fish, Astatoreochromis alluaudi, which has been the subject of morphological studies of plasticity for 50 years. In response to a hard diet, its Lower Pharyngeal Jaw (LPJ) develops a ‘molariform’ morphology, with molar-like teeth set in an enlarged, dense jaw, compared with the smaller, finer ‘papilliform’ morphology which represents the ground state for this species. We performed a common garden experiment where siblings were fed either whole snails (hard diet), or finely minced snails (soft diet) and analysed the resulting morphological and transcriptional phenotypes. Genome-wide transcriptome analysis was performed on the LPJs of molariform and papilliform morphs that resulted from the diet treatments, shedding light on the environmentally sensitive pathways that modulate LPJ morphology. Numerous genes of mechanically responsive pathways (such as fos and jun) were upregulated in the molariform LPJs, indicating that mechanical strain intersects with bone developmental pathways that shape the molariform morphology. Intriguingly we also observe the down-regulation of various inflammatory factors and redox pathway members, suggesting that microenvironmental changes within the LPJ medullary cavity may alter cellular differentiation and proliferation. Through identifying numerous pathways involved with plasticity in the LPJ of A. alluaudi, our research opens the door to assess the role of phenotypic plasticity in generating morphological novelties amongst the explosive radiation of East African cichlid fishes.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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