TAXONOMY OF HOUSE SPARROWS AND THEIR ALLIES IN THE MEDITERRANEAN BASIN RICHARD F. JOHNSTON Museum of Natural History and Department of Zoology The University of Kansas Lawrence, Kansas 66044 Approximately 3606 years ago there occurred the biology of these sparrows is that geograph- a significant movement of northern European ically disjunct populations may be phenetically agricultural man into southern European and much alike. This has suggested that they may Mediterranean regions (establishment of the also be genetically similar, but experimental Lake Dwellers in northern Italy, see Brea 1946 verification of this hypothesis is lacking. It is et seq.). Seemingly also with man came his known that the phenotypic feather coat of the newly-acquired commensal, the House Sparrow sparrows has a highly polygenic basis (see be- (Passer domesticus), which had been living low), and it is thus entirely possible that with man in northern Europe since its pre- similar phenotypes can have different geno- sumptive origins in the Near East, perhaps types, and vice versa. some 5500 years earlier. Indigenous sparrows Polygenic control of gross phenotype may in Italy, probably also commensal in 1600 BC well be the expected condition, but we need and almost certainly Willow Sparrows (con- not merely assume it for Mediterranean spar- ventionally considered a species by most tax- rows; Macke (1965; see also table 7) has shown onomists as Passer hispaniolmwis), shared a that the F1 of the cross, House Sparrow x common ancestry with House Sparrows but Willow Sparrow, may include a sampling of were phenotypically distinct. Interbreeding of nearly the entire range of intermediate pheno- the two phenetic kinds ensued, followed by types, hence of genotypes. The importance of establishment of populations of phenetic het- this finding cannot be exaggerated. It means erogeneity throughout the Italian peninsula. at one level that wherever there is a restricted Similar instances of commingling of gene pools range of phenotypes (= genotypes) the ac- occurred in other places in and around the tion of selection or restricted founder gene- Mediterranean, but on the Balearic Islands frequencies is strongly implied. But, if clines only House Sparrows became established and in phenotypes occur, then clines in gene- on Sardinia only Willow Sparrows. frequencies occur, and these can only be re- Later, only 300 to 400 years ago, there oc- sponses to differential selection pressures. It curred persistent cold weather, the “Little Ice means also, but conversely, that we must be Age,” sufficient to close Alpine passes for most prepared to find populations in which a wide of each year, with the result that the sparrows range of phenotypes occurs. of the Italian peninsula were cut off from Consequent opportunities for “hybrid mainland European sparrows for many tens swarms” or for geographically-oriented spec- of generations. This short period of fairly tra of phenotypes, or for intermediate condi- stringent isolation presumably allowed the on- tions, have been only in part realized, owing going processes of selective reassortment of variously to coincident gene frequencies in Italian sparrow genotypes to proceed toward founder populations, selection of coincident relative stability more quickly than they would characters, gene-flow, absence of gene-flow, have otherwise, and upon re-establishment of etc. Current distribution of phenotypes and Alpine contact gene flow between Italian spar- rows and Ho,use Sparrows did not occur as possible causal factors for such distributions freely a3 formerly. are set forth below. These events, or some such similar set, have One of the aims of the initial phases of this given us a remarkable complex of sparrows study was detection of phenetic change in around the Mediterranean Sea, and their vari- sparrows at localities where good samples able geographic, phenetic, and genetic char- were obtained by W. Meise 30 and more years acteristics provide a continual challenge to ago. Persistent effort therefore is made to re- understanding present relationships (e.g., late present findings to those of Meise (1936) Brehm 1842; Chigi 1914; Meise 1936; Macke and the chronological comparisons are an im- 1965). One of the most intriguing aspects of portant part of this preliminary report. [1291 The Condor, 71:129-139, 1969 130 RICHARD F. JOHNSTON TABLE 1. Scoring of characters on a hybrid index for male Mediterranean sparrows. Quality in House Quality in Willow Range Sparrow and minimum Sparrow and maximum in Character point value point value score Color of back Orange, rufous, Pale buff, whitish, buff, and black (0) cream, and black (2) o-2 Color of rump spots Rufous, pale, or none (0) Black ( 2) o-2 Posterior margin of bib Abrupt (0) Spearpoint-shaped black streaks (2) o-2 Flanks Buffy or gray, but Black or blackish lacking shaft streaks (0) shaft streaks (3) o-3 Color of shoulder Rufous with Black with little black (0) little rufous (2) O-2 Crown Gray (0) Rufous (6) O-6 Totals : O-17 MATERIALS the conditions and bearing arbitrary numerical The total number of specimens is 2033, of which 882 values corresponding to the conditions. Sev- (males) are housed in European museums and 1151, eral characters are scored (table 1 ), and the taken in 1965-66, are at the Museum of Natural His- numerical index value for each specimen is tory, The University of Kansas. Of the Kansas ma- the sum of the scores for all characters exam- terial, 918 specimens were prepared as conventional study skins, and of these 494 were males. This part ined. Finally, for a given locality, mean scores of the study therefore includes reference to 1376 male are determined. This routine differs from that specimens. of Meise in 1936 in that fewer characters are In field sampling no specimen was discarded for scored, and it is not possible to make direct any reason; those chosen for preparation as skins or as skeletons were selected on a random basis. A work- comparison of present values with those of ing assumption in this report is that individuals taken Meise. However, a rough conversion to Meises’ at a locality were hatched there or close by. This scale can be made by rendering present index assumption holds that meaningful, numerically sig- values as per cent of the possible maximum nificant migration does not occur in the populations and minimum scores (thus, 0 = 0% and 17 = sampled. Long-distance dispersal no doubt occurs, but it is impossible to distinguish between birds that 100%). Such conversions are included in have dispersed from another locality and some of the tables 2, 3, and 4. recombinant residents. To claim that this is possible Because House Sparrows show significant (as have some earlier students) is to beg the question. age variation in male plumage (Selander and The major consequence of such dispersal movement, since it is essentially random within major geographic Johnston 1967), index scores are different for units, should be to increase the apparent variability adults and subadults from many localities. The of characters in any sample. extent to which such age variation can in- fluence scores may be seen in the histograms METHOD OF ANALYSIS of figure 2, where several localities are indi- The technique used here stems directly from cated. Determination of ages of specimens that of Meise ( 1936), which was equivalent was made by examining the skull, with totally to the “hybrid index” then being used for the pillared bone being considered to represent first time by Anderson ( 1936). This technique adult age and any unpillared bone subadult uses simultaneous comparison of several char- age (Nero 1951). Such examination was pos- acters in the samples and it codes subjective sible only with specimens collected in the estimates of non-quantified characters of pat- course of the present study, and none of the tern, shape, and color onto a convenient nu- other specimens could be allocated to age by merical scale. This kind of descriptive analysis any comparable method. Index values for is especially useful in evaluating the mor- museum samples other than those for Kansas phology of populations in which there are are therefore of both adults and subadults, several, concordant variables (see Sibley 1954; in unknown proportions. Mean values for the Selander 1964). The work here treats House Kansas samples are presented in tables here Sparrows as one end of a phenetic spectrum as weighted means calculated on the assump- and Willow Sparrows as the other; “Italian” tion of equal numbers of adults and subadults. sparrows and other phenetic intermediates are A further word on the nature of extant mu- intermediate in value. seum samples is necessary, so that one bias of In scoring on this hybrid index a given char- the samples can be emphasized at the outset. acter is subdivided into several, graded condi- As has been noted just above, there is a slight tions of expression, with specimens defining influence of age of individual on hybrid index SPARROWS OF THE MEDITERRANEAN BASIN 131 FIGURE 1. Sketch map of the Mediterranean basin, showing localities from which samples were taken for this study. The numerals indicate the following localities (with their hybrid index scores in parentheses) : 1, Karlovac, Yugoslavia (0.5); 2, Trieste, Italy (3.0); 3, Udine, Italy (6.2); 4, Bordighera, Italy (3.0); 5, Cuneo, Italy (6.1); 6, Aosta, Italy (6.4); 7, Sondrio, Italy (6.2); 8, BoIzano, Italy (7.2); 9, Trento, Italy (6.4); 10, Bergamo, Italy (7.0); 11, Novara, Italy (7.2); 12, Mantova,