Phylogeography and genetic structure of endemic <i>Acmispon argophyllus</i> and <i>A. dendroideus</i> (Fabaceae) across the California Channel Islands

Wallace, Lisa E.; Wheeler, Gregory L.; McGlaughlin, Mitchell E.; Bresowar, Gerald E.; Helenurm, Kaius

doi:10.3732/ajb.1600429

Cited by 5 publications

(13 citation statements)

References 54 publications

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“…dendroideus in all analyses, which also supports the findings of Wallace et al (2017). Based on the results of Wallace et al (2017) and our data presented here, we suggest that additional research should examine the consistency of A. d. var. veatchii morphological traits in relationship to A. d. var.…”

Section: Acmispon Dendroideus Taxonomy and Genetic Structuresupporting

confidence: 89%

“…Under all analyses, A. d. var. traskiae was substantially diverged from other members of A. dendroideus confirming the result of Wallace et al (2017). Although our mainland sampling is not detailed enough to determine whether A. d. var.…”

Section: Acmispon Dendroideus Taxonomy and Genetic Structuresupporting

confidence: 67%

“…veatchii samples into 2 island groups, with San Miguel and Santa Rosa forming one group, and Santa Cruz, Anacapa, and Santa Catalina forming a second group (Fig. 3), as observed in Wallace et al (2017). The A. argophyllus STRUCTURE HAR-VESTER analyses supported groupings of 2 and 10 genetic clusters (Supplementary Material 4).…”

Section: Genetic Structurementioning

confidence: 52%

“…dendroideus on Santa Rosa from A. d. var. dendroideus on Santa Cruz and Anacapa as observed in the phylogenetic analyses of Wallace et al (2017). This genetic structure within the northern islands may be attributable to the Santa Cruz Channel, which separates Santa Rosa and Santa Cruz and served as the first major split of Santa Rosae when sea levels rose after the last glacial maximum.…”

Section: Acmispon Dendroideus Taxonomy and Genetic Structurementioning

confidence: 77%

“…traskiae is both state listed as endangered and federally listed as Threatened (USFWS 1977, California Department of Fish andWildlife 2017). Wallace et al (2017) recently conducted a phylogeographic study of this group utilizing nuclear DNA sequence, chloroplast DNA sequence, and chloroplast microsatellite data to resolve historical patterns of colonization and divergence.…”

mentioning

confidence: 99%

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Does Channel Island Acmispon (Fabaceae) form cohesive evolutionary groups?

McGlaughlin

Riley

Helenurm

et al. 2018

Western North American Naturalist

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The California Channel Islands are unique relative to other island chains due to their close proximity to the California mainland and the fact that individual islands, or groups of islands, vary in their distance to the mainland and other islands. This orientation raises questions about whether island taxa with widespread distributions form cohesive evolutionary units, or if they are actually composed of several distinct evolutionary entities, either derived from independent mainland-to-island colonization events or divergence due to prolonged allopatric isolation. The 4 northern islands are clustered in a line (6-8 km separation among islands), while the 4 southern islands are widely spaced (34-45 km separation among islands), which should impact the amount of gene flow and genetic connectivity among islands. We used nuclear microsatellite markers to examine the genetic structure and cohesion of 2 island shrubs, Acmispon dendroideus and A. argophyllus, which are widely distributed across the California Channel Islands. Both focal species contain varieties with multi-island distributions, with A. dendroideus exhibiting a greater distribution on the northern islands and A. argophyllus exhibiting a greater distribution on the southern islands. Substantial genetic divergence was observed for 2 single-island endemic varieties, A. dendroideus var. traskiae and A. agrophyllus var. niveus, confirming that allopatric isolation can lead to genetic divergence. The widespread Acmispon dendroideus var. dendroideus and single-island endemic A. dendroideus var. veatchii formed a cohesive evolutionary group that spans all 4 northern islands and 1 southern island, Santa Catalina, indicating that the northern and southern islands have been genetically linked in the past but do not display evidence of contemporary gene flow. In contrast, widespread A. argophyllus var. argenteus was composed of moderately distinct genetic groups on each of the 4 southern islands, with no evidence of recent gene flow among islands. These results demonstrate that isolation among islands has led to significant divergence among the southern islands, but that the commonly recognized split between northern and southern islands does not impact all taxa equally.RESUMEN.-Las Islas del Canal de California son únicas en comparación a otras cadenas de islas dada su proximidad con California y al hecho de que las islas individuales, o grupos de islas, difieren en cuanto a su distancia con el continente y con otras islas. Tal orientación plantea interrogantes sobre si los taxa insulares de amplia distribución forman unidades evolutivas cohesivas o si se componen, en realidad, de diversas entidades evolutivas, sean derivadas por sucesos independientes de colonización del continente a la isla o por divergencia debido al aislamiento alopátrico prolongado. Las cuatro islas del norte se encuentran agrupadas en una línea (6-8 km de separación entre las islas), mientras que las cuatro islas del sur están espaciadas (34-45 km de separación entre las islas), lo que segur...

