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Genetic variation in bitter taste receptor genes influences the foraging behavior of plateau zokor (Eospalax baileyi).

Zhao F, Zhang T, Xie J, Zhang S, Nevo E, Su J, Lin G - Ecol Evol (2016)

Bottom Line: Bitter plant selection indices (E bitter) were estimated.We also sequenced 26 candidate Tas2r genes from zokors and determined their relationships with the E bitter of their caches.Our results link Tas2r variation with food selection behavior at the population level for the first time.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Adaptation and Evolution of Plateau BiotaNorthwest Institute of Plateau BiologyChinese Academy of SciencesXining810001China; University of Chinese Academy of SciencesBeijing100049China.

ABSTRACT
The ability to detect bitter tastes is important for animals; it can help them to avoid ingesting harmful substances. Bitter taste perception is mainly mediated by bitter taste receptor proteins, which are encoded by members of the Tas2r gene family and vary with the dietary preference of a specific species. Although individuals with different genotypes differ in bitterness recognition capability, little is known about the relationship between genetic variation and food selection tendencies at the intraspecific level. In this study, we examined the relationship between genotypes and diet in plateau zokor (Eospalax baileyi), a subterranean rodent endemic to the Qinghai-Tibet Plateau that caches food for the winter. We assayed the composition and taste profile of each plant contained in temporary caches and vicinity quadrats, which were representative of selected and available food, respectively. Bitter plant selection indices (E bitter) were estimated. We also sequenced 26 candidate Tas2r genes from zokors and determined their relationships with the E bitter of their caches. We identified four key results: (1) zokors varied considerably in both bitter food preference and Tas2r sequences; (2) five genes (zTas2r115,zTas2r119,zTas2r126,zTas2r134, and zTas2r136) exhibited allelic variation that was significantly associated with E bitter; (3) synonymous SNPs, nonsynonymous SNPs, and pseudogenization are involved in the genotype-phenotype relationship; (4) the minor genotypes of zTas2r115,zTas2r134, and zTas2r136 and the major genotypes of zTas2r119 and zTas2r126 cached more bitter plants. Our results link Tas2r variation with food selection behavior at the population level for the first time.

No MeSH data available.


Related in: MedlinePlus

(A) frontal view of a plateau zokor; (B) a cache in the zokor burrow system; (C) weight percentages (average) of plants with different tastes to humans in quadrats and caches (P values showed two‐related samples Wilcoxon signed ranks test between quadrats and caches); (D) Ebitter (selection index of bitter plants) distribution of the surveyed zokors (N = 56).
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ece32041-fig-0001: (A) frontal view of a plateau zokor; (B) a cache in the zokor burrow system; (C) weight percentages (average) of plants with different tastes to humans in quadrats and caches (P values showed two‐related samples Wilcoxon signed ranks test between quadrats and caches); (D) Ebitter (selection index of bitter plants) distribution of the surveyed zokors (N = 56).

Mentions: Subterranean rodents comprise a widely distributed collection of taxa that live primarily underground and are highly adapted to their environments (Nevo 1999). The subterranean niche protects subterranean rodents from both predators and the environmental fluctuations that predominate above ground. However, these animals typically have extremely diminished vision (Begall et al. 2007); hence, directly tasting (and probably also smelling) plants in the dark burrows may be fundamental to effective foraging. Plateau zokors (Rodentia, Spalacidae, Eospalax baileyi) (Fig. 1A) are a typical subterranean rodent in the Qinghai–Tibet Plateau (QTP). They spend most of their life underground and collect nearly all of their food resources (either underground organs or whole plants) through digging activities. Soil in the QTP is frozen solid throughout the coldest half of the year, and during this time, plateau zokors are unable to forage. Each autumn, these animals store food in their caches for the approaching and long cold season (Fig. 1B). The caching behavior of plateau zokors enables researchers to accurately characterize diet selection in the field by surveying their cache composition. Our previous studies demonstrated that plateau zokors do not forage randomly when collecting food for winter caches (Xie et al. 2014a,b). Rather, these animals generally prefer sweet and bitter plants while avoiding plant materials characterized by other tastes (including tasteless, pungent, sour, and other tastes that are difficult to describe but do not taste bitter at all; Xie 2014), indicating that taste plays an important role in food selection behaviors.


