Article

Morphological Variation and Evolution in Some North American Orioles

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Rising, James D. (Univ. Toronto, Dept. Zoology, Ramsay Wright Zoological Laboratories, Toronto 5, Ontario, Canada) 1970. Morphological variation and evolution in some North American orioles. Syst. Zool., 19:315–351 [oriole: Icterus galbula; Icterus bullockii; Icterus abeillei; hybridization; hybrid zone; introgression; species concepts; step dines].—Patterns of morphological variation of three taxa of orioles, Icterus galbula (Baltimore oriole), I. bullockii (Bullock oriole) and I. abeillei (black-backed oriole) (Icteridae; Aves) are discussed. Baltimore orioles breed in eastern North America, Bullock orioles in the western half of that Continent, and black-backed orioles on the Mexican Plateau. Distributional overlap is minimal. In most parts of their ranges individuals of either sex can be easily identified as to type by any of an array of features of size, color pattern, or vocalization. However, where the distributions of the morphs appear to abut, considerable phenetic variation is manifest. Special attention is here given to one such region of apparent abutment, the central Great Plains, where there is an abrupt east-to-west transition of Baltimore-morph to Bullock-morph and where some populations consist of orioles that are obviously phenetically intermediate. It has been suggested that the two forms are incipient bio-species, hybridizing in a geographically narrow region where secondary contacts have recently occurred. It is pointed out that step-clines of the sort manifest among Plains populations of orioles can arise by means other than secondary contact, and in the present context it seems unnecessarily speculative to postulate such rejunctions. On the basis of logical, distributional, and historical evidence, there is no reason to believe that the human activities of the past 150 years have had any fundamental effect on the distribution of the orioles in the Plains, and neither the incidence of phenetically intermediate individuals nor the width of the zone that essentially describes their distribution seems to be increasing. Rather, all evidence suggests that there is considerable stability among these populations, such that the patterns of distribution of the various morphs are coincident with some of those of the climatic environment. Doubtless many agencies of selection are acting in concert to dynamically maintain the “steps” in the oriole morph-clines in the Plains. Among these, the demonstrable difference between Baltimore and Bullock orioles' high temperature tolerance must be of considerable significance. Also, the differences between the Baltimore- and Bullockmorphs are so great that birds that disperse across the “hybrid zone” are probably selected against as being “unrecognizable” or as “odd birds.” It is impossible, within the described limits of non-phenetic concepts of the species, to designate as separate species or not these groups of orioles without relying upon a priori assumptions that are untenable or teleological, or without inviting a posteriori circularity. I have preferred nomenclatural separation for the groups for the sake of convenience, but such a decision is arbitrary.

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... These natural corridors have allowed these woodland-breeding birds to meet in secondary contact, despite the surrounding matrix of grassland habitat. These corridors also provide natural sampling transects through the hybrid zone-notably the Cimarron and Arkansas rivers in Kansas (Rising 1970(Rising , 1983a(Rising , 1983b(Rising , 1996 and the Platte River in Nebraska (Sibley and Short 1964, Corbin and Sibley 1977, Corbin et al. 1979)-that have been historically well sampled. The replicated sampling of these river transects allows for an unprecedented level of resolution (e.g., Corbin and Sibley 1977, Rising 1983a, 1996 of the location of the hybrid zone over time and space. ...
... Sutton (1938) was the first to describe hybrid orioles, from specimens collected in western Oklahoma, although he was unable to confirm that intermediate-plumaged birds were indeed hybrids and instead described them as "oddly plumaged" orioles. In subsequent decades the Baltimore and Bullock's orioles and their hybrids were studied extensively (Sibley and Short 1964, Sutton 1968, Rising 1969, 1970, 1973, 1983a, 1996Corbin and Sibley 1977, Corbin et al. 1979, Jacobsen and Omland 2012. These diverse investigations better defined the patterns and consequences of hybridization in these orioles, and featured in the more general discussions of the role J. Walsh, S. M. Billerman, V. G. Rohwer, et al. ...
... Ironically, some of the findings presented here-particularly the extensive levels of hybridization and admixture within the hybrid zone and the relative rarity of non-hybrids in those admixed populations-would likely have been considered additional evidence for lumping these species by Charles Sibley and his colleagues in the 1960s, at a time when there was less appreciation of the potential negative fitness consequences of hybridization as an additional isolating mechanism. Based on the findings of Rising (1969Rising ( , 1970Rising ( , 1996, the prevailing opinion on orioles later swung back to recognizing 2 distinct species, on the basis of new evidence of strong apparent selection for thermoregulatory differences as well as selection against hybrids outside of the hybrid zone (American Ornithologists' Union 1995). ...
Article
Hybrid zones are powerful natural settings for investigating how birds diversify into distinct species. Here we present the first genomic-scale exploration of the Baltimore (Icterus galbula) and Bullock’s (I. bullockii) oriole hybrid zone, which is notable for its long history of study and for its prominence in debates about avian species concepts and species limits. We used a reduced-representation sequencing approach to generate a panel of 3,067 genetic markers for 297 orioles sampled along the Platte River, a natural west-to-east transect across the hybrid zone. We then explored patterns of hybridization and introgression by comparing variation in genomic and plumage traits. We found that hybridization remains prevalent in this area, with nearly all orioles within the hybrid zone showing some degree of genomic mixing, and 41% assigned as recent-generation (F1/F2) hybrids. The center and width of the genomic and plumage gradients are concordant and coincident, supporting our finding that classically scored plumage traits are an accurate predictor of pure vs. hybrid genotypes. We find additional support for previous suggestions that the center of this hybrid zone has moved westward since it was first intensively sampled in the 1950s, but that this westward movement had slowed or ceased by the 1970s. Considered in concert, these results support previous inferences that some form of ongoing selection is counteracting the potential homogenization of these orioles via hybridization, thereby supporting their continued taxonomic separation as distinct species.
... The present distributions of Baltimore and Bullock's orioles are shown in Fig. 2. Hybridization between these has been studied in detail in Oklahoma (Sutton, 1968), Kansas (Rising, 1970(Rising, , 1983, Nebraska (Sibley and Short, 1964;Corbin and Sibley, 1977), South Dakota (Anderson, 1971), and the Canadian Prairies (Rising, 1973). ...
