Variation in the intermittent buzzing songs of male medflies (diptera: tephritidae) associated with geography, mass-rearing, and courtship success

Varios aspectos de los patrones temporales de los sonidos del zumbido intermitente producido durante el cortejo pre-copulatório de los machos de la mosca del Mediterráneo variaron entre moscas silvestres de Costa Rica, Argentina y Hawaii, y entre moscas de sepas de cría masiva de Costa Rica, Argentina, Mexico y Hawaii. No se presentaron diferencias consistentes cuando se compararon las sepas de cría masiva en Costa Rica, Argentina y Hawaii con moscas silvestres de los sitios de origen. Los sonidos producidos durante cortejos que terminaron en cópulas no difieron de los sonidos producidos durante cortejos que llevaron a montas que fracasaron en moscas de Costa Rica y Argentina. Pero en sepas de todos los sitios los zumbidos intermitentes que incluyeron pequeñas pausas tuvieron una mayor probabilidad de no terminar en un intento de monta. Los zumbidos intermitentes de las moscas de las crias masivas tuvieron una tendencia leve a interumpirse mas frecuentemente.Many aspects of the temporal pattern of sounds produced during the intermittent buzzing displays of pre-copulatory courtship by male medflies varied between wild flies from Costa Rica, Argentina, and Hawaii, and between mass-reared flies from Costa Rica, Argentina, Mexico, and Hawaii. There were no consistent differences when mass-reared strains were compared with the wild strains from the area where they originated in Costa Rica, Argentina and Hawaii. Buzzing sounds produced prior to successful mounting attempts did not differ consistently from those preceding unsuccessful mounts in flies from Costa Rica and Argentina. In strains from all sites, however, courtships in which buzzes were interrupted were more likely not to result in mounting of the female. There was a weak tendency for interruptions to be more common in mass-reared strains.Universidad de Costa Rica. Universidad de Buenos Aires. El Colegio de la Frontera Sur, Tapachula, Chiapas, Mexico. USDA-ARS.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Non random distribution patterns of supernumerary segments and B chromosomes in Dichroplus elongatus (Orthoptera)

Dichroplus elongatus is a grasshopper, which exhibits parallel polymorphisms for B chromosomes and supernumerary segments in chromosomes S10 (SS10), S9 (SS9) and M6 (SS6) in natural populations of Argentina. The patterns of simultaneous variation of different forms of supernumerary heterochromatin from 7 populations of two biogeographic provinces located at Northwest and East regions of this country were analysed. Spatial chromosome differentiation for all heterochromatic variants was observed. Different degree of differentiation among populations for supernumerary segments, evaluated through F(ST), was observed. This suggests that genetic drift and migration may not be the only factors involved in the maintenance of the detected chromosome patterns. The differentiation for SS9 and SS10 may be explained mainly by heterogeneity within the Northwest Region. On the contrary, the differences for SS6 and B chromosomes explained through isolation by distance. However, the absence or the low frequency of both chromosome mutations in some populations may not be explained by historical factors. A principal component analysis showed that the patterns of chromosome variation do not agree with the geographical distribution of the populations. The relationship between frequencies of each supernumerary segment and B chromosome depends on the segment. An analysis of partial correlation showed that the frequencies of B chromosomes were positively correlated with the frequency of SS6 and negatively with the frequency of the SS10. In agreement with this, a multiple regression analysis of B chromosome frequency on supernumerary segment frequencies depends on the incidence of SS6 and SS10. The covariation of the heterochromatic forms may act as another factor that establish limits to stochastic factors, may also affect the probable negative selection on B, and could be involved in the non random pattern detected in D. elongatus.Fil:Remis, M.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Clemente, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Pensel, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Vilardi, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Mitochondrial DNA and phylogeography of the grasshopper Trimerotropis pallidipennis in relation to clinal distribution of chromosome polymorphisms

