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Diana Tomback
My research and that of my students focuses on the evolution, ecology,
and population biology of several species of white pines (genus Pinus,
subgenus Strobus, family Pinaceae) and the nutcrackers or jays (family
Corvidae) that disperse their seeds. Basically, we work at the
plant-animal interface, studying both the behavior and ecology of the
seed dispersers and the ecology and population biology of the pines that
they disperse. Much of our work has involved the coevolved mutualism
between whitebark pine (Pinus albicaulis) and Clark’s
Nutcracker (Nucifraga columbiana). My initial studies documented
the fundamental nutcracker-whitebark pine interaction. This led to more
detailed investigations of the impact of seed dispersal by nutcrackers
on the ecology and population biology of pines. Investigations made use
of stand-replacing fires to examine patterns of forest regeneration
resulting from nutcracker seed dispersal, and other studies were based
on allozyme analyses of tree growth forms and fitness comparisons among
them.
Recently, information on whitebark pine ecology has become particularly
valuable as a consequence of major population declines in the northern
Rocky Mountains (and elsewhere throughout its range). These losses
result from a combination of past fire exclusion policies and white pine
blister rust, a fatal fungal disease introduced from Europe early this
century (see "Trouble at timberline," Natural History,
November 1998). Management strategies, based in part on our previous
work, are being devised and implemented by colleagues at the Fire
Sciences Laboratory, USDA Forest Service, Rocky Mountain Research
Station.
Since 1996, my lab and that of Dr. Leo Bruederle’s at UCD have joined
forces to investigate the evolutionary origins of seed dispersal by
corvids in pines. We are studying the seed dispersal ecology and
population structure of the Pinus flexilis-P. strobiformis-P.
ayacahuite (limber pine-southwestern white pine-Mexican white pine)
white pine species complex to elucidate the environmental selection
pressures that favor the transition from wind-dispersal of seeds to
bird-dispersal. Within Pinus ayacahuite, there are pine
populations with seeds adapted for primary dispersal by wind and seeds
that appear transitional to corvid-mediated primary seed dispersal.
Recent Research Interests
- Effectiveness
of seed dispersal by wind vs. seed dispersal by nutcrackers (click for
photos)
- functional relationship between distance from seed source and
density of post-fire whitebark pine regeneration; forest process
model incorporating this information
- age structure and time frame of whitebark pine post-fire
regeneration in comparison to wind-dispersed forest associates
- effects of delayed seed germination on patterns of post-fire
whitebark pine recruitment in the Greater Yellowstone Area
- growth form analysis of whitebark, limber (P. flexilis) and
Swiss stone pine (P. cembra): the "tree cluster"
form arises from multi-seed nutracker caches
- fitness comparison among growth forms in limber pine
- genetic population structure of whitebark pine in the Greater
Yellowstone Area
- infection incidence of white pine blister rust (Cronartium
ribicola) in post-fire whitebark pine seedlings
Professional Information
Professor
Department
of Biology
Univ.
of Colorado at Denver
Recent publications:
Tomback, D.F., A.J. Anderies, K. S. Carsey, M. L. Powell, and S.
Melmann-Brown.
Delayed seed germination in whitebark pine and regeneration patterns
following the Yellowstone fires. Ecology, in press.
Tomback, D. F., S. F. Arno, and R. E. Keane, editors. 2000 Whitebark
pine communities: ecology and restoration. Island Press, Washington,
D. C.
Feldman, R., D.F. Tomback, and J. Koehler. 1999. Cost of mutualism:
Competition, tree morphology, and pollen cone production in limber
pine clusters. Ecology, 80:324-329.
Tomback, D.F. 1998. Clark’s Nutcracker (Nucifraga columbiana).
In The Birds of North America, No. 331 (A. Poole and F. Gill, eds.).
The Academy of Natural Sciences, Philadelphia, PA, and The American
Ornithologists’ Union, Washington, DC, 24 pp.
Johnson, S.A., L.P. Bruederle, and D.F. Tomback. 1998. A mating system
conundrum: hybridization in Apocynum (Apocynaceae). American Journal
of Botany 85:1316-1323.
Bruederle, L.P., D.F. Tomback, K.K. Kelly, and R.C. Hardwick. 1998.
Population genetic structure in a bird-dispersed pine, Pinus
albicaulis Engelm. (Pinaceae). Canadian Journal of Botany
76:83-90.
Torick, L.L., D.F. Tomback, and R. Espinoza. 1996. Occurrence of
multi-genet tree clusters in "wind-dispersed" pines.
American Midland Naturalist 136:262-266.
Fleck, D.C., and D.F. Tomback. 1996. Tannin and protein in the diet of
a food-hoarding granivore, the Western Scrub Jay. The Condor
98:474-482.
Tomback, D.F. 1995. Possible breeding record for Clark’s Nutcracker
in northwestern Nebraska in 1987. The Nebraska Bird Review 63:114-115.
Tomback, D.F., J.K. Clary, J. Koehler, R.J. Hoff, and S.F. Arno. 1995.
The effects of blister rust on post-fire regeneration of whitebark
pine: the Sundance Burn of northern Idaho. Conservation Biology
9:654-664.
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