... In Nebraska, hybridization was common in the central to western part of the state in the 1950s and 1960s (Sibley and Short, 1964;Rising, 1970). In the 1950s, the "center" of the hybrid zone in Nebraska apparently ran through Valentine along the Niobrara River (samples from the northern part of the state are small) and through Big Spring along the Platte River. ...
... At Big Springs, 15 of the 18 specimens collected by Sibley and Short were intermediate between Baltimore and Bullock's orioles in plumage pattern characteristics ( Fig. 3A; three looked like Bullock's orioles). In 1967, Rising (1970) collected seven specimens there, and all were hybrids. In 1974, however, many of the 25 specimens collected by Corbin at Big Springs appeared to be Baltimore orioles, indicating that Baltimore orioles were displacing Bullock's and hybrids at this site (Corbin and Sibley, 1977). ...
Article
About 130 taxa of birds reach distributional limits in the central US Great Plains; 28 of these are replaced there by closely related taxa that appear to be their ecological counterparts. Hybridization between counterparts occurs at least occasionally in 22 (11 pairs of taxa) cases, and many of the commonly hybridizing taxa occur commonly on the Plains. Only the eastern and western meadowlarks (Sturnella magna and S. neglecta) are grassland hybridizing species; the others are birds of deciduous thicker or woodland edge. Accounts are provided of hydridization in the following genera: Otus, Colaptes, Centurus, Myiarchus, Contopus, Cyanocitta, Parus (both chickadees and crested titmice), Sialia, Sturnella, Icterus, Pheucticus, Passerina and Pipilo. Discussion centres on the stability of hybrid zones, increased variability in zones, suture zones in the Great Plains, and certain taxonomic implications.-P.J.Jarvis
... Predation by squirrels may also be a contributing factor. Orioles may build on the tips of branches high in trees to make their nests inaccessible to squirrels where such are abundant, at the risk of having their nests blown out by strong winds (Rising 1970). ...
... My analysis of nest structure indicates that the nest of the Bullock's Oriole is deeper and wider than that of the Baltimore Oriole. Bullock's Oriole is the larger morph in the Great Plains (Rising 1970); the difference in nest; may reflect a difference in the size of the birds. However, the diameter of the opening to the nest is smaller for Bullock's Orioles, perhaps conferring some benefits through shading. ...
... Southern nests tended to be larger than northern ones (the difference between the Texas Panhandle localities and the Ontario-Quebec and Platte regions is significant). This may again reflect size differences in the birds, or it may be due to geographic variation in clutch size; the Texas Panhandle nest may be larger, on the average, to accommodate the slightly larger clutches in the southwestern Great Plains (Rising 1970). ...
... We prefer to treat these taxa as biological species because the number of important differences between them suggest that gene flow is restricted. They differ in: male, female and immature plumages; vocalizations (Rising 1970); thermoregulatory abilities (Rising 1969); allele frequencies (Corbin et al. 1979); number of molts and molt-migration schedule (Rohwer and Manning 1990); nest-site placement and dispersion (Rising 1970); and body size (Sibley and Short 1964, Rising 1973, 1983 ...
... We prefer to treat these taxa as biological species because the number of important differences between them suggest that gene flow is restricted. They differ in: male, female and immature plumages; vocalizations (Rising 1970); thermoregulatory abilities (Rising 1969); allele frequencies (Corbin et al. 1979); number of molts and molt-migration schedule (Rohwer and Manning 1990); nest-site placement and dispersion (Rising 1970); and body size (Sibley and Short 1964, Rising 1973, 1983 ...
... This group includes the well-known hybrid zone between the eastern Baltimore oriole (Icterus galbula) and Bullock's oriole (I. bullockii) (Sutton 1938Sutton , 1968 Sibley and Short 1964; Rising 1969 Rising , 1970 Rising , 1983 Rising , 1996 Corbin et al. 1979). I. galbula breeds across the eastern United States south to Louisiana, and across most of Canada from Alberta in the west to Nova Scotia in the east (Fig. 2). ...
... The two orioles interbreed extensively in this contact zone, which falls within the " Rocky Mountain-Great Plains " suture zone (Remington et al. 1968), a hotspot of avian hybrid zones between eastern and western species pairs (e.g., Carling and Brumfield 2008; Flockhart and Wiebe 2009; Mettler and Spellman 2009). Documentation of viable hybrid offspring within this contact zone (Sutton 1938; Sibley and Short 1964; Sutton 1968; Rising 1970) led to the lumping of I. galbula and I. bullockii (including I. abeillei) into a single species, the northern oriole (AOU 1973). Later studies found that the I. galbula–I. ...
Article
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Until recently, studies of divergence and gene flow among closely-related taxa were generally limited to pairs of sister taxa. However, organisms frequently exchange genes with other non-sister taxa. The "northern oriole" group within genus Icterus exemplifies this problem. This group involves the extensively studied hybrid zone between Baltimore oriole (Icterus galbula) and Bullock's oriole (I. bullockii), an alleged hybrid zone between I. bullockii and black-backed oriole (I. abeillei), and likely mtDNA introgression between I. galbula and I. abeillei. Here, we examine the divergence population genetics of the entire northern oriole group using a multipopulation Isolation-with-Migration (IM) model. In accordance with Haldane's rule, nuclear loci introgress extensively beyond the I. galbula-I. bullockii hybrid zone, while mtDNA does not. We found no evidence of introgression between I. bullockii and I. abeillei or between I. galbula and I. abeillei when all three species were analyzed together in a three-population model. However, traditional pairwise analysis suggested some nuclear introgression from I. abeillei into I. galbula, probably reflecting genetic contributions from I. bullockii unaccounted for in a two-population model. Thus, only by including all members of this group in the analysis was it possible to rigorously estimate the level of gene flow among these three closely related species.
... Differences between yearling and adult male orioles are diagnostic (Bent 1958 ;p. 273) but there is no consistent difference that separates yearling and adult females (Rising 1970) . However, few females develop a completely black throat by one year of age (only three of 27 examined by Peters, in Bent 1958 ;p. ...
