Moderate Heritability Research Articles

Assessment of Genetic Variability for Seed Yield and Related Traits in Some Mutant and Non-mutant Lines of Indian Mustard (Brassica juncea L.)

A study was conducted to evaluate the genetic variability for seed yield and related traits in 29 genotypes of Indian mustard during Rabi 2019-20 and Rabi 2020-21 at Experimental Farm, Department of Plant Breeding and Genetics, AAU, Jorhat. The genotypes comprised of 21 M4-5 mutant lines developed by gamma irradiation of the parent varieties TM-2 and PM-27, 5 newly developed F6-7 lines, and 3 check varieties (TM-2, PM-27 and NRCHB-101). Pooled analysis of variances over the years revealed significant variation for most of the characters observed. The characters seed yield per plant, number of primary branches per plant and number of secondary branches per plant exhibited moderate genetic variation. Moderate heritability coupled with high genetic advance was observed for number of secondary branches per plant whereas, number of primary branches per plant showed high heritability with moderate genetic advance. The genotypes JMM-TM2-17, JMM-TM2-15, JMM-TM2-34, JMM-TM2-10, JMM-PM27-1, JM13-6 and the variety NRCHB-101 were found promising for most of the yield attributing characters. The mutant line JMM-TM2-28 and recombinant line JM13-4 may be exploited for the development of early-maturing mustard varieties.

Genome-wide association study for resistances to yellow rust, powdery mildew, and Septoria tritici blotch in cultivated emmer

Emmer is a progenitor of bread wheat and evolved in the Levant together with the yellow rust (YR), powdery mildew (PM) fungi, and a precursor of Zymoseptoria tritici causing Septoria tritici blotch (STB). We performed a genome-wide association mapping for the three disease resistances with 143 cultivated emmer accessions in multi-environmental trials. Significant (P < 0.001) genotypic variation was found with high heritabilities for the resistances to the two biotrophs and a moderate heritability for STB resistance. For YR, PM, and STB severity nine, three, and seven marker-trait associations, respectively, were detected that were significant across all environments. Most of them were of low to moderate effect, but for PM resistance a potentially new major gene was found on chromosome 7AS. Genomic prediction abilities were high throughout for all three resistances (≥ 0.8) and decreased only slightly for YR and PM resistances when the prediction was done for the second year with the first year as training set (≥ 0.7). For STB resistance prediction ability was much lower in this scenario (0.4). Despite this, genomic selection should be advantageous given the large number of small QTLs responsible for quantitative disease resistances. A challenge for the future is to combine these multiple disease resistances with better lodging tolerance and higher grain yield.

Sustained looking at faces at 5months of age is associated with socio-communicative skills in the second year of life.

Efficiently processing information from faces in infancy is foundational for nonverbal communication. We studied individual differences in 5-month-old infants' (N=517) sustained attention to faces and preference for emotional faces. We assessed the contribution of genetic and environmental influences to individual differences in these gaze behaviors, and the association between these traits and other concurrent and later phenotypes. We found an association between the mean duration of looking at a face (before looking away from it) at 5months and socio-communicative abilities at 14months (β=0.17, 95% CI: 0.08; 0.26, p<0.001). Sustained attention to faces predicted socio-communicative abilities over and above variance captured by mean fixation duration. We also found a statistically significant but weak tendency to prefer looking at smiling faces (relative to neutral faces), but no indication that variability in this behavior was explained by genetic effects. Moderate heritability was found for sustained attention to faces (A=0.23, CI: 0.06; 0.38), while shared environmental influences were non-significant for both phenotypes. These findings suggest that sustained looking at individual faces before looking away is a developmentally significant 'social attention' phenotype in infancy, characterized by moderate heritability and a specific relation to later socio-communicative abilities.

Scald resistance in hybrid rye (Secale cereale): genomic prediction and GWAS.

