Traits In Progeny Research Articles

Improved polycross breeding of tall fescue through marker‐based parental selection

With 2 figures and 6 tablesAbstractThe aim of this study was to investigate whether key agronomic traits of tall fescue synthetic progeny could be improved by using genetically diverse parents selected from a large breeding pool. Syn1 progeny of four polycrosses composed using six parental plants with contrasting levels of diversity based on phenotypic and expressed sequence tag (EST)‐simple sequence repeat (SSR) markers were investigated together with the progeny of a fifth polycross composed using six genotypes with highest general combining ability. Syn1 progeny from parents with high general combining ability generally showed lower values for most traits investigated when compared to progeny derived from other polycrosses. Progeny from parents selected for high molecular genetic diversity showed comparable or higher values than the other progeny for all traits investigated. The assessment of phenotypic and molecular genetic diversity of the five Syn1 populations showed high congruence with the diversity observed among the respective parental plants and decreased from parents to Syn1 as expected. Our results demonstrate that EST‐SSR markers provide a reliable means to predict genetic diversity in Syn1 progeny that may allow for efficiently selecting parental genotypes and enhancing tall fescue breeding programmes.

Paternity analysis in a progeny test of Cryptomeria japonica revealed adverse effects of pollen contamination from outside seed orchards on morphological traits

To evaluate the effects of pollen contamination from outside of Cryptomeria japonica seed orchard on the growth performance (height and diameter at breast height, DBH) and morphological traits (stem straightness and basal stem straightness), paternity testing using seven microsatellite markers was performed in a progeny test. In the studied progeny test, high rates of inconsistency were found between the observed and expected genotypes. The average rates of pollen contamination from outside the orchard and self-fertilization were 58.47% and 0.65%, respectively. We divided the individuals of the studied progeny test into two groups based on their genotype data, for which: (1) both parents were elite trees and (2) only the mother trees were elite trees, and then compared them with respect to the growth performance and morphological traits of progenies using data at 20 and 30 years old. Significant adverse effects of contaminating pollen were detected in relation to straightness, but not tree height and DBH. The results suggest that the genetic gains for straightness generally show higher narrow-sense heritability than growth traits, which should be increased by reduction of pollen contamination. Breeding with paternal analysis (BWPA) is an effective approach for evaluating breeding materials based on maternal and paternal information revealed by DNA markers. The use of BWPA in progeny test allows effective forward- and backward selection without laborious and time-consuming tasks. In this study, we also suggest that the significant pollen contamination and paternal deviation found in the open-pollinated progeny test are serious impediments for BWPA.

Contribution of synthetic tetraploids (AAAA) and diploids (AA) to black Sigatoka resistance and bunch weight to their triploid progenies

The generation of banana triploids from tetraploid–diploid crosses requires knowledge on the influence of the parents on black Sigatoka resistance and agronomic traits to the triploid progenies. The objective of this investigation was to determine the influence of tetraploid and diploid parents on black Sigatoka resistance and agronomic traits in the triploid progenies generated from tetraploid–diploid crosses. The mating scheme was designed as a 4 × 5 North Carolina II mating design. Due to problems in seed set and germination, progenies from 2 male parents with 4 female parents were evaluated at two sites in Uganda. The results showed that the male-parent triploid progeny heritability estimate for the number of leaves at harvest was greater than the female parent estimate. The diploid parents had higher correlation coefficients for the total leaves at harvest with the triploid progenies than tetraploid parents with triploid progenies. Disease development over time took more days in diploid parents than in the tetraploid parents with the triploid progenies as intermediates. These results suggested that diploids transferred black Sigatoka resistance to the triploid progenies as measured by the number of standing leaves and disease development overtime. There was a positive correlation ( P < 0.05) between tetraploid female parents and triploid progenies for plant height and bunch weight. The triploid progeny–tetraploid female parent heritability estimates for plant height (0.92) and bunch weight (0.72) were highly significant. These results indicated that the female synthetic tetraploids influenced plant height and bunch weight in the triploid progenies. Therefore, it is important to select the tetraploids with heavy bunches to effectively improve yield in triploid progenies generated by tetraploid–diploid crosses. The tetraploid–diploid progenies had a significant ( P < 0.05) family-by-site interaction for bunch weight indicating that new banana genotypes need to be tested across different environments to select stable genotypes to promote to end-users.

