BIT

Bitter Taste Aversion

Class: I - Natural Selection

EPA Total Score: 28 /100

Shi, P., & Zhang, J., Yang, H., & Zhang, Y. (2003). Adaptive diversification of bitter taste receptor genes in mammalian evolution. Molecular Biology and Evolution, 20(5), 805-814.

Abstract: The diversity and evolution of bitter taste perception in mammals is not well understood. Recent discoveries of bitter taste receptor (T2R) genes provide an opportunity for a genetic approach to this question. We here report the identification of 10 and 30 putative T2R genes from the draft human and mouse genome sequences, respectively, in addition to the 23 and 6 previously known T2R genes from the two species. A phylogenetic analysis of the T2R genes suggests that they can be classified into three main groups, which are designated A, B, and C. Interestingly, while the one-to-one gene orthology between the human and mouse is common to group B and C genes, group A genes show a pattern of species- or lineage-specific duplication. It is possible that group B and C genes are necessary for detecting bitter tastants common to both humans and mice, whereas group A genes are used for species-specific bitter tastants. The analysis also reveals that phylogenetically closely related T2R genes are close in their chromosomal locations, demonstrating tandem gene duplication as the primary source of new T2Rs. For closely related paralogous genes, a rate of nonsynonymous nucleotide substitution significantly higher than the rate of synonymous substitution was observed in the extracellular regions of T2Rs, which are presumably involved in tastant-binding. This suggests the role of positive selection in the diversification of newly duplicated T2R genes. Because many natural poisonous substances are bitter, we conjecture that the mammalian T2R genes are under diversifying selection for the ability to recognize a diverse array of poisons that the organisms may encounter in exploring new habitats and diets.

DJGlass


Supporting Evidence

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45/100

Submitted by DJGlass

48/100

Submitted by DJGlass

No one has (yet) rated this source as containing any supporting Hunter-Gatherer evidence for this EPA.

Supporting Evidence is evidence that suggests that this trait is an Evolved Psychological Adaptation (EPA) - i.e., that it has been shaped by natural selection to solve a particular adaptive problem.

Challenging Evidence

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0/100

Submitted by DJGlass

0/100

Submitted by DJGlass

No one has (yet) rated this source as containing any challenging Hunter-Gatherer evidence for this EPA.

Challenging Evidence is evidence that suggests that this trait is not an EPA - e.g., that it is a product of cultural learning or genetic drift, or maybe it does not exist at all. However over each line of evidence for a description.