Rye (Secale cereale L.) is an important cereal crop used for food, beverages, and feed, especially in North-Eastern Europe. While rye is generally more tolerant to biotic and abiotic stresses than other cereals, it still can be infected by several diseases, including scald caused by Rhynchosporium secalis. The aims of this study were to investigate the genetic architecture of scald resistance, to identify genetic markers associated with scald resistance, which could be used in breeding of hybrid rye and to develop a model for genomic prediction for scald resistance. Four datasets with records of scald resistance on a population of 251 hybrid winter rye lines grown in 2 years and at 3 locations were used for this study. Four genomic models were used to obtain variance components and heritabilities of scald resistance. All genomic models included additive genetic effects of the parental components of the hybrids and three of the models included additive-by-additive epistasis and/or dominance effects. All models showed moderate to high broad sense heritabilities in the range of 0.31 (SE 0.05) to 0.76 (0.02). The model without non-additive genetic effects and the model with dominance effects had moderate narrow sense heritabilities ranging from 0.24 (0.06) to 0.55 (0.08). None of the models detected significant non-additive genomic variances, likely due to a limited data size. A genome wide association study was conducted to identify markers associated with scald resistance in hybrid winter rye. In three datasets, the study identified a total of twelve markers as being significantly associated with scald resistance. Only one marker was associated with a major quantitative trait locus (QTL) influencing scald resistance. This marker explained 11-12% of the phenotypic variance in two locations. Evidence of genotype-by-environment interactions was found for scald resistance between one location and the other two locations, which suggested that scald resistance was influenced by different QTLs in different environments. Based on the results of the genomic prediction models and GWAS, scald resistance seems to be a quantitative trait controlled by many minor QTL and one major QTL, and to be influenced by genotype-by-environment interactions.

Studies on the genotypic co-efficient of variation and phenotypic co-efficient of variation in chickpea (Cicer arientinum L.) germplasm for yield-attributing characters

The magnitude of the genotypic co-efficient of variation (GCV) and phenotypic co-efficientof variation (PCV) in chickpea germplasm was observed high for characters like seed yield per plant followed by number of pods per plant, 100 seed weight, plant height, number of secondary branches per plant and number of primary branches per plant. The characteristics viz., seed yield per plant showed high GCV and PCV, moderate heritability and high genetic advance as a per cent of the mean. The characters viz. number of pods per plant, 100 seed weight, harvest index, number of secondary branches per plant and plant height recorded a highly positive significant correlation with seed yield at both genotypic and phenotypic levels. This indicates the simultaneous improvement of these characters through the selection of chickpeas.

Adding behavior traits to select for heat tolerance in dairy cattle

The increase in periods of heat waves leads to an increase in heat stress events in dairy cattle leading to welfare issues, production losses, and health issues. However, the low frequency of milk recording data makes genetic evaluation for heat tolerance still a challenge. A possible solution could be to add behavior data captured through sensors which are recorded permanently, mostly reported on a daily basis. The objective of this study was to evaluate the potential gain of adding behavior traits as proxies for genetic evaluation of heat tolerance. Behavior traits including activity time (ACT), rumination time (RUM), and eating time (EAT) were recorded for 453 Holstein cows equipped with SenseHub (Allflex Livestock Intelligence) collars from October 2019 to July 2022 in 6 herd located in the Walloon Region of Belgium. A multitrait reaction norm model based on separate temperature and humidity index (THI) thresholds was used. Results showed that behavior traits present not only interesting characteristics for genetic evaluation of heat tolerance but also for heat stress detection in farms. Indeed, sensors allow recording of behavior for all events of heat stress in lactating and nonlactating animals. Moderate heritability values were also found for the behavior traits (0.14 for ACT, 0.19 for RUM, and 0.12 for EAT), and a high ratio between the general and thermotolerance additive genetic variances was obtained. In addition, positive correlations of thermotolerance for ACT and EAT with thermotolerance for milk production (fat- and protein-corrected milk: 0.45 and 0.28, respectively) and negative genetic correlations of thermotolerance for ACT with somatic cells (somatic cell score: −0.39) were estimated. The genetic correlation matrix allows us to explain a high part of the variation for the reaction to heat stress of 2 economic traits (fat- and protein-corrected milk: 59% and somatic cell score: 31%) based on behavior data. Based on these results, behavior traits could be used to assess heat stress in nonlactating cattle for which the number of genetic evaluations for heat tolerance is still limited.

