Ecological and Genetic Implications of Foliar Polymorphism inMetrosideros polymorphaGaud. (Myrtaceae) in a Habitat Matrix on Mauna Loa, Hawaii

Kitayama, Kanehiro; Pattison, Robert J.; Cordell, Susan; Webb, David T.; Mueller‐Dombois, Dieter

doi:10.1006/anbo.1996.0473

Cited by 73 publications

(65 citation statements)

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“…incana and glaberrima on Hawaiʻi Island documented different leaf nitrogen contents , and the differential adaptation of their seedlings to light and nitrogen (Morrison and Stacy, 2014), both of which vary significantly between new and old substrates on east Hawaiʻi Island (Crews et al, 1995). Other studies of glabrous and pubescent seedlings or trees from lower elevations (indicative of these two varieties) grown in a common garden revealed differences in water retention (Stemmermann, 1983), cuticle thickness and possibly osmotic potentials and photosynthesis rates (Kitayama et al, 1997). The direction of these differences is consistent with specialization of var.…”

Section: Introductionmentioning

confidence: 96%

“…('ohi'a lehua or 'ohi'a) is a landscape-dominant tree species in Hawaii that offers the opportunity to examine the genetic architecture of key phenotypic traits at the early stages of ecological divergence in trees. This hypervariable species comprises both pubescent and glabrous forms that are differentially distributed across elevation and rainfall gradients on the Hawaiian Islands (Dawson and Stemmermann, 1990;Kitayama et al, 1997). Four of Hawaiʻi Island's five named varieties share the same common chloroplast haplotype (Percy et al, 2008) and show significant within-taxon cohesion across the island and isolation from each other at neutral genetic loci, suggesting M. polymorpha as an unusual case of incipient radiation in trees .…”

Section: Introductionmentioning

confidence: 99%

“…All forms have hermaphrodite red (or less often orange or yellow), shaving-brush-shaped flowers arranged in showy inflorescences, but differ from each other in vegetative traits (Dawson and Stemmermann, 1990). Common garden studies reveal heritable differences among varieties (or among populations sampled across environmental gradients) in morphological (Corn and Hiesey, 1973), leaf anatomical and physiological (Stemmermann, 1983;Kitayama et al, 1997;Cordell et al, 1998Cordell et al, , 2000 traits, including leaf pubescence (Stemmermann, 1983;Kitayama et al, 1997). Whereas these studies indicate heritability of the traits that are used to distinguish varieties of M. polymorpha on Hawaiʻi Island, heritabilities within varieties are unknown.…”

Section: Introductionmentioning

confidence: 99%

“…incana and late-successional var. glaberrima, are ecotypes (Turesson, 1922) that dominate new and old lava flows, respectively, anywhere moisture is sufficient below roughly 1200 m above sea level (Mueller-Dombois, 1983;Stemmermann, 1983;Mueller-Dombois, 1987;Kitayama et al, 1997). Var.…”

Section: Introductionmentioning

confidence: 99%

“…incana by late-successional var. glaberrima on an aging lava flow occurs over a period of 41400 but o3000 years, depending on lava type and elevation (Drake and Mueller-Dombois, 1993;Drake, 1993;Kitayama et al, 1997). The forms can be distinguished entirely through leaf characters; the appressed (abaxial) pubescent leaves of var.…”

Section: Introductionmentioning

confidence: 99%

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Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai‘i Island

et al. 2016

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Intraspecific hybrid zones involving long-lived woody species are rare and can provide insights into the genetic basis of earlydiverging traits in speciation. Within the landscape-dominant Hawaiian tree, Metrosideros polymorpha, are morphologically distinct successional varieties, incana and glaberrima, that dominate new and old lava flows, respectively, below 1200 me on volcanically active Hawaiʻi Island, with var. glaberrima also extending to higher elevations and bogs. Here, we use morphological measurements on 86 adult trees to document the presence of an incana-glaberrima hybrid zone on the 1855 Mauna Loa lava flow on east Hawaiʻi Island and parent-offspring analysis of 1311 greenhouse seedlings from 71 crosses involving 72 adults to estimate heritabilities and genetic correlations among vegetative traits. Both the variation in adult leaf pubescence at the site and the consistency between adult and offspring phenotypes suggest the presence of two hybrid classes, F 1 s and var. incana backcrosses, as would be expected on a relatively young lava flow. Nine nuclear microsatellite loci failed to distinguish parental and hybrid genotypes. All four leaf traits examined showed an additive genetic basis with moderate to strong heritabilities, and genetic correlations were stronger for the more range-restricted var. incana. The differences between varieties in trait values, heritabilities and genetic correlations, coupled with high genetic variation within but low genetic variation between varieties, are consistent with a multi-million-year history of alternating periods of disruptive selection in contrasting environments and admixture in ephemeral hybrid zones. Finally, the contrasting genetic architectures suggest different evolutionary trajectories of leaf traits in these forms.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai‘i Island

et al. 2016

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Early detection of a tree pathogen using airborne remote sensing