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Section: Acmispon Dendroideus Taxonomy and Genetic Structuresupporting

confidence: 89%

Section: Acmispon Dendroideus Taxonomy and Genetic Structuresupporting

confidence: 67%

Section: Genetic Structurementioning

confidence: 52%

Section: Acmispon Dendroideus Taxonomy and Genetic Structurementioning

confidence: 77%

mentioning

confidence: 99%

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Does Channel Island Acmispon (Fabaceae) form cohesive evolutionary groups?

McGlaughlin

Riley

Helenurm

et al. 2018

Western North American Naturalist

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In situ glacial survival maintains high genetic diversity of Mussaenda kwangtungensis on continental islands in subtropical China

Shi

Wang

Duan

et al. 2020

Ecology and Evolution

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Generally, island populations are predicted to have less genetic variation than their mainland relatives. However, a growing number of studies have nevertheless reported exceptions, indicating that the relationships were impacted by several factors, for example, historical processes. In the present study, we chose a group of subtropical islands located in South China as the study system, which are quite younger and much closer to the mainland than most of the previous studied island systems, to test the hypothesis that in situ glacial survival contributes to high levels of genetic diversity in island populations. We conducted a comparison of genetic variation between 12 island and 11 nearby mainland populations of Mussaenda kwangtungensis using eleven nuclear microsatellite and three chloroplast markers, evaluated effects of the island area and distance to mainland on genetic diversity of island populations, and simulated the potential distribution over the past by ecological niche modeling, together with the genetic data to detect the role of islands during the glacial periods. The island populations displayed comparable levels of genetic diversity and differentiation with mainland populations, overall high levels of unique polymorphisms, and the greatest values of specific within‐population genetic diversity. No significant correlation was detected between genetic diversity of island populations and distance to mainland, as well as area of islands, except that allelic richness was significantly positively correlated with the area of islands. Nuclear microsatellites revealed two main clusters, largely corresponding to islands and inland populations, which divergence dated to a time of island formation by ABC analysis. Ecological niche modeling predicted a highly climatic suitability on islands during the last glacial maximum (LGM). Our results suggest that the islands have acted as refugia during the LGM and highlight the role of in situ glacial survival in maintaining high levels of genetic diversity of M. kwangtungensis in continental islands of subtropical China.

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Genetic Variation and Structure in an Endemic Island Oak,Quercus tomentella, and Mainland Canyon Oak,Quercus chrysolepis

Ashley

Backs

Kindsvater³

et al. 2018

International Journal of Plant Sciences

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Premise of research. Quercus tomentella is a tree species endemic to the California Channel Islands and Isla Guadalupe. Given its distribution across six widely separated islands, significant genetic structure would be expected, despite the propensity of oaks for long-distance pollen dispersal. In comparison, its close mainland relative, Quercus chrysolepis, has a more continuous range and fewer barriers to gene flow.Methodology. We sampled Q. tomentella from all the islands in its range (N p 345) and Q. chrysolepis from five mainland sites and on the islands where it occurs (N p 100) and genotyped the trees using eight polymorphic microsatellite loci. Genetic differentiation within and between species was examined using genetic distances, analysis of molecular variance, Bayesian clustering (both spatial and nonspatial approaches), a neighbor-joining tree, and genetic discontinuities indicative of barriers to gene flow. We also looked for evidence of population bottlenecks.Pivotal results. A high level of clonality was found in Q. tomentella on Santa Catalina Island and Santa Rosa Island, but genetic variability was high in both species and at all sites, including the tiny surviving population on Isla Guadalupe. Genetic distance measures were significant between most populations of both species. The most surprising result is that the two species were not clearly differentiated, and genetic clusters identified through both spatial and nonspatial analyses were shared between species.Conclusions. The island endemic Q. tomentella and the widespread Q. chrysolepis are not well-differentiated species. Further work is needed to clarify the relationships within and among these species. Insular populations of Q. tomentella are genetically diverse and distinct; the remaining population found on Isla Guadalupe warrants protection and management to support recruitment.

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Phylogeography and genetic structure of endemic Acmispon argophyllus and A. dendroideus (Fabaceae) across the California Channel Islands

Cited by 5 publications

References 54 publications

Does Channel Island Acmispon (Fabaceae) form cohesive evolutionary groups?

Does Channel Island Acmispon (Fabaceae) form cohesive evolutionary groups?

In situ glacial survival maintains high genetic diversity of Mussaenda kwangtungensis on continental islands in subtropical China

Genetic Variation and Structure in an Endemic Island Oak,Quercus tomentella, and Mainland Canyon Oak,Quercus chrysolepis

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