Modelling the lactation curve in Alpine × Beetal crossbred dairy goats using random regression models fitted with Legendre polynomial and B-spline functions.

The current study sought to genetically assess the lactation curve of Alpine × Beetal crossbred goats through the application of random regression models (RRM). The objective was to estimate genetic parameters of the first lactation test-day milk yield (TDMY) for devising a practical breeding strategy within the nucleus breeding programme. In order to model variations in lactation curves, 25,998 TDMY records were used in this study. For the purpose of estimating genetic parameters, orthogonal Legendre polynomials (LEG) and B-splines (BS) were examined in order to generate suitable and parsimonious models. A single-trait RRM technique was used for the analysis. The average first lactation TDMY was 1.22 ± 0.03 kg and peak yield (1.35 ± 0.02 kg) was achieved around the 7th test day (TD). The present investigation has demonstrated the superiority of the B-spline model for the genetic evaluation of Alpine × Beetal dairy goats. The optimal random regression model was identified as a quadratic B-spline function, characterized by six knots to represent the central trend. This model effectively captured the patterns of additive genetic influences, animal-specific permanent environmental effects (c2 ) and 22 distinct classes of (heterogeneous) residual variance. Additive variances and heritability (h2 ) estimates were lower in the early lactation, however, moderate across most parts of the lactation studied, ranging from 0.09 ± 0.04 to 0.33 ± 0.06. The moderate heritability estimates indicate the potential for selection using favourable combinations of test days throughout the lactation period. It was also observed that a high proportion of total variance was attributed to the animal's permanent environment. Positive genetic correlations were observed for adjacent TDMY values, while the correlations became less pronounced for more distant TDMY values. Considering better fitting of the lactation curve, the use of B-spline functions for genetic evaluation of Alpine × Beetal goats using RRM is recommended.

Exome sequencing identifies genes associated with sleep-related traits.

Sleep is vital for human health and has a moderate heritability. Previous genome-wide association studies have limitations in capturing the role of rare genetic variants in sleep-related traits. Here we conducted a large-scale exome-wide association study of eight sleep-related traits (sleep duration, insomnia symptoms, chronotype, daytime sleepiness, daytime napping, ease of getting up in the morning, snoring and sleep apnoea) among 450,000 participants from UK Biobank. We identified 22 new genes associated with chronotype (ADGRL4, COL6A3, CLK4 and KRTAP3-3), daytime sleepiness (ST3GAL1 and ANKRD12), daytime napping (PLEKHM1, ANKRD12 and ZBTB21), snoring (WDR59) and sleep apnoea (13 genes). Notably, 20 of these genes were confirmed to be significantly associated with sleep disorders in the FinnGen cohort. Enrichment analysis revealed that these discovered genes were enriched in circadian rhythm and central nervous system neurons. Phenotypic association analysis showed that ANKRD12 was associated with cognition and inflammatory traits. Our results demonstrate the value of large-scale whole-exome analysis in understanding the genetic architecture of sleep-related traits and potential biological mechanisms.

Inheritance of feed intake-based resilience traits and their correlation with production traits in Finnish pig breeds.