... Females mated to yearling males are more likely to be yearlings (and hence naive) than females mated to adult males . Male orioles appear to be more numerous than females (Rising 1970) and competition with adult males makes it unlikely that yearling males would succeed in forming pair bonds with adult females . My assumption that females mated to yearling males are themselves yearlings is supported by data on breeding dates . ...
Article
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Rejection of non-mimetic eggs occurs at nearly all the nests of certain species of passerines. Rejection behaviour is almost certainly genetically programmed. However, addition of artificial brown-headed cowbird (Molothrus ater) eggs to empty northern oriole (Icterus galbula) nests indicates that the type of egg orioles consider their own is learned in an imprinting process that occurs during a sensitive period beginning several days before and ending shortly after the onset of laying. Furthermore, orioles habituate to a cowbird egg they cannot eject and reduce rejection attempts after several days. Orioles are relatively unresponsive to eggs that differ from their own eggs only by being smaller. Selection may favour orioles that are most responsive to egg-colour and maculation, the egg-parameters by which oriole eggs differ most strongly from those of the parasitic cowbird.
... A leading hypothesis for east-west divergences is that populations were separated into two or more disjunct Pleistocene forest refugia south of the glacial extent, an idea supported by climatic modeling of ecoregions (Hargrove and Hoffman, 2005) and ecological niche modeling of historical species distributions (Peterson and Ammann, 2013;Puckett et al., 2015;Loveless et al., 2016;Ferguson et al., 2017). These populations then diverged in allopatry, potentially with the eastern counterpart adapting to wetter and cooler environments and the western to drier and warmer environments (Rising, 1970(Rising, , 1983Webb and Bartlein, 1992;Swenson, 2006). Changing climatic conditions at the end of the Pleistocene (∼12,000 ybp) permitted refugia to expand into secondary contact, with exogenous (i.e., environmental) factors such as temperature (Rising, 1969;Swenson, 2006), precipitation (Moore and Price, 1993), and/or vegetation (Moore, 1977) gradients at the Great Plains likely playing pivotal roles in maintaining species boundaries along the hybrid zone, perhaps in combination with endogenous (i.e., genetic-based) factors (Bronson et al., 2003). ...
Article
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We examined phylogeographic structure in gray fox (Urocyon cinereoargenteus) across the United States to identify the location of secondary contact zone(s) between eastern and western lineages and investigate the possibility of additional cryptic intraspecific divergences. We generated and analyzed complete mitochondrial genome sequence data from 75 samples and partial control region mitochondrial DNA sequences from 378 samples to investigate levels of genetic diversity and structure through population- and individual-based analyses including estimates of divergence (FST and SAMOVA), median joining networks, and phylogenies. We used complete mitochondrial genomes to infer phylogenetic relationships and date divergence times of major lineages of Urocyon in the United States. Despite broad-scale sampling, we did not recover additional major lineages of Urocyon within the United States, but identified a deep east-west split (∼0.8 million years) with secondary contact at the Great Plains Suture Zone and confirmed the Channel Island fox (Urocyon littoralis) is nested within U. cinereoargenteus. Genetic diversity declined at northern latitudes in the eastern United States, a pattern concordant with post-glacial recolonization and range expansion. Beyond the east-west divergence, morphologically-based subspecies did not form monophyletic groups, though unique haplotypes were often geographically limited. Gray foxes in the United States displayed a deep, cryptic divergence suggesting taxonomic revision is needed. Secondary contact at a common phylogeographic break, the Great Plains Suture Zone, where environmental variables show a sharp cline, suggests ongoing evolutionary processes may reinforce this divergence. Follow-up study with nuclear markers should investigate whether hybridization is occurring along the suture zone and characterize contemporary population structure to help identify conservation units. Comparative work on other wide-ranging carnivores in the region should test whether similar evolutionary patterns and processes are occurring.
... The time since divergence for the control region was calculated using the geometric mean of mutation rates which was 0.025 s/s/l/m (substitution/site/lineage/million years; Kondo et al. 2004). We used TRACER 1.5 (Rambaut and Drummond 2009) to visualize the results and to ensure convergence and ESS values. In addition, we used STRUCTURE 2.3.X (Pritchard et al. 2000) to look for signs of population differentiation between north and south ranges; we include all six introns and the control region in this analysis and we set K to 2 and 4 populations. ...
Article
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Geographic barriers between populations of a species can result in divergence of genes, morphology, or behaviors that can lead to speciation. The Yellow-backed Oriole (Icterus chrysater) is distributed from southern Mexico to Colombia, but with a major range disjunction of 600 km in Costa Rica. We examined molecular and morphological data for differences between northern and southern populations. We sequenced the mitochondrial control region and six nuclear introns. Genetic data show strong north-south population structure with evidence of gene flow. The evidence of gene flow between populations is surprising because of the large geographic break between populations. We also measured six morphological characters from specimens collected along the species' distribution and found shallow north-south divergence.
... Because Schadonophasma fourth instar larvae could not be identified on the basis of discrete characters, I employed a compound character index to recognize fourth instar larvae of Chaoborus trivittatus and Chaoborus cooki. Although this index has been used primarily to recognize hybrids and analyze zones of hybridization (Freitag, 1965, and papers cited therein; Hubbs and Peden, 1969;Rising, 1970) it is also useful to distinguish morphologically similar species. Compound character indices compile an overall measure of difference to test for morphological discontinuity (i.e. ...
... Hybridization in the wild is of interest in both evolutionary (Barton and Hewitt 1985, Moore 1987, Coyne 1992, Grant and Grant 1992, Harrisson 1993, Green 1996, and conservation biology (O'Brien andMayr 1991, Grant andGrant 1992). In birds hybridization commonly implies morphological shift (Mayr 1970), and introgression of plumage characters has been observed in many taxa (Rising 1970, 1983, Gill and Murray 1971, Emlen et al. 1975, Moore 1987, Lockley 1996. Body measurements (e.g. ...
