A method is described for the extraction of phytochrome from chlorophyllous shoots of Avena sativa L. Poly(ethyleneimine) and salt fractionation are used to reduce chlorophyll and to increase the phytochrome concentration sufficiently to permit spectral and immunochemical analyses. The phototransformation difference spectrum of this phytochrome is distinct from that of phytochrome from etiolated shoots in that the maximum in the red region of the difference spectrum is shifted about 15 nm to a shorter wavelength. Immunochemical probing of electroblotted proteins (Western blotting), using a method sensitive to 50 pg, demonstrates the presence of two polypeptides in green tissue that bind antiphytochrome antibodies: a predominant species with a relative molecular mass (Mr) of 118000 and a lesser-abundant 124000-Mr polypeptide. Under nondenaturing conditions all of the 124000-Mr species is immunoprecipitable, but the 118000-Mr species remains in the supernatant. Peptide mapping and immunochemical analysis with monoclonal antibodies show that the 118000-Mr species has structural features that differ from etiolated-oat phytochrome. Mixing experiments show that these structural differences are intrinsic to the molecular species from these two tissues rather than being the result of post-homogenization modifications or interfering substances in the green-tissue extracts. Together the data indicate that the phytochrome that predominates in green-tissue has a polypeptide distinct from the well-characterized molecule from etiolated tissue.

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We studied between-year dispersal of adult females within a population of cooperatively breeding Red-cockaded Woodpeckers (Picoides borealis) in the Sandhills of North Carolina, using data collected between 1980 and 1995. We tested four hypotheses about the cause of breeding dispersal: inbreeding avoidance, mate choice, site choice, and social constraints. In addition, we assessed relationships among age, reproductive failure, and breeding dispersal, and we estimated cost of breeding dispersal by plotting mortality against dispersal rate as a function of circumstance.Breeding dispersal in the population that we studied is associated with multiple factors. Inbreeding avoidance influences dispersal of females whose sons inherit their natal territories. Mate choice influences dispersal of females whose mates have died; these females acquire older, higher quality mates by dispersing. In this study, there was no clear relationship between site choice and breeding dispersal. Social constraints do not appear to affect breeding dispersal in this population: no evidence was found to suggest that dispersal is associated with female-female competition, within-group competition for resources, or reproductive competition between mothers and helper sons.The effect of reproductive failure on breeding dispersal changes with female age. Reproductive failure is associated with breeding dispersal in young females only (those Ͻ3 yr old). Estimated mortality rates for breeding females that attempt to disperse vs. those that do not attempt to disperse were 59% and 26%, respectively; the difference between those rates is the estimated cost of breeding dispersal in this population, an additional 33% probability of mortality. Thus, breeding females more than double their risk of mortality by dispersing.

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Abstract. Estimates of distributions of natal dispersal distances and juvenile recruitment rates in open populations are strongly influenced by the extent and shape of the areas sampled. Techniques to improve biased dispersal and survival estimates include area-ratio methods based on weighting observations by sampling effort, the extent and shape of the area sampled, and the amount and distribution of preferred habitat surrounding the area sampled. We partitioned territories within the boundaries of a large, almost geographically closed, population of individually marked Red-cockaded Woodpeckers (Picoides borealis) and estimated dispersal and survival parameters from hypothetical smaller study areas (sampling areas) of varying sizes and shapes in order to examine whether an area-ratio method provides accurate or improved estimates of juvenile dispersal distance and survival. Non-aggregated sampling areas resulted in the detection of fewer dispersal events, but because of their large spatial extent, produced unbiased dispersal estimates. The use of aggregated sampling areas (circular or linear) resulted in the detection of higher numbers of dispersal events, but produced biased dispersal estimates that were generally improved by the area-ratio method. Area-ratio corrections usually provided better estimates of median dispersal distance than uncorrected estimates. Survival to breeding was usually underestimated and often not improved by the area-ratio method, regardless of extent and shape of the sampling area. Estimates of juvenile survival to breeding were improved by assuming that rates of emigration were equivalent to immigration, and correcting survival estimates accordingly. Small, local studies should use an area-ratio method to improve their estimates of median dispersal distance. Because the correction method estimates relative, but not absolute, numbers of individuals dispersing across distance categories, the area-ratio method should not be used for estimating survival. Non-aggregated sampling areas may be an effective design to increase spatial extent (and thus decrease bias) without proportionately increasing the amount of habitat sampled.