High resilience against diseases, changing environmental conditions, and other stress factors and the ability to efficiently recover to normal status, is becoming increasingly important in pig production. Finding new phenotypes that relate to resilience is a crucial step for improving the resilience of pigs through selection. The objective of this study was to extract resilience-related phenotypes based on fluctuations in daily feed intake (DFI, g) and time spent in feeding per day (TPD, min) and to estimate the heritability of these traits and genetic correlations with production traits (PT). Resilience-related traits with high enough heritability and with either favorable or neutral genetic correlation with PT could be used in the selection program to improve the productivity and welfare of pigs. In this study, we used data from 7,347 Finnish Yorkshire, Landrace, and crossbred pigs raised at the test station. Six pig-specific resilience-related phenotypes were extracted from the individual DFI and TPD: root mean square error (RMSE), quantile regression (QR), and coefficient of variation (CV). RMSE was calculated from the differences between the actual DFI (or TPD) and the pig-specific predicted values. QR was based on the number of days that a pig belonged to the group with the lowest 5% of pigs based on DFI (or TPD), and CV was calculated over the daily observations of DFI (or TPD). PT included average daily gain (ADG, g), backfat thickness (BF, mm), and feed conversion rate (FCR, g/g). The heritability estimates for resilience-related traits varied between 0.07 ± 0.02 (QRDFI) and 0.20 ± 0.03 (RMSETPD). The genetic correlations between resilience-related traits and PT were mostly neutral, but for example, RMSEDFI had a favorable genetic correlation with FCR and BF but an unfavorable correlation with ADG. Lastly, we observed that pigs belonging to the lowest 10% group based on their breeding value (BV) for QRTPD had a lower proportion (10% incidence) of sick days compared to the highest 10% BV group (30% incidence). Therefore, pigs exhibiting small TPD variation (related to high resilience) tend to be less susceptible to sickness than pigs with large TPD variation (related to low resilience). Given its moderate heritability, neutral genetic correlation with PT, and positive effect on health, QRTPD can be considered the most promising resilience-related trait in the Finnish production system.

Understanding the Biological Basis of Polygenic Risk Scores and Disparities in Prostate Cancer: A Comprehensive Genomic Analysis.

For prostate cancer (PCa), hundreds of risk variants have been identified. It remains unknown whether the polygenic risk score (PRS) that combines the effects of these variants is also a sufficiently informative metric with relevance to the molecular mechanisms of carcinogenesis in prostate. We aimed to understand the biological basis of PRS and racial disparities in the cancer. We performed a comprehensive analysis of the data generated (deposited in) by several genomic and/or transcriptomic projects (databases), including the GTEx, TCGA, 1000 Genomes, GEO and dbGap. PRS was constructed from 260 PCa risk variants that were identified by a recent trans-ancestry meta-analysis and contained in the GTEx dataset. The dosages of risk variants and the multi-ancestry effects on PCa incidence estimated by the meta-analysis were used in calculating individual PRS values. The following novel results were obtained from our analyses. (1) In normal prostate samples from healthy European Americans (EAs), the expression levels of 540 genes (termed PRS genes) were associated with the PRS (P < .01). (2) Ubiquitin-proteasome system in high-PRS individuals' prostates was more active than that in low-PRS individuals' prostates. (3) Nine PRS genes play roles in the cancer progression-relevant parts, which are frequently hit by somatic mutations in PCa, of PI3K-Akt/RAS-MAPK/mTOR signaling pathways. (4) The expression profiles of the top significant PRS genes in tumor samples were capable of predicting malignant PCa relapse after prostatectomy. (5) The transcriptomic differences between African American and EA samples were incompatible with the patterns of the aforementioned associations between PRS and gene expression levels. This study provided unique insights into the relationship between PRS and the molecular mechanisms of carcinogenesis in prostate. The new findings, alongside the moderate but significant heritability of PCa susceptibility contributed by the risk variants, suggest the aptness and inaptness of PRS for explaining PCa and disparities.

