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Abstract Detail

Hybrids and Hybridization

Buck, Ryan [1], Ortego del Vecchyo, Diego [2], Flores-Renteria, Lluvia [3].

Syngameonic Hybridization in Pinyon Pines.

The two-needled pinyon pine (Pinus edulis) experiences some of the highest mortality rates among forest species after prolonged periods of drought, which are expected to increase in intensity with climate change. A close relative, Pinus monophylla, has one needle-per-fascicle, a trait thought to be adapted to more arid environments. Both species are dominant in the Southwestern US and Baja California and play important ecological roles in supporting biodiversity. Despite occupying different ecological niches, they have overlapping distributions, facilitating potential hybridization. Two additional needle types have been observed near contact zones: fallax-type and californiarum-type. Both have one needle-per-fascicle but have varying numbers of resin canals and stomatal rows. Additionally, californiarum-type overlaps in distribution with Pinus quadrifolia, which has four needles-per-fascicle and is sister to P. monophylla. Individuals with intermediate morphology have been observed in their contact zones, leading some to believe they also hybridize. In this study, we used morphological and next-generation sequencing data to test for hybridization, detect the direction of gene flow, and determine the extent of the hybrid zones in this complex. We examined the entire range of these five pinyon pine taxa to determine the evolutionary patterns of gene flow among species and discover the extent of hybridization. We hypothesize that the three previously described taxa, P. edulis, P. monophylla, and P. quadrifolia will be independent species that hybridize and are parent lineages of californiarum-type and fallax-type, which both result from that hybridization. Genetic population structure was determined using the software fastSTRUCTURE, a Discriminant Analysis of Principal Components (DAPC), and a Principal Coordinates Analysis (PCoA) in R. Lamarc and fastsimcoal2 were used to examine the magnitude and direction of gene flow as well as possible hybrid speciation events. A four taxon D-statistic (ABBA BABA) was run in Dsuite to corroborate the evidence of admixture signals. Our results support P. edulis, P. monophylla, and P. quadrifolia being independent species, with fallax-type resulting from hybridization between P. edulis and californiarum-type, and californiarum-type possibly being its own species. Additionally, hybridization events among all species pairs were detected, suggesting the presence of a rare multidirectional multispecies network called a syngameon. These hybridization events could have profound impacts on species' abilities to survive in future drought conditions.

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1 - San Diego State University, Evolutionary Biology, 5500 Campanile Drive, San Diego, CA, 92182, United States
2 - National Autonomous University of Mexico, International Laboratory for Human Genome Research, Mexico City, MX
3 - San Diego State University, 4319 Yale Ave, San Diego State University, La Mesa, CA, 91942, United States


Presentation Type: Oral Paper
Session: HH2, Hybrids and Hybridization II
Location: /
Date: Wednesday, July 21st, 2021
Time: 1:45 PM(EDT)
Number: HH2006
Abstract ID:1092
Candidate for Awards:Margaret Menzel Award

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