Abstract Detail

Extreme conservation measures for plants at the extremes in the Hawaiian archipelago model system

Hawaii’s landscape-dominant genus Metrosideros comprises many taxa of conservation concern.

Metrosideros is a hypervariable and dominant feature of Hawaii’s landscape that spans a remarkable range of environments from wet and subalpine forests, to bogs, deserts, riparian zones, new lava flows, and wind-swept cliffs. Through extensive field observations, we have identified 25 tentative Metrosideros “taxa” across Hawai`i, including the 13 varieties and species recognized in the most recent taxonomic treatment plus an additional 12 morphotypes (races). A majority of taxa are restricted to individual islands or even volcanoes. We have examined neutral genetic divergence, differential adaptation, leaf trait variation, and reproductive isolating barriers among taxa using nuclear microsatellites and genome-wide single-nucleotide polymorphisms, field and controlled-environment experiments, and microscopy studies. Across the archipelago, the strength of isolation among taxa ranges widely with strong isolation most often observed in taxa that are restricted to harsh environments or high elevations (on O`ahu). Common-garden studies reveal heritability of taxon-diagnostic phenotypes, and seedling experiments show evidence of differential adaptation of all 12 taxa examined to abiotic conditions that vary across Hawaii’s heterogeneous landscape. Lastly, preliminary results from studies of cross-fertility and hybrid fitness involving 12 taxon pairs suggest a range of postzygotic reproductive isolating barriers between sympatric/parapatric taxa and a high genetic load in two monotypic species endemic to O`ahu. Hawaiian Metrosideros appears to be a rare example of incipient adaptive radiation in trees that captures multiple stages of speciation. This group is also under threat from introduced fungal pathogens, invasive plants, and climate change. Studies on Hawai`i Island suggest that differential local adaptation of populations across elevations may be too slow to track changing climates. I will summarize these findings and highlight taxa of particular concern.

1 - University Of Nevada Las Vegas, School of Life Sciences, Las Vegas, NV, 89154, USA

Keywords:
adaptive radiation
Hawaii
Metrosideros
reproductive isolation
population genomics.

Presentation Type: Colloquium Presentations
Session: COL05, Extreme conservation measures for plants at the extremes in the Hawaiian archipelago model system
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 3:15 PM
Number: COL05010
Abstract ID:863
Candidate for Awards:None