Ga Vanoortmerssen

STUDIES IN WILD HOUSE MICE - GENOTYPE-ENVIRONMENT INTERACTIONS FOR ATTACK LATENCY

Winning chances of fast- and slow attacking genotypes were determined in contests of wild male house mice with standard inbred conspecifics, using a variety of conditions. Genotype-environment interactions are shown to determine winning chances. Differences are connected with social experience, familiarity of terrain, exploratory behaviour and relative weight. It is argued that, as a result, the fitness of slow attacking males is higher than that of fast attackers in unfamiliar environmental conditions (e.g. when migrating), but lower when on familiar ground. This leads to diversifying selection, which may explain the distribution of attack latency scores found in wild house mice.

Studies on wild house mice. V: Aggression in lines selected for attack latency and their Y-chromosomal congenics

Congenic lines were made for the Y chromosome between aggressive and nonaggressive lines of house mice, which were previously established by artificial selection in wild mice for short attack latencies (SAL line) and long attack latencies (LAL line). The aggressiveness of the males in successive backcross generations of the congenic lines is reported. Results fit the hypothesis that the Y-chromosomal effect that is often found for aggression in house mice may be located on the pseudo-autosomal region of this chromosome.

No evidence for a Y chromosomal effect on alternative behavioral strategies in mice.

This study takes the first step toward testing a Y chromosomal effect on both aggression and thermoregulatory nest-building behavior in mouse lines either bidirecrionally selected for short (SAL) and long (LAL) attack latency or high (HIGH) and low (LOW) nest-building behavior. Using reciprocal crosses between SAL and LAL, and between HIGH and LOW, we found no indications for Y chromosomal effects on thermoregulatory nest-building behavior. As for aggression, we confirmed earlier studies on SAL and LAL, i.e., the origin of the Y chromosome influences attack latency, i.e., aggression. However, we did not find indications for a Y chromosomal effect on aggression in the HIGH and LOW lines. Since aggression and nest-building behavior have been shown to be characteristic parameters of two fundamentally different behavioral strategies, the present data underline the improbability of Y chromosomal genes underlying the genetic architecture of alternative behavioral strategies.

INDIFFERENCE OF TERT-ALLELES ON THE SAMPLING OF WILD HOUSE MOUSE-POPULATIONS UNDER EXPERIMENTAL CONDITIONS

This study tries to explain the discrepancy between the frequencies of t-alleles found in house mouse populations and those expected on the basis of a deterministic model, by hypothesizing a difference in trappability between + /+ and +/t genotypes. We found variation in t-genotypes to be of no influence on trappability of the individuals in ten experimental populations.