Diallel analysis and inbreeding depression of commercial maize hybrids aiming the formation of base populations

The development of base populations derived from high yield commercial hybrids is considered one of the main strategies to initiate a maize breeding program, mainly because these hybrids have already been tested in many environments, and so, associating high yield and a large proportion of favorable loci fixed. Therefore, the objective of the present study is to estimate the combining abilities and inbreeding depression of commercial maize hybrids for agronomic traits. Eighteen commercial hybrids divided in two groups accordingly to their respective companies, seventy-two F combinations from a partial diallel scheme, eighteen S populations and one check were evaluated in a randomized complete block design in two experiments, both in Sementes Balu Experimental Unit, Sabáudia (PR), Brazil, for growing seasons from 2011/2012 and 2012/2013. The Griffing method (1956), adapted to a partial diallel by Geraldi and Miranda Filho (1988) was applied for the evaluation of the general com- bining ability (GCA) and specific combining ability (SCA). The hybrids P1630, P4285, 30B39Y and DKB370 showed increased yield, and hybrids P1630, 32R22H, and DKB615 showed reduced plant and ear height. These hybrids can be recommended for the extraction of inbred lines and formation of composites followed by intrapopulation selection. The combinations P1630 x DKB330, P4285 x DKB245, 30F53 x DKB370, and 32R22H x DKB370 showed desirable SCA effects for grain yield and are recommended for use in interpopulation breeding programs. Among the hybrids with desirable GCA effects, 30B39Y showed the lowest inbreeding depression effect for the analyzed traits

Global urban environmental change drives adaptation in white clover.

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Terrestrial behavior in titi monkeys (Callicebus, Cheracebus, and Plecturocebus) : potential correlates, patterns, and differences between genera

For arboreal primates, ground use may increase dispersal opportunities, tolerance to habitat change, access to ground-based resources, and resilience to human disturbances, and so has conservation implications. We collated published and unpublished data from 86 studies across 65 localities to assess titi monkey (Callicebinae) terrestriality. We examined whether the frequency of terrestrial activity correlated with study duration (a proxy for sampling effort), rainfall level (a proxy for food availability seasonality), and forest height (a proxy for vertical niche dimension). Terrestrial activity was recorded frequently for Callicebus and Plecturocebus spp., but rarely for Cheracebus spp. Terrestrial resting, anti-predator behavior, geophagy, and playing frequencies in Callicebus and Plecturocebus spp., but feeding and moving differed. Callicebus spp. often ate or searched for new leaves terrestrially. Plecturocebus spp. descended primarily to ingest terrestrial invertebrates and soil. Study duration correlated positively and rainfall level negatively with terrestrial activity. Though differences in sampling effort and methods limited comparisons and interpretation, overall, titi monkeys commonly engaged in a variety of terrestrial activities. Terrestrial behavior in Callicebus and Plecturocebus capacities may bolster resistance to habitat fragmentation. However, it is uncertain if the low frequency of terrestriality recorded for Cheracebus spp. is a genus-specific trait associated with a more basal phylogenetic position, or because studies of this genus occurred in pristine habitats. Observations of terrestrial behavior increased with increasing sampling effort and decreasing food availability. Overall, we found a high frequency of terrestrial behavior in titi monkeys, unlike that observed in other pitheciids

Potencial agronômico e divergência genética entre genótipos de berinjela nas condições do Caribe Colombiano Agronomic potential and genetic divergence among eggplant genotypes in the Colombian Caribbean region

Foram avaliados 24 genótipos (híbridos, cultivares e variedades locais) de berinjela quanto às características produtivas no Caribe Colombiano para quantificar a divergência genética entre estes e indicar possíveis cruzamentos. Visa-se dar início a um programa de melhoramento genético da cultura na região, considerando a divergência genética e as características agronômicas desses genótipos. Utilizou-se delineamento em blocos casualizados, com três repetições. As variáveis estudadas foram comprimento do fruto, número de frutos por planta, massa média do fruto, rendimento, firmeza do fruto e altura da planta. Os dados foram submetidos à análise de variância univariada e estatísticas multivariadas utilizando-se diferentes métodos de agrupamento hierárquico e as variáveis canônicas. As médias foram agrupadas pelo teste de Scott-Knott. Verificou-se elevada divergência entre os genótipos estudados. Quando se considerou isoladamente os híbridos, as cultivares e as variedades locais, observou-se maior variabilidade entre os híbridos seguido das cultivares e, por fim, das variedades locais. O método UPGMA foi mais fidedigno no agrupamento que os métodos Ward e Vizinho Mais Próximo, pois obteve maior valor de Coeficiente de Correlação Cofenética. Pelos critérios pseudo-F e pseudo-t² verificou-se que o ponto de máximo foi atingido quando da forma��ão de quatro grupos, sendo este considerado o número ideal de grupos para o UPGMA. Houve concordância entre os grupos formados pelo UPGMA e pelas variáveis canônicas. Com os resultados pode-se inferir que os cruzamentos CC08 x CC02; CC08 x EU01 e CC08 x C016 têm grande potencial visando à produção e a firmeza do fruto.<br>We evaluated 24 genotypes (hybrids, cultivars and landraces) of eggplant related to yield traits in the Colombian Caribbean region, to quantify the genetic divergence among these genotypes and to indicate possible crosses. With the results of the genetic diversity and agronomic traits we intend to initiate a program of eggplant breeding in that region. A randomized block design with three replications was used. The analyzed variables were fruit length, number of fruits per plant, mean fruit weight, yield, fruit firmness and plant height. The data were submitted to variance analysis and the averages grouped by Scott-Knott test. A multivariate analysis was also performed using different methods of hierarchical clustering and canonical variables. There was high divergence among the studied genotypes even when considered within hybrids, cultivars and landraces, with highest variability among the cultivars and hybrids followed by the landraces. The UPGMA method was more reliable than Ward and Single Linkage methods since UPGMA presented greater value of Cophenetic Correlation Coefficient (CCC). Using pseudo-F and pseudo-t² criteria the maximum point was reached when four clusters were formed, being considered the ideal number of groups for the UPGMA. There was agreement among the groups formed for UPGMA analysis and canonic variables. Crosses between CC08 x CC02; CC08 x EU01 and CC08 x C016 may be recommended to start an eggplant breeding program aiming to improve yield and fruit firmness