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Abstract The abiotic range limitation hypothesis states that species distributions are shaped by physiological constraints imposed by temperature and precipitation. To test this hypothesis, we assessed the impacts of climate on hatch rates by reciprocally translocating complete clutches of both Setophaga caerulescens (Black-throated Blue Warbler) and S. citrina (Hooded Warblers) across a local range boundary of S. caerulescens in the southern Appalachian Mountains. The S. caerulescens population occurs at the trailing edge of its breeding range, whereas the S. citrina population occurs near the core of its range. The hatching probability of S. caerulescens eggs declined from 0.93 ± 0.02 to 0.60 ± 0.07 when moved to S. citrina nests in warmer conditions. Translocation, however, had little effect on hatching probability of S. citrina eggs when moved to S. caerulescens nests in cooler environments. Thirteen reciprocal clutch translocations were performed; 17 clutches were moved as controls; and 49 nests were not manipulated. We monitored species-specific incubation behavior, measured microclimate conditions inside and outside nests using hygrochron iButtons, and examined the effects of temperature and humidity on nestling growth rates. Higher ambient temperatures had a greater effect on hatching probability than did humidity, but we were unable to determine if reduced hatching was caused by changes in temperature, humidity, or their interaction. We suggest that, in warmer conditions, S. caerulescens eggs in S. citrina nests may have been unable to cool sufficiently to avoid excessive water loss due to higher ambient temperatures but not a difference in relative humidity. Our finding that hatch rates of S. caerulescens declined when translocated to warmer conditions supports the hypothesis that distributions of trailing-edge populations are limited in part by climate effects on reproductive rates. 

Abstract Single‐nucleotide polymorphisms (SNPs) are preferred over microsatellite markers in many evolutionary studies, but have only recently been applied to studies of parentage. Evaluations ofSNPs and microsatellites for assigning parentage have mostly focused on special cases that require a relatively large number of heterozygous loci, such as species with low genetic diversity or with complex social structures. We developed 120SNPmarkers from a transcriptome assembled usingRNA‐sequencing of a songbird with the most common avian mating system—social monogamy. We compared the effectiveness of 97 novelSNPs and six previously described microsatellites for assigning paternity in the black‐throated blue warbler,Setophaga caerulescens. We show that the full panel of 97SNPs (meanH_o = 0.19) was as powerful for assigning paternity as the panel of multiallelic microsatellites (meanH_o = 0.86). Paternity assignments using the two marker types were in agreement for 92% of the offspring. Filtering individual samples by a 50% call rate andSNPs by a 75% call rate maximized the number of offspring assigned with 95% confidence usingSNPs. We also found that the 40 most heterozygousSNPs (meanH_o = 0.37) had similar power to assign paternity as the full panel of 97SNPs. These findings demonstrate that a relatively small number of variableSNPs can be effective for parentage analyses in a socially monogamous species. We suggest that the development ofSNPmarkers is advantageous for studies that require high‐throughput genotyping or that plan to address a range of ecological and evolutionary questions.