The success in competitions may be stressful for animals and costly in terms of immune functions and longevity. Focusing on Aosta Chestnut and Aosta Black Pied cattle, selected for their fighting ability in traditional competitions, this study investigated the genetic relationships of fighting ability with udder health traits (somatic cell score and two threshold traits for somatic cells), longevity (length of productive life and number of calvings) and test-day milk, fat and protein yield. Herdbook information and phenotypic records that have been routinely collected for breeding programs in 16 years were used for the abovementioned traits. Data belonged to 9328 cows and 19 283 animals in pedigree. Single-trait animal model analyses were run using a Gibbs sampling algorithm to estimate the variance components of traits, and bivariate analyses were then performed to estimate the genetic correlations. Moderate positive genetic correlations (ra) were found for fighting ability with somatic cell score (ra=0.255), suggesting that greater fighting ability is genetically related to a detriment in udder health, in agreement with the theory. The high positive genetic correlation between fighting ability and longevity (average ra=0.669) suggests that the economic importance of fighting ability (the winning cows get an higher price at selling) had probably masked the true genetic covariances. The genetic correlation between milk yield traits and fighting ability showed large intervals, but the negative values (average ra=−0.121) agreed with previous research. This study is one of the few empirical studies on genetic correlations for the competitive success v. immune functions and longevity traits. The knowledge of the genetic correlations among productive and functional traits of interest, including fighting ability, is important in animal breeding for a sustainable genetic improvement.

We report on how a long-term study of the reproductive biology of the Critically Endangered Schiedea adamantis (Caryophyllaceae), one of Hawai‘i's rarest plant species, was leveraged for conservation purposes. Our major goals were to provide seeds with the greatest genetic variation possible for reintroduction and to ensure that both female and hermaphroditic plants of this wind-pollinated species were reintroduced in a manner that maximized both outcrossing and seed production. Schiedea adamantis was one of the first Hawaiian plant species listed under the Endangered Species Act (USA). The species has been studied intensively to test hypotheses addressing the evolution of breeding systems. Information on outcrossing levels and the extent of inbreeding depression was integrated into ongoing reintroduction efforts. Population size peaked in 1994, when 267 flowering individuals were found on Lē‘ahi (Diamond Head Crater). By 2016 only 17 flowering individuals were present, with drought and invasive species being possible causes of this decline. Reintroduction attempts in 1998 using genetically diverse seeds were unsuccessful because of drought and a lack of sufficient supplemental irrigation. Additional reintroduction attempts in 2012 and 2014 were more successful because of increased supplemental irrigation. Plants used in reintroductions represent genotypes long since absent in the natural population, and may contain the genetic variability essential for evolutionary responses to climate change and the spread of invasive species. The destruction of many plants reintroduced in 2015 and 2016 by a fire in March 2016 highlights the need for additional restoration areas at Lē‘ahi and elsewhere, and storage of seeds for future use.

In farmed fish, selective breeding for feed conversion ratio (FCR) may be possible via indirectly selecting for easily-measured indicator traits correlated with FCR. We tested the hypothesis that rainbow trout with low lipid% have genetically better FCR, and that lipid% may be genetically related to retention efficiency of macronutrients, making lipid% a useful indicator trait. A quantitative genetic analysis was used to quantify the benefit of replacing feed intake in a selection index with one of three lipid traits: body lipid%, muscle lipid% or viscera% weight of total body weight (reflecting visceral lipid). The index theory calculations showed that simultaneous selection for weight gain and against feed intake (direct selection to improve FCR) increased the expected genetic response in FCR by 1·50-fold compared with the sole selection for growth. Replacing feed intake in the selection index with body lipid%, muscle lipid% or viscera% increased genetic response in FCR by 1·29-, 1·49- and 1·02-fold, respectively, compared with the sole selection for growth. Consequently, indirect selection for weight gain and against muscle lipid% was almost as effective as direct selection for FCR. Fish with genetically low body and muscle lipid% were more efficient in turning ingested protein into protein weight gain. Both physiological and genetic mechanisms promote the hypothesis that low-lipid% fish are more efficient. These results highlight that in breeding programmes of rainbow trout, control of lipid deposition improves not only FCR but also protein-retention efficiency. This improves resource efficiency of aquaculture and reduces nutrient load to the environment.

Complex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

The 20th Century saw an astonishing advance in our understanding of genetics and the scientific basis of the genetic improvement of farm animals. The application of genetic principles to chickens in the 1950s and 1960s led to a rapid change in the productivity and efficiency of laying hens and broiler chickens, turkeys and ducks. Subsequently, the application of increasingly powerful computers and sophisticated mathematical algorithms has increased the range of traits that could be successfully incorporated into breeding programs. Random sample tests of the performance of laying hens enjoyed a period of popularity and more recently the few remaining tests included husbandry systems in addition to strain evaluation. Characterisation of avian blood groups has led to the identification of the B21 haplotype that confers resistance to Marek's disease and to selection for this locus in commercial lines. The decade following the millennium saw the publication of the genome sequence of the chicken and the identification of millions of single nucleotide polymorphisms that, coupled with technological advances, made the application of whole genome selection practical in poultry. In parallel, the molecular basis for some Mendelian traits described a century ago is now being deciphered. Similar technologies have been applied to study genetic diversity in chickens and have provided insights into the evolution and domestication of chicken breeds. Finally, in this review, the recent development of the European Poultry Genetics Symposia coordinated by Working Group 3 ‘Genetics and Breeding’ that was based on combining the British Poultry Breeders Round Table and AVIAGEN from West and Eastern Europe, is discussed.

