Haldane's rule has multiple genetic causes

Article Abstract:

J.B.S. Haldane conjectured in 1922 that when the offspring of two species is sterile or inviable it is the heterogametic (XY) sex. Haldane's rule does not have a single clear genetic basis. The traditional explanation is that one X chromosome from each species must be present to be compatible with autosomes from each. This has been shown to be false by the fertility of XX offspring where both chromosomes are from a single parent. Research using Drosophila shows that the traditional explanation also fails for inviability: there are XX hybrids that are inviable.

Species, Species (Biology), Breeding, Infertility in animals, Animal infertility

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Confidence in evolutionary trees from biological sequence data

Article Abstract:

Use of a frequency-dependant test in the construction of evolutionary trees may help overcome the limits of nucleotide sequences. In such sequences independently acquired similar G + C base compositions can result in misleading tree estimates. Nucleotide, cyanelle and chloropast sequences can be used in combination with the bootstrap and cladistic permutation tail probability methods to arrive at more reliable results. Examples of the methodology are included.

Nucleotide sequence, Base sequence

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Echoes of D4 receptor repeats

Article Abstract:

Similarities between the human and rat dopamine D4 receptor gene sequences indicate that this receptor evolved well before the divergence of primates and rodents. Four regions of the rat D4 sequence were observed to repeat portions of the human sequence. However, the 63 to 71% observed similarity was not enough to prove an evolutionary relationship. Moreover, other causes besides common derivation may account for the repeat sequence.

Dopamine receptors

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