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We collected blood for allozyme analysis from Northern Goshawks (Accipiter gentilis atricapillus) on the Kaibab Plateau in northern Arizona during 1991-1993 to quantify frequency of extra-pair fertilizations (EPFs). Northern Goshawks are socially monogamous, territorial, noncolonial, synchronous breeders, and their nests are relatively far apart, characteristics that suggest that EPFs should be low. We sampled 103 adults and 122 nestlings from 64 nests. Both putative parents were sampled at 39 nests, but we were able to capture and sample only one putative parent at 25 other nests (84%, female only: 16%, male only). Of the 39 complete families sampled, only 1 of 77 (1.3%) nestlings (or in 1 of 39 clutches, 2.6%)...
Biological invasions can be substantially influenced by the genetic sampling associated with a species? introduction. As a result, we assessed the genetic and evolutionary consequences of the entry and spread of the invasive grass Bromus tectorum (cheatgrass) across the United States midcontinent through an analysis of 54 populations, using enzyme electrophoresis. On average, these populations display 1.04 alleles per locus (A), 4.1% percent polymorphic loci per population (%P) and an expected mean heterozygosity (Hexp) value of 0.009. Heterozygotes, which have been rarely reported for B. tectorum in North America, occur in three populations in the midcontinent and are likely novel multilocus genotypes that arose...
Hybridization between the southwestern toad (Bufo microscaphus) and Woodhouse's toad (B. woodhousii) along the Agua Fria and Hassayampa rivers in central Arizona was investigated over a 3-yr period. Variation in allozymes and the pulse rate of male release calls was compared with morphological variation in these taxa and their hybrids. At two sites on the Agua Fria drainage, data on release calls, but not morphology, were concordant with allozyme evidence of hybridization. At a third site on the Agua Fria, morphological data, but not release calls, corroborated electrophoretic evidence of hybridization. Along the Hassayampa River, all lines of evidence indicated that there has not yet been any hybridization in an...