Intraspecific diversity was studied in three species using the control region sequences: the willow tit (II), the great tit (III) and the blue tit (IV). The samples from the willow and the great tit showed no structuring; all the studied populations seemed to belong to one panmictic population. The blue tits, however, revealed two maternal lineages. The ‘southern’ lineage found in Barcelona differed from the northern lineage by a mean genetic distance of 1.3 %.
The nucleotide diversity (π ) estimated within lineages was 0.53 % in the willow tit, 0.19% in the great tit and 0.19% in the northern lineage of the blue tits (diversity within southern lineage was 0.3%, but consisted of only two birds). The estimated number of segregating nucleotide sites (θ ) was 1.10% in willow tits, 0.94% in great tits and 0.73% in northern blue tits. All the willow tits sampled from two Fennoscandian populations had unique haplotypes (haplotype diversity 0.96). In contrast, seven out of the eight European populations sampled from the great tit shared the same most common haplotype. Altogether, one third of the great tits had this common haplotype (haplotype diversity was 0.86). The pattern in the blue tit was quite similar to the great tits. Four of six populations shared the most common haplotype, which was found altogether in 37% from the birds (haplotype diversity was 0.84, table 1).
Table 1. Nucleotide diversity (%π ) and haplotype diversity (1 − Σfi2) of the great, blue and willow tit populations studied.
| Population | Great tit | Blue tit | Willow tit | ||||||
|---|---|---|---|---|---|---|---|---|---|
| %π | 1 − Σfi2 | N | %π | 1 − Σfi2 | N | %π | 1 − Σfi2 | N | |
| Barcelona | 0.25 | 0.82 | 9 | 0.79 | 0.83 | 6 | |||
| Tübingen | 0.14 | 0.75 | 8 | 0.08 | 0.40 | 8 | |||
| Veluwe | 0.11 | 0.50 | 6 | ||||||
| Gotland | 0.19 | 0.78 | 8 | 0.18 | 0.80 | 5 | |||
| Tartu | 0.13 | 0.79 | 9 | ||||||
| Stockholm/Uppsala | 0.20 | 0.78 | 8 | 0.50 | 0.92 | 12 | |||
| Oslo | 0.26 | 0.78 | 6 | ||||||
| Harjavalta | 0.33 | 0.90 | 10 | ||||||
| Oulu | 0.15 | 0.78 | 10 | 0.16 | 0.60 | 10 | 0.55 | 0.92 | 13 |
| Kilpisjärvi | 0.13 | 0.78 | 8 | ||||||
| Total | 0.19 | 0.86 | 68 | 0.30 | 0.84 | 43 | 0.53 | 0.96 | 25 |
The estimate of the female effective population size also reflects the fact that diversity within the populations varied extensively. Willow tits had the largest estimate of effective population size (115 000) while great tits and the northern lineage of blue tits had lower estimates (47 000 and 49 000, respectively).
The estimate of coalescence time, which is just the female effective population size divided by the generation time, is as well dependent on the present diversity of the populations. Within lineage coalescence times are the longest for the willow tit (260 000 years), falling into the period of Middle Pleistocene. The coalescence time of the great tits and the blue tits (93 500 years and 96 000-120 000 years, respectively) was more recent and fits to the occurrence of the latest glaciation. The divergence of the two blue tit lineages probably happened at the beginning of the Middle Pleistocene, 650 000 years ago.