Genetic variation in bitter taste receptor genes influences the foraging behavior of plateau zokor (Eospalax baileyi).

Zhao F, Zhang T, Xie J, Zhang S, Nevo E, Su J, Lin G - Ecol Evol (2016)

(A) frontal view of a plateau zokor; (B) a cache in the zokor burrow system; (C) weight percentages (average) of plants with different tastes to humans in quadrats and caches (P values showed two‐related samples Wilcoxon signed ranks test between quadrats and caches); (D) Ebitter (selection index of bitter plants) distribution of the surveyed zokors (N = 56).
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Related In: Results  -  Collection

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ece32041-fig-0001: (A) frontal view of a plateau zokor; (B) a cache in the zokor burrow system; (C) weight percentages (average) of plants with different tastes to humans in quadrats and caches (P values showed two‐related samples Wilcoxon signed ranks test between quadrats and caches); (D) Ebitter (selection index of bitter plants) distribution of the surveyed zokors (N = 56).
Mentions: Subterranean rodents comprise a widely distributed collection of taxa that live primarily underground and are highly adapted to their environments (Nevo 1999). The subterranean niche protects subterranean rodents from both predators and the environmental fluctuations that predominate above ground. However, these animals typically have extremely diminished vision (Begall et al. 2007); hence, directly tasting (and probably also smelling) plants in the dark burrows may be fundamental to effective foraging. Plateau zokors (Rodentia, Spalacidae, Eospalax baileyi) (Fig. 1A) are a typical subterranean rodent in the Qinghai–Tibet Plateau (QTP). They spend most of their life underground and collect nearly all of their food resources (either underground organs or whole plants) through digging activities. Soil in the QTP is frozen solid throughout the coldest half of the year, and during this time, plateau zokors are unable to forage. Each autumn, these animals store food in their caches for the approaching and long cold season (Fig. 1B). The caching behavior of plateau zokors enables researchers to accurately characterize diet selection in the field by surveying their cache composition. Our previous studies demonstrated that plateau zokors do not forage randomly when collecting food for winter caches (Xie et al. 2014a,b). Rather, these animals generally prefer sweet and bitter plants while avoiding plant materials characterized by other tastes (including tasteless, pungent, sour, and other tastes that are difficult to describe but do not taste bitter at all; Xie 2014), indicating that taste plays an important role in food selection behaviors.

Bottom Line: Bitter plant selection indices (E bitter) were estimated.We also sequenced 26 candidate Tas2r genes from zokors and determined their relationships with the E bitter of their caches.Our results link Tas2r variation with food selection behavior at the population level for the first time.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Adaptation and Evolution of Plateau BiotaNorthwest Institute of Plateau BiologyChinese Academy of SciencesXining810001China; University of Chinese Academy of SciencesBeijing100049China.

ABSTRACT
The ability to detect bitter tastes is important for animals; it can help them to avoid ingesting harmful substances. Bitter taste perception is mainly mediated by bitter taste receptor proteins, which are encoded by members of the Tas2r gene family and vary with the dietary preference of a specific species. Although individuals with different genotypes differ in bitterness recognition capability, little is known about the relationship between genetic variation and food selection tendencies at the intraspecific level. In this study, we examined the relationship between genotypes and diet in plateau zokor (Eospalax baileyi), a subterranean rodent endemic to the Qinghai-Tibet Plateau that caches food for the winter. We assayed the composition and taste profile of each plant contained in temporary caches and vicinity quadrats, which were representative of selected and available food, respectively. Bitter plant selection indices (E bitter) were estimated. We also sequenced 26 candidate Tas2r genes from zokors and determined their relationships with the E bitter of their caches. We identified four key results: (1) zokors varied considerably in both bitter food preference and Tas2r sequences; (2) five genes (zTas2r115,zTas2r119,zTas2r126,zTas2r134, and zTas2r136) exhibited allelic variation that was significantly associated with E bitter; (3) synonymous SNPs, nonsynonymous SNPs, and pseudogenization are involved in the genotype-phenotype relationship; (4) the minor genotypes of zTas2r115,zTas2r134, and zTas2r136 and the major genotypes of zTas2r119 and zTas2r126 cached more bitter plants. Our results link Tas2r variation with food selection behavior at the population level for the first time.

No MeSH data available.


Related in: MedlinePlus