Variability and divergence in Pongamia pinnata for further use in tree improvement

A total of 24 candidate plus trees (CPTs) of Pongamia pinnata (L.) Pierre. were selected to elucidate their variation and diversity based on thirteen quantitative traits (4 pod traits, 6 seed traits of parent trees and 3 progeny traits) at Forest Research Centre, Institute of Forest Productivity — Mandar, Ranchi district during 2005–2007. The results show that, CPT-19 had maximum for seven traits viz, pod length (65.6 mm), 100-pod weight (542.4 g), seed 2D (two dimension) area (351.2 mm2), seed length (27.9 mm), seed breadth (17.4 mm), 100-seed weight (217.9 g) and plant height (164.3 cm). The traits, 100-pod weight and 100-seed weight had a high heritability (98.4%, 96.9%) accompanied with high genetic advance (46.0%, 34.9%). There is a positive significant correlation between 100-pod weight and 100-seed weight traits at both genotypic and phenotypic levels with plant height, collar diameter and volume index at 30 MAS (months after sowing). Volume index expressed a moderate heritability (47.4%) accompanied with high genetic advance (48.4%), indicating that the character is governed by additive gene effects. In divergence study, 24 accessions were grouped into 6 clusters on the basis of non-hierarchical euclidian cluster analysis. The genotypes in cluster IV (CPT-5, CPT-6, CPT-7, CPT-12, CPT-16, CPT-18, CPT-22) and cluster III (CPT-4, CPT-8, CPT-9, CPT-20, CPT-21) were most heterogeneous and can be best used within group hybridization. The wide diversity exists between the cluster V and II, followed by cluster II and I and crosses between CPTs of these clusters may result in substantial segregates. It is revealed that the existence of substantial variation and diversity can be utilized for genetic resource conservation and further tree improvement programmers of the species.

Genetic variability of oil palm parental genotypes and performance of its’ progenies as revealed by molecular markers and quantitative traits

Studies were conducted to assess the genetic relationships between the parental palms ( dura and pisifera) and performance of their progenies based on nine microsatellite markers and 29 quantitative traits. Correlation analyses between genetic distances and hybrids performance were estimated. The coefficients of correlation values of genetic distances with hybrid performance were non-significant, except for mean nut weight and leaf number. However, the correlation coefficient of genetic distances with these characters was low to be used as predicted value. These results indicated that genetic distances based on the microsatellite markers may not be useful for predicting hybrid performance. The genetic distance analysis using UPGMA clustering system generated 5 genetic clusters with coefficient of 1.26 based on quantitative traits of progenies. The genotypes, DP16, DP14, DP4, DP13, DP12, DP15, DP8, DP1 and DP2 belonging to distant clusters and greater genetic distances could be selected for further breeding programs.

Embryonic exposure to maternal testosterone influences age-specific mortality patterns in a captive passerine bird

Hormones are potent mediators of developmental programming and maternal epigenetic effects. In vertebrates, developmental exposure to maternal androgen hormones has been shown to impact multiple behavioral and physiological traits of progeny, but the possible consequences of this early exposure in terms of aging-related changes in mortality and fitness remain largely unexplored. Avian eggs naturally contain variable doses of maternal hormones-in particular, androgens-which have documented effects on embryo growth and differentiation as well as adult behavior and physiology. Here, we report that injections of a physiological dose of testosterone (T) into yolks of freshly laid eggs of a small, seasonally breeding songbird, the house sparrow (Passer domesticus), increased survivorship in a semi-natural aviary environment. In addition, survival effects of developmental T exposure were sex-dependent, with males generally having a higher risk of death. Separate analyses for young birds in their first year of life (from hatching up to the first reproductive period the following calendar year) and in adulthood (after the first breeding season) showed similar effects. For first-year birds, mortality risk was higher during the winter than during the period after fledging; for adults, mortality risk was higher during the reproductive than the non-reproductive phase (post-breeding molt and winter). T treatment did not affect nestling body mass, but resulted in higher body mass at 3-4months of age; T and body mass at this age interacted to influence mortality risk. Embryonic exposure to maternal testosterone may result in lower adult mortality by modifying intrinsic physiological processes involved in health or aging over the lifespan of adult birds.

