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H e r d i t o s 105: 107-111 (1986)

Genetic differentiation among some populations of the House Sparrow, Passer domesticus, from southwestern Norway H. BJORDAL’, S.R. COLE’and D.T. PARKIN*

’ Department of Animal Ecology, Museum of Zoology, University of Bergen, Norway

’Department of Genetics, University Park, Nottingham, NG7 2RD, U .K .

BJORDAL., H., COLE,S.R.and PARKIN.D.T. 1986. Genetic differentiation among some populationsof the House Sparrow. Passer domesricus, from southwestern Norway. -Hereditas 105: 107-1 14. Lund. Sweden. ISSN 001X-0661. Received December 2, 1985

Eleven samples of house sparrows (Passer domesticus) were taken from the area around Bergen, and analysed by starch gel electrophoresis and isoelectric focussing. Eleven loci were found to be polymorphic. Samples taken from larger populations were found to be more similar than those from smaller populations. Genetic distance analysis suggests that the Norwegian populations have been isolated from southwestern Europe for about 10,000 years HCvard Bjordal, Department of Animal Ecology, Museum of Zoology, University of Bergen, N-5000 Bergen, Norway. Present address: Myrdalsskogen 363, N-5095 Lllset, Norway

The Rouse sparrow, Passer domesticus, is a of a series of samples from lowland eastern Engwidespread bird in Europe, occurring extensively land. They found a pattern of slight but significant from the Mediterranean Sea northwards into the differentiation between populations that could be Arctic Circle in Scandinavia and Finland. They interpreted in terms of inbreeding and drift in contihave even reached as far north as Finnmark where guous populations. FLEISCHER (1983) undertook they are believed to have arrived by boat (HAFTORNessentially the same analysis in Kansas, U.S.A., 1971). In the south, the species is virtually conti- except that his populations were more disjunct, and nuous with only local increases in density around he also examined fewer loci. The sparrows that he human habitation. In the more extreme climate of studied were thus more akin to the ‘island’ model of the north, however, it is a close commensal of man, population structure (KIMURA and WEIS 1964), as being virtually unable to survive the winter in areas opposed to the ‘isolation by distance’ model where natural food supplies are not supplemented (WRIGHT 1951) that PARKIN and COLE (1984) applied. by animal feed or stored grain. The populations of house sparrows that are Morphological variation in house sparrows has found in western Norway are more similar to the ‘isand land’ model, since they are very disjunct (BIORDAL been studied extensively in Europe by JOHNSTON his colleagues (e.g., JOHNSTON 1969; JOHNSTON and 1981). The birds inhabit a series of towns and settleSELANDER 1973), and at a more local level in south- ments along the edges of fjords, and the majority of west Norway by BJORDAL (1981), who found signifi- the populations are probably very isolated from cant differences in the dimensions of external char- each other. Indeed, of 177 house sparrows ringed in acters. For example, wing and leg length appeared Norway that have subsequently been recovered, to increase with distance from the coast, and al- only 1.7 % had moved more than 4 km from the though the changes appeared to be selectively ringing site (BIORDAL, unpubl.). As part of a study of morphological variation in based, they were not absolutely consistent. More recentIy, there have been several studies of the Norwegian populations of the house sparrow, one genetics of house sparrows by means of polymor- of us (HB) collected a series of samples from the phic enzyme systems to establish the structure of sites shown in Fig. 1. He dissected the livers from populations, both in Europe and North America. these birds, and sent them to Nottingham where the PARKIN and COLE(1985) examined the composition enzyme genotypes were assayed by SRC and DTP.

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Hereditas 10.7 (1986)

H. BJOKDAI. E T A L

cient material for the two PGM loci to be screened in four of the samples. Nevertheless, the data are sufficiently complete for some interesting results to emerge.

Results

Fig. 1. Locations in western Norway from which samples were taken. Solid circles indicate populations estimated to exceed 500 birds. A = Askvoll; B = Sogndal; C = Bjordal; D = Vik; E = Herdla; F = Granvin; G = Bergen; H = Haukeland; I = Vaksdal; 3 = Rldalen; K = Halhjem.

