Evolutionary processes and its environmental correlates in the cranial morphology of western chipmunks (Tamias).

The importance of the environment in shaping phenotypic evolution lies at the core of evolutionary biology. Chipmunks of the genus Tamias (subgenus Neotamias) are part of a very recent radiation, occupying a wide range of environments with marked niche partitioning among species. One open question is if and how those differences in environments affected phenotypic evolution in this lineage. Herein we examine the relative importance of genetic drift versus natural selection in the origin of cranial diversity exhibited by clade members. We also explore the degree to which variation in potential selective agents (environmental variables) are correlated with the patterns of morphological variation presented. We found that genetic drift cannot explain morphological diversification in the group, thus supporting the potential role of natural selection as the predominant evolutionary force during Neotamias cranial diversification, although the strength of selection varied greatly among species. This morphological diversification, in turn, was correlated with environmental conditions, suggesting a possible causal relationship. These results underscore that extant Neotamias represent a radiation in which aspects of the environment might have acted as the selective force driving species' divergence

Genetic analysis of rennet coagulation time, curd-firming rate, and curd firmness assessed over an extended testing period using mechanical and near-infrared instruments

Abstract The aims of this study were (1) to analyze rennet coagulation time (RCT), curd-firming rate, and curd firmness obtained by extending the standard 30-min testing time to 45min; (2) to estimate heritabilities of the aforementioned traits determined by mechanical (Formagraph; Foss Electric, Hillerod, Denmark) and near-infrared optical (Optigraph; Ysebaert, Frepillon, France) instruments, and to assess the statistical relevance of their genetic background by using the Bayes factor procedure, the deviance information criterion, and the mean squared error; (3) to estimate phenotypic and genetic relationships between instruments within trait and between traits within instrument; and (4) to obtain correlations for sire rankings based on the used instruments. Individual milk samples were collected from 913 Brown Swiss cows reared in 63 herds located in Trento Province (Italy). Milk coagulation properties (MCP) were measured using 2 different instruments: Formagraph and Optigraph. Both instruments were housed in the same laboratory and operated by the same technician. Each sample was analyzed simultaneously on each instrument. All experimental conditions (milk temperature and the concentration and type of rennet) were identical. For the analysis, univariate and bivariate animal models were implemented using Bayesian methods. Univariate analyses were conducted to test the hypothesis that the traits showed additive genetic determination. Deviance information criterion, Bayes factor, and mean squared error were used as model choice criteria. The main results were that (1) RCT could be measured on all samples by extending the observation time to 45min, and its genetic parameters ( h 2 =0.23) and breeding values could be estimated while avoiding the bias of noncoagulating samples; (2) curd-firming rate could be measured on almost all milk samples, and its genetic parameters could be estimated for the first time on a field data set ( h 2 =0.21); (3) for the first time, genetic parameters of curd firmness 45min after rennet addition ( h 2 =0.12) were estimated, and they were compared with curd firmness 30min after rennet addition ( h 2 =0.17); and (4) MCP estimated using the Optigraph appeared to be genetically different from those determined by Formagraph, with the partial exception of RCT (genetic correlation=0.97). Breeding strategies for the improvement of MCP must be planned with caution. Currently, the high throughput, ease of use, and reduced costs of analysis make predictions obtained from mid-infrared spectroscopy (MIRS) on untreated milk samples a promising alternative to produce relevant data at the population level. The use of mechanical lactodynamographs to establish reference data for MIRS calibrations have been already studied, whereas the use of near-infrared optical lactodynamographs as a reference method for MIRS calibrations needs to be investigated

Genetic parameters for casein and urea content in the Italian Brown Swiss dairy cattle

A total of 137,753 test day records of 20,745 Italian Brown Swiss dairy cows from 26 provinces of Italy were used to estimate heritability for casein and urea content in milk and their genetic correlations with other production traits and milk somatic cell score. Milk component values were obtained by Fourier Transformed Infrared (IR) Spectroscopy from milk samples collected during national routine recording and were analysed using test day repeatability animal models. Fixed effects included 1,001 levels of herd-test date, 15 classes of days in milk, and 13 classes of age at calving within parity. The variation among cows was large for most of the traits. The heritability value for casein content was 0.31, as for protein content, and genetic and phenotypic correlations between these two traits were large (0.99 and 0.97 respectively). Milk urea content had a heritability of 0.17 and a positive genetic relationship with fat (0.12), null with protein (0.03) and casein (0.002) content and a negative genetic correlation with milk yield (-0.17) suggesting that the genetic improvement for milk urea content would be possible, but genetic gain would be affected by other traits included as selection criteria in the economic index and by their relative economic emphasis

Genetic parameters and selection for casein content in Italian Holstein and Brown Swiss.

A total of more than 2,000,000 records on casein contents were collected in Lombardia (Italy) during routine milk recording of Italian Holstein and Brown Swiss dairy cows. Variance components for casein were estimated as well as all the genetic correlations of casein with production and type traits considered in selection. According to the heritabilities estimated (12.4% for Brown and 9.36% for Holstein), breeding values were calculated for bulls and compared to the breeding values for total protein. The results of two different selection scenarios were compared for each breed when including protein or casein as selection criterion. Genetic progress expected for all traits selected were compared after 10 years of selection. The genetic variability of casein allows the use of this trait as selection criterion with the estimation of breeding values and its inclusion in selection indexes. Ranking of breeding values for casein and protein are very similar in both breeds. But some differences in genetic values for casein exist for the same level of breeding value for protein. Nevertheless results in genetic gain differ between breeds depending mainly on genetic correlations with the other traits selected. The positive results in selection response estimated for several traits suggest to the Brown Swiss Association the replacement of protein selection with casein. In contrast the smaller effects estimated for the Italian Holstein suggest to wait for more casein data collected before any change in selection program

Genetic relationships among grapevine cultivars grown in Oltrepò Pavese (Italy)

In order to evaluate the genetic distance among 47 grapevine accessions, including major and minor local cultivars grown in Oltrepò pavese (Pavia, Italy), DNA has been analysed with the AFLP approach (VOS et al. 1995). The electrophoretic analysis of the products amplified by 3 primer combinations showed high polymorphism.Furthermore, considering that DNA markers for haploid, uniparentally inherited genomes, such as the chloroplast DNA, are important indicators of pedigree, CpSSR analysis was also performed and this identified cases of maternal common origin among the analysed cultivars. The results show that these molecular tools allow univocal genotype identification and that the analysed germplasm has a wide genetic dissimilarity. Results are coherent with the postulation of a polycentric origin for the Oltrepò pavese cultivars and of a multiple varietal flow from different viticultural regions. The molecular information gathered in this research is essential for the establishment of an appropriate presentation programme of autochthonous varieties

Molecular approach to assess the origin of cv. Marzemino

DNA marker analysis was used to determine the varietal identity of Marzemino accessions in public collections and private Italian vineyards; relationships among this varietal group and Vertzami, a traditional Greek cultivar, were also investigated through SSR and AFLP approaches. Molecular results strongly support the relationship among Vertzami cultivars growing in Greece, Marzemino and several Italian accessions selected on the basis of etymological similarity. SSR data exclude a direct descent of Marzemino, or other related Italian varieties, from Vertzami; on the other hand the level of similarity among Vertzami, Marzemino and some related varieties indicates a possible common ancestor. None of the accessions is considered as common ancestor but on the basis of genomic variability in the Marzemino group and of the relationships with the other Italian cultivars a probable Italian ancestor is supposed.