Evaluation of Reproductive Performance and Egg quality Traits in Progenies of Dominant Black Strain Crossed with Fulani Ecotype Chicken

This study was undertaken to contribute to the genetic improvement of the indigenous chicken by direct andreciprocal crossing with an exotic egg type strain Dominant Black (DB). Results indicated significant (P<0.05)effect of genotype on fertility and hatchability of eggs. Percentage fertility across the genotypes was, 73.00,76.24, 59.88 and 54.12%, while hatchability was 73.90, 78.30, 70.45 and 70.10%, for DBxDB, DBxFE, FExDBand FExFE, respectively. There was no significant (P>0.05) difference in hatch weight of the chicks. The crossbred (DBxFE and FExDB) had higher egg weight (51.45g and 51.35g vs. 47.19), total egg number for 100 days(51 and 53 vs. 40) and hen day production (50.87 and 52.47 vs. 46.05) than the pure bred Fulani Ecotype.FExDB had significantly higher body weight at first egg (1408g) than DBxFE (1388g). Mortality wassignificantly (P<0.05) higher in DBxDB than other genotypes during the laying period. Significant and nonsignificant differences existed in internal and external egg quality traits across the genotypes.

Survival and height of pedunculate oak (Quercus robur L.) in Chrostowa I experimental trial in Brzesko Forest District

Przeżywalność i wysokość dębu szypułkowego (Quercus robur l.) testowanego na powierzchni doświadczalnej "Chrostowa I" w Nadleśnictwie Brzesko

Outbreeding Depression Caused by Intraspecific Hybridization Between Local and Nonlocal Genotypes in Abies sachalinensis

To evaluate the effects of intraspecific hybridization of local and nonlocal genotypes on growth traits of progeny in Abies sachalinensis, we performed reciprocal crossing between nonlocal trees in a high‐elevation zone (1,100–1,200 m asl) and local trees in a low‐elevation zone (530 m asl) in Hokkaido, northern Japan, in 1979 and established a common garden experiment using local × local (female × male ), local × nonlocal , nonlocal × local , and nonlocal × nonlocal progeny in the low‐elevation zone in 1986. Survival, height, diameter at breast height (dbh), needle nitrogen content, specific leaf area (SLA), and needle area per shoot diameter (NA) of 25‐year‐old progeny were measured in 2005. The survival rate was consistently high (&gt;85% on average). Reductions in height and dbh were apparent in F1 hybrids compared with local × local progeny. Furthermore, outbreeding depression was significant in height growth of nonlocal × local F1 hybrids and in dbh of both F1 hybrids. Reductions in growth traits may be related to morphological needle traits, such as the low values of SLA and NA. Elevation guidelines for A. sachalinensis seed zones are discussed to ensure the long‐term viability of both restored and native populations.

Divergência genética entre acessos de espinheira-santa (Maytenus ilicifolia Mart. ex Reissek e M. aquifolium Mart.) com base em caracteres morfológicos e fisiológicos

Maytenus ilicifolia e M. aquifolium (espinheira-santa) são espécies medicinais nativas do Brasil ameaçadas de extinção devido à forte ação antrópica nas populações naturais. O objetivo deste trabalho foi avaliar a divergência genética em germoplasma de espinheira-santa, e agrupar os acessos através de análises multivariadas, com base em caracteres morfo-fisiológicos das progênies. Foram avaliados 89 acessos do banco ativo de germoplasma de espinheira-santa da Embrapa Clima Temperado/Universidade Federal de Pelotas. Os caracteres avaliados foram dias da semeadura à emergência; altura e diâmetro à base do caule, aos 90, 180, 270 e 360 dias; crescimento em altura e diâmetro à base do caule; comprimento e largura de folha e número de espinhos por folha. O delineamento experimental foi em blocos casualizados, com quatro repetições e cinco plantas por parcela. Os dados foram submetidos à análise de variância e análise de variância multivariada, sendo estimadas as variáveis canônicas. Os caracteres avaliados foram eficientes para separar os acessos em três grupos. As variáveis altura, diâmetro à base do caule aos 360 dias e número de folhas aos 180 dias são as mais importantes para caracterização do germoplasma de espinheira-santa.