The present paper reports upon the results of this electrophoresis, and discusses them in the light of house sparrow evolutionary genetics.

Methods The birds were trapped in mist nets, killed with chloroform, and the livers stored at -15°C. They were later shipped to Nottingham in dry ice, and subsequently treated as described in PARKIN and COLE(1984). The homogenates were examined for 18 enzyme systems plus haemoglobin, coded by 30 gene loci. Not every bird was screened for every enzyme, but sufficient were analysed to confirm that those loci found to be invariant in Britain were similarly so in Norway. The following loci were found to be invariant in the Norwegian populations: Malate dehydrogenase (2 loci), Glucosephosphate isomerase, Glutamate oxalate transaminase (2 loci), Esterase-1, Phosphoglucomutase-3, Dipeptidase-2, Superoxide dismutase (2 loci), Lactate dehydrogenase ( 2 loci), Acid phosphatase, Glutamate dehydrogenase, a -glycerophosphate dehydrogenase, Guanine deaminase, and Haemoglobin (3 loci). Eleven loci were found to be variable in the Norwegian populations, and the allele frequencies are shown in Table 1. Unfortunately, there was insuffi-

For reasons of space, the complete genotype data are not given here; however, as elsewhere, there was no evidence of any consistent departure from the Hardy-Weinberg equilibrium. Five of the loci include rare alleles whose frequencies are too low for individual analysis. The use of G-statistics to test for heterogeneity between samples is unwise, since the numbers in some gene classes are very small. We have consequently erred on the side of caution, and pooled the less cgmmon alleles into a single class for the preliminary analyses, thereby producing a single alternative classification: commonest allele versus the rest. Comparing these ‘allele’ frequencies between samples, locus by locus, using the G-statistic with Williams correction (SOKALand ROHLF 1981) produces the results shown in Table 2. Seven of the values of G attain formal significance, and the remaining two approach this, so that the additive property of G yields an overall value that is highly significant. The overall heterozygosity values are also given in Table 1. VAISANEN and LEHVASLAIHO (1984) have recently reported upon a sample of house sparrows that was collected from a series of sites in the city of Helsinki, Finland. They comment that their birds are appreciably less polymorphic, and hence heterozygous, than those from elsewhere. Although they do not give the actual heterozygosity value, it is possible to calculate this from their data. However, their results are not directly comparable 1981) since with ours (or those of COLEand PARKIN a different array of loci was screened. VAISANEN and LEHVASLAIHO (1984) examined Adenylate kinase which we have not, but did not screen 6-PGD, PEPD, PEP-T, SORDH, ADA or ACON, all of which are variable in our samples. They also used starch gel electrophoresis to examine PGM, and PARKIN and COLE(1984) showed that isoelectric focussing reveals significantly more variation so that we have used the latter technique. Finally, they only comment upon single loci for IDH, GOT and SOD whereas we have followed COLEand PARKIN (1981) in recognizing two of each. Fortunately, VAISANEN and LEHVASLAIHO (1984) list their observed heterozygotes in the ‘Resulrs’ section of their paper, so that it is possible to compute the hetero-

Hereditas 105 ( I 986)

GENETIC DIFFERENTIATION IN THE HOUSE SPARROW

zygosities for the nine comparable loci in the two data sets. Assuming that they were able to successfully screen all 145 birds for the three variable loci, VAISANEN and LEHVASLAIHO'S (1984) data suggest a per-locus heterozygosity of 0.2 YOcompared with one of 8.2 YO for the sparrows around Bergen, which is largely due to significantly lower heterozygosities at the EST-2, IDH-A and 6-PGD loci. Such a difference could be due to a very small inoculate of birds during the initial founding event, as disand COLE(1985) for Australian cussed by PARKIN and New Zealand populations. Returning to our Norwegian samples, it is difficult to compare the allele frequencies with data from elsewhere in Europe because of their heterogeneity. However, we can analyse the allele frequencies over all loci using the coefficient of genetic

