The genetics of the rumpless fowl with evidence of a case of changing dominance

Dunn, L. C.; Landauer, Walter

doi:10.1007/bf02982198

Cited by 41 publications

(21 citation statements)

References 10 publications

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“…We are aware of objections to Fisher's hypothesis for the evolution of dominance in the context of natural populations, but we speculate that these objections do not apply to maize populations in which stringent artificial selection has been practiced. The modification, by selection, of the level or direction of dominance has been shown in Drosophila (Helfer 1939), poultry (Dunn and Landauer 1934), cotton (Gossypium spp., Harland 1936) and different moth species (Ford 1940;Kettlewell 1965). On the other hand, we note that true overdominance for grain yield in maize contradicts the results of Duvick (1999).…”

Section: Discussionmentioning

confidence: 97%

Genetic basis of heterosis explored by simple sequence repeat markers in a random-mated maize population

2003

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The genetic basis of heterosis in crop plants has not been completely resolved. Our objective in this study was to determine the level of dominance for quantitative trait loci (QTLs) that underlie heterosis in maize (Zea mays L.). An F2 population of an elite maize single cross, LH200 x LH216, was random mated for three generations in an attempt to break up repulsion linkages that might lead to pseudo-overdominance. The population was analyzed with 160 simple-sequence repeat markers. Phenotypic data analyses indicated overdominance for grain yield and partial dominance for plant height, grain moisture and stalk lodging. A total of 28 QTLs were identified for grain yield, 16 for grain moisture, 8 for stalk lodging, and 11 for plant height. For grain yield, 24 QTLs (86%) showed overdominance. In contrast, most of the QTLs for plant height, grain moisture and stalk lodging showed partial to complete dominance. Little epistasis was detected among the QTLs for any of the traits. Our results can be interpreted in one of two ways, or a combination of both: (1) QTLs for grain yield in maize exhibit true overdominance, or (2) QTLs for grain yield show partial to complete dominance, but they are so tightly linked such that three generations of random mating failed to separate their individual effects.

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Section: Discussionmentioning

confidence: 97%

Genetic basis of heterosis explored by simple sequence repeat markers in a random-mated maize population

2003

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“…The haplotype is present in the heterozygous or homozygous state in rumpless birds. All 7 birds with partial tails are heterozygous for the rumpless haplotype and likely represent the intermediate phenotype described by Dunn and Landauer [3]. Because rumpless is dominant and fully penetrant, we further delimited the critical interval by identifying regions of the haplotype shared by tailed birds.…”

Section: Discussionmentioning

confidence: 99%

“…The rumpless phenotype is characterized by the absence of all free caudal vertebrae and the uropygial gland [3] . Without underlying skeletal support, birds with caudal truncation lack a fleshy rump and tail feathers [3] .…”

Section: Introductionmentioning

confidence: 99%

Genome-Wide Association Mapping and Identification of Candidate Genes for the Rumpless and Ear-tufted Traits of the Araucana Chicken

Noorai

Freese²,

Wright³

et al. 2012

PLoS ONE

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Araucana chickens are known for their rounded, tailless rumps and tufted ears. Inheritance studies have shown that the rumpless (Rp) and ear-tufted (Et) loci each act in an autosomal dominant fashion, segregate independently, and are associated with an increased rate of embryonic mortality. To find genomic regions associated with Rp and Et, we generated genome-wide SNP profiles for a diverse population of 60 Araucana chickens using the 60 K chicken SNP BeadChip. Genome-wide association studies using 40 rumpless and 11 tailed birds showed a strong association with rumpless on Gga 2 (P raw = 2.45×10−10, P genome = 0.00575), and analysis of genotypes revealed a 2.14 Mb haplotype shared by all rumpless birds. Within this haplotype, a 0.74 Mb critical interval containing two Iroquois homeobox genes, Irx1 and Irx2, was unique to rumpless Araucana chickens. Irx1 and Irx2 are central for developmental prepatterning, but neither gene is known to have a role in mechanisms leading to caudal development. A second genome-wide association analysis using 30 ear-tufted and 28 non-tufted birds revealed an association with tufted on Gga 15 (P raw = 6.61×10−7, P genome = 0.0981). We identified a 0.58 Mb haplotype common to tufted birds and harboring 7 genes. Because homozygosity for Et is nearly 100% lethal, we employed a heterozygosity mapping approach to prioritize candidate gene selection. A 60 kb region heterozygous in all Araucana chickens contains the complete coding sequence for TBX1 and partial sequence for GNB1L. TBX1 is an important transcriptional regulator of embryonic development and a key genetic determinant of human DiGeorge syndrome. Herein, we describe localization of Rp and Et and identification of positional candidate genes.

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“…Iroquois genes are tied to Notch, Wnt, and Bmp/Shh signaling [ 146 - 148 ], and in addition to their proneural role, they establish tissue borders during development. Interestingly, heterozygotes of the rumpless locus retain 2 to 4 caudal vertebrae, and these are irregularly fused (Figure 8 B) [ 149 , 150 ], adding this mutation to those that cause both short tails and fused vertebrae. The most caudal somites are never generated and the pygostyle, therefore, never forms.…”

Section: Introductionmentioning

confidence: 99%

From dinosaurs to birds: a tail of evolution

Rashid

Chapman

Larsson

et al. 2014

EvoDevo

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A particularly critical event in avian evolution was the transition from long- to short-tailed birds. Primitive bird tails underwent significant alteration, most notably reduction of the number of caudal vertebrae and fusion of the distal caudal vertebrae into an ossified pygostyle. These changes, among others, occurred over a very short evolutionary interval, which brings into focus the underlying mechanisms behind those changes. Despite the wealth of studies delving into avian evolution, virtually nothing is understood about the genetic and developmental events responsible for the emergence of short, fused tails. In this review, we summarize the current understanding of the signaling pathways and morphological events that contribute to tail extension and termination and examine how mutations affecting the genes that control these pathways might influence the evolution of the avian tail. To generate a list of candidate genes that may have been modulated in the transition to short-tailed birds, we analyzed a comprehensive set of mouse mutants. Interestingly, a prevalent pleiotropic effect of mutations that cause fused caudal vertebral bodies (as in the pygostyles of birds) is tail truncation. We identified 23 mutations in this class, and these were primarily restricted to genes involved in axial extension. At least half of the mutations that cause short, fused tails lie in the Notch/Wnt pathway of somite boundary formation or differentiation, leading to changes in somite number or size. Several of the mutations also cause additional bone fusions in the trunk skeleton, reminiscent of those observed in primitive and modern birds. All of our findings were correlated to the fossil record. An open question is whether the relatively sudden appearance of short-tailed birds in the fossil record could be accounted for, at least in part, by the pleiotropic effects generated by a relatively small number of mutational events.

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The genetics of the rumpless fowl with evidence of a case of changing dominance

Cited by 41 publications

References 10 publications

Genetic basis of heterosis explored by simple sequence repeat markers in a random-mated maize population

Genetic basis of heterosis explored by simple sequence repeat markers in a random-mated maize population

Genome-Wide Association Mapping and Identification of Candidate Genes for the Rumpless and Ear-tufted Traits of the Araucana Chicken

From dinosaurs to birds: a tail of evolution

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