Association of bovine leptin polymorphisms with energy output and energy storage traits in progeny tested Holstein-Friesian dairy cattle sires

BackgroundLeptin modulates appetite, energy expenditure and the reproductive axis by signalling via its receptor the status of body energy stores to the brain. The present study aimed to quantify the associations between 10 novel and known single nucleotide polymorphisms in genes coding for leptin and leptin receptor with performance traits in 848 Holstein-Friesian sires, estimated from performance of up to 43,117 daughter-parity records per sire.ResultsAll single nucleotide polymorphisms were segregating in this sample population and none deviated (P > 0.05) from Hardy-Weinberg equilibrium. Complete linkage disequilibrium existed between the novel polymorphism LEP-1609, and the previously identified polymorphisms LEP-1457 and LEP-580. LEP-2470 associated (P < 0.05) with milk protein concentration and calf perinatal mortality. It had a tendency to associate with milk yield (P < 0.1). The G allele of LEP-1238 was associated (P < 0.05) with reduced milk fat concentration, reduced milk protein concentration, longer gestation length and tended to associate (P < 0.1) with an increase in calving difficulty, calf perinatal mortality and somatic cells in the milk. LEP-963 exhibited an association (P < 0.05) with milk fat concentration, milk protein concentration, calving difficulty and gestation length. It also tended to associate with milk yield (P < 0.1). The R25C SNP associated (P < 0.05) with milk fat concentration, milk protein concentration, calving difficulty and length of gestation. The T allele of the Y7F SNP significantly associated with reduced angularity (P < 0.01) and reduced milk protein yield (P < 0.05). There was also a tendency (P < 0.1) for Y7F to associate with increased body condition score, reduced milk yield and shorter gestation (P < 0.1). A80V associated with reduced survival in the herd (P < 0.05).ConclusionsSeveral leptin polymorphisms (LEP-2470, LEP-1238, LEP-963, Y7F and R25C) associated with the energetically expensive process of lactogenesis. Only SNP Y7F associated with energy storage. Associations were also observed between leptin polymorphisms and calving difficulty, gestation length and calf perinatal mortality. The lack of an association between the leptin variants investigated with calving interval in this large data set would question the potential importance of these leptin variants, or indeed leptin, in selection for improved fertility in the Holstein-Friesian dairy cow.

Parental effects on embryonic viability and growth in Arctic charrSalvelinus alpinusat two incubation temperatures

The parental influences on three progeny traits (survival to eyed-embryo stage, post-hatching body length and yolk-sac volume) of Arctic charr Salvelinus alpinus were studied under two thermal conditions (2 and 7 degrees C) using a factorial mating design. The higher temperature resulted in elevated mortality rates and less advanced development at hatching. Survival was mostly attributable to maternal effects at both temperatures, but the variation among families was dependent on egg size only at the low temperature. No additive genetic variation (or pure sire effect) could be observed, whereas the non-additive genetic effects (parental combination) contributed to offspring viability at 2 degrees C. In contrast, any observable genetic variance in survival was lost at 7 degrees C, most likely due to the increased environmental variance. Irrespective of temperature, dam and sire-dam interaction contributed significantly to the phenotypic variation in both larval length and yolk size. A significant proportion of the variation in larval length was also due to the sire effect at 2 degrees C. Maternal effects were mediated partly through egg size, but as a whole, they decreased in importance at the high temperature, enabling a concomitant increase in non-additive genetic effects. For larval length, however, the additive component, like maternal effects, decreased at 7 degrees C. The present results suggest that an exposure to thermal stress during incubation can modify the genetic architecture of early developmental traits in S. alpinus and presumably constrain their short-term adaptive potential and evolvability by increasing the amount of environmentally induced variation.

Tree and fruit traits of progenies from the cross between (Annona cherimola Mill. × A. squamosa L.) × A. reticulata L. and approaches for the introgression of valuable genes from A. reticulata L.