Transforming Agriculture through Nanotechnology: A Comprehensive Overview

Nanotechnology has emerged as a transformative force in agriculture, offering innovative solutions to address critical challenges in food production, sustainability, and resource management. This comprehensive overview explores the multifaceted impact of nanotechnology on agriculture, providing insights into its potential to revolutionize the sector and by elucidating the fundamental principles of nanotechnology and its applicability in agriculture, emphasizing nanomaterials’ unique properties that enable precise manipulation at the molecular and nanoscale levels. It explores diverse applications, including nanoparticle-based nutrient delivery systems, nanoencapsulation for controlled release of agrochemicals, and the development of nanosensors for real-time monitoring of crop health and environmental parameters. Furthermore, this delves into the emerging field of precision farming enabled by nanotechnology, where data-driven decision-making and targeted interventions optimize resource utilization, minimize environmental impacts, and maximize crop yields. It examines the potential of nano pesticides in integrated pest management, highlighting their eco-friendly nature and reduced environmental contamination. Nanotechnology’s role in soil management and remediation is also discussed, showcasing its capacity to improve soil health, remediate contaminated lands, and enhance nutrient availability. The review sheds light on the application of nanofertilizers, which not only enhance nutrient use efficiency but also mitigate nutrient runoff, contributing to sustainable agriculture. While nanotechnology holds immense promise, it is imperative to consider safety and environmental implications. This examines the challenges and regulatory considerations surrounding the use of nanomaterials in agriculture, emphasizing the need for responsible development and rigorous risk assessment.

Genetic parameters, genetic trends and selection response for gestation length and traits used as selection criteria in Angus breed in Brazil

Context The knowledge of the genetic variability of gestation length and its correlations with other traits is relevant for selection decisions in beef cattle. Aims Genetic parameters and trends were estimated for gestation length (first (GL1), repeated measures range of 1–6 (GL)) and traits currently used as selection criteria (birth weight (BW), weight gain from birth to weaning (BWG), weight gain from weaning to yearling (WYG), scrotal circumference (SC), score of conformation (YC), score of precocity (YP), and score of muscling (YM)) in Brazilian Angus cattle. In addition, direct and correlated selection responses were predicted. Methods A series of single- and two-trait Bayesian analyses were performed on beef cattle data from 14 farms across different regions of Brazil, by using linear and threshold animal models. Key results A moderate heritability was estimated for GL1 (0.356 ± 0.058); however, the estimate for GL was low (0.189 ± 0.028) as was that for repeatability (0.204 ± 0.027). Lower accuracies of breeding values were obtained for GL than for GL1, ranging from 0.490 ± 0.161 to 0.687 ± 0.037. Direct heritability estimates for growth and body composition traits were low, except for SC and BWG (0.301 ± 0.060 and 0.241 ± 0.019 respectively). Genetic correlations of 0.558 ± 0.121 and 0.739 ± 0.131 were estimated between GL1 and BW, and between GL and BW respectively. The other traits studied were estimated to have weak or near-zero genetic correlations with gestation length traits. Positive and moderate genetic associations were estimated between BW and BWG, SC, and visual scores (ranging from 0.338 ± 0.095 to 0.458 ± 0.092), but a near-zero estimate was obtained with WYG (0.127 ± 0.150). Weight gains were more highly genetically correlated with visual scores than between themselves (BWG and WYG) and with SC. The SC was highly genetically correlated with visual scores (0.684 ± 0.054 to 0.714 ± 0.050). Genetic trends showed that all traits studied have been changing in a positive direction, being unfavourable for BW and GL. Higher genetic gains were expected from using direct selection than from using indirect selection for GL1. Conclusions Rapid growth is genetically associated with superior conformation, precocity and musculature, as well as a large scrotal circumference in males. However, selection decisions that heavily focus on these traits are likely to lead to more calving difficulties in the longer term. Implications Selection indices should incorporate traits that measure calving difficulty directly if relevant records are available. Currently, considering its practical implications in primiparous anoestrus, the first-gestation length could serve as a viable alternative for inclusion in selection indices. Due to the low repeatability of the gestation length, decisions to cull on the basis of only one or two records of GL are highly inaccurate.

Genetic analysis of first lactation and lifetime performancetraits in composite Vrindavani cattle: important considerations for higher milk production.

