The genetical theory of natural selection

Anti-predator defence mechanisms in sawfly larvae of Arge (Hymenoptera, Argidae)

“…Bright colouration and gregariousness are generally linked traits in insects (Fisher, 1930;Guilford, 1990;Ruxton and Sherratt, 2006), which is observed as a trend in Arge species. Two of the three brightly coloured species were truly gregarious, whereas the cryptic species were generally aggregated or encountered in groups composed of a few individuals only.…”

Experimental determination of invasive fitness in Caenorhabditis elegans

“…Nevertheless, fitness estimates obtained in this manner do not necessarily give a measure of invasion ability, since factors such as frequency-or density-dependence effects may be present, thus these estimates do not reflect the intrinsic growth rate of a given genotype 1,9,19 . To estimate the intrinsic growth rate, the invading genotype must be rare, so that interactions between individuals with that genotype are negligible, and the overall dynamics of the population, which are determined by the resident genotypes, do not change 20 .…”

“…Briefly, random fluctuations of allele frequencies, which characterize genetic drift, occur because populations are finite and the genetic pool of the following generations is obtained by a random sampling of alleles. After the appearance of a new allele by mutation, these fluctuations often result in extinction of the allele, even if it confers a fitness advantage 4,9 . For this reason, an experimental setup to reflect these 'chance dynamics' must enable the experimenter to control precisely the initial number of invaders that harbor the new alleles.…”

The role of duplications in evolution

“…Kojima (Nei et al, 1967) has shown, by arguments which follow closely those of Fisher (1930) for a single locus, that if such a region contained many dominant favourable alleles, it could increase very rapidly in frequency if these were initially rare. In general, such obviously favourable conditions are unlikely to be met.…”