Phenotype Frequencies (phenotype + frequency)

Distribution by Scientific Domains


Selected Abstracts


Effects of Social Structure on the Behaviour and Performance of Alternative Reproductive Phenotypes in Male Rock Shrimp, Rhynchocinetes typus

ETHOLOGY, Issue 4 2008
Stefan Dennenmoser
Males that adopt alternative mating tactics within a conditional strategy often undergo costly morphological changes when switching to the next phenotype during ontogeny. Whether costs of changing to a subsequent reproductive phenotype are outweighed by a higher mating probability may depend on the frequencies of different phenotypes in a group of competitors. Benefits and costs associated with different phenotype frequencies depend on interactions within and between alternative phenotypes, but the underlying behavioural mechanisms have rarely been studied. Herein, we used the rock shrimp Rhynchocinetes typus as a model: ontogenetic male stages of this species differ in morphological and behavioural traits that indicate alternative reproductive phenotypes. The small, subordinate, male stage (typus) develops via several intermediate stages (intermedius) to the dominant male stage (robustus): in competitive interactions the typus males usually employ the sneaking tactic, while the robustus males invariably employ the monopolizing fighter tactic. In laboratory experiments, we manipulated phenotype frequencies to examine whether there are frequency-dependent effects on searching behaviour, aggressiveness and mating probability. With increasing frequency of robustus males, the rate of aggressive interactions among them increased. Furthermore, robustus males increased walking velocity when more than one robustus male was present. In contrast, typus males did not adjust their searching or aggressive behaviour. The increase of aggressive interactions among robustus males provided more opportunities for typus males to seize a temporarily unguarded female. While typus males exploit fights among robustus males that produce mating opportunities for them, robustus males benefit from typus males, which reveal the presence of receptive females. We suggest that each phenotype benefits from the presence of the other phenotype and suffers costly interference among individuals of the same phenotype. Whether frequency-dependent effects on the mating probability of subordinates also affect their ontogenetic switchpoint should be examined in future studies. [source]


Association of CTLA-4 gene polymorphism with oral submucous fibrosis in Taiwan

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 4 2004
Yi-Ning Shin
Background:, Oral submucous fibrosis (OSF) is an insidious, pre-cancerous, chronic disease that may affect the entire oral cavity and sometimes extend to the pharynx. It has been reported to be associated with immune function. Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4; CD (cluster of differentiation) 152) is a negative regulator of T-lymphocyte activation. Particular genotypes of the locus encoding the CTLA-4 glycoprotein have been associated with susceptibility to various autoimmune diseases. This study was designed to investigate the role of CTLA-4 polymorphism in susceptibility to OSF. Methods:, We genotyped 62 patients with OSF and 147 healthy controls for allelic determinants at the exon 1 +49 polymorphism site by restriction fragment length polymorphism. Genotype and phenotype frequencies were evaluated with Chi-squared test. Results:, The G allele at position +49 of exon 1 was significantly associated with OSF. The frequency of A/A homozygotes was higher in controls than in patients (17.0% vs. 3.2%; ,2 = 7.65, P = 0.02); the G phenotype was more frequent in patients than in controls (96.8% vs. 83.0%; ,2 = 9.31, P = 0.002). Compared with controls, the G allele genotype and phenotype frequencies were increased in patients with OSF. Conclusion:, This is the first report that the CTLA-4 +49 G allele confers an increased risk of OSF in Taiwan. [source]


FEMALE SOLDIER BEETLES DISPLAY A FLEXIBLE PREFERENCE FOR SELECTIVELY FAVORED MALE PHENOTYPES

EVOLUTION, Issue 5 2005
Denson Kelly Mclain
Abstract In Georgia (USA) the soldier beetle, Chauliognathus pennsylvanicus (Coleoptera; Cantharidae), exhibits clinal variation in the length of the spot on its elytron. This suggests that the viability of phenotypes varies by habitat. Evidence of viability selection comes from within-site changes in the spot length distribution across a breeding season. When males with spots of intermediate length became less frequent, they became disproportionately less likely to mate, consistent with either a loss of vigor among remaining males or female rejection of disfavored phenotypes. Persistent, daily courtship by males provides females with the opportunity to track changes in male phenotype frequency and to exercise choice for phenotypes favored under natural selection. A laboratory experiment in which the frequency of one spot morph (long) or the other (short) was increased from 25% to 75% over a period of 30 days revealed that females possess a flexible preference that leads them to prefer whichever spot type has become more common over time. A haploid genetic model demonstrates that a flexible female preference for the locally favored male phenotype can be selected for when different viability alleles, genetically correlated with the male trait, are favored in different habitats that are linked by gene flow. Thus, migration between different kinds of habitat patches of a metapopulation could maintain the variation in male quality. This variation favors female choice for any trait that is directly or indirectly favored by natural selection. Such choice imparts positive frequency-dependent selection that could rapidly fix traits pleiotropically linked to viability. Rapid fixation would cause differentiation between populations of colonizing species as females exercise choice for mates favored under new ecological conditions. [source]


HLA typing in Taiwanese patients with oral submucous fibrosis

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 4 2004
Hsin-Ming Chen
Background:, A significant association of certain human leukocyte antigens (HLA) and haplotypic pairs with oral submucous fibrosis (OSF) has been reported. However, controversial result of no HLA association with OSF has also been reported. In this study, the phenotype and haplotype frequencies of HLA-A, -B, -C, -DRB1, and -DQB1 in 135 Taiwanese OSF patients were calculated and compared with those in 540 healthy control Taiwanese. Methods:, The analysis of HLA-A, -B, and -C antigens, and of HLA-DRB1 and -DQB1 alleles in OSF patients and healthy control subjects, was performed by serologic typing and DNA typing using polymerase chain reaction with sequence-specific primers (PCR-SSP), respectively. Results:, We found that the phenotype frequency of HLA-B76 (3.0%) in OSF patients was significantly greater than that (0%) in healthy control subjects (corrected P (Pc) = 0.000). In addition, the haplotype frequencies of HLA-B48/Cw7 (3.0%), -B51/Cw7 (6.7%), and -B62/Cw7 (8.2%) in OSF patients were significantly greater than the corresponding haplotype frequencies (0, 0.7, and 1.9%, respectively) in healthy control subjects (Pc = 0.000). The relative risk (RR) values of haplotypes B51/Cw7 (9.57) and B62/Cw7 (4.7) were greater than the RR values of phenotypes B51 (1.81), B62 (2.31), and Cw7 (1.91) in OSF patients. In addition, the etiologic fraction (EF) value of haplotype B51/Cw7 (0.63) was higher than the EF values of phenotypes B51 (0.2) and Cw7 (0.59). Conclusions:, We conclude that some Taiwanese areca quid (AQ) chewers with particular HLA phenotypes and haplotypes are prone to have OSF. In addition, some particular HLA haplotypes may play more important roles than the individual HLA phenotypes for the genetic susceptibility to OSF. However, the significantly increased HLA phenotype B76 and three of the common HLA haplotypes detected are present in only about 20% of incident cases of OSF. [source]