Article
Icterine Warbler Hippolais icterina and Melodious Warbler H. polyglotta are closely related species with parapatric breeding ranges. Their breeding ranges overlap only in a narrow zone in western Europe, where the Icterine Warbler population is presently declining and the Melodious Warbler population expanding. In eastern Burgundy (France), both species have bred in sympatry for at least forty years, but the Icterine Warbler started to decline in the mid-seventies. The two species differ in wing length and wing formula. Morphological variations of the wing were compared for the Icterine Warbler population in eastern Burgundy between 1965/76 and 1985/96. In the second period, wing length and wing characteristics of the Icterine Warbler approached those of the Melodious Warbler. The number of recorded heterospecific pairs also differed between the two periods. No similar morphological change was observed for the Melodious Warbler between the two periods. We discuss the evidence for unidirectional generic introgression from the Melodious into the Icterine Warbler population as a likely explanation for this observed situation.
... Hybridization with Bullock's Oriole and varied taxonomic treatment of the galbula-bullocki complex has deterred collection of precise field data with which to determine the status of these 2 orioles. Intermediates occur or have occurred in the study area, with some of the original specimens used to document hybridization collected at Sutherland, just to the east of the study area, and at Big Springs, just to the west of the study area (Corbin and Sibley 1977, Rising 1970, Sibley and Short 1964. Most breeding individuals in the study area are hybrids or pure Baltimore types. ...
Article
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The North Platte River valley (elev. ca 3300 ft/990 m) in Garden and Keith counties, Nebraska, has an avifauna of 305 species, the richest known north of Texas in the Great Plains. More than 25 years of observations, mist-netting, banding, and breeding-bird surveys by the authors and others have revealed 104 breeding, 17 probably breeding, and 184 transient, casual, and accidental species. Hybridization of eastern with western species is evidenced by intermediates between Rose-breasted and Black-headed grosbeaks, Indigo and Lazuli buntings, Eastern and Spotted towhees, Baltimore and Bullock's orioles, and yellow- and red-shafted morphs of Northern Flicker; Eastern and Western wood-pewees potentially hybridize because both breed in the area.
... Many complexes of parapatric akin taxa fall into one of the scenarios of allopatric speciation described above (Sibley & Short, 1964;Ferry & Deschaõ Ãntre, 1966, 1974Remington, 1968;Haffer, 1969Haffer, , 1974Haffer, , 1986Haffer, , 1989Rising, 1970;Meise, 1975;Corbin & Sibley, 1977;Dubois, 1977;Ferry, 1977;Lundberg, 1980;Prigogine, 1980;Schifferli & Schifferli, 1980;Vuilleumier, 1980Vuilleumier, , 1993Motis et al., 1983Motis et al., , 1997Prigogine & Louette, 1983;Baumgart, 1984;Sorjonen, 1986;Tegelstro È m & Gelter, 1990;Motis, 1992;Prager et al., 1993;Sage et al., 1993;De la Cruz-Cardiel et al., 1997;Sñtre et al., 1997;Caton, 1999). The list of the publications on the subject is far from exhaustive. ...
Article
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AimDifferent continental and insular speciation processes are reviewed. The areal and clinal conceptions of speciation studies are discussed. I propose a revisited cline theory reconciling cline mechanics and allopatric speciation as cline analysis allows quantification in speciation description more easily and integrates polymorphism within speciation processes. In addition, insular speciation illustrates what could have been the first allopatric stages of many current continental speciations. Intrinsic correspondence is shown between areal and clinal conceptions, and between continental and insular speciation processes; this article is thus an essay towards a unified theory of speciation biogeography.
... bullockii) and Baltimore oriole (I. galbula) (Sibley and Short, 1964; Rising, 1969 Rising, , 1970 Rising, , 1973 Rising, , 1983 Rising, , 1996 Allen, 2002) and there is alleged hybridization between I. bullockii and a close Mexican relative I. abeillei (Miller, 1906; but see Rising, 1973 ). In this paper, we utilized multiple approaches and seven independent nuclear loci to infer the phylogeny of Icterus clade C and compare the different approaches to species tree inference. ...
Article
Recent computational advances provide novel opportunities to infer species trees based on multiple independent loci. Thus, single gene trees no longer need suffice as proxies for species phylogenies. Several methods have been developed to deal with the challenges posed by incomplete and stochastic lineage sorting. In this study, we employed four Bayesian methods to infer the phylogeny of a clade of 11 recently diverged oriole species within the genus Icterus. We obtained well-resolved and mostly congruent phylogenies using a set of seven unlinked nuclear intron loci and sampling multiple individuals per species. Most notably, Bayesian concordance analysis generally agreed well with concatenation; the two methods agreed fully on eight of nine nodes. The coalescent-based method ∗BEAST further supported six of these eight nodes. The fourth method used, BEST, failed to converge despite exhaustive efforts to optimize the tree search. Overall, the results obtained by new species tree methods and concatenation generally corroborate our findings from previous analyses and data sets. However, we found striking disagreement between mitochondrial and nuclear DNA involving relationships within the northern oriole group. Our results highlight the danger of reliance on mtDNA alone for phylogenetic inference. We demonstrate that in spite of low variability and incomplete lineage sorting, multiple nuclear loci can produce largely congruent phylogenies based on multiple species tree methods, even for very closely-related species.
Article
Studies of natural hybrid zones can provide documentation of range shifts in response to climate change and identify loci important to reproductive isolation. Using a temporal (36-38 years) comparison of the black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee hybrid zone, we investigated movement of the western portion of the zone (western Missouri) and assessed whether loci and pathways underpinning reproductive isolation were similar to those in the eastern portion of the hybrid zone. Using 92 birds sampled along the hybrid zone transect in 2016 and 68 birds sampled between 1978 and 1980, we generated 11,669 SNPs via ddRADseq. These SNPs were used to assess movement of the hybrid zone through time and to evaluate variation in introgression among loci. We demonstrate that the interface has moved ~5 km to the northwest over the last 36-38 years, i.e., at only one-fifth the rate at which the eastern portion (e.g., Pennsylvania, Ohio) of the hybrid zone has moved. Temperature trends over the last 38 years reveal that eastern areas have warmed 50% more than western areas in terms of annual mean temperature, possibly providing an explanation for the slower movement of the hybrid zone in Missouri. Our results suggest hybrid zone movement in broadly distributed species, such as chickadees, will vary between areas in response to local differences in the impacts of climate change.