The present study was aimed to evaluate the influence ofnon-genetic factors on several first lactation and lifetime performance traits and elucidate their genetic parameters in an organized Vrindavani cattle population.Data on eight first-lactation and thirteen lifetime traits were collected on 2400 cows with pedigree records that werereared during33-year period (1989-2021). The first-lactation traits included age at first calving (AFC), total milk yield (FTMY), standard milk yield (FSMY305), peak yield (FPY), lactation length (FLL), dry period (FDP), service period (FSP) and calving interval (FCI). Whereas, the lifetime traits mainly included total lifetime milk yield (TLMY), total standard milk yield (TSMY), number of lactations completed (NL), total lactation length (TLL), herd life (HL), productive life (PL), average milk yield per day of herd life (TLMY/HL), average milk yield per day of productive life (TLMY/PL), average milk yield per day of productive life (TLMY/TLL). Other lifetime production traits included average service period (ASP), average dry period (ADP), average calving interval (ACI) and unproductive days (UD).The heritability estimates of first-lactation traits ranged between 0.026 and 0.228and were found to be low for AFC (0.180 ± 0.042), FCI (0.191 ± 0.125), FSMY305 (0.145 ± 0.061), FTMY (0.165 ± 0.048), FDP (0.052 ± 0.049) and FSP (0.026 ± 0.033); however, FLL (0.229 ± 0.044) and FPY (0.202 ± 0.046) showed moderate heritability. Positive phenotypic correlation (p < 0.001) was revealed among FTMY, TLMY, TLL, HL and PL. The AFC produced a significant effect (p < 0.05) on several traits i,e, TLL, TLMY/HL, FSMY305, FPY, TLMY, HL and TLMY/PL.Lower AFC was associated with higher TLMY, TLL and TLMY/HL; while FSMY305, FPY, HL and TLMY/PL were higher in heifers that calved late in their life. The results revealed that AFCmay be optimized with first lactation and lifetime traits for this population.

Genetic parameters for host-response to acanthocephaliasis caused by the endoparasite Neoechinorhynchus buttnerae in the Amazon fish Colossoma macropomum

Tambaqui (Colossoma macropomum) is the main native fish produced by Amazon aquaculture. However, the production chain of this fish has been significantly affected by acanthocephaliasis, caused by the endoparasite Neoechinorhynchus buttnerae. The selection of superior genotypes for resistance and resilience to acanthocephaliasis is a fundamental approach to improve production in the context of environmental sustainability and food security. Thus, the objectives of this study were to 1) conduct an experimental challenge against the endoparasite N. buttnerae in tambaqui, and 2) determine the genetic parameters of disease traits caused by N. buttnerae in an experimental breeding population of tambaqui. Estimation of genetic parameters was performed using a genomic relationship matrix (SNPs data) obtained from an experimental challenge performed in 70 full-sib families. The experimental challenge was successfully performed in three replicate tanks, using the parasite eggs in the ichthyoplankton as source for a natural route of infection, which in turn was induced through oral filtration the plankton. The total gain in body weight of all individuals was measured during the infestation period, as a measure of Resilience (RSF) and averaged 42 g (SD = 21.8). The average parasite abundance per animal at the end of the challenge period, indicating Resistance (RTCT), was about 205.2 parasites (SD = 178.6). The heritability estimates for these traits ranged from 0.17 ± 0.04 to 0.20 ± 0.04, indicating the presence of low to moderate heritability levels for host response against N. buttnerae in tambaqui. Genetic correlations between resistance and resilience traits were consistently negative (favorable) and statistically significant, ranging from −0.512 ± 0.134 to −0.252 ± 0.166. These results suggest the possibility of selecting animals for both resistance and resilience simultaneously. The significant genetic variation found for N. buttnerae resistance and favorable genetic correlations with resilience in tambaqui indicated that selecting superior genotypes is a viable approach to reduce the impact of acanthocephaliasis disease in aquaculture.

