Detection of transfluthrin and metofluthrin genotoxicity in the ST cross of the Drosophila Wing Spot Test

In this study, different concentrations of transfluthrin and metofluthrin have been assayed for genotoxicity by using the Wing Spot Test on Drosophila melanogaster. Standard cross was used in the experiment. Third-instar larvae that were trans-heterozygous for the two genetic markers mwh and flr³ were treated at different concentrations (0.0103 mg mL⁻¹, 0.103 mg mL⁻¹ for transfluthrin and 6 μg mL⁻¹, 60 μg mL⁻¹ for metofluthrin) of the test compounds. Feeding ended with pupation of the surviving larvae and the genetic changes induced in somatic cells of the wing’s imaginal discs lead to the formation of mutant clones on the wing blade. Results indicated that two experimental concentrations of transfluthrin and 60 μg mL⁻¹ metofluthrin showed mutagenic and recombinogenic effects in both the marker-heterozygous (MH) flies and the balancer-heterozygous (BH) flies.     

Do dominants have higher heterozygosity? Social status and genetic variation in brown trout, Salmo trutta

A key question of evolutionary importance is what factors influence who becomes dominant. Individual genetic variation has been found to be associated with several fitness traits, including behaviour. Could it also be a factor influencing social dominance? We investigated the association between social status and the amount of intra-individual genetic variation in juvenile brown trout (Salmo trutta). Genetic variation was estimated using 12 microsatellite loci. Dominant individuals had higher mean heterozygosity than subordinates in populations with the longest hatchery background. Heterozygosity–heterozygosity correlations did not find any evidence of inbreeding; however, single-locus analysis revealed four loci that each individually differed significantly between dominant and subordinate fish, thus giving more support to local than general effect as the mechanism behind the observed association between genetic diversity and a fitness-associated trait. We did not find any significant relation between mean d ² and social status, or internal relatedness and social status. Our results suggest that individual genetic variation can influence dominance relations, but manifestation of this phenomenon may depend on the genetic background of the population.     

Extra-pair paternity in alpine marmots, <Emphasis Type="Italic">Marmota marmota</Emphasis>: genetic quality and genetic diversity effects

Assuming that a male’s genetic characteristics affect those of his offspring, extra-pair copulation has been hypothesized to increase heterozygosity of the progeny—the “genetic compatibility” hypothesis—and the genetic diversity within litters—the “genetic diversity” hypothesis. We tested these two hypotheses in the alpine marmot (Marmota marmota), a socially monogamous mammal showing a high rate of extra-pair paternity (EPP). In a first step, we tested the assumption that a male’s genetic characteristics (heterozygosity and genetic similarity to the female) affect those of his offspring. Genetic similarity between parents influenced offspring heterozygosity, offspring genetic similarity to their mother, and litter genetic diversity. The father’s heterozygosity also influenced litter genetic diversity but did not affect offspring heterozygosity. Hence, heterozygosity seems not to be heritable in the alpine marmot. In a second step, we compared genetic characteristics of extra-pair young (EPY) and within-pair young (WPY). EPY were less genetically similar to their mother but not more heterozygous than WPY. EPY siblings were also less genetically similar than their WPY half siblings. Finally, the presence of EPY promoted genetic diversity within the litter. Thus, our data support both the “genetic compatibility” and the “genetic diversity” hypotheses. We discuss further investigations needed to determine the primary causes of EPP in this species.     

Prenatal diagnosis of fragile X in a heterozygous female fetus and postnatal follow-up

An apparently normal female infant was born after the prenatal diagnosis of fragile Xq27×28 present in about 4 per cent of amniocytes. The mildly retarded mother had been found in early pregnancy to be heterozygous for fragile X. The child, now 9 months old. showed about the same level of fragile X expression as her mother. Variations in the proportion of cells with fragile X appeared to be related to cell type and laboratory techniques. The infant's growth and development have been normal. Different techniques to induce or increase the expression of fragile X are discussed.     

Female tree swallows (<Emphasis Type="Italic">Tachycineta bicolor</Emphasis>) increase offspring heterozygosity through extrapair mating

Recent attention has focused on genetic compatibility as an adaptive function for why females engage in extrapair mating. We tested the genetic compatibility hypothesis in tree swallows (Tachycineta bicolor) over five breeding seasons using data from ten microsatellite loci. Tree swallows are socially monogamous passerines exhibiting high levels of extrapair paternity. Overall, we found that 47% of offspring were the result of extrapair fertilizations, and 83% of females produced at least one extrapair offspring. Consistently for all years, extrapair offspring were more heterozygous than their maternal half-siblings, which is in accordance with the genetic compatibility hypothesis. The difference was largely caused by the high heterozygosity of extrapair offspring sired by unknown males, suggesting that females are engaging in extrapair copulations with geographically distant males to increase the likelihood of being inseminated by a more compatible mate. Our findings support the idea that postcopulatory mechanisms are important for females when assessing potential sires for their offspring.     