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Studies of natural hybrid zones can provide documentation of range shifts in response to climate change and identify loci important to reproductive isolation. Using a deep temporal (36-38 years) comparison of the black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee hybrid zone, we investigated movement of the western portion of the zone (western Missouri) and assessed whether loci and pathways underpinning reproductive isolation were similar to those in the eastern portion of the hybrid zone. Using 92 birds sampled along the hybrid zone transect in 2016 and 68 birds sampled between 1978 and 1980, we generated 11,669 SNPs via ddRADseq. These SNPs were used to assess movement of the hybrid zone through time and to evaluate variation in introgression among loci. We demonstrate that the interface has moved ~5 km to the northwest over the last 36-38 years, i.e., at only one-fifth the rate at which the eastern portion (e.g., Pennsylvania, Ohio) of the hybrid zone has moved. Temperature trends over the last 38 years reveal that eastern areas have warmed 50% more than western areas in terms of annual mean temperature, possibly providing an explanation for the slower movement of the hybrid zone in Missouri. Our results suggest hybrid zone movement in broadly distributed species, such as chickadees, will vary between areas in response to local differences in the impacts of climate change.
Article
This book provides basic information on all the species of birds that have been reliably reported from the Nebraska Sandhills region as of 2020. They include 46 permanent residents, 125 summer breeders, 125 migrants, and 102 rare or accidental species, totaling 398 species. Information on status, migration, and habitats is provided for all but the very rare and accidental species. There are also descriptions of 46 refuges, preserves, and other public-access natural areas in the region and seven suggested birding routes. The text contains more than 90,000 words and over 250 literature references along with more than 20 drawings, 9 maps, and 32 photographs by the authors. Preface • The Nebraska Sandhills and Their Unique Wetlands • The Drums of April and the Dances of Life • Biological Profiles of Some Typical Sandhills Birds Introduction: Natural History of the Nebraska Sandhills • Geography • Lakes and Rivers • Wetlands • Landscape Ecology • Climate • Birds and Humans in the Nebraska Sandhills • Human Impacts on Birds • Ornithological Research and Regional Birding Species Accounts: Anatidae (Swans, Geese, and Ducks) • Odontophoridae (New World Quails) • Phasianidae (Pheasants, Grouse, and Turkeys) • Podicipedidae (Grebes) • Columbidae (Pigeons and Doves) • Cuculidae (Cuckoos) • Caprimulgidae (Goatsuckers) • Apodidae (Swifts) • Trochilidae (Hummingbirds) • Rallidae (Rails, Gallinules, and Coots) • Gruidae (Cranes) • Recurvirostridae (Stilts and Avocets) • Charadriidae (Plovers) • Scolopacidae (Sandpipers and Snipes) • Laridae (Gulls and Terns) • Stercorariidae (Jaegers) • Gaviidae (Loons) • Phalacrocoracidae (Cormorants) • Pelecanidae (Pelicans) • Ardeidae (Herons and Egrets) • Threskiornithidae (Ibises and Spoonbills) • Cathartidae (New World Vultures) • Pandionidae (Ospreys) • Accipitridae (Hawks, Eagles, and Kites) • Tytonidae (Barn Owls) • Strigidae (Typical Owls) • Alcedinidae (Kingfishers) • Picidae (Woodpeckers) • Falconidae (Falcons and Caracaras) • Tyrannidae (Tyrant Flycatchers) • Laniidae (Shrikes) • Vireonidae (Vireos) • Corvidae (Crows, Jays, and Magpies) • Alaudidae (Larks) • Hirundinidae (Swallows) • Paridae (Chickadees and Titmice) • Sittidae (Nuthatches) • Certhiidae (Creepers) • Troglodytidae (Wrens) • Cinclidae (Dippers) • Polioptilidae (Gnatcatchers) • Regulidae (Kinglets) • Turdidae (Thrushes) • Mimidae (Mockingbirds, Thrashers, and Catbirds) • Bombycillidae (Waxwings) • Sturnidae (Starlings) • Passeridae (Old World Sparrows) • Motacillidae (Pipits) • Fringillidae (Boreal Finches) • Calcariidae (Longspurs and Snow Buntings) • Passerellidae (New World Sparrows and Towhees) • Icteriidae (Chats) • Icteridae (Blackbirds, Orioles, and Meadowlarks) • Parulidae (New World Warblers) • Cardinalidae (Cardinals, Tanagers, and Grosbeaks) Refuges, Preserves, and Other Natural Areas in the Sandhills Region Suggested Birding Routes in the Western and Central Nebraska Sandhills References: General Surveys • Geology, Physiography, and Wetlands • Botany, Zoology, and Ecology • Birds Index to Bird Species and Families Maps: 1. Location of the Nebraska Sandhills, Ogallala aquifer, and other features • 2. Distribution of wetlands in the Nebraska Sandhills • 3. Rivers and counties in the Nebraska Sandhills • 4. The extent of surface sand and associated counties in the Nebraska Sandhills • 5. Wetlands and roads in the western Sandhills of Garden County and southern Sheridan County • 6. Major roads and highways in the Nebraska Sandhills • 7. Locations of counties, wildlife refuges, and other protected areas in the Nebraska Sandhills • 8. Crescent Lake National Wildlife Refuge and northern approaches • 9. Vicinities of Antioch and Lakeside, showing suggested birding routes Tables: 1. Sandhills County Codes, Areas, and Human Populations • 2. Geographic and Ornithological Aspects of the Nebraska Sandhills Counties • 3. Relative Spring and Summer Abundance Indices of Mostly Wetland Bird Species in Three Sandhills National Wildlife Refuges Figures: Greater prairie-chicken • Burrowing owl • Northern harrier • Long-billed curlew, in flight • Upland sandpiper • Snow geese • Sharp-tailed grouse, male display postures • Greater prairie-chicken, male display postures • American bittern, pied-billed grebe, double-crested cormorant, American white pelican, sandhill crane, and whooping crane • Long-billed curlew and piping plover • Forster’s terns, mating • Ferruginous hawk • Burrowing owl • Prairie falcon and green-winged teal • Loggerhead shrike • Grasshopper sparrow • Savannah sparrow, clay-colored sparrow, lark bunting, grasshopper sparrow, and horned lark • Eastern and western meadowarks and bobolink • Baltimore oriole, Bullock’s oriole, and hybrid phenotypes Photographs: Long-billed curlew, adult female flying • Trumpeter swan • Trumpeter swan family • Wood duck, male • Northern pintail, males • Sharp-tailed grouse, male • Greater prairie-chicken, male • Pied-billed grebe, adult • Eared grebe, adults • Clark’s and western grebe, adults • Sora, adult • Black-necked stilt, adult • American avocet, adult • Upland sandpiper, adult • Long-billed curlew, adult female • Long-billed dowitcher, adults • Wilson’s snipe, adult • Wilson’s phalarope, adults • American bittern, adult male • Great blue heron, adult • Black-crowned night-heron, adult • Swainson’s hawk, adult • Great horned owl, adult • Burrowing owl, adult • Loggerhead shrike, adult • Horned lark, adult • Cliff swallow, adults • Grasshopper sparrow, male • Lark sparrow, adult • Yellow-headed blackbird, male • Red-winged blackbird, male • Common yellowthroat, male
