Gilberto Gandolfi

Bio: Gilberto Gandolfi is an academic researcher from University of Parma. The author has contributed to research in topics: Padogobius & Cytochrome b. The author has an hindex of 15, co-authored 40 publications receiving 787 citations.

Molecular Evidence for Introgression and Loss of Genetic Variability in Salmo (trutta) macrostigma as a Result of Massive Restocking of Apennine Populations (Northern and Central Italy)

Abstract: We assessed structural gene variation (allozymes and mtDNA) of brown trout to evaluate the genetic variability of Apennine stream populations (Northern and Central Italy) and the possibility of introgression by alien genomes after massive restocking with hatchery strains (Atlantic stocks). Genetic variability within and between Apennine populations was extremely low in our samples. Only two allozyme loci were polymorphic and mean hetero-zygosity was also reduced compared to other brown trout populations. Allelic frequencies determined for both loci were similar to the ones detected in the corresponding hatchery spawners. The reduction or total absence of the Mediterranean nuclear (LDH-5) and mitochondrial (16S rDNA) diagnostic markers suggests the domestic origin of most populations, and the introgression effects carried out by non-native genomes. From a taxonomic point of view, a clear differentiation emerges among basins placed on opposite sides of the Apennine chain (Tyrrhenian and Adriatic regions). In particular, the presence of Mediterranean genotypes and haplotypes characterizing Salmo (trutta) macrostigma is sporadic along the eastern Apennine side, adding additional doubts on the original presence and wide distribution of this salmonid along the Adriatic side of the mountain chain. In spite of conservation programs devoted to preservation of local genetic characteristics of S. t. macrostigma, massive restocking practices with hatchery strains obtained by a few spawners is the major cause of significant `founder effect' and `inbreeding depression' even in Apennine regions.

Breeding ecology and male spawning success in two hill-stream populations of the freshwater goby, Padogobius martensi.

Abstract: This investigation was carried out at two study sites to examine the influence of shelter availability, nest site quality and male body size on spawning success of malePadogobius martensi. At Stirone Stream (first study site) individuals were not randomly distributed with respect to usable stones; larger males and females were consistently found to occupy larger stones. Laboratory experiments showed that the bottom surface area of the shelter was the relevant cue for the choice. The number of nesting males settled in a given area increased with increasing availability of local stone cover; inter-nest distance was directly correlated with male size. At Rivarolo Stream (second study site), which was characterized by lower nest density and a greater shortage of large stones, the pattern of shelter occupation was similar. These results suggest the presence of competition among individuals for the possession of larger-sized shelter sites. At both sites, the number of eggs in the nest increased as stone size increased; however, at the first study site, male body size played a major role in male spawning success as it concerns both the numbers of females mated and the number of eggs, while at the second study site, male body size was not shown to influence male spawning success. Factors responsible for between-site differences in male spawning success are discussed.

Natural selection on color patterns in poecilia reticulata.

Abstract: All too often in evolutionary biology we are led to speculate or infer the mode of action of natural selection; we usually do not know why some individuals are more adaptive than others. Very often attempts to measure natural selection are unsuccessful, leading to heated arguments about' the relative importance of selection, genetic drift, and epistasis in evolution (Lewontin, 1974). Until we know more about how and why natural selection occurs, attempts to measure it are quixotic, and discussions of its importance are theandric. It is no coincidence that most of the successful studies of natural selection have dealt with animal color patterns; it should be obvious which color patterns are more adaptive in the presence of visually hunting predators. The adaptive significance of warning coloration and mimicry of distasteful species has been worked out (Cott, 1940; Wickler, 1968; Edmunds, 1974; Rothschild, 1975; Turner, 1977). But most species are neither distasteful nor mimetic; most have inconspicuous or cryptic color patterns in their natural habitats (Poulton, 1890; Thayer, 1909; Cott, 1940; Endler, 1978). Most field and experimental studies have shown that the overall color or tone of inconspicuous species matches or approximates the background (DiCesnola, 1904; Sumner, 1934, 1935; Isley, 1938; Popham, 1942; Dice, 1947; Kettlewell, 1956, 1973; Turner, 1961; Kaufman, 1974; Wicklund, 1975; Curio, 1976), but they treated species with solid colors or

A Predator’s View of Animal Color Patterns

Abstract: It has long been known that the general colors and tones of animals tend to match their backgrounds (E. Darwin, 1794; Poulton, 1890). The adaptive significance of this has been borne out in numerous experimental studies (DiCesnola, 1904; Sumner, 1934, 1935; Isley, 1938; Popham, 1942; Dice, 1947; Turner, 1961; Kettlewell, 1956, 1973; Kaufman, 1974; Wiklund, 1975; Curio, 1976). There is also a good understanding of warning coloration (Cott, 1940; Wickler, 1968; Edmunds, 1974; Rothschild, 1975). However, the determinants of color pattern are poorly known, although it is known in a general way that the patterns and forms of animals are similar to their backgrounds (Poulton, 1890; Thayer, 1909; Cott, 1940; Wickler, 1968; Robinson, 1969; Edmunds, 1974; Fogden and Fogden, 1974). It is the purpose of this paper to explore the factors that determine color patterns under various specific conditions. The basic assumption is that a color pattern must resemble a random sample of the background seen by predators in order to be cryptic, and must deviate from the background in one or more ways in order to be conspicuous. As a result, the actual pattern evolved in a particular place represents a compromise between factors which favor crypsis and those which favor conspicuous color patterns.

DNA barcoding for ecologists

Abstract: DNA barcoding - taxon identification using a standardized DNA region - has received much attention recently, and is being further developed through an international initiative. We anticipate that DNA barcoding techniques will be increasingly used by ecologists. They will be able to not only identify a single species from a specimen or an organism's remains but also determine the species composition of environmental samples. Short DNA fragments persist in the environment and might allow an assessment of local biodiversity from soil or water. Even DNA-based diet composition can be estimated using fecal samples. Here we review the new avenues offered to ecologists by DNA barcoding, particularly in the context of new sequencing technologies.

Natural and sexual selection on color patterns in poeciliid fishes

Abstract: In poeciliid fishes, sexual dichromism is associated with larger size and larger broods, but there is no relationship between sexual size dimorphism and sexual dichromism, or between degree of dichromism and color pattern polymorphism. Factors are discussed which influence the evolution of color pattern polymorphisms, sexual dimorphism and dichromism. Detailed studies of South American species have shown that the color patterns of poeciliid fishes have predictable effects in (1) avoiding diurnal visually hunting predators; (2) mating success; and (3) species recognition. Data from some Central American species indicate that some color pattern elements may be closely linked to physiologically variable loci, which further affect the variation in color patterns. Different elements of any given color pattern can be influenced by different modes of natural selection; in guppies the relationship between predation intensity and color pattern is different for melanin, carotenoid, and structural colors. Different color patterns have different degrees of conspicuousness on different backgrounds, and may appear differently to predators and mates with differing visual abilities.

Armaments and ornaments: an evolutionary explanation of traits of dual utility

Abstract: Secondary sexual characters in many species function both in male-male competition and as cues for female choice. Based on a literature compilation of existing knowledge of traits with this dual fu ...