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Genetic Similarities Between Subspecies of the White-Crowned Sparrow’

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Genetic Similarities Between Subspecies of the White-Crowned Sparrow’ The Condor 9Qz637-647 0 The Cooper Ornithological Society 1988 GENETIC SIMILARITIES BETWEEN SUBSPECIES OF THE WHITE-CROWNED SPARROW’ KENDALL W. CORBIN Departmentof Ecologyand BehavioralBiology, University of Minnesota,Minneapolis, MN 55455 PATRICIA J. WILKIE Departmentof LaboratoryMedicine and Pathology,University of Minnesota,Minneapolis, MN 55455 Abstract. Tissue samples from 121 birds representing two subspeciesof the White- crowned Sparrow, Zonotrichialeucophrys, and their zone of intergradation, were obtained from a linear seriesof eight localities along the Pacific coastof California and Oregon. The region sampled included all of the range of 2. 1. nuttalli,and a portion of the range of Z. 1. pugetensis.Allozyme variation at 46 presumptive geneloci was examined by means of starch gel electrophoresis;15 of these loci (32.6%) were polymorphic. Allelic frequenciesof these loci are reported here; they are used in an analysisof Wright’s F-statistics and to estimate gene flow and indices of genetic distance. The population genetic structure of at least one deme within the zone of intergradation differs from that of the two intergradingsubspecies, but the subspeciesthemselves apparently are not geneticallydifferentiated from one another. This conclusionis supportedby severallines of evidence:allelic frequenciesof the subspecies are not significantlydifferent, as determined by estimatesof geneticdistance; the association between interlocality F,, values and geographicdistances is not significant,as measuredby the Mantel test; and a reconstructionof the evolutionary relationshipsbased on the genetic distancesof Nei, Rogers, and Cavalli-Sforza and Edwards groupslocalities representingthe two subspeciestogether, but separatefrom localities within the zone of intergradation. All lines of evidence suggesthigh levels of gene flow between the subspecies. Key words: Zonotrichia leucophrys;subspecies; population genetic structure; electropho- resis;protein polymorphism; gene flow; intergradation. INTRODUCTION of Z. 1.oriantha were subsequently synonymized Breeding populations of the White-crowned with Z. 1. leucophrysby Banks (1964). Sparrow, Zonotrichia leucophrys,are widely dis- Two of the three western subspecies, Z. 1. nut- tributed in North America, and among them there talli and Z. 1. pugetensis,meet and intergrade is a fair degree of geographic variation. Taxo- along the Pacific coast of northern California. nomic studies have dealt with this variation in The region in which intergradation occurs is a different ways, but at present four subspecies are narrow band of coastal chaparral extending from recognized (Banks 1964). These include an east- about as far south as Bodega Head in Sonoma ern Canadian and southern Rocky Mountain race, County, California, northward through Mendo- Z. 1. leucophrys,an Alaskan and western Cana- cino County into Humboldt County, California dian race, Z. 1.gambelii, a Pacific northwest race, (Grinnell 1928, Blanchard 1941, Banks 1964, Z. 1.pugetensis, and a central Pacific coast race, Mewaldt et al. 1968, Corbin 1981). This is a Z. 1. nuttalli. Earlier, Oberholser (1932) recog- region of the coast in which the ecology and floral nized the populations in the region of the Warner components change from being predominantly Mountains of Lake County, Oregon, as a separate those of a Baccharis-Lupinuschaparral south of subspecies, Z. 1.oriantha, and subsequently pop- Cape Mendocino to a coastal evergreen forest on ulations in the Sierra Nevada Mountains of Cal- Cape Mendocino (Munz 1959). ifornia were informally included in Z. 1.oriantha. Several lines of evidence bear upon the issue To these Miller (194 1) formally added the pop- of what geographic region constitutes the zone ulations of the Rocky Mountains and Great Ba- of contact and intergradation between popula- sin of the United States. All of these populations tions currently designated as Z. 1. nuttalli and Z. 1.pugetensis. The subspecies Z. 1. nuttalli, as cur- rently defined, is comprised primarily of non- ’ ’ Received 