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ASTOR C. L. BREHM (1787-1864) de-scribed hundreds of species from his native haunts near Thuringen, Germany, at a time when our current concept of species as populations unified by repro-ductive compatability was in its infancy. Brehm's descriptions include 14 different species of House Sparrows alone, and re-flect the then common view of species as "types," rigidly defined by appearance, and mostly lacking variation. We now recognize that within species variation is more the rule than the exception, and is in some instances a result of natural selec-tion At least 315 subspecies of North American breeding birds, including Har-lan's Hawk (Buteo jamaicensis harlani), were described initially as full species (Mayr and Short 1970). Different species may show different amounts of variation both locally and throughout their ranges. This requires us to learn not only the prin-cipal species characteristics, but also the nature and geographic distribution of its variation. Although the work of early naturalists such as Brehm, and in our own country Alexander Wilson and John James Audubon, as seen in hindsight, gave rise to a classification top-heavy with species, their focus on variation re-mains a modem concern, providing in-sight into relationships of populations both within and between species. The Red-tailed Hawk (Buteo jamai-censts) is one of several North American Buteo species that show sufficient geo-graphic variation to warrant naming of subspecies (polytypy), as well as discon-tinuous variation within local populations (polymorphism). The subspecies B. j. harlani breeds in portions of Alaska and western Canada where relatively few ob-servers have an opportunity to become familiar with its plumage variations.
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Species compositions of populations along a transect across a narrow hybrid zone between Ranidella insignifera‡ and R. pseudinsignifera‡ were determined using diagnostic enzyme loci and multivariate analysis of skeletal parameters. These were compared with subjective assessments of male mating call choruses in the same populations. The three independent characters all demonstrated a sharp transition from one species to the other over a distance of 24 km indicating some barrier to gene flow between the species beyond this narrow hybrid zone. It is suggested that the contact between the two species is a relatively old and stable one. Possible explanations for the maintenance of the 480 km parapatric boundary between the two species are examined.
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Variation in eight morphological variables was analysed for the three New Zealand species of oystercatchers, Haematopus ostralegus finschi, Martens, H. unicolor, Forster, and H. chathamensis, Hartert. Within species, significant size variation was detected among age classes and between the sexes, making it necessary to use measurements only from adults and to treat the sexes separately in ensuing taxonomic comparisons. Analysis of morphological variation in hybridizing forms of H. unicolor suggests that gene exchange between the parental black and pied phases is extensive. Univariate and multivariate statistical analyses isolated three phenetic entities, consistent with three species as proposed in recent classification.
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The Tete veld rat Aethomys ineptus Thomas & Wroughton, 1908 is a newly recognized, widely distributed species in southern Africa. Analysis of geographic variation among samples of A. ineptus from southern Africa across a more comprehensive geographical range than has previously been considered suggests that the species has a clinal pattern of variation in which overall cranial size was positively and significantly correlated with longitude. While the suggested clinal pattern of cranial size variation may be valid, the status of some operational taxonomic units, however, may require further refinement involving additional sampling as well as other systematic techniques, such as DNA analysis, cytogenetics and geometric morphometrics. These additional studies may have to include geographic information systems, step-wise multiple regression, and trend-surface analysis involving a wide range of environmental parameters to identify factors that may explain the nature and extent of the delineated pattern of geographic variation within A. ineptus from southern Africa. Consequently, the seven previously recognized subspecies recently assigned to A. ineptus in southern Africa (A. chrysophilus tzaneenensis Jameson, 1909; A. c. pretoriae Roberts, 1913; A. c. magalakuini Roberts, 1926; A. c. capricornis Roberts, 1926; A. c. tongensis Roberts, 1931; A. c. fouriei Roberts, 1946; and A. c. harei Roberts, 1946) are only provisionally synonymized.
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Both nongeographic and geographic variation was assessed in southern banner-tailed kangaroo rats of the nominal species Dipodomys phillipsii and D. ornatus . Univariate and multivariate analyses were employed in consideration of geographic variation. D. ornatus is arranged as a subspecies of D. phillipsii, in which four races (phillipsii, ornatus, perotensis, and oaxacae) are recognized. Some observations on natural history also are included.
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Aim The aim of this study is to test whether Bergmann's rule, a general intraspecific tendency towards larger body size in cooler areas and at higher latitudes, holds for birds throughout the world. Location This study includes information on species of birds from throughout the world. Methods I gathered data on body size variation from the literature and used two general meta-analytical procedures to test the validity of Bergmann's rule in birds: a modified vote-counting approach and calculation of overall effect sizes. Related species may show similar body size trends, thus I performed all analyses using nonphylogenetic and phylogenetic methods. I used tests of phylogenetic signal for each data set to decide which type of statistical analysis (nonphylogenetic or phylogenetic) was more appropriate. Results The majority of species of birds (76 of 100 species) are larger at higher latitudes, and in cooler areas (20 of 22 species). Birds show a grand mean correlation coefficient of +0.32 for body size and latitude, and −0.81 for body size and temperature, both significant trends. Sedentary species show stronger body size trends in some, but not all, analyses. Neither males nor females consistently have stronger body size trends. Additionally, the strength of body size trends does not vary with latitude or body mass. Conclusions Bergmann's rule holds for birds throughout the world, regardless of whether temperature or latitude (as a proxy) is used. Previous studies have suggested that Bergmann's rule is stronger for sedentary than migratory species, males than females and temperate than tropical taxa. I did not find strong support for any of these as general themes for birds, although few studies of tropical taxa have been conducted. The processes responsible for Bergmann's rule remain somewhat of a black box; however, fasting endurance is probably a more important factor than the traditional hypothesis of heat conservation.