Trimerotropis pallidipennis is an American grasshopper whose South American populations are polymorphic for pericentric inversions. Colonization of southern latitudes was by North American grasshoppers with basic chromosome arrangements, presumably along the Andean dry lands of South America. In Argentina, the frequencies of some of the rearrangements are correlated with geographical and climatic variables, following similar patterns among different ecological gradients, and are probably maintained by geographically variable coefficients of selection. Restriction site variation of mitochondrial DNA is used as a tool for determining the species history in relation to the formation of clines. Populations located along an altitudinal gradient, and others outside the cline, are analysed through phylogeographical studies. There is no strong geographical orientation in the unrooted tree connecting all 17 mitochondrial DNA haplotypes found. Many of them are present in most of the populations analysed, indicating high gene flow. The fact that there is no obvious differentiation in haplotype distribution between both extremes of the cline nor between chromosomally differentiated populations shows that the cline is not the result of a hybrid zone and reinforces the selection hypothesis. The estimation of the overall nucleotide divergence between the hypothetical ancestral haplotype and the other molecules shows that T. pallidipennis haplotypes started diverging from each other about 3 Myr ago. This result is in agreement with the time when the Isthmus of Panama rose (2-3 Myr ago), probably favouring the migration of many species between both hemispheres.Fil:Confalonieri, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Sequeira, A.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Todaro, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Vilardi, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Mating system parameters in species of genus Prosopis (Leguminosae)

The section Algarobia of genus Prosopis involves important natural resources in arid and semiarid regions of the world. Their rationale use requires a better knowledge of their biology, genetics and mating system. There are contradictory information about their mating system. Some authors claim they are protogynous and obligate outcrosser. However, some evidence have been shown indicating that they might not be protogynous and that they might be somewhat self-fertile. The current paper analyses genetic structure and mating system parameters in populations of seven species of this section from South and North America based on isozyme data. In all species a significant homozygote excess was found in the offspring population but not in mother plant genotypes. Multilocus and mean single locus outcrossing rates (tm, ts) indicated that about 15 % selfing can occur in the studied populations. The heterogeneity between pollen and ovule allele frequencies was low suggesting population structuration, in agreement with the estimates of correlation of tm within progeny (rt) and correlation of outcrossed paternity (rp). The difference of F(IS) estimates between offspring and mother plants suggest some selection favouring heterozygotes between seedling and adult stages.Fil:Bessega, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Ferreyra, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Saidman, B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Vilardi, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Consistency between marker- and genealogy-based heritability estimates in an experimental stand of Prosopis alba (Leguminosae)

Prosopis represents a valuable forest resource in arid and semiarid regions. Management of promising species requires information about genetic parameters, mainly the heritability (h2) of quantitative profitable traits. This parameter is traditionally estimated from progeny tests or half-sib analysis conducted in experimental stands. Such an approach estimates h 2 from the ratio of between-family/total phenotypic variance. These analyses are difficult to apply to natural populations of species with a long life cycle, overlapping generations, and a mixed mating system, without genealogical information. A promising alternative is the use of molecular marker information to infer relatedness between individuals and to estimate h 2 from the regression of phenotypic similarity on inferred relatedness. In the current study we compared h2 of 13 quantitative traits estimated by these two methods in an experimental stand of P. alba, where genealogical information was available. We inferred pairwise relatedness by Ritland's method using six microsatellite loci. Relatedness and heritability estimates from molecular information were highly correlated to the values obtained from genealogical data. Although Ritland's method yields lower h 2 estimates and tends to overestimate genetic correlations between traits, this approach is useful to predict the expected relative gain of different quantitative traits under selection without genealogical information.Fil:Bessega, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Saidman, B.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Darquier, M.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Vilardi, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Host association of Spodoptera frugiperda (Lepidoptera: Noctuidae) corn and rice strains in Argentina, Brazil and Paraguay

Spodoptera frugiperda (J.E. Smith) is composed of two genetically distinct strains, the so-called corn strain and the rice strain. Whether the two strains differ in their host use is unclear, because laboratory experiments have not been able to show consistent host performance or preference differences between them, and field studies showed high rates of hybridization, as well as some degree asymmetric host use. To determine the distribution of the two strains and their association with host plants, we collected fall armyworm larvae from different crops (corn, rice, alfalfa, and sorghum) and grasses in 15 different localities over 4 yr in Argentina, Brazil, and Paraguay. The strain identity was analyzed using two polymorphisms in the mitochondrial cytochrome oxidase subunit I gene. We identified the corn and rice haplotypes and three types of populations were characterized based on the frequencies of the individuals that belonged to any of these haplotypes: in 44% of populations the corn haplotype predominated, in 44% of populations the rice haplotype was the most frequent, and 11% of populations showed both haplotypes at similar proportions. In total, eight populations (47%) showed the expected pattern, two populations (12%) were polymorphic within the same field, and seven populations (41%) showed the inverse pattern. Taken together, there was no consistent pattern of host association between the two sympatric genotypes and their respective host plants. This investigation supports the need for additional studies to determine which other forces keep the genotypes separate, and what is the degree of genetic differentiation between these populations