Weingarten

Martin

Hughes

et al. 2022

Ecological Applications

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Native forests of Hawaiʻi Island are experiencing an ecological crisis in the form of Rapid ʻŌhiʻa Death (ROD), a recently characterized disease caused by two fungal pathogens in the genus Ceratocystis. Since approximately 2010, this disease has caused extensive mortality of Hawaiʻi's keystone endemic tree, known as ʻōhiʻa (Metrosideros polymorpha). Visible symptoms of ROD include rapid browning of canopy leaves, followed by death of the tree within weeks. This quick progression leading to tree mortality makes early detection critical to understanding where the disease will move at a timescale feasible for controlling the disease. We used repeat laser‐guided imaging spectroscopy (LGIS) of forests on Hawaiʻi Island collected by the Global Airborne Observatory (GAO) in 2018 and 2019 to derive maps of foliar trait indices previously found to be important in distinguishing between ROD‐infected and healthy ʻōhiʻa canopies. Data from these maps were used to develop a prognostic indicator of tree stress prior to the visible onset of browning. We identified canopies that were green in 2018, but became brown in 2019 (defined as “to become brown”; TBB), and a corresponding set of canopies that remained green. The data mapped in 2018 showed separability of foliar trait indices between TBB and green ʻōhiʻa, indicating early detection of canopy stress prior to the onset of ROD. Overall, a combination of linear and non‐linear analyses revealed canopy water content (CWC), foliar tannins, leaf mass per area (LMA), phenols, cellulose, and non‐structural carbohydrates (NSC) are primary drivers of the prognostic spectral capability which collectively result in strong consistent changes in leaf spectral reflectance in the near‐infrared (700–1300 nm) and shortwave‐infrared regions (1300–2500 nm). Results provide insight into the underlying foliar traits that are indicative of physiological responses of M. polymorpha trees infected with Ceratocycstis and suggest that imaging spectroscopy is an effective tool for identifying trees likely to succumb to ROD prior to the onset of visible symptoms.

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Incipient ecological speciation between successional varieties of a dominant tree involves intrinsic postzygotic isolating barriers

Stacy

Paritosh

Johnson

et al. 2017

Ecology and Evolution

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Whereas disruptive selection imposed by heterogeneous environments can lead to the evolution of extrinsic isolating barriers between diverging populations, the evolution of intrinsic postzygotic barriers through divergent selection is less certain. Long‐lived species such as trees may be especially slow to evolve intrinsic isolating barriers. We examined postpollination reproductive isolating barriers below the species boundary, in an ephemeral hybrid zone between two successional varieties of the landscape‐dominant Hawaiian tree, Metrosideros polymorpha, on volcanically active Hawai'i Island. These archipelago‐wide sympatric varieties show the weakest neutral genetic divergence of any taxon pair on Hawai'i Island but significant morphological and ecological differentiation consistent with adaptation to new and old lava flows. Cross‐fertility between varieties was high and included heterosis of F1 hybrids at the seed germination stage, consistent with a substantial genetic load apparent within varieties through low self‐fertility and a lack of self‐pollen discrimination. However, a partial, but significant, barrier was observed in the form of reduced female and male fertility of hybrids, especially backcross hybrids, consistent with the accumulation of genetic incompatibilities between varieties. These results suggest that partial intrinsic postzygotic barriers can arise through disruptive selection acting on large, hybridizing populations of a long‐lived species.

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Ecological and Genetic Implications of Foliar Polymorphism inMetrosideros polymorphaGaud. (Myrtaceae) in a Habitat Matrix on Mauna Loa, Hawaii

Cited by 73 publications

References 17 publications

Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai‘i Island

Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai‘i Island

Early detection of a tree pathogen using airborne remote sensing

Incipient ecological speciation between successional varieties of a dominant tree involves intrinsic postzygotic isolating barriers

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