109

identity derived by NEI(1972). We have computed these for the 11samples, omitting the data from the two PGM loci, and the results are shown in Table 3. It is difficult to gain much impression of data such as these in tabular form, and so we have pictorially represented them in Fig. 2, using the UPGMA cluster analysis routine from the GENSTAT packet al. 1977). It is now apparent that one age (ALVEY group of populations is quite similar. Reference to Fig. 1 will reveal that these points are not geographically adjacent. The 11 samples from Norway came from an area some 160 km in diameter, which is broadly similar to those from the east midlands of England reporand COLE(1984). Since precisely the ted by PARKIN same loci are involved, it is possible to compare the identities from the two regions. The data are

TahL I . Allele frequency data from 11 samples of Passer domesticus taken in south-western Norway

PEP-T

PEP-D

ADA -

RADAL ASKVL SOGN GKNVN VIK BERGN HRDLA BJORD HAUKL HLJEM VKSDL

X

A

B

C

D

B

C

A

C

D

A

B

C

A

B

0 0 0 0 0 0

0 1 1 2 1 0

21 20

0 0

0

1 1 0

105 100 113 68 88 80 78 72 62 41 48

0 0 3 0 4 2 1 0 5 9 I

7 5 8 12 9 2 13 2 0 0 0

119 115 113 64 93 92 82 76 61 45 65

0

1

73 69 62 34 59 59 44 55 26 26 26

0 0 0 0 0 0

0

53 50 61 40 46 39 52 22 31 21 21

17 16 10 20 14 13 16 7 5 5 14

109 I in 114 56 91 83 80 71 61 49 52

42 27 35 3n 28 39 29 20 24 21 19

84 93 89 46 74 57 67 58 42 33 47

4 1

PGM-I

6-PG D A RADAL ASKVL SOGND GRNVN VIK BERGN HRDLA BJORD HAUKL HLJEM VKSDL

IDH-C

IDH-A

119 115 117 64 98 94 94 76 54 47 66

B

7 5 7 10 8 4 2 2 10 7 0

9

8 18 16 18 6 4 5 18

0

0 0 0 2

PGM-2

B

C

*

*

*

*

25

95

I2

106

2

*

26 25 37

*

19 9 20

80 69 57

*

47 45 46

Abbreviations: R A D A L = KBdalen; GRNVN = Granvin; HRDLA = Herdla; HLJEM = Halhjelm;

B

SORDH

5 5 11 3

4 4 ASKVL VIK BJRDL VKSDL

C

A

* *

99 89 83

*

63 50 62 = Askvoll; = Vik; = Bjordal; = Vaksdal;

* *

2 0 0

*

0 0

0

0

0 0 1 0

0 0 0 0

0

EST-2

A CON

A

B

C

A

B

A

B

C

8 4 5 6 9

83 84 75 50 62 54 52 50 34 38 31

35 32 44 20 35 40 36 26 30 14 33

1 0

89 91 90 57 72 70 67 52 50 45 53

41 30 31 22 24 21 20

85 92 87 54 70 71 70 61 46 47 54

0 0 0 0 0 2

-

4 8 2

2 2 2

SOGND = Sogndal; BERGN = Bergen; HAUKL= Haukeland

Allele nomenclature follows PARKIN and COLE (1984) with the most anodal being listed first

1

0 1

0 0 5 1

0 0

11

20 7 12

0

0 0

n

0

110

Heredims 10.7 (1986)

I I DJORDALtTAI.

0.999

0 998

0.997

Fig. 2. Clustering of Norwegian samples based upon Nei's coefficient of genetic identity, and using the Unweighted Paired Group Method in the GENSTAT package.

somewhat skewed, so we have used Mann-Whitney U-test (SOKAL and ROHLF 1981) to compare the data and COLE (1984). in Table 3 with that from PARKIN This generates U=3436 which is significantly different from the expected value of U=2145 (p