Effects of fire and grazing on grasshopper sparrow nest survival

ABSTRACT Patch-burn grazing is a management framework designed to promote heterogeneity in grasslands, creating more diverse grassland structure to accommodate the habitat requirements of many grassland species, particularly grassland birds. Published studies on the effects of patch-burn grazing on passerines have been conducted on relatively large (430-980 ha pastures), contiguous grasslands, and only 1 of these studies has investigated the reproductive success of grassland birds. We assessed the effects of the patch-burn grazing and a more traditional treatment on the nesting ecology of grasshopper sparrows (Ammodramus savannarum) in small (<37 ha pastures) grasslands located in southern Iowa from May to August of 2008 and 2009. The study pastures were grazed from May to September and prescribed burns were conducted in the spring. We investigated the effects of treatments on clutch size and modeled grasshopper sparrow nest survival as a function of multiple biological and ecological factors. We found no difference in clutch size between treatments; however, we did find a reduction in clutch size for nests that were parasitized by brown-headed cowbirds (Molothrus ater). Constant daily survival rates were greater in patch-burn grazed pastures than in grazed-and-burned pastures (patch-burn grazed rate x ¼ 0:930 and grazed-and-burned rate x ¼ 0:907). Competitive survival models included year, stage of nest, nest age, and cool-season grass (csg) abundance within 5 m of the nest. Overall, csg abundance had the greatest effect on survival and had a negative influence. Although survival rates were highest in patch-burn grazed pastures, multiple factors influenced grasshopper sparrow survival. Nest survival rates for both treatments were relatively low, and variables other than treatment were more instrumental in predicting grasshopper sparrow survival. We recommend decreasing overall vegetation cover if increasing nesting habitat for grasshopper sparrows is a management goal. In addition, we recommend further investigation of heterogeneity management in fragmented landscapes to better understand how it affects biodiversity in relatively small management units that typify grassland habitats in the Midwest. ß 2011 The Wildlife Society

Appendix A. Site locations, biocontrol histories, soil nutrient data and percent cover estimates.

Site locations, biocontrol histories, soil nutrient data and percent cover estimates

Data from: Hybridization alters early life-history traits and increases plant colonization success in a novel region

Hybridization is hypothesized to promote invasiveness, but empirical tests comparing the performance of hybrid versus parental taxa in novel regions are lacking. We experimentally compared colonization ability of populations of wild radish (Raphanus raphanistrum) versus populations of advanced-generation hybrids between wild and cultivated radish (R. sativus) in a southeast Texas pasture, well beyond the known invasive range of hybrid radish. We also manipulated the strength of interspecific competition to better generalize across variable environments. In both competitive environments, hybrid populations produced at least three times more seeds than wild radish populations, a distinction that was driven by greater hybrid seedling emergence, earlier hybrid emergence and more hybrid seedlings surviving to flower, rather than by greater individual fecundity. Flowering duration in hybrids was less negatively affected by competition than it was in wild radishes, while early emergence was associated with subsequent high seed output in both biotypes. Our data show that hybridization can enhance colonization success in a novel region, and, by comparison with previous studies, that the life-history traits enhancing hybrid success can differ across regions, even for lineages originating from the same hybridization event. These results imply a much larger arena for hybrid success than previously appreciated

Genetic and Morphological Comparisons of Lesser Celandine (Ficaria verna) Invasions Suggest Regionally Widespread Sexual Reproduction

Both asexual and sexual reproduction can provide important keys to the success of invasive species. A species with potential for both is lesser celandine (Ficaria verna), a European native with multiple subspecies that have been introduced in North America as ornamentals and escaped cultivation. Asexual reproduction via bulbils is prolific in many introduced populations of lesser celandine, with sexual reproduction reportedly rare. Although genetic and morphological diversity of European celandine has been studied, few have examined invasive North American populations. We aimed to document introduced genotypic and phenotypic diversity at a regional scale. We first compared sequence-related amplified polymorphism (SRAP) genotypes of 64 individuals collected from Columbus, Cincinnati, and Cleveland, OH. In a second experiment, we phenotyped 129 individuals from the same regions and from Louisville, KY, measuring traits in an outdoor common garden experiment. The SRAP markers were highly polymorphic and revealed surprising genetic differentiation. Genetic and trait variation were both structured across regions, but we also saw high variation within regions. Cleveland populations differed the most genetically and morphologically. Nearly every individual made asexual bulbils, and many individuals that flowered produced expanded achenes. Trait data suggested subspecies verna or ficariiformis occur in these regions. Genetic admixture within regions and within individuals, along with achene expansion, suggests sexual reproduction may be widespread. Sexual and asexual propagules may spread by different vectors, and our resistance analyses indicated water dispersal and habitat availability contribute to genetic structure. These findings suggest that celandine has substantial potential for further spread and evolutionary change

Radish DATA_IND

Radish DATA_IN

Radish DATA_PLOT

Radish DATA_PLO

Data from: QTL mapping identifies candidate alleles involved in adaptive introgression and range expansion in a wild sunflower

The wild North American sunflowers Helianthus annuus and H. debilis are participants in one of the earliest identified examples of adaptive trait introgression, and the exchange is hypothesized to have triggered a range expansion in H. annuus. However, the genetic basis of the adaptive exchange has not been examined. Here, we combine quantitative trait locus (QTL) mapping with field measurements of fitness to identify candidate H. debilis QTL alleles likely to have introgressed into H. annuus to form the natural hybrid lineage H. a. texanus. Two 500-individual BC1 mapping populations were grown in central Texas, genotyped for 384 single nucleotide polymorphism (SNP) markers and then phenotyped in the field for two fitness and 22 herbivore resistance, ecophysiological, phenological and architectural traits. We identified a total of 110 QTL, including at least one QTL for 22 of the 24 traits. Over 75% of traits exhibited at least one H. debilis QTL allele that would shift the trait in the direction of the wild hybrid H. a. texanus. We identified three chromosomal regions where H. debilis alleles increased both female and male components of fitness; these regions are expected to be strongly favoured in the wild. QTL for a number of other ecophysiological, phenological and architectural traits colocalized with these three regions and are candidates for the actual traits driving adaptive shifts. G × E interactions played a modest role, with 17% of the QTL showing potentially divergent phenotypic effects between the two field sites. The candidate adaptive chromosomal regions identified here serve as explicit hypotheses for how the genetic architecture of the hybrid lineage came into existence

Linkage Map

This Excel file contains the estimated linkage map for the H. a. annuus x H. debilis backcross1 mapping populations. The position of each marker on the linkage group is given in centiMorgans (cM)

Phenotype and SNP Genotype Data

This Excel file contains information on 906 field-grown backcross1 sunflower plants. Field site is identified in column Z. Plants are identified by the number in column AA. Columns A-Y contain field-measured trait data. Trait names correspond to the abbreviations in Table 1 of the associated manuscript. Columns AH - HO contain SNP genotype data; A = H. a. annuus allele; D = H. debilis allele