Abstract Detail

Population Genetics/Genomics

Choi, Jae Young [1], Dai, Xiaoguang [2], Alam, Ornob [1], Peng, Julie [3], Rughani, Priyesh [2], Hickey, Scott [4], Harrington, Eoghan [2], Juul, Sissel [2], Ayroles, Julien [3], Sakishima, Tomoko [5], Kirby, Angalee [6], Purugganan, Michael [1], Stacy, Elizabeth [7].

The role of ancestral polymorphisms and hybrid incompatibilities in Hawaii’s Metrosideros adaptive radiation.

Some of the most spectacular adaptive radiations begin with founder populations on remote islands. How genetically limited founder populations give rise to the striking phenotypic and ecological diversity characteristic of adaptive radiations is a paradox of evolutionary biology. We conducted an evolutionary genomics analysis of genus Metrosideros, a landscape-dominant, incipient adaptive radiation of woody plants that spans a striking range of phenotypes and environments across the Hawaiian Islands.  Using long-read nanopore sequencing and multi-contact chromosome conformation capture (Pore-C), we created a chromosome-level  genome assembly for M. polymorpha var. incana and analyzed whole-genome sequences of 131 individuals from 11 taxa sampled across the islands. Demographic modeling and population genomics analyses suggested that Hawaiian Metrosideros originated from a single colonization event and subsequently spread across the archipelago following the formation of new islands. The evolutionary history of Hawaiian Metrosideros shows evidence of extensive reticulation associated with significant sharing of ancestral variation between taxa and secondarily with admixture. Taking advantage of the highly contiguous genome assembly, we investigated the genomic architecture underlying the adaptive radiation and discovered that divergent selection drove the formation of differentiation outliers in paired taxa representing early stages of speciation/divergence. Evolutionary analysis of the origins of the outlier SNPs showed enrichment for ancestral variations under divergent selection and a distribution of allele states consistent with differential sorting of incompatibility alleles. We propose an ancient hybridization model of origin for the Hawaiian Metrosideros species complex, wherein reassortment of ancestral variation generated from hybridization of genomically distinct predecessors has fueled the island adaptive radiation. Separately, ongoing studies of reproductive isolating barriers within the group are revealing partial intrinsic barriers between taxa consistent with segregating incompatibility alleles. To date, partial intrinsic isolating barriers are apparent at the stages of F1 fertility and backcross fertility in particular taxon pairs.   A summary of these results to date will be discussed.

Related Links:
Stacy Lab

1 - New York University, Center for Genomics and Systems Biology, New York, NY, USA
2 - Oxford Nanopore Technologies Inc., New York, NY, USA
3 - Princeton University, Department of Ecology and Evolutionary Biology, Princeton, NJ, USA
4 - Oxford Nanopore Technologies Inc., San Franscisco, CA, USA
5 - University of Hawaii Hilo, 200 W. Kawili Street, Dept. of Biology, Hilo, HI, 96720, USA
6 - University of Hawaii Hilo, 200 W. Kawili Street, Dept. of Biology, Hilo, Hawaii, 96720, USA
7 - University Of Nevada Las Vegas, School Of Life Sciences, 4505 South Maryland Parkway, Mail Stop: 4004, Las Vegas, NV, 89154, United States

Keywords:
Metrosideros
adaptive radiation
Population genomics
Speciation
Reproductive Isolation.

Presentation Type: Oral Paper
Session: PGG1, Population Genetics and Genomics I
Location: /
Date: Tuesday, July 20th, 2021
Time: 4:30 PM(EDT)
Number: PGG1007
Abstract ID:928
Candidate for Awards:Margaret Menzel Award