|Nutritional and genetic adaptation of galliform birds: implications for hand-rearing and restocking|
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According to Hewitt (1999) “population structure is the distribution of genotypes in space and time, and is the result of both present processes and past history”. Conspecific populations may be structured at a variety of evolutionary depths: slight molecular separations may reflect more recent population subdivisions, whereas deep subdivisions may evidence a major source of intraspecific evolutionary gene pool diversity (Avise 1992). The population structuring of the grey partridge was relatively strong when compared with the blue tit Parus caeruleus (Kvist et al. 1999b), or the greenfinch Carduelis chloris (Merilä et al. 1997), but of the same magnitude as the rock partridge (Lucchini & Randi 1998), and the dunlin Calidris alpina (Wenink et al. 1996). This may reflect allopatric divergence of refugial populations, and subsequent low maternal gene flow between the populations. The grey partridge is considered a relatively sedentary bird, with a short natal dispersal and high site-fidelity of adults. The mean dispersal distance of released grey partridges is 5.96 km ± 1800 m (SE) (Finnish Game and Fisheries Research Institute; Ringing Centre, Finnish Museum of Natural History). On the average the breeding dispersal distance of radio-tagged wild hens is 3.1 km 525 m, and that of released hens 2.32 km 764 m (Putaala & Hissa 1998). The negative correlation between the geographical distance and genetic variation in the populations can be explained by the genetic similarity among distant populations of Bulgarian, Greek, Finnish and Irish birds.
A star-like minimum-spanning network structure has been found among several bird species using either the mtDNA RFLP (Ball et al. 1988, Ellsworth et al. 1994, Seutin et al. 1995) or mtDNA control region (Merilä et al. 1997, Kvist et al. 1999a). This type of network may be an expression of rapid population expansion. The ancient history of the grey partridge was reflected in the minimum-spanning network. There were at least two separate refuges where ancestral Perdix perdix bottlenecked but survived the glaciations. A marked increase in the population size followed the retreat of the continental ice. Both lineages exhibited a star-like haplotype network, which referred to expanding populations.
In the eastern lineage, the expansion of the population was supported by the observed distribution of pairwise genetic distances, and the significantly negative Tajima’s D. Deviations from the neutral patterns of nucleotide variation expected at equilibrium may result from past changes in population size (Aris-Brosou & Excoffier 1996, Fry & Zink 1998). In the western lineage the observed distribution of pairwise genetic distances did not follow the expected distribution of either the expansion or the equilibrium model. A very recent population crash, maybe back in the 1950s, was reflected in τ , which was 0 (Rogers & Harpending 1992). This would explain the close kinship of a large part of the birds. The significantly negative Tajima’s D and the shape of the minimum-spanning network reflected a population under expansion.
|A deep divergence between the two lineages of the grey partridge||Up||The impact of ice ages can be seen in present day grey partridge populations|