Annona reticulata L. possesses many traits desirable in other edible annonas, and hybridization is the simplest means to combine desirable features of related species. In this study, A. reticulata was hybridized with atemoya (A. cherimola Mill. × A. squamosa L.), and 250 trispecies hybrids were studied for 28 traits (12 tree traits and 16 fruit traits) with the objective of salvaging useful genes from the three edible annonas and determining the extent of variation in the progeny. The heterozygous nature of Annona spp. and simultaneous segregation of three distant genomes resulted in a tremendous heterogeneity in the progenies. The fitness of the progenies ranged from very vigorous to very weak, with a wide range of values for tree height (1.75–5.9 m), canopy spread (1.15–5.07 m) and trunk circumference (11–38.5 cm). The occurrence of diverse and novel segregants for tree shape and branching pattern suggested the possibility of identifying efficient ideotypes. Variation in fruit shape, skin colour and skin surface in addition to wide range of values for total soluble solids (17–32°B), acidity (0.16–2.2%) and number of seeds per/100 g fruit (3–49) showed that exciting opportunities existed in terms of selecting for desirable traits. Among the segregating population were slow-fruit-ripening genotypes that required up to 12 days from harvesting to ripening. Interestingly, some recombinants produced fruits resembling A. glabra and A. muricata fruits, suggesting that one or the other parental species of the trihybrid could be progenitor of these two non-parental species. These results demonstrate that A. reticulata is potentially a valuable source of a variety of novel traits. However, the F1 trihybrids exhibited reduced fertility with pronounced undesirable traits of A. reticulata, and the survival of F2 trees was poor, with those that did survive being extremely weak and failing to flower or set fruit. Consequently, backcrossing may be more suitable approach than advancing trihybrid generation for transferring desirable genes from A. reticulata. Backcrossing F1 progeny of [(A. cherimola × A. squamosa) × A. reticulata] to A. squamosa, a highly fertile species, is expected to yield productive introgressants in which the contribution of the A. squamosa genome will be extended from 25 to 62.5% in the F1BC1 generation. The genetics is described herein based on the expressions of certain tree and fruit traits in the progeny.

Evaluation of estimated genetic merit for carcass weight in beef cattle: Live weights, feed intake, body measurements, skeletal and muscular scores, and carcass characteristics

Genetic merit for growth rate, expressed as expected progeny difference for carcass weight (EPD CWT), is available for dairy and beef sires used in Ireland. The once predominantly Friesian (FR) dairy herd has experienced significant introgression of Holstein (HO) genes over the past two decades, and cross-breeding of dairy cows, not required to produce herd replacements, with beef bulls is common. The objective of this study was to compare growth rate, feed intake, live animal measurements and slaughter traits of progeny of Holstein–Friesian dairy cows and bulls of two contrasting maturity beef breeds namely Aberdeen Angus (AA) and Belgian Blue (BB), each selected for either high (H) or low (L) estimated genetic merit for carcass weight. Two dairy strains (FR and HO) were also included giving six genetic groups in total. A total of 170 male progeny from spring-calving cows were artificially reared indoors and subsequently managed together at pasture until the end of their second grazing season when they were assigned to one of two mean slaughter weights (i) 560 kg (Light) or (ii) 620 kg (Heavy). Daily feed intake was recorded during the first winter and during finishing. Body measurements were recorded four times during the animals' life, and linear scoring was carried out at 9 months of age and again at slaughter. Carcasses were graded for conformation and fatness (15 point scale). Slaughter and carcass weights per day of age for AAH, AAL, BBH, BBL, FR and HO were 782, 719, 795, 793, 804 and 783 (SE 12.9) g, and 415, 372, 438, 436, 413 and 401 (SE 5.8) g, respectively. Corresponding values for carcass weight, kill-out proportion, carcass conformation class (15 point scale) and carcass fat class (15 point scale) were 314, 283, 334, 333, 317 and 305 (SE 4.7) kg, 526, 518, 553, 550, 519 and 511 (SE 2.9) g/kg, 6.2, 5.4, 8.0, 7.9, 5.3 and 3.7 (SE 0.26), and 9.8, 9.3, 7.4, 7.2, 9.3 and 8.2 (SE 0.26). There were significant interactions between estimated genetic merit for carcass weight and beef breed with the differences between H and L mainly expressed for AA only. Feed intake differences between H and L animals were negligible and largely attributable to the differences in live weight. Following scaling for live weight, beef breeds of high estimated genetic merit for carcass weight had lower skeletal measurements, indicating greater compactness, with the effect more pronounced in AA. It is concluded that using beef sires of estimated high genetic merit for carcass weight on dairy cows increases growth rate and carcass weight of the progeny but the effect may not be similar for all breeds.

