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- Scofield, Douglas G., et al.
(författare)
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Foraging patterns of acorn woodpeckers (Melanerpes formicivorus) on valley oak (Quercus lobata N,e) in two California oak savanna-woodlands
- 2011
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 166:1, s. 187-196
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Tidskriftsartikel (refereegranskat)abstract
- Landscape characteristics and social behavior can affect the foraging patterns of seed-dependent animals. We examine the movement of acorns from valley oak (Quercus lobata) trees to granaries maintained by acorn woodpeckers (Melanerpes formicivorus) in two California oak savanna-woodlands differing in the distribution of Q. lobata within each site. In 2004, we sampled Q. lobata acorns from 16 granaries at Sedgwick Reserve in Santa Barbara County and 18 granaries at Hastings Reserve in Monterey County. Sedgwick has lower site-wide density of Q. lobata than Hastings as well as different frequencies of otherQuercus species common to both sites. We found acorn woodpeckers foraged from fewer Q. lobata seed source trees (K g = 4.1 ± 0.5) at Sedgwick than at Hastings (K g = 7.6 ± 0.6) and from fewer effective seed sources (N em* = 2.00 and 5.78, respectively). The differences between sites are due to a greater number of incidental seed sources used per granary at Hastings than at Sedgwick. We also found very low levels of seed source sharing between adjacent granaries, indicating that territoriality is strong at both sites and that each social group forages on its own subset of trees. We discovered an interesting spatial pattern in the location of granaries. At Sedgwick, acorn woodpeckers situated their granaries within areas of higher-than-average tree density, while at Hastings, they placed them within areas of lower-than-average tree density, with the outcome that granaries at the two sites were located in areas of similar valley oak density. Our results illustrate that landscape characteristics might influence the number of trees visited by acorn woodpeckers and the locations of territories, while woodpecker social behavior, such as territoriality, shapes which trees are visited and whether they are shared with other social groups.
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| 2. |
- Smouse, Peter E., et al.
(författare)
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Using Seedling and Pericarp Tissues to Determine Maternal Parentage of Dispersed Valley Oak Recruits
- 2012
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 103:2, s. 250-259
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Tidskriftsartikel (refereegranskat)abstract
- The spatial pattern of established seedlings yields valuable information about variation in fecundity, dispersal, and spatial structure of distributed recruits, but separating maternal and paternal contributions in monoecious species has been hampered by the “2 parent” problem. It is now possible to determine the maternal parentage of established recruits with genetic assay of maternally derived tissues of the seed or fruit, but the DNA of weathered maternal tissues often yields unreliable genotypes, reducing the practical range of such assay. We develop a mixed assay of seedling and seed (pericarp) tissues and illustrate it with distributed recruits of California valley oak (Quercus lobata Née). Detailed analysis indicates correct maternal assignment rates of canopy patch recruits of 56% (seedling assay only) versus 94% (mixed assay). For open patch recruits, maternal assignment rates were less than 50% (seedling assay only) versus 91% (mixed assay). The strategy of choice is to use seedling genotypes to identify a small set of credible parental candidates and then deploy 3–4 well-chosen pericarp/endocarp loci to reduce that list to a single obvious maternal candidate. The increase in the number of recruits available for subsequent analysis is pronounced, increasing precision and statistical power for subsequent inference.
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