28 October 1987. Final acceptance 29 migratory birds (Blanchard 194 l), whose breed- April 1988. ing range is restricted to the coastal areas of central [6371 638 KENDALL W. CORBIN AND PATRICIA J. WILKIE TABLE 1. Frequencies of alleles at polymorphic gene loci within demes of Zonotrichiuleucophrys nuttulli, Z. 1.pugetensis, and their intergrades. Demes of Z. I. nuttalli include Jalama, Point Piedras Blancas, Marina, and Point Reyes, California. Demes of intergrades include Manchester Beach and Rockport, California. Femdale, California and Yachats, Oregon, are within the range of Z. I. pugetensis.n is the number of genomes examined at each locus and population, h is the heterozygosity. Point Locus and Piedras Point MUI- allele Jalama Blancas MXiIIa Reyes Chester Rockport Femdale Yachats Acp a 0.100 0.0 0.067 0.175 0.063 0.154 0.0 b E94 0.500 0.222 0.300 0.650 0.500 0.423 0.643 C 0:412 0.333 0.556 0.567 0.125 0.250 0.269 0.286 d 0.294 0.067 0.222 0.067 0.050 0.188 0.154 0.071 34 30 18 30 40 16 26 28 h” 0.657 0.624 0.593 0.580 0.529 0.648 0.701 0.500 Gdh-1 a 0.429 0.200 0.300 0.633 1.000 1.ooo 0.600 0.313 b 0.571 0.800 0.700 0.367 0.000 0.000 0.267 0.469 C 0.0 0.0 0.0 0.0 0.0 0.0 0.133 0.219 28 30 20 30 10 30 32 z 0.490 0.320 0.420 0.464 i.000 0.000 0.551 0.635 Idh a 0.0 0.0 0.0 0.029 0.025 0.150 0.067 b 0.111 0.0 0.0 0.059 0.025 0.050 0.033 E C 0.889 1.0 1.0 0.912 0.950 0.800 0.900 1:o 36 30 20 34 40 20 30 32 h” 0.198 0.000 0.000 0.164 0.096 0.335 0.184 0.000 Mea 0.0 0.0 0.0 0.033 0.0 0.0 b 0.111 0.033 0.0 0.200 0.125 K50 0.200 LE50 0.778 0.967 0.900 0.767 0.775 0:700 0.800 0:625 : 0.111 0.0 0.100 0.0 0.100 0.050 0.125 36 30 20 30 40 20 3oo.O 32 h” 0.370 0.064 0.180 0.371 0.374 0.445 0.320 0.531 Pep-A a 0.038 0.100 0.0 0.167 0.375 0.111 0.100 0.219 b 0.962 0.900 1.0 0.833 0.625 0.889 0.867 0.78 1 C 0.0 0.0 0.0 0.0 0.0 0.0 0.033 0.0 26 30 2 18 40 18 30 32 h” 0.074 0.180 0.000 0.278 0.469 0.198 0.238 0.342 Pep-B a 0.0 0.0 0.050 0.176 0.100 0.0 0.100 0.031 b 0.792 0.933 0.950 0.618 0.875 0.833 0.733 0.750 C 0.208 0.067 0.0 0.206 0.025 0.167 0.167 0.219 24 30 20 34 40 18 30 32 h” 0.330 0.124 0.095 0.545 0.224 0.278 0.424 0.389 Pep-Ca 0.0 0.0 0.0 0.038 0.075 0.0 0.0 0.03 1 b 1.0 0.933 1.0 0.962 0.925 1.0 0.969 C 0.0 0.067 0.0 0.0 0.0 ;:: 0.0 0.0 26 30 6 26 40 18 26 32 h” 0.0 0.124 0.0 0.074 0.139 0.0 0.0 0.061 6-pgdha 0.0 0.0 0.029 0.0 0.0 0.0 b 0.206 0.100 z11 0.0 z 0.0 0.0 0.067 C 0.324 0.267 0:500 0.676 0:618 0.650 0.500 0.233 d 0.206 0.300 0.167 0.029 0.029 0.050 0.0 0.267 0.206 0.233 0.222 0.265 0.206 0.200 0.500 0.167 ; 0.059 0.100 0.0 0.0 0.147 0.100 0.0 0.267 34 30 18 34 34 20 2 30 h” 0.765 0.764 0.660 0.47 1 0.554 0.525 0.500 0.771 Pgi-I a 0.0 0.0 0.100 0.0 0.0 0.0 0.0 0.0 b 0.706 0.692 0.600 0.250 0.412 0.600 0.533 0.467 0.294 0.308 0.250 0.500 0.353 0.150 0.300 0.367 : 0.0 0.050 0.194 0.235 0.250 0.100 0.100 e z 0.0 0.0 0.056 0.0 0.0 0.067 0.067 34 ’ 26 20 36 34 20 30 30 h” 0.415 0.426 0.565 0.647 0.65 1 0.555 0.611 0.633 GENETICS OF WHITE CROWNED SPARROWS 639 TABLE 1. Continued. Point Locusand Piedras Point Mall- allele Jalama Blancas Marina Reyes Chester Rockport Femdale Yachats Pgm-1 a 0.611 0.808 0.750 0.618 0.625 0.500 0.533 0.656 b 0.389 0.192 0.250 0.382 0.375 0.500 0.467 0.344 36 26 20 34 40 20 30 32 h” 0.415 0.311 0.375 0.472 0.469 0.500 0.498 0.451 Pgm-2 a 0.882 1.0 0.900 0.750 1.0 1.0 0.967 0.938 b 0.118 0.0 0.100 0.250 0.0 0.0 0.033 0.063 34 30 10 8 40 10 30 32 : 0.208 0.0 0.180 0.375 0.0 0.0 0.064 0.117 MP-3 a 1.0 1.0 1.0 0.971 1.0 1.0 1.0 b 0.0 0.0 0.0 0.029 A*: 0.0 0.0 0.0 36 30 20 34 40’ 20 30 32 h” 0.0 0.0 0.0 0.057 0.0 0.0 0.0 0.0 MP-5 a 0.0 0.0 0.0 0.059 0.0 0.0 0.0 0.0 b 0.972 1.000 1.ooo 0.941 0.700 1.ooo 1.ooo 0.938 C 0.028 0.0 0.0 0.0 0.300 0.0 0.0 0.063 36 30 20 34 40 20 30 32 ; 0.054 0.0 0.0 0.111 0.420 0.0 0.0 0.117 PP-I a 1.0 0.967 0.900 0.941 1.0 1.0 0.967 1.0 b 0.0 0.033 0.100 0.059 0.0 0.0 0.033 0.0 36 30 20 34 40 20 30 32 : 0.0 0.064 0.180 0.111 0.0 0.0 0.064 0.0 PP-3 a 0.0 0.0 0.000 0.0 0.0 0.167 0.0 b 0.0 ::: 0.0 0.029 0.053 0.0 0.167 0.0 1.0 1.0 0.853 0.737 0.900 0.661 0.0 : A:: 0.0 0.0 0.059 0.211 0.100 0.0 0.0 e 0.0 0.0 0.0 0.059 0.0 0.0 0.0 0.0 2 10 16 34 38 20 24 : 0.0 0.0 0.0 0.265 0.410 0.180 0.500 i.0 and northern California (Banks 1964).
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