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Reported is an evaluation (using discriminant and principal component analyses) of the incidence of interbreeding occurring (1) between populations of eastern and western meadowlarks, Sturnella magna and S. neglecta, respectively, from the central and southern Great Plains, and (2) between neglecta and an isolated southwestern population of magna (S. m. lilianae ) from the desert grassland of west Texas and eastern New Mexico. Individuals in reference samples taken out of sympatry could be segregated sufficiently to leave a distinct phenetic gap between groups. Evaluation of specimens taken in sympatry also revealed phenetic gaps separating both pairs of meadowlarks, indicating that their genetic integrity is being maintained in both areas of sympatry. Nonetheless, certain specimens from both areas of contact fell in phenetic positions highly intermediate to the reference specimens and were presumed to be of mixed ancestry. There was an apparently higher incidence of intermediate females than males, and it is suggested that females of mixed ancestry have a greater probability of survival than males in the polygynous meadowlarks. The geographic distribution of 16 of the most intermediate specimens from the plains sympatry was such that incidence of intermediates from the Platte River drainage was two to three times higher than that for other drainage systems. Coincidentally, the flood plains of the Platte River system were the only ones examined along which magna was not more or less continuously distributed up to its westernmost point of occurrence. Along the Platte, magna was found only in several small and isolated colonies in which appropriate mate selection may have been rendered difficult by the low numbers of conspecifics and the presumed year to year instability of these colonies. Song was thought to play an important role in selection of conspecific mates. In both zones of sympatry the meadowlarks maintain interspecific territories, and song is important in territory establishment and maintenance. Yet, there has been no convergence toward a common song type in either of the zones of sympatry, despite a considerable information loss when songs are used in interspecific communication. Presumably strong selection opposing interspecific matings has maintained the remarkable differences in songs of these siblings in both areas of sympatry.
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Principal Component Analysis of Variation in Form within Oncaea conifera Giesbrecht, 1891, a Species of Copepod(Crustacea). Syst. Zool. 22:141– 156.— The variability in form within the species Oncaea conifera is analysed using principal component analysis. A rapid and repeatable method of measurement was developed. The groupings of operational taxonomic units(OTUs)in both the analysis of taxonomic distance and the principal component analysis are found to be similar and in agreement with the subjective grouping with minor anomalies. The effect of removing an aberrant OTU from each analysis was investigated. The trends in variability of “important” measurements(as revealed by the principal component analysis)indicate a complex pattern of between-group variability, thus suggesting that the observed variability is not under the control of a simple polymorphism. The possibilities of more complex genetic control or of genetic isolation, are discussed.
Article
1. An earlier study (Sokal, 1952) of character variation in the gall making aphid Pemphigus populi-transversus was extended to investigate character relations among localities in eastern North America. 2. Twenty-three localities of 15 galls each ranging from Massachusetts to Kansas and Wisconsin to Florida were used in the study. Eighteen characters were measused on two alates per gall. The study involved 12,420 measurements on 690 aphids. 3. Hierarchic analyses of variance showed that almost every character differed significantly among localities and most differed among galls within localities. These analyses permitted the study of the percentage of variation attributable to each level of variation; this is shown in table 1. 4. The hierarchic structure of these data made it possible to compute five separate correlation matrices, product-moment matrices at the intragall, intergall, and interlocality levels, and component correlation matrices at the intergall and interlocality levels. Appreciable differences among the three levels of correlation were observed. The product-moment correlation matrices at the higher levels appear to be intermediate between the next lower matrix and the appropriate component correlation matrix. 5. The differences in the correlation matrices are reflected by cluster analyses of some of the highest correlations (shown in figs. 2, 3, and 4). The highest correlations at the intragall level exhibit a regional morphogenetic pattern, while those at the intergall and interlocality levels appear to be adaptational trends not necessarily of adjacent structures and not immediately related to morphogenesis. 6. Multiple factor analysis with rotation to simple structure was undertaken on all correlation matrices. Partial results are shown in table 5. In all but one correlation matrix, three common factors appear to account for nearly all of the observed correlations. 7. The differences in factor pattern must be caused by different genetic and environmental variation patterns at the different hierarchic levels in this study. The implications of this phenomenon for sampling problems in studies of geographic variation is discussed. 8. By means of factor analysis one is able to determine a few common factors, which represent the variational patterns in the species at the level which one wishes to study.
Article
Electrophoretic variation in 36 proteins controlled by 41 genetic loci was analyzed in 99 house mice representing two subspecies (M. m. domesticus and M. m. musculus) from six geographic regions of the Jutland Peninsula, Denmark. Of the 36 proteins, 16 or 44% are polymorphic for two or three alleles in one or more of the six samples. In terms of the 41 controlling genetic loci, 17 or 41% are polymorphic. This is the best estimate of the proportion of polymorphic loci in the genome of the species as a whole, and is closely similar to values available for Drosophila and humans. Individual Danish mice are, on the average, heterozygous at 8.5% of their loci. At 13 of the 17 polymorphic loci there is a substantial difference in allele frequencies between the subspecies, and, at six of these loci, alternate alleles are fixed or nearly so in the two subspecies, or an allele that is almost fixed in one subspecies does not occur in the other subspecies. This degree of genetic difference, occurring in a geographic region over which there is no apparent variation in the external environment, is attributed, in major part, to intersubspecific variation in genetic environment, with identical alleles having different selective values and equilibrium frequencies in the two subspecies. In overall genetic character, as reflected by Sneath's coefficient of similarity, M. m. domesticus of the southern Jutland Peninsula is more similar to M. m. brevirostris, introduced to North America from Europe, than to M. m. musculus of the northern Jutland Peninsula. This finding, which is consistent with the taxonomic assignment of M. m. domesticus and M. m. musculus to different subspecies groups, is interpreted as evidence of cohesion of coadapted gene pools in populations of the two subspecific groups. Evidence provided by Hubby and Throckmorton (1968) that sibling species of Drosophila differ, on the average, at 50% of their loci and the present demonstration of significant intersubspecific differences at 32% of 41 loci examined in Danish house mice are advanced in support of the thesis that major reorganizations of gene pools normally accompany the speciation process.