High Resolution Mapping of Cia3: A Common Arthritis Quantitative Trait Loci in Different Species

Murine collagen induced arthritis (CIA) is a widely used model of rheumatoid arthritis (RA). Identification of CIA susceptibility genes will aid in the understanding of RA pathogenesis and development of therapeutic targets. This study aims to identify and refine quantitative trait loci (QTL) controlling CIA. Major CIA clinical traits were evaluated in both (DBA/1xFVB/N) F(2) and advanced intercross line (AIL) mice; QTLs were confirmed and refined in AIL. To search for candidate genes, we applied multiple approaches, including gene expression profiling, identification of nonsynonymous polymorphism, and comparative genomic mapping. We identified six suggestive QTLs controlling CIA clinical traits in the F(2) progeny; one of these was confirmed and refined in AIL. This QTL is located on chromosome 6 and overlaps with Cia3, which was identified previously. We refined the 2-log support interval of Cia3 into a 5.6 Mb genomic region; 15 of 77 genes are differentially expressed or carry nonsynonymous polymorphisms between two parental strains. The counterpart genomic region of Cia3 on the rat and human genomes are linked to RA. Twenty-nine of 77 genes are located in the arthritis-linked genomic regions of all three species. Five of those 29 genes are differentially expressed or carry nonsynonymous polymorphisms between parental strains: Timp4, Tmem40, Mbd4, Cacna1c, and Lrtm2. Taken together, we refined Cia3 into a 5.6 Mb genomic region on mouse chromosome 6 and identified candidate genes. This will aid in the search for susceptibility gene(s) controlling arthritis development within Cia3 and its counterpart regions in rat and human genomes.

Intake, growth and carcass traits in male progeny of sires differing in genetic merit for beef production

Validation of economic indexes under a controlled experimental environment, can aid in their acceptance and use as breeding tools to increase herd profitability. The objective of this study was to compare intake, growth and carcass traits in bull and steer progeny of high and low ranking sires, for genetic merit in an economic index. The Beef Carcass Index (BCI; expressed in euro (€) and based on weaning weight, feed intake, carcass weight, carcass conformation and fat scores) was generated by the Irish Cattle Breeding Federation as a tool to compare animals on genetic merit for the expected profitability of their progeny at slaughter. A total of 107 male suckler herd progeny, from 22 late-maturing ‘continental’ beef sires of high (n = 11) or low (n = 11) BCI were compared under either a bull or steer production system, and slaughtered at approximately 16 and 24 months of age, respectively. All progeny were purchased after weaning at approximately 6 to 8 months of age. Dry matter (DM) intake and live-weight gain in steer progeny offered grazed grass or grass silage alone, did not differ between the two genetic groups. Similarly, DM intake and feed efficiency did not differ between genetic groups during an ad libitum concentrate-finishing period on either production system. Carcasses of progeny of high BCI sires were 14 kg heavier (P < 0.05) than those of low BCI sires. In a series of regression analyses, increasing sire BCI resulted in increases in carcass weight (P < 0.01) and carcass conformation (P = 0.051) scores, and decreases in carcass fat (P < 0.001) scores, but had no effect on weaning weight or DM intake of the progeny. Each unit increase in sire expected progeny difference led to an increase in progeny weaning weight, DM intake, carcass weight, carcass conformation score and carcass fat score of 1.0 (s.e. = 0.53) kg, 1.1 (s.e. = 0.32) kg, 1.3 (s.e. = 0.31) kg, 0.9 (s.e. = 0.32; scale 1 to 15) and 1.0 (s.e. = 0.25; scale 1 to 15), respectively, none of which differed from the theoretical expectation of unity. The expected difference in profitability at slaughter between progeny of the high and low BCI sires was €42, whereas the observed phenotypic profit differential of the progeny was €53 in favour of the high BCI sires. Results from this study indicate that the BCI is a useful tool in the selection of genetically superior sires, and that actual progeny performance under the conditions of this study is within expectations for both bull and steer beef production systems.

