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Figure 4 | BMC Evolutionary Biology

Figure 4

From: The role of genome and gene regulatory network canalization in the evolution of multi-trait polymorphisms and sympatric speciation

Figure 4

Phenotypic Diversity under Canalization. A and B As in Figure 3, we show two different, simplified genomes, and the genome sequences we obtain from aligning them. Now we indicate in the aligned genome sequence which genes are not expressed (off), using the same grey color as for alignment gaps. Next, on the left the genes-only aligned sequences are shown if only expressed genes are displayed, and unexpressed genes are given the same grey color as alignment gaps. Likewise, on the right the URR-only aligned sequences are shown if only TFBS bound by a TF (the TF gene is expressed) are displayed, and unbound TFBS are given the same grey color as absent TFBS. A Data: Aligned genome order in which only genes that are expressed (on) are shown, non-expressed genes are colored grey. Genomes shown are the same as those in Figure 3B. B Data: TFBS present in upstream regions of genes, showing only TFBS that are bound by their corresponding TF. Non-occupied TFBS are colored grey. Genomes and TFBS are the same as those in Figure 3C. C Cartoon showing characteristics of the non-linear genotype-phenotype mapping of our model. In 1 we show a default genome, the network it codes for, a gene expression birth-state and the phenotype arising from this birth-state and the network dynamics. In 2, 3 and 4 we show different genomes, coding for different networks, that use this same birth-state as a start state. In 2 we show a very different genome and regulatory network (only 2 of the 8 connections are the same as in 1), resulting in exactly the same phenotype. In 3 and 4 we show genomes that differ from the default genome only by the deletion of a single TFBS (red star), resulting in networks that differ from the default one by missing a single regulatory link (grey line). In 3 this small genotypic change results in a large phenotypic change (4 of the 6 genes change their expression), whereas in 4 this small genotypic change results in a small phenotypic change (only 1 gene changes its expression).

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