Genetic variation and trait association of fine rice genotypes

To explore high yielding genotype and significant yield contributing trait, field experiment was conducted using alpha lattice design replicated three times at the National Wheat Research Program (NWRP), Bhairahawa, Nepal in 2022. Eighteen fine rice genotypes were evaluated based on nine quantitative traits (Heading days, maturity days, plant height, panicle length, effective tillers, filled grains per panicle, unfilled grains per panicle, thousand grain weight and grain yield per hectare). Variance analysis, correlation and estimation of genetic parameters were conducted to comprehend genetic variations and interrelationships among traits within genotypes. The results showed most of traits except unfilled grains had statistical significance differences. Tarahara-107 (3940 kg/ha) had the highest grain yield followed by Tarahara-2 (3700 kg/ha) and NR 2381-RGA1-RGA2 (3665 kg/ha). Similarly, grain yield showed positive and significant association with filled grains at both phenotypic and genotypic level (rp = 0.7074 ** and rg= 0.9482 **). Elevated values of PCV and GCV were recorded for filled grains (22.05 and 17.57). The high value GAM coupled with high heritability was recorded for filled grains (28.83%), plant height (23.10%), number of effective tillers (21.57%) and thousand grain weight (19.37%). Thus, identified genotypes NR 2380-RGA1-RGA2 and NR 2381-RGA1-RGA2 exhibited early and potential high yielding genotypes while Tarhara-107 and Tarhara-2 identified as high yield, medium maturity and good filled grain number per panicle. In addition, filled grains trait displayed tightly linked with grain yield and possess high GCV, PCV, GAM with moderate heritability indicated direct selection could be employed for trait enhancement in breeding program.

Plastic and genomic change of a newly established lizard population following a founder event.

Understanding how phenotypic divergence arises among natural populations remains one of the major goals in evolutionary biology. As part of competitive exclusion experiment conducted in 1971, 10 individuals of Italian wall lizard (Podarcis siculus (Rafinesque-Schmaltz, 1810)) were transplanted from Pod Kopište Island to the nearby island of Pod Mrčaru (Adriatic Sea). Merely 35 years after the introduction, the newly established population on Pod Mrčaru Island had shifted their diet from predominantly insectivorous towards omnivorous and changed significantly in a range of morphological, behavioural, physiological and ecological characteristics. Here, we combine genomic and quantitative genetic approaches to determine the relative roles of genetic adaptation and phenotypic plasticity in driving this rapid phenotypic shift. Our results show genome-wide genetic differentiation between ancestral and transplanted population, with weak genetic erosion on Pod Mrčaru Island. Adaptive processes following the founder event are indicated by highly differentiated genomic loci associating with ecologically relevant phenotypic traits, and/or having a putatively adaptive role across multiple lizard populations. Diverged traits related to head size and shape or bite force showed moderate heritability in a crossing experiment, but between-population differences in these traits did not persist in a common garden environment. Our results confirm the existence of sufficient additive genetic variance for traits to evolve under selection while also demonstrating that phenotypic plasticity and/or genotype by environment interactions are the main drivers of population differentiation at this early evolutionary stage.

BIODEMOGRAPHY OF AGING: INSIGHTS FROM TWINS AND THE OLDEST-OLD IN DENMARK

Abstract The Danish Twin Registry holds health information from surveys and registers on more than 180,000 twins born in Denmark since 1870. Life course studies of the oldest twin cohorts show moderate heritability of lifespan but a substantial genetic influence on physical and cognitive functioning throughout life, i.e., twins are growing old but not growing apart, in terms of health phenotypes. Twins experience substantial growth restriction in the last intrauterine trimester. The generalizability of aging studies of twins hinges on whether this early life exposure has long-lasting health consequences. Generally, after the infant period, twin-singleton health differences are small, and during the 20th century, they have vanished. In the older twin cohorts, sex differences in the association between number of offspring and oral health late in life provided support for the proverb known in many countries: “A tooth per child”. Twin studies of biomarkers of aging revealed that perceived age estimated by lay assessors based on photos is a strong biomarker of aging. The 1895, 1905, 1910 and 1915 Danish Birth Cohort Studies of the oldest old were established to study secular trends in the health and functioning of the very old. Among the main findings of the studies are: Exceptional longevity does not lead to exceptional levels of disability; summed over cohorts, more people are living to the highest ages and are functioning better – and this progress is seen across the spectrum of health and functioning – offering hope for continued progress in health and survival among the oldest in society.