Subcutaneous fat from Norwegian Landrace (n = 3230) and Duroc (n = 1769) pigs was sampled to investigate the sources of variation and genetic parameters of various fatty acids, fat moisture percentage and fat colour, with the lean meat percentage (LMP) also included as a trait representing the leanness of the pig. The pigs were from half-sib groups of station-tested boars included in the Norwegian pig breeding scheme. They were fed ad libitum to obtain an average of 113 kg live weight. Near-infrared spectroscopy (NIRS) was applied for prediction of the fatty acids and fat moisture percentage, and Minolta was used for the fat colour measurements. Heritabilities and genetic correlations were estimated with a multi-trait animal model using average information-restricted maximum likelihood (AI-REML) methodology. Fat from Landrace pigs had considerably more monounsaturated fatty acids, polyunsaturated fatty acids (PUFAs) and fat moisture, as well as less saturated fatty acids (SFAs) than fat from Duroc pigs. The heritability estimates (s.e. 0.03 to 0.08) for the various fatty acids were as follows: Palmitic, C16:0 (0.39 and 0.51 for Landrace and Duroc pigs, respectively); Palmitoleic, C16:1n-7 (0.41 and 0.50); Steric, C18:0 (0.46 and 0.54); Oleic, C18:1n-9 (0.67 and 0.57); Linoleic, C18:2n-6 (0.44 and 0.46); α-linolenic, C18:3n-3 (0.37 and 0.25) and n-6/n-3 ratio (0.06 and 0.01). The other fat quality traits revealed the following heritabilities: fat moisture (0.28 and 0.33), colour values in subcutaneous fat: L* (whiteness; 0.22 and 0.21), a* (redness; 0.13 and 0.24) and b* (yellowness; 0.07 and 0.17) and LMP (0.46 and 0.47). LMP showed high positive genetic correlations to PUFA (C18:2n-6 and C18:3n-3), which implies that selecting leaner pigs changes the fatty acid composition and deteriorates the quality of fat. Higher concentrations of PUFA are not beneficial as the ratio of n-6 and n-3 fatty acids becomes unfavourably high. Owing to the high genetic correlation between C18:2n-6 and C18:3n-3 and a low heritability for this ratio, the latter is difficult to change through selection. However, a small reduction in the ratio should be expected if selection aims at reducing the level of C18:2n-6. Selection for more C18:1n-9 is possible in view of the genetic parameters, which are favourable for eating quality, technological quality and human nutrition. The NIRS technology and the high heritabilities found in this study make it possible to implement fat quality traits to achieve the breeding goal in the selection of a lean pig with better fat quality.

Species of Echinococcus (Cestoda: Taeniidae) require 2 mammalian hosts to complete their life-cycle; a carnivorous definitive host, and a herbivorous or omnivorous intermediate host. For most species of Echinococcus, the definitive host range is restricted to 1 or a few species, but the intermediate host range is very broad. Programmes to control hydatid disease attempt to break the life-cycle of the parasite and their effectiveness is therefore enhanced by an understanding of local patterns of transmission. Although it is known that the rostellar hooks of protoscoleces may be influenced by the species of intermediate host in which they develop, the application of this knowledge to infer transmission cycles has been limited, because the intermediate host effect has not been isolated from other environmental and genetic components of phenotypic variance. This study presents a method for separating these potentially confounding genetic and environmental effects, by combining quantitative genetic analyses of hook traits with data on population structure from neutral genetic markers. The method was applied to 5 hook traits (hook number, total length of large hooks, blade length of large hooks, total length of small hooks, blade length of small hooks) measured on protoscoleces from 2 intermediate host types (sheep and macropod marsupials) in Australia. Although genetic variance was similar for all traits, they differed markedly in the extent of environmental variance attributed to development in different host types. Total length of small hooks was the trait most affected, with 49–60% of phenotypic variance being explained by environmental differences between intermediate host species. Blade length of small hooks was least affected, with none of the phenotypic variance due to intermediate host origin. These data suggest that hook measurements of adult worms from naturally infected definitive hosts could be used to determine the intermediate host species from which infection was acquired, if the appropriate traits are measured.

The genetic and environmental effects on the levels of 17 serum biochemical quantitative traits (calcium, phosphorus, glucose, urea nitrogen, uric acid, total protein, albumin, total bilirubin, alkaline phosphatase, lactate dehydrogenase (LDH), glutamic-oxaloacetic transaminase (SGOT), total lipid, cholesterol, triglyceride, α-lipoprotein, pre-β-lipoprotein and β-lipoprotein) were estimated in 105 pairs of healthy twins of both sexes (57 MZ and 48 DZ) by path analysis. The genotype effect was significant for all traits (P < 0.001) and its value extended from 0.52 (α-lipoprotein) to 0.81 (alkaline phosphatase), whereas environmental effect was significant (P < 0.05) in only 10 traits of the 17 analyzed, with the maximum value of 0.13 (cholesterol). Correlations between genotypes of paired traits were estimated and, of 136 values, 47 were significant at the 5% levels, thus indicating partial and common genetic mechanisms.

We study the situation in which individuals occur in ‘families' or similar groups, individuals within a ‘family' being correlated with one another, as for example a biological population. In such a population, the number of individuals will usually vary from one family to another. We assume that a sample chosen from the population consists of whole families rather than unrelated individuals. A similar situation might occur in experimental design, if individuals occur in ‘blocks' (of varying sizes) within which they share a common environment. In the simplest case considered here two measurements are made on each individual, namely y, the character of interest, and x (not necessarily a random variable), some other character which is believed to influence y. We discuss how to estimate the regression of y on x, and the within and between family variance components for y (and hence the intrafamily correlation) when the effect of x is eliminated. Generalizations of this are briefly discussed.