Saturday, 24 December 2011


As far as we know, just two studies have been made on Northern Bald Ibis genetics. They approache two different levels: 
- the differences between eastern and western populations
- the differences between an extinct and an extant populations in Morocco.

The first of them (Pegoraro et al., 2001) examined two segments of the mitochondrial genome of Moroccan and Turkish Bald Ibises. One point mutation was consistently discovered in a 307 bp (base pairs) portion of the cytochrome b gene (widely used in phylogenetics and population genetics) . This mutation was population specific, that is, it shows differences of an isolation of both populations. This finding has big consequences for the conservation of the highly endangered species and reinforces the idea that in captive breeding and releasing programmes, only birds of known origin should be used. Some physical differences had been previously detected.

The other work analysed 882bp of mitochondrial DNA control region sequence from 30 individuals, 19 wild birds from recent mortalities (1996 onwards) in the Souss-Massa area and eleven founders from Rabat Zoo. Those last birds were caught from the Middle Atlas Mountains in 1976-77.
The sequencing revealed 15 closely related haplotypes (groups of DNA that is transmitted together), nine from Souss-Massa and eight from Rabat with only two haplotypes shared at low frequency between these two populations.  Preliminary analyses indicate that these two populations are significantly different on haplotype frequencies.  That is, the Souss colony and the now extinct Middle Atlas colonies were demographically isolated exchanging few individuals. 
Those preliminary results were very interesting.
The Middle Atlas colonies have either gone extinct in situ or emigrated to the Souss-Massa colony.  The genetic data is inconsistent with a mass influx of birds into this last population because, if this were the case, the two colonies should share more haplotypes. 
Most of the captive population of northern bald ibis around the world originates from collections made from the Middle Atlas colonies. That means that the genetic resources of this extinct population are well represented in captivity, but Souss-Massa population probably is not.
It is very important to develop deeper and wider studies including captive populations of known origin and also skins and other biological material in scientific collections. This will allow to improve our knowledge of the relationship among the extinct and the extant populations.

Broderick, D. & Korrida, A. 2001. Latest genetic evidence for historical population structuring among colonies of Northern Bald Ibis (Geronticus eremita) in Morocco. In Bowden, C. I.A.G.N.B.I. Newsletter 1.
Pegoraro, K. ; Föger, M. & Parson, W. 2001. First evidence of mtDNA sequence differences between Northern Bald Ibises (Geronticus eremita) of Moroccan and Turkish origin. Journal of Ornithology, 142 (4): 425–28.

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