Dataset Information

Progressive island colonization and ancient origin of Hawaiian Metrosideros (Myrtaceae).

ABSTRACT: Knowledge of the evolutionary history of plants that are ecologically dominant in modern ecosystems is critical to understanding the historical development of those ecosystems. Metrosideros is a plant genus found in many ecological and altitudinal zones throughout the Pacific. In the Hawaiian Islands, Metrosideros polymorpha is an ecologically dominant species and is also highly polymorphic in both growth form and ecology. Using 10 non-coding chloroplast regions, we investigated haplotype diversity in the five currently recognized Hawaiian Metrosideros species and an established out-group, Metrosideros collina, from French Polynesia. Multiple haplotype groups were found, but these did not match morphological delimitations. Alternative morphologies sharing the same haplotype, as well as similar morphologies occurring within several distinct island clades, could be the result of developmental plasticity, parallel evolution or chloroplast capture. The geographical structure of the data is consistent with a pattern of age progressive island colonizations and suggests de novo intra-island diversification. If single colonization events resulted in a similar array of morphologies on each island, this would represent parallel radiations within a single, highly polymorphic species. However, we were unable to resolve whether the pattern is instead explained by ancient introgression and incomplete lineage sorting resulting in repeated chloroplast capture. Using several calibration methods, we estimate the colonization of the Hawaiian Islands to be potentially as old as 3.9 (-6.3) Myr with an ancestral position for Kaua'i in the colonization and evolution of Metrosideros in the Hawaiian Islands. This would represent a more ancient arrival of Metrosideros to this region than previous studies have suggested.

SUBMITTER: Percy DM

PROVIDER: S-EPMC2602662 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

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Progressive island colonization and ancient origin of Hawaiian Metrosideros (Myrtaceae).

Percy Diana M DM Garver Adam M AM Wagner Warren L WL James Helen F HF Cunningham Clifford W CW Miller Scott E SE Fleischer Robert C RC

Proceedings. Biological sciences 20080701 1642

Knowledge of the evolutionary history of plants that are ecologically dominant in modern ecosystems is critical to understanding the historical development of those ecosystems. Metrosideros is a plant genus found in many ecological and altitudinal zones throughout the Pacific. In the Hawaiian Islands, Metrosideros polymorpha is an ecologically dominant species and is also highly polymorphic in both growth form and ecology. Using 10 non-coding chloroplast regions, we investigated haplotype divers ...[more]

PMID: 18426752

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Project description:The Hawaiian psyllids (Psylloidea, Triozidae) feeding on Metrosideros (Myrtaceae) constitute a remarkable radiation of more than 35 species. This monophyletic group has diversified on a single, highly polymorphic host plant species, Metrosideros polymorpha. Eleven Metrosideros-feeding species included in the Insects of Hawaii by Zimmerman are redescribed, and an additional 25 new species are described. Contrary to previous classifications that placed the Metrosideros-feeders in two genera, Trioza Foerster, 1848 and Kuwayama Crawford, 1911, all 36 named species are placed in Pariaconus Enderlein, 1926; and the relationship of this genus to other Pacific taxa within the family Triozidae, and other Austro-Pacific taxa feeding on host plants in Myrtaceae is clarified. The processes of diversification in Pariaconus include shifts in galling habit, geographic isolation within and between islands, and preferences for different morphotypes of the host plant. Four species groups are recognized: the bicoloratus and minutus groups are free-living or form pit galls, and together with the kamua group (composing all of the Kauai species) form a basal assemblage; the more derived closed gall species in the ohialoha group are found on all major islands except Kauai. The diversification of Pariaconus has likely occurred over several million years. Within island diversification is exemplified in the kamua group, and within species variation in the ohialoha group, but species discovery rates suggest this radiation remains undersampled. Mitochondrial DNA barcodes are provided for 28 of the 36 species. Genetic divergence, intraspecific genetic structure, and parallel evolution of different galling biologies and morphological traits are discussed within a phylogenetic framework. Outgroup analysis for the genus Pariaconus and ancestral character state reconstruction suggest pit-galling may be the ancestral state, and the closest outgroups are Palaearctic-Australasian taxa rather than other Pacific Metrosideros-feeders.

Project description:BackgroundMarine iguanas (Amblyrhynchus cristatus) inhabit the coastlines of large and small islands throughout the Galápagos archipelago, providing a rich system to study the spatial and temporal factors influencing the phylogeographic distribution and population structure of a species. Here, we analyze the microevolution of marine iguanas using the complete mitochondrial control region (CR) as well as 13 microsatellite loci representing more than 1200 individuals from 13 islands.ResultsCR data show that marine iguanas occupy three general clades: one that is widely distributed across the northern archipelago, and likely spread from east to west by way of the South Equatorial current, a second that is found mostly on the older eastern and central islands, and a third that is limited to the younger northern and western islands. Generally, the CR haplotype distribution pattern supports the colonization of the archipelago from the older, eastern islands to the younger, western islands. However, there are also signatures of recurrent, historical gene flow between islands after population establishment. Bayesian cluster analysis of microsatellite genotypes indicates the existence of twenty distinct genetic clusters generally following a one-cluster-per-island pattern. However, two well-differentiated clusters were found on the easternmost island of San Cristóbal, while nine distinct and highly intermixed clusters were found on youngest, westernmost islands of Isabela and Fernandina. High mtDNA and microsatellite genetic diversity were observed for populations on Isabela and Fernandina that may be the result of a recent population expansion and founder events from multiple sources.ConclusionsWhile a past genetic study based on pure FST analysis suggested that marine iguana populations display high levels of nuclear (but not mitochondrial) gene flow due to male-biased dispersal, the results of our sex-biased dispersal tests and the finding of strong genetic differentiation between islands do not support this view. Therefore, our study is a nice example of how recently developed analytical tools such as Bayesian clustering analysis and DNA sequence-based demographic analyses can overcome potential biases introduced by simply relying on FST estimates from markers with different inheritance patterns.

Dataset Information

Progressive island colonization and ancient origin of Hawaiian Metrosideros (Myrtaceae).

Publications

Progressive island colonization and ancient origin of Hawaiian Metrosideros (Myrtaceae).

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