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Eggshell Strength (eggshell + strength)
Selected AbstractsThe evolution of host-specific variation in cuckoo eggshell strengthJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 8 2010C. N. SPOTTISWOODE Abstract Cuckoo eggs are renowned for their mimicry of different host species, leading to the evolution of host-specific races (or ,gentes') defined by egg colour and pattern. This study aims to test the prediction that another property of parasitic eggs, namely shell strength, might also have experienced divergent selection within cuckoo species. Host races of the common cuckoo Cuculus canorus encountering stronger host rejection have thicker-shelled eggs than those parasitising less discriminating species, as expected if egg strengthening discourages host rejection. Moreover, in the diederik cuckoo Chrysococcyx caprius, eggshell thickness was correlated across cuckoo gentes and host species, as expected if eggshell strength has been involved in coevolutionary interactions. This is the first report of host-specific differences in cuckoo egg properties other than colour and pattern and lends correlational support to the hypothesis that the strong eggshells of brood parasites are an adaptation to reduce host rejection. [source] Association between ovocalyxin-32 gene haplotypes and eggshell quality traits in an F2 intercross between two chicken lines divergently selected for eggshell strengthANIMAL GENETICS, Issue 5 2010H. Takahashi Summary Broken and cracked eggshells contribute significantly to economic losses in the egg production industry. We previously identified ovocalyxin-32 as a potential gene influencing eggshell traits, by analysing an intercross between two parent lines developed from the same founder population by a two-way selection for eggshell strength with non-destructive deformation (DEF) conducted over 14 generations. We determined the nucleotide sequences of six ovocalyxin-32 exons in the parent individuals and analysed the association between ovocalyxin-32 and eggshell traits in the F2 individuals. We identified three haplotypes (W, M and S) of ovocalyxin-32 in the parent individuals. A mismatch amplification mutation assay was performed to distinguish six diplotype individuals (WW, MM, SS, WM, MS and WS) in the F2 population. The egg weight (EW) of SS-diplotype individuals was significantly higher than that of WW-, WM- and WS-diplotypes. Short length of the egg (SLE) of SS-diplotype individuals was significantly higher than that of WW-, WM- and MS-diplotypes. Long length of the egg (LLE) of SS-diplotype individuals was significantly higher than that of WM- and WS-diplotypes. DEF of WW-diplotype individuals was significantly higher than that of SS-, WM, MS and WM-diplotypes. Haplotypic effect analyses showed significant differences between the W-haplotype and the S-haplotypes in the EW, SLE, LLE and DEF. The DEF of M-haplotype was significantly lower than that of W- and S-haplotypes. These results suggest that S- and M-haplotypes are critical for high quality of eggshells in the F2 population. In conclusion, ovocalyxin-32 is a useful marker of eggshell traits and can be used to develop strategies for improving eggshell traits in commercial layer houses. [source] Mapping of quantitative trait loci affecting eggshell quality on chromosome 9 in an F2 intercross between two chicken lines divergently selected for eggshell strengthANIMAL GENETICS, Issue 5 2009H. Takahashi Summary Broken and cracked eggshells are major causes of significant economic losses to the egg production industry. The quantitative trait loci (QTL) on chromosome 9 influencing the quality of eggshells were identified by analysing an intercross between two parent lines developed from the same founder population by a two-way selection for eggshell strength with non-destructive deformation conducted over 14 generations. Chromosome-wide highly significant (P < 0.01) QTL associated with egg weight (EW), short length of egg (SLE), long length of egg (LLE) and eggshell weight were mapped to the distal region of chromosome 9. Among the QTL affecting EW, SLE and LLE, ovocalyxin-32 was identified as a potential candidate gene influencing eggshell traits. Marker-assisted selection based on these QTL could be used to develop strategies for reducing the breakage and cracking of eggs in commercial layer houses. [source] | ||||||||||