Secondary sexual characters and female quality in primates

Honest advertisement models of sexual selection propose that exaggerated secondary sexual ornaments are condition-dependent, and that only individuals with superior disease resistance will be able to express costly ornamentation. Studies of secondary sexual ornamentation and their maintenance by sexual selection tend to focus on males. However, females may also possess showy ornaments. We investigated whether female ornaments, in the form of sexual swellings, reliably signal female fitness in a semifree-ranging colony of mandrills (Mandrillus sphinx) at the Centre International de Recherches Médicales, Franceville (CIRMF), Gabon. We measured swelling height and width using photographs of periovulatory females over three mating seasons and compared swelling size with parasitism (using fecal analysis over one annual cycle), immune status (ratio of lymphocytes to neutrophils in blood smears made during captures), and genetic diversity (microsatellite heterozygosity). Swelling size varied by up to 10% between cycles in individual females, giving some support to the hypothesis that size differences may indicate the quality of individual swelling cycles. However, there was no significant difference in swelling size between conceptive and nonconceptive cycles. Measures of swelling size varied more between females than within females across swelling cycles, implying that swelling size was a relatively consistent characteristic of individual females. Swelling size was not significantly related to either general measures of parasitism and immune status, or to the closest available measures to each swelling cycle. Nor was swelling size significantly related to genetic diversity. The healthy, provisioned nature of the colony and problems associated with observational, correlational studies restrict interpretation of our data. However, in combination with previous findings that females of higher reproductive success do not show larger swellings, and that males do not allocate mating effort as a function of swelling size, these results imply that sexual swelling size does not indicate female quality in these semifree-ranging mandrills.     

Extra-pair paternity in the monogamous alpine marmot (Marmota marmota): the roles of social setting and female mate choice

Extra-pair paternity (EPP) can be influenced by both social setting and female mate choice. If evidence suggests that females try to obtain extra-pair copulations (EPCs) in order to gain genetic benefits when mated to a homozygous and/or to a related male, females may not be able to choose freely among extra-pair mates (EPMs) as the social mate may constrain female access to EPMs. In this study, we investigated, first, how EPP depended on social setting and specifically on the number of subordinate males in the family group in a highly social and monogamous mammal, the alpine marmot. Second, we investigated how EPP depended on female mate choice for genetic benefits measured as male mate-heterozygosity and within-pair relatedness. Our results reveal, first, that EPP depended on the social setting, increasing with the number of subordinate males. Second, EPPs were related to relatedness between mates. Third, EPMs were found to be more heterozygous than within-pair males. Thus, social setting may constrain female choice by limiting opportunities for EPC. However, after accounting for social confounding factors, female choice for genetic benefits may be a mechanism driving EPP in monogamous species.     

The importance of heterozygosity in a frog’s life

High genetic variability may increase metabolic efficiency and thus allows responding to environmental challenges as limits to adaptation are approached. Therefore, it has been suggested that high genetic variability contributes strongly to the fitness of an individual. Survival to high age may thus depend on high genetic variability, and genetically variable individuals may have a higher survival rate to high ages in comparison to less variable sympatric conspecifics. Such a heterozygosity × age relationship might be more readily detectable in stressful as compared to benign environments. For testing the relationship between age and heterozygosity, we genetically analyzed 71 individuals of the frog species Rana perezi from a total of seven populations at 13 allozyme loci. The age of the individuals was determined by skeletochronology. We found effects on age of both environment and allozyme heterozygosity, especially in populations with high stress regimes. A significant heterozygosity × age relationship has so far rarely been shown in natural populations. The result of our analysis suggests that more heterozygous individuals have a higher longevity and may be an important source of genetic variability of a population, likely contributing to a stabilization of the effective population size.     

Determining size and dispersion of minimum viable populations for land management planning and species conservation

The concept of minimum populations of wildlife and plants has only recently been discussed in the literature. Population genetics has emerged as a basic underlying criterion for determining minimum population size. This paper presents a genetic framework and procedure for determining minimum viable population size and dispersion strategies in the context of multiple-use land management planning. A procedure is presented for determining minimum population size based on maintenance of genetic heterozygosity and reduction of inbreeding. A minimum effective population size (N _e ) of 50 breeding animals is taken from the literature as the minimum shortterm size to keep inbreeding below 1% per generation. Steps in the procedure adjustN _e to account for variance in progeny number, unequal sex ratios, overlapping generations, population fluctuations, and period of habitat/population constraint. The result is an approximate census number that falls within a range of effective population size of 50–500 individuals. This population range defines the time range of short- to long-term population fitness and evolutionary potential. The length of the term is a relative function of the species generation time. Two population dispersion strategies are proposed: core population and dispersed population.