kayological evolution

Evolution of Karyotypes: 

Evolution of Karyotypes R.Jayashree

Evolutionary sequence of domestication : 

Evolutionary sequence of domestication Dog -14000 years ago- multiple genetic contribution from Grey wolf Goats -10000 years ago-Fertile crescent Sheep -8000-9000 years ago Pigs -9000 years ago in Near east Cattle - 9000 years ago North eastern parts of Africa from Aurochs ( Bos primigenius ),sub species B.primigenius and B.opisthonomous ) Humped Zebu cattle ( Bos indicus )- 7000-8000 years ago in the Indus valley region from the sub species B.nomadicus .

Evolutionary sequence of domestication Contd.: 

Evolutionary sequence of domestication Contd. River buffaloes -5000 years ago- Indus valley and Euphrates and Tigris Swamp Buffaloes -4000 years ago-China Horse ?-3700-3100 BC Donkey -6000-6500 years ago Camel -5000 years ago- South eastern part of Arabian peninsular Mithun and Gaur -7000 years ago-Thailand Nature 418 , 700-707 (8 August 2002)

Normal Karyotype of domestic animals: 

Normal Karyotype of domestic animals Cattle chromosomes, 2n=60,XY. Stain method BrdU incorporation - Acridine Orange

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Karyotype of Goat

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Karyotype of Sheep 54 XY & 54 XX Ram Ewe

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Karyotype of Buffalo 50 XX and 50XY

Swine chromosomes, 2n=38,XX: 

Swine chromosomes, 2n=38,XX

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Karyotype of Dog

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Cat chromosomes, 2n=38,XX.

Karyotype of Horse 64 XY: 

Karyotype of Horse 64 XY

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Deletion Duplication Inversion Chromosome mutations

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Insertion Translocation

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Chromosome conservation Studies based on : Constant autosomal arm number (NAA) ranging from 30-60. 2. Chromosomal mutation- Centric fusion. 3. Similarity in the chromosome arms noticed based on various banding techniques.

Comparison of Chromosomes of Livestock: 

Comparison of Chromosomes of Livestock Cattle & Goat have 60 pairs and Sheep has 54 pairs. All autosomes are acrocentric in Cattle and Goats. The X-chromosome Goat - acrocentric Cattle's -X sub-metacentric) Y Chromosome Smaller Larger In sheep the same differences in the sex-chromosomes are found, but in addition there are three centromere fusions of autosomes. The chromosomes, 1/3, 2/8 and 5/11, are fused in comparison with those in cattle and goat. Therefore, the sheep has only 54 chromosomes.

Chromosomes of Buffaloes 50,XX or 50XY: 

Chromosomes of Buffaloes 50,XX or 50XY Based on banding the chromosome 1 to 5 in buffaloes has been formed by centric fusion of ten acrocentric autosomes of cattle: 1 and 27, 2 and 23, 8 and 19, 5 and 28 and 16 and 29, respectively.

Comparison of River and Swamp Buffalo: 

Comparison of River and Swamp Buffalo Riverine Buffalo-2n=50 Chromosome 4 &9 are separate. Swamp Buffalo-2n=48 Chromosome 4 & 9 appear as enlarged pair due to chromosome translocation. Crossbreds -2n=49 due to the 4/9 tandem fusion F2’s may have 2n as 48,49 and 50. Beyond 75% inheritance 2n=50

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X chromosome homology Cattle- Submetacentric River Buffalo -Acrocentric Sheep -Acrocentric with small visible ‘p’ arm Bands are conserved except that in Buffaloes the centromere is repositioned with loss of constitutive heterochromatin. Comparison of Bovine with Caprine -four chromosome transposition including centromere repositioning

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Y chromosome homology Bos taurus -Submetacentric Bos indicus -Acrocentric with small visible pericentric inversion Buffaloes -It larger than Bos taurus of because of addition of heterochromatic region

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Based on NOR banding NOR’s are located at telomeres autosome of 5 in Cattle, Sheep, Goat and Swamp buffalo and 6 in River buffalo Homology between autosomes of Buffalo- 6 Bos taurus -3,Sheep -3 and Goat -1p Sheep and Goat share the same NOR confirming evolutionary proximity.

Comparison of Chromosomes of Canines: 

Comparison of Chromosomes of Canines Dogs have 78 chromosomes which are acrocentric except the X chromosome which is metacentric. The red fox has 34 chromosomes. All autosomes are metacentric and 1-5 additional micro chromosomes. The blue fox has 50 chromosomes in which two pairs are acrocentric and the rest metacentric.

Other species in comparison to Goats: 

Other species in comparison to Goats Barbary sheep ( Ammotragus lervia )- 58 chromosomes due to centric fusion of two autosomes (Evan et.,al1973,Schnedl & Czaker, 1974). Female Oryx - 56 pairs (Robertsonian translocation of 2/20 and 1/25) Hartebeest-40 pairs (Robertsonian translocation of 1/10,5/7,4/11,6/12,3/14,9/15,2/26,8/20, 14/16, 23/25

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Bison -60 XX. All Bands similar to Goats except 11 & 12 Pairs. African Buffalo-53 XX Chromosome 9 & 25 appear smaller than goats. Robertsonian translocation of 2/3,1/13,9/25,4/19 and chromosome 22 has a short arm.

Chromosome 11 & 12: 

Chromosome 11 & 12 Caprine type- Barbari sheep, Hartebeest, Wilde beest & Oryx, Domestic sheep Bovine type -African buffalo, Eland, Bison Greater kudu, & Giraffe Banding similarities has been noticed in the distal regions of Caprine type 11 and bovine type 12 and Caprine type 12 and bovine 11 (Reciprocal translocation).

References: 

References Cytogenetics aspects of phylogeny in Bovidae ,R.A Buckland and H.J.Evans,Cytogenetics Cell genetics,21:42-63,1978. The X Chromosomes of mammals: Karyological homology as revealed by banding techniques,Sen Pathak and A.Dean Stock,Genetics 78:703-714 October,1974. Phylogenomics of the dog and fox family (Canidae, Carnivora)revealed by chromosome painting,Alexander S. Graphodatsky et al., Chromosome Research 16:129-143 2008. Chromosome and gene mapping homology between River buffalo, Cattle and sheep using Molecular markers, Othman E. Othman, Biotechnology,3(2):119-125,2004. http://vet.unne.edu.ar/revista/21-suple-1/00%20invitados.pdf