Evolutionary diversification and geographical isolation in Dubautia laxa (Asteraceae), a widespread member of the Hawaiian silversword alliance

McGlaughlin, Mitchell E.; Friar, Elizabeth A.

doi:10.1093/aob/mcq252

Cited by 18 publications

(26 citation statements)

References 68 publications

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“…(), studying orchid populations ( Epidendrum secundum ) sympatric with Ameroglossum , found evidence only for IBD when analysing plastid microsatellites but for neither IBD nor IBE when analysing nuclear microsatellites, indicating genetic homogenisation among populations through gene flow by pollen. Unique signs of IBD driving populations and species divergence in island‐systems have been found in a member of the Hawaiian silversword alliance ( Dubautia laxa ) and in sister‐species of Primulaceae from sky‐islands in Europe (Boucher et al., ; McGlaughlin & Friar, ). Similar to Ameroglossum , a combination of IBD and IBE associated with genetic variation within and between species from isolated habitat patches was found for Argyroderma in the Cape Floristic Region of South Africa (Ellis et al., ).…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, although some studies have shown that the significance of geographic and environmental isolation varies among types of islands (e.g. Boucher et al., ; Ellis et al., ; McGlaughlin & Friar, ), their relative contributions have not been quantified. Therefore, the roles of these types of isolation in population and species divergence in terrestrial‐island systems remains poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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The roles of geography and environment in divergence within and between two closely related plant species inhabiting an island‐like habitat

Wanderley

Machado

Almeida

et al. 2017

Journal of Biogeography

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Aim In island‐like habitats, geographic isolation facilitates population and species divergence by constraining gene flow, while environmental isolation can enhance divergence. We tested the relative contribution of geographic and environmental isolation in genetic and phenotypic divergence within and between two species of the figwort Ameroglossum (Scrophulariaceae) inhabiting spatially isolated habitats, known as inselbergs. Location Borborema Plateau, north‐eastern Brazil. Methods Multivariate models of redundancy (RDAs) and partial redundancy analyses (pRDAs) were used to partition the geographic and climate components of genetic variation in 48 microsatellite alleles, and phenotypic variation in 11 leaf and flower traits. We also used linear mixed‐effect models (LMEs) to test independent associations of floral tube length variation among inselbergs with local pollinator phenotypes, climate and geography. In each approach, we analysed the data for each species separately and in pooled models for both species. Results RDAs revealed that genetic variation within and between the species of Ameroglossum was associated similarly with geography and climate. Phenotypic variation within A. manoel‐felixii and between species was also associated similarly with geography and climate but, within A. pernambucense, phenotype was more strongly associated with climate. Linear mixed‐effect models revealed that flower divergence in A. manoel‐felixii was associated only with the bill length of local hummingbirds, whereas floral variation in A. pernambucense was associated with geography, bill length and climate. Only climate was associated with flower divergence between species. Main conclusions Genetic and phenotypic variation in Ameroglossum are associated with geographic and environmental isolation. These findings indicate a significant role of ecological factors shaping plant divergence among inselbergs, irrespective of their spatial distances.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The roles of geography and environment in divergence within and between two closely related plant species inhabiting an island‐like habitat

Wanderley

Machado

Almeida

et al. 2017

Journal of Biogeography

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“…In addition to the S. menziesii- S. salicaria hybrid zone discussed here, Willyard et al [43] uncovered several instances of cryptic chloroplast introgression throughout Schiedea . As expected of recently evolved systems, many of these hybridization events occur between species that are not widely divergent genetically [44], and ecological barriers are typically stronger than genetic barriers to gene flow [39], [45]. Given the increased detection of interspecific hybridization in continental and island plant systems, a more detailed understanding of the adaptive nature of hybridization [46] is warranted.…”

Section: Discussionmentioning

confidence: 99%

Asymmetrical Gene Flow in a Hybrid Zone of Hawaiian Schiedea (Caryophyllaceae) Species with Contrasting Mating Systems

et al. 2011

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Asymmetrical gene flow, which has frequently been documented in naturally occurring hybrid zones, can result from various genetic and demographic factors. Understanding these factors is important for determining the ecological conditions that permitted hybridization and the evolutionary potential inherent in hybrids. Here, we characterized morphological, nuclear, and chloroplast variation in a putative hybrid zone between Schiedea menziesii and S. salicaria, endemic Hawaiian species with contrasting breeding systems. Schiedea menziesii is hermaphroditic with moderate selfing; S. salicaria is gynodioecious and wind-pollinated, with partially selfing hermaphrodites and largely outcrossed females. We tested three hypotheses: 1) putative hybrids were derived from natural crosses between S. menziesii and S. salicaria, 2) gene flow via pollen is unidirectional from S. salicaria to S. menziesii and 3) in the hybrid zone, traits associated with wind pollination would be favored as a result of pollen-swamping by S. salicaria. Schiedea menziesii and S. salicaria have distinct morphologies and chloroplast genomes but are less differentiated at the nuclear loci. Hybrids are most similar to S. menziesii at chloroplast loci, exhibit nuclear allele frequencies in common with both parental species, and resemble S. salicaria in pollen production and pollen size, traits important to wind pollination. Additionally, unlike S. menziesii, the hybrid zone contains many females, suggesting that the nuclear gene responsible for male sterility in S. salicaria has been transferred to hybrid plants. Continued selection of nuclear genes in the hybrid zone may result in a population that resembles S. salicaria, but retains chloroplast lineage(s) of S. menziesii.

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“…Mort et al, 2002;McGlaughlin & Friar, 2011;Wallace et al, 2011). The coalescence of individual LFY copies within each taxon, long branches between recognized species and concordance of the molecular, morphological and traditional taxonomic data suggest that the LFY gene tree reflects the species tree.…”

Section: Colonizationmentioning

confidence: 99%

Narrow water barriers prevent multiple colonizations and limit gene flow among California Channel Island wild buckwheats (Eriogonum: Polygonaceae)

2016

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The relative roles of chance colonization and subsequent gene flow in the development of insular endemic biotas have been extensively studied in remote oceanic archipelagos, but are less well characterized on nearshore island systems. The current study investigated patterns of colonization and divergence between and within two wild buckwheat species (Polygonaceae), Eriogonum arborescens and E. giganteum, endemic to the California Channel Islands to determine whether geographical isolation is driving diversification. Using plastid and nuclear sequence data and microsatellite allele frequencies, we determined that gene flow in these Eriogonum spp. is restricted by isolation. The data suggest that successful colonization of and gene flow among the islands are infrequent. Colonization appears to have followed a stepping-stone model that is consistent with a north-to-south pattern across the islands. This colonization pattern coupled with relatively little post-colonization inter-island gene flow, particularly among southern islands, has generated a pattern of more divergent lineages on the isolated southern islands. These results run counter to the general expectation that all islands close to a continental source should receive a high level of gene flow. Finally, management recommendations focused on protecting the lineages from loss of private alleles and the erosion of the remaining genetic diversity are offered.

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Evolutionary diversification and geographical isolation in Dubautia laxa (Asteraceae), a widespread member of the Hawaiian silversword alliance

Cited by 18 publications

References 68 publications

The roles of geography and environment in divergence within and between two closely related plant species inhabiting an island‐like habitat

The roles of geography and environment in divergence within and between two closely related plant species inhabiting an island‐like habitat

Asymmetrical Gene Flow in a Hybrid Zone of Hawaiian Schiedea (Caryophyllaceae) Species with Contrasting Mating Systems

Narrow water barriers prevent multiple colonizations and limit gene flow among California Channel Island wild buckwheats (Eriogonum: Polygonaceae)

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