Keragaan Genetik dan Pendugaan Heritabilitas pada Komponen Hasil dan Kandungan β-Karoten Progeni Kelapa Sawit

An experiment to study heritability, general combining ability (GCA), and specific combining ability (SCA) of some traits in oil palm progeny was conducted at Kebun Surya Adi, PT. Bina Sawit Makmur, Sampoerna Agro, Ogan Komering Ilir, Sumatera Selatan, from July 2006 until September 2008. The research was arranged in alpha design with two replications , 50 progenies and 12 palms for each replication, respectively . The results showed that broad sense heritability estimates were high for mesocarp to fruit, oil to fresh mesocarp, and kernel to fruit content ratio s , and β-carotene content ; medium for bunch number and oil to bunch ratio ; and low for fresh bunch and fruit to bunch ratio. The general combining ability (GCA) of bunch number, mesocarp to fruit, oil to fresh mesocarp, and kernel to fruit ratio s and β-carotene content were highly significant. Similarly, the specific combining ability (SCA) of mesocarp to fruit, oil to fresh mesocarp, and kernel to fruit ratios and β-carotene content were also highly significant. Key words: Heritability, combining ability, Elaeis guineensis Jacq ., alpha design, β-carotene

Variabilidade genética para caracteres morfológicos e fisiológicos em espinheira-santa (Maytenus ilicifolia (Schrad.) Planch. e M. aquifolium Mart.)

O objetivo deste trabalho foi avaliar a variabilidade genética, estimar parâmetros genéticos e a correlação entre caracteres morfo-fisiológicos em progênies de meios-irmãos de 93 acessos de espinheira-santa do banco ativo de germoplasma da Embrapa Clima Temperado. Foram analisados os caracteres dias da semeadura à emergência; estatura de planta; diâmetro à base do caule; número de folhas por planta; taxa de crescimento em estatura e em diâmetro à base do caule, comprimento e largura de folha e número de espinhos por folha. O delineamento experimental foi em blocos casualizados, com quatro repetições e cinco plantas por parcela. Os dados foram submetidos à análise da variância e comparação entre médias e foram estimados os parâmetros genéticos herdabilidade, coeficiente de variação genético (CVG) e relação entre coeficiente de variação genético e coeficiente de variação do erro experimental (CVE) (b) bem como as correlações fenotípicas entre os caracteres. Foi identificada variabilidade genética para todos os caracteres. As variâncias de ambiente foram baixas e as variâncias genotípicas foram altas, o que resultou em altos valores de herdabilidade. Os CVG foram altos e os CVE foram baixos, o que levou a elevados valores para o quociente b. Estes parâmetros são importantes na seleção para estes caracteres em programas de melhoramento. Foram identificadas correlações significativas entre os caracteres morfo-fisiológicos.

Natural Variation of Male Ornamental Traits of the Guppy,Poecilia reticulata

Male ornamental traits of the guppy, Poecilia reticulata, provide an outstanding example of natural variation in sex-linked male-advantageous traits that are shaped by both sexual and environmental selection. A substantial fraction of the underlying genes is known to be genetically linked to the sex-determining region on the differentiating Y-chromosome. Intercrosses between parental populations originating from geographically distant locations in East Trinidad and Cumaná (Venezuela) were used to study segregation of ornamental traits in male progeny. In addition, we performed backcrosses to compare segregation of ornaments in presence or absence of prominent traits linked to the Y-chromosome. Another backcross strategy involving XY females from the laboratory strain zebrinus maculatus allowed studying additive and dominant effects of alleles on two different Y-chromosomes on pattern formation. For genetic mapping, we have previously developed nuclear SNP markers linked to expressed genes, including several genes known to be important for pattern formation in other species. Of these candidate genes 15 were placed on 11 different linkage groups. Our phenotypic and genotypic analysis of progeny from mapping crosses and backcrosses suggests several genetic mechanisms that enhance natural variation, namely, additive effects of codominant alleles, suppressive actions of dominant alleles, and a complex interplay between sex-linked and autosomal cofactors.

Maternal size effects on early life traits of the temperate fish Symphodus roissali

The relative importance of maternal influences and time of reproduction on early life- history traits in the temperate five-spotted wrasse Symphodus roissali was examined. On 5 occasions during the reproductive period, groups of 4 small and 4 large females were collected and their eggs were fertilized with milt from 1 male. This multiple female fertilization experiment allowed the eval- uation and comparison of potential contribution of maternal size on the following early life traits of progeny: egg properties (diameter and dry weight) and larval properties (larval length and dry weight). Large females (>9 cm) produced larger eggs and larvae than did small females (<9 cm). The differences in progeny properties between both size groups of females were maintained throughout the reproductive period, with increasing variations in larval length at the end. As juvenile survival of S. roissali is affected by larval size at hatching and this is, in turn, affected by maternal size and time of spawning, it can be concluded that the size of females plays a major role in reproductive success, with larger females maximizing the survival of the young.