TY - JOUR T1 - The role of hybridization during ecological divergence of southwestern white pine (Pinus strobiformis) and limber pine (P. flexilis) JF - Molecular Ecology Y1 - 2018 A1 - Mitra Menon A1 - Justin C. Bagley A1 - Christopher J. Friedline A1 - Amy V. Whipple A1 - Anna W. Schoettle A1 - Alejandro Leal-Saenz A1 - Christian Wehenkel A1 - Francisco Molina-Freaner A1 - Lluvia Flores-Renterıa A1 - M. Socorro Gonzalez-Elizondo A1 - Richard A. Sniezko A1 - Samuel A. Cushman A1 - Kristen M. Waring A1 - Andrew J. Eckert KW - conifers KW - ecological speciation KW - extrinsic barriers KW - hybrid zone KW - introgression KW - population genomics AB -
Interactions between extrinsic factors, such as disruptive selection and intrinsic factors,
such as genetic incompatibilities among loci, often contribute to the maintenance
of species boundaries. The relative roles of these factors in the establishment
of reproductive isolation can be examined using species pairs characterized by gene
flow throughout their divergence history. We investigated the process of speciation
and the maintenance of species boundaries between Pinus strobiformis and Pinus
flexilis. Utilizing ecological niche modelling, demographic modelling and genomic
cline analyses, we illustrated a divergence history with continuous gene flow. Our
results supported an abundance of advanced generation hybrids and a lack of loci
exhibiting steep transition in allele frequency across the hybrid zone. Additionally,
we found evidence for climate-associated variation in the hybrid index and niche
divergence between parental species and the hybrid zone. These results are consistent
with extrinsic factors, such as climate, being an important isolating mechanism.
A build-up of intrinsic incompatibilities and of coadapted gene complexes is also
apparent, although these appear to be in the earliest stages of development. This
supports previous work in coniferous species demonstrating the importance of extrinsic factors in facilitating speciation. Overall, our findings lend support to the
hypothesis that varying strength and direction of selection pressures across the long
lifespans of conifers, in combination with their other life history traits, delays the
evolution of strong intrinsic incompatibilities.
Southwestern white pine (Pinus strobiformis; SWWP) is a conifer species that occurs at mid to high elevations in
the mountains of Arizona, New Mexico, and northern Mexico. A key component of mixed conifer forests in the
region, SWWP is an important species for wildlife and biodiversity. The dual threats of the non-native fungal
pathogen that causes white pine blister rust (WPBR) and a warmer, drier projected future climate have created
an uncertain future for SWWP. In this study, we used a novel multi-scale optimization approach including an
ensemble of four species distribution modeling methods to explore the relationship between SWWP occurrence
and environmental variables based on climate, soil, and topography. Spatial projections of these models reflecting
the present climate provide an improved range map for this species that can be used to guide field data
collection and monitoring of WPBR outbreaks. Future projections based on two emissions scenarios and an
ensemble of 15 general circulation models project a large range shift and range contraction by 2080. Changes in
the future distribution were particularly extreme under the higher emissions scenario, with a more than 1000 km
northerly shift in the mean latitude and 500m increase in the mean elevation of the species’ suitable habitat.
This coincided with a range contraction of over 60% and a significant increase in habitat fragmentation. The
ability of SWWP to realize its projected future range will depend on colonization at the leading edge of the range
shift, including dispersal dynamics, resistance to WPBR, competition with other species, and genetic adaptations
to local climate. Our results provide information that can be used to guide monitoring efforts and inform conservation
planning for this keystone species.
Waring, K, Cushman, S, Eckert A, Flores Renteria, L, Sniezko, R, Still,C, Wehenkel, C, Whipple, A, and Wing, M. 2017. A holistic approach to genetic conservation in Pinus strobiformis. International Scientific Conference on Genetics of Populations: Progress and Perspectives, commemorating the 80th birthday of Academician Yury P. Altukhov and dedicated to the 45th Anniversary of the Laboratory of Population Genetics named after Yu. P. Altukhov, 17-21 April 2017, Zvenogorod Biological Station, Russia.
JF - International Scientific Conference on Genetics of Populations Progress and Perspectives commemorating the 80th birthday of Academician Altukhov and dedicated to the 45th Anniversary of the Laboratory of Population Genetics named after Yu P Biological Sta T3 - International Scientific Conference on Genetics of Populations Progress and Perspectives commemorating the 80th birthday of Academician Altukhov and dedicated to the 45th Anniversary of the Laboratory of Population Genetics named after Yu P Biological Sta CY - Zvenogorod Biological Station, Russia VL - 2017 N1 - [Original String]:Waring, K, Cushman, S, Eckert A, Flores Renteria, L, Sniezko, R, Still, C, Wehenkel, C, Whipple, A, and Wing, M. 2017. A holistic approach to genetic conservation in Pinus strobiformis. International Scientific Conference on Genetics of Populations: Progress and Perspectives, commemorating the 80th birthday of Academician Yury P. Altukhov and dedicated to the 45th Anniversary of the Laboratory of Population Genetics named after Yu. P. Altukhov, 17-21 April 2017, Zvenogorod Biological Station, Russia. ER - TY - CONF T1 - Collaborative research for sustainable management of southwestern white pine. T2 - Society of American Foresters National Convention Y1 - 2016 A1 - K Waring A1 - Cushman,S A1 - Eckert,A A1 - L Flores-Renteria A1 - Lintz,H A1 - R Sniezko A1 - Still,C A1 - Wehenkel,C A1 - AV Whipple A1 - Wing,M AB -
Waring, K., Cushman, S., Eckert, A., Flores-Renteria, L., Lintz, H.,Sniezko, R., Still, C., Wehenkel, C., Whipple, A., and Wing, M. 2016. Collaborative research for sustainable management of southwestern white pine. Society of American Foresters National Convention, November 2-5, 2016, Madison, WI.