Abstract Detail



Ecology

Marquardt, Paula [1], Miranda, Brian [1], Willyard, Ann [2], Prom, Ben [1], Telewski, Frank [3].

Climatic Impacts on the Genetic Structure and Annual Growth of Sky Island Pines.

Ponderosa pine of the southwestern Sky Islands, USA are distinctive because of their desert mountain ecology.  Not only do steep climate gradients permit the coexistence of species filling different niches, but discontinuous distributions restrict gene flow and increase population differentiation through stochastic and selective processes.   We collected ponderosa pine tree-rings from three contact zones near Tucson, AZ for cross-dating and response function analysis, and needle tissue for genetic analysis with six-chloroplast microsatellite markers.  Frequencies for paternal multi-locus haplotypes were examined for three ponderosa pine taxa: 5-needle Pinus arizonica, 3-needle Pinus ponderosa var. brachyptera, and a mixed-needle putative hybrid.  Needle tissue for genetic data was also collected at lower and higher elevations to describe haplotype frequencies in populations of pure 5- and 3-needle types, respectively.  Overall, we determined haplotype frequencies for 21 populations (by site, taxon and age) from 427 individual trees. The morphological data (average needle counts) along with chloroplast haplotype frequencies explained 90% of the total variation for needle types in principal coordinate analysis, implying that integrating morphologic characters with haplotype data can be used to classify populations.  Analysis of molecular variance indicated mixed-needle type is more closely related to 3-needle P. ponderosa var. brachyptera than to 5-needle P. arizonica, and that genetic haplotype diversity for P. arizonica is 40% lower than for P. ponderosa var. brachyptera, suggesting the former was near its northern range boundary and has experienced a recent bottleneck.  We combined our recent cores with archived chronologies collected in the 1960s along with climate data to evaluate growth responses to climate variables. Significant positive climate-growth correlations were observed in summer prior to 1950 for all three taxa.  In contrast, spring precipitation (rather than summer precipitation) was the strongest predictor of tree growth for all needle types after 1950.  Positive climate-growth correlations revealed a seasonal shift in growth response from summer precipitation to spring precipitation dominance since 1950, impacting tree phenology, growth, and reproduction.  The annual growth of mixed- and 5-needle types also correlated positively with winter precipitation, but the annual growth of 3-needle type did not.  Winter growth responses implied that soil moisture controls the length of growing season.  The acquired chloroplast genetic and tree-ring data will be combined with nuclear genetic data for hybrid analysis.


Related Links:
Article published in TREES about tree ring response to climate
https://link.springer.com/article/10.1007/s00468-018-1778-9


1 - USDA Forest Service, Northern Research Station, 5985 Hwy K, Rhinelnader, WI, 54501, USA
2 - Hendrix College, Biology, 1600 Washington Ave, Conway, AR, 72032, USA
3 - Dept Plant Biology-Pl Bio Bldg, Michigan State University, Ann Arbor, MI, 48824, United States

Keywords:
dendrochronology
genetic structure
Pinaceae
plastid
Ponderosae.

Presentation Type: Oral Paper
Number: 0009
Abstract ID:333
Candidate for Awards:None


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