| responses of songbirds to aerial spraying of the microbial insecticide bacillus thuringiensis var. kurstaki (foray 48b) on vancouver island, british columbia, canada. | use of bacterial insecticides containing bacillus thuringiensis var. kurstaki (btk) is gaining popularity as an environmentally safe control measure against lepidopteran pests, but indirect effects on nontarget organisms through reduced prey base have received little attention. aerial spraying of btk (foray 48b) over a 12,803-ha area on southeastern vancouver island (bc, canada) in may to june 1999 as part of a gypsy moth (lymantria dispar) control program provided us with an opportunity to exam ... | 2002 | 12152767 |
| female song sparrow, melospiza melodia, response to simulated conspecific and heterospecific intrusion across three seasons. | to investigate female responses to territorial intrusion i presented female song sparrows with either a simulated female song sparrow intrusion or a simulated spotted towhee, pipilo maculatus, intrusion as a control during either the prebreeding, breeding or postmoult seasons. aggressive and nonaggressive behaviours and vocalizations were compared between intrusion types and across seasons. principle components analysis suggested that female responses fell into three categories: (1) responses di ... | 2000 | 10715177 |
| heterogeneity and concordance in locus-specific differentiation and introgression between species of towhees. | the maintenance or breakdown of reproductive isolation is an observable outcome of secondary contact between species. in cases where hybrids beyond the f1 are formed, the representation of each species' ancestry can vary dramatically among genomic regions. this genomic heterogeneity in ancestry and introgression can offer insight into evolutionary processes, particularly if introgression is compared in multiple hybrid zones. similarly, considerable heterogeneity exists across the genome in the e ... | 2017 | 28009485 |
| genomic variation in cline shape across a hybrid zone. | hybrid zones are unique biological interfaces that reveal both population level and species level evolutionary processes. a genome-scale approach to assess gene flow across hybrid zones is vital, and now possible. in mexican towhees (genus pipilo), several morphological hybrid gradients exist. we completed a genome survey across one such gradient (9 populations, 140 birds) using mitochondrial dna, 28 isozyme, and 377 aflp markers. to assess variation in introgression among loci, cline parameters ... | 2012 | 23170209 |
| three-dimensional analysis of avian song control nuclei. | analysis of seasonal and developmental changes in the morphology of avian song control nuclei has traditionally been performed using two-dimensional (2-d) cross-sectional traces from brain sections. this method, although reliable, does not encompass the possibility that subdivisions of a nucleus might change in size to different degrees. three-dimensional (3-d) analysis of song nuclei under different conditions could provide insight on this issue. this approach could also be of value in guiding ... | 2002 | 12393163 |