Genetic Analysis of Diallel Crosses of Rapeseed (B. rapa) for Screening High Temperature Tolerant Genotypes under Phytotron Facility and Late Field Sown Condition

High temperature tolerance is assuming importance in breeding rapeseed-mustard. In the present investigation attempt was made to study genetic variation for traits in response to high temperature and screened during flowering to pod formation stage. Populations of diallel crosses involving three yellow sarson and two toria varieties were used in this study. The diallel populations were exposed to high temperature at National Phytotron Facility, IARI, New Delhi and also grown in late sown field conditions which generally experience high temperature terminal stress. The temperature treatment was given only to the crosses as the parents did not come to flowering in the normal growth chamber. B9 x Jeuti, B9 x TS46, YSH401 x Jeuti and NRCYS05-03 x Jeuti were found to be promising for yield attributes under phytotron facility. In field experiments, Jeuti, B9 x NRCYS05-03, B9 x YSH401, B9 x Jeuti, NRCYS05-03 x Jeuti, YSH401 x Jeuti and YSH401 x NRCYS05-03 were found promising for seed yield and its attributes. Main shoot length, siliquae on main shoot, seeds per siliqua, percent flower drop, siliqua density and biological yield per plant showed high to moderate heritability with high genetic advance.

Genetic and environmental influences on alpha amylase stress reactivity and shared genetic covariation with cortisol

Salivary alpha amylase (sAA) is a common measure of stress reactivity, primarily reflecting sympathetic nervous system activity. Salivary cortisol is also a reliable, frequently used biomarker of stress and reflects the hypothalamic-pituitary-adrenal (HPA) axis response. This study examined heritability across varying metrics of sAA in response to a social evaluative stressor, the Trier Social Stress Test (TSST). The goal of this study was to estimate genetic and environmental influences on measurements of sAA stress reactivity. Moreover, we evaluated the shared genetic covariation between sAA and cortisol. Participants included twins aged 15–20 years (54% female). We measured alpha amylase and cortisol reactivity to the TSST via serial salivary cortisol samples collected pre- and post-TSST. Modest to moderate heritability estimates (11–64%) were observed across measures purported to capture alpha amylase stress reactivity (peak, area under the curve, baseline-to-peak change). Findings also indicate that sAA baseline and peak are primarily influenced by a shared genetic factor. There was no evidence of shared genetic influences between sAA and cortisol. These findings suggest the genetic control of the HPA and Sympathetic Adreno-Medullar axis are genetically independent of one another despite both playing a role in response to stressors.

Genetic selection for reduced parasite load in Atlantic salmon: Zero-sum game or a tool for group-level protection against sea lice?

Sea lice are copepod ectoparasites of major importance in salmonid aquaculture. Under controlled challenge testing, individual lice count has moderate heritability and has been suggested as a trait in genetic selection for parasite control, under the assumption that selection for reduced individual parasite burden provides group-level protection against the parasite. Recent studies indicate that genetic variation of lice count in Atlantic salmon is mostly explained by variation in initial infestation, rather than ability to limit parasite burden after infestation. Results from a selection experiment are presented, with two Atlantic salmon (Salmo salar) lines divergently selected for low/high parasite burden, showing substantial between-strain difference under common-garden testing. An experiment was performed where the final generation of the divergently selected salmon lines were challenge tested separately to assess potential for group-level protection against sea lice. The results showed that, despite the two groups being clearly different under common garden testing, the line difference was not significant when tested separately, i.e., no evidence for group-level protection. However, in a follow-up experiment, using a more realistic lice challenge model under water-flow, expected to be less favorable for the parasite, significant group-level differences were found, albeit smaller than under common garden testing. The results show that the potential for group-level protection is lower than suggested by within-group genetic variation in lice count, and more so for environments giving the parasites easy access to hosts. These results cast some doubt about the efficacy of selective breeding for reduced lice count as a tool for group-level parasite control in densely populated fish farm environments.