Article
Thesis (Ph. D.) - Cornell Univ., June, 1959.
Article
The northern form of the common grackle, Q. q. versicolor, mhabiting pine forest and mixed pine-hardwood forest, ranges south in Louisiana to the latitude of Baton Rouge, Opelousas, and De Ridder, where it interbreeds freely in a narrow zone with the southern form, Q. q. quiscula, inhabiting cypress-tupelogum swamp forest and coastal marshes, to produce viable and fertile hybrids. Analysis of geographical variation in four color characters in 637 males from 21 sample areas in Louisiana and the application of discriminant function analysis to form a weighted hybrid index demonstrate that a complete transition in color characters between Q. q. versicolor and Q q. quiscula occurs between 30⚬ and 31⚬ N latitude. Populations of the northern form are only slightly introgressed with genes from Q q. quiscula, whereas those of the southern form are heavily introgressed with genes from Q. q. versicolor Geographical variation in characters of size is smoothly clinal, lacking the step-cline feature seen in characters of color. The position and width of the hybrid zone in Louisiana is related to the pattern of distribution of the major vegetation types. Where the mixed pine-hardwood habitat of Q q. versicolor contacts the cypress-tupelogum habitat of Q q. quiscula, the zone is 15 miles wide, but it widens to 40 miles where the two habitat types are separated by areas of disturbed bottomland hardwood forest. A comparison of morphological variation in material taken in the period 1890-1942 with that taken in the period 1962-1965 demonstrates that, since the 1930's, the zone of hybridization in Louisiana has shifted northward approximately 20 miles. Apparently the northward shift was not accompanied by a change in the width of the zone. In the absence of evidence of the functioning of reproductive isolating mechanisms, the extraordinary narrowness and temporal stability of width of the zone of hybridization can only be explained in terms of the hybrid inferiority hypothesis.
Hist; Mani-toba Mus. of Man and Nature Moore Laboratory Ornithology (Occidental College); Museum of Vertebrate Zool
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Field Mus. Nat. Hist; Mani-toba Mus. of Man and Nature; Montana State Univ. Mus. Zool.; Moore Laboratory Ornithology (Occidental College); Museum of Vertebrate Zool. (Univ. California);
Canada (Ottawa); Peabody Museum
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Na-tional Mus. Canada (Ottawa); Peabody Museum (Harvard Univ.);
Audubon and his journals. Dover Publications (reprint)
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AUDUBON, MARIA R. 1897. Audubon and his journals. Dover Publications (reprint). New York. Vol. 2, v-vii, 3-554.
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BAIRD, S. F., T. M. BREWER, AND R. RIDGWAY. 1874. A history of North American birds. Little Brown & Co., Boston. Vol. 2, i-vi, 1-590.
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BENT, A. C. 1908. Summer birds of southwest-ern Saskatchewan (Pt. 2). Auk, 25:25-35.
Boston, Pp. v-lii, 1-504. at Russian Archive on February 3Davian Behavior Complex" in grounds squirrels The road to Santa Fe
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DEVOTO, B. 1953. The journals of Lewis and Clark. Houghton Mifflin Co., Boston, Pp. v-lii, 1-504. at Russian Archive on February 3, 2014 http://sysbio.oxfordjournals.org/ Downloaded from VARIATION AND EVOLUTION IN ORIOLES 351 DICKERMAN, R. W. 1960. "Davian Behavior Complex" in grounds squirrels. J. Mammalogy, 41:403. GREGG, K. L. 1952. The road to Santa Fe. Univ. New Mexico Press, Albuquerque. Pp. v-viii, 1-280.
An account of an expedition from Pittsburgh to the Rocky Mountains H. C. Carey and I
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The ribbon-tailed bird of paradise (Astrapia mayeri) and its allies
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Peter's check-list of birds of the world
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Geographic variation of red-winged blackbirds in central North America Systematic and evolutionary aspects of interbreeding between the orioles Icterus galbula and I. bullockii in North America A comparison of metabolism and evaporative water loss of Baltimore and Bullock orioles
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POWER, D. M. 1970. Geographic variation of red-winged blackbirds in central North America. Univ. Kansas Publ. Mus. Nat. Hist., in press. RISING, J. D. 1968. Systematic and evolutionary aspects of interbreeding between the orioles Icterus galbula and I. bullockii in North America. Ph.D. Thesis, Univ. Kansas. 80pp. RISING, J. D. 1969. A comparison of metabolism and evaporative water loss of Baltimore and Bullock orioles. Comp. Biochem. Physiol., 31: 915-925.
Hybridization and isolating mechanisms Vertebrate speciation Hy-bridization in the orioles of the Great Plains
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SIBLEY, C. G. 1961. Hybridization and isolating mechanisms. Pp. 69-88, in Blair, W. F. (ed.), Vertebrate speciation. Univ. Texas Press, Austin. SIBLEY, C. G., AND L. L. SHORT, JR. 1964. Hy-bridization in the orioles of the Great Plains. Condor, 66:130-150.
Oddly plumaged orioles from western Oklahoma
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Oriole hybridization in Oklahoma
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Occurrence of voles, mice, and rats (Muridae) in Denmark, with a special note on a zone of intergradation between two sub-species of the house mouse
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URSIN, E. 1952. Occurrence of voles, mice, and rats (Muridae) in Denmark, with a special note on a zone of intergradation between two sub-species of the house mouse (Mus musculus L.).
A distributional sur-vey of the birds of Sonora
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VAN ROSSEM, A. J. 1945. A distributional sur-vey of the birds of Sonora, Mexico. Occas. Pap. No. 21, Louisiana State Univ., Baton Rouge. Pp. 3-379.