Testing hybridization hypotheses and evaluating the evolutionary potential of hybrids in mangrove plant species

Lo, Eugenia

doi:10.1111/j.1420-9101.2010.02087.x

Cited by 33 publications

(26 citation statements)

References 100 publications

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“…Recent molecular studies have confirmed that R. × lamarckii is a hybrid between Rhizophora apiculata and Rhizophora stylosa ; R . × annamalayana is a hybrid between R. apiculata and Rhizophora mucronata ; and R. selala is a hybrid between R. stylosa and Rhizophora samoensis in the Indo-West Pacific region [49]. Despite frequent hybridization in sympatric sites, reproductive isolation between all the parental species of Rhizophora is ensured by F 1 hybrid sterility.…”

Section: Discussionmentioning

confidence: 99%

Genomic Markers Reveal Introgressive Hybridization in the Indo-West Pacific Mangroves: A Case Study

Sun

2011

PLoS ONE

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Biodiversity of mangrove ecosystems is difficult to assess, at least partly due to lack of genetic verification of morphology-based documentation of species. Natural hybridization, on the one hand, plays an important role in evolution as a source of novel gene combinations and a mechanism of speciation. However, on the other hand, recurrent introgression allows gene flow between species and could reverse the process of genetic differentiation among populations required for speciation. To understand the dynamic evolutionary consequences of hybridization, this study examines genomic structure of hybrids and parental species at the population level. In the Indo-West Pacific, Bruguiera is one of the dominant mangrove genera and species ranges overlap extensively with one another. Morphological intermediates between sympatric Bruguiera gymnorrhiza and Bruguiera sexangula have been reported as a variety of B. sexangula or a new hybrid species, B. × rhynchopetala. However, the direction of hybridization and extent of introgression are unclear. A large number of species-specific inter-simple sequence repeat (ISSR) markers were found in B. gymnorrhiza and B. sexangula, and the additive ISSR profiling of B. × rhynchopetala ascertained its hybrid status and identified its parental origin. The varying degree of scatterness among hybrid individuals in Principal Coordinate Analysis and results from NewHybrids analysis indicate that B. × rhynchopetala comprises different generations of introgressants in addition to F 1s. High genetic relatedness between B. × rhynchopetala and B. gymnorrhiza based on nuclear and chloroplast sequences suggests preferential hybrid backcrosses to B. gymnorrhiza. We conclude that B. × rhynchopetala has not evolved into an incipient hybrid species, and its persistence can be explained by recurrent hybridization and introgression. Genomic data provide insights into the hybridization dynamics of mangrove plants. Such information can assist in biodiversity assessment by helping detect novel taxa and/or define species boundaries.

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Section: Discussionmentioning

confidence: 99%

Genomic Markers Reveal Introgressive Hybridization in the Indo-West Pacific Mangroves: A Case Study

Sun

2011

PLoS ONE

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“…Hybrids of Rhizophora (specifically R. ×lamarckii , R. ×selala , and R. ×annamalayana ) are not included in this study because these hybrids have been shown to be F 1s [81] and are sterile or have much reduced fertility [6,42]. Inclusion of hybrid individuals can create conflict between chloroplast and nuclear trees [81], and obstruct our goal of inferring biogeographic history of the genus. Individuals of Bruguiera gymnorrhiza , from the sister genus to Rhizophora , were used as outgroup to root phylogenetic trees.…”

Section: Methodsmentioning

confidence: 99%

Phylogeographic pattern of Rhizophora (Rhizophoraceae) reveals the importance of both vicariance and long-distance oceanic dispersal to modern mangrove distribution

2014

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BackgroundMangroves are key components of coastal ecosystems in tropical and subtropical regions worldwide. However, the patterns and mechanisms of modern distribution of mangroves are still not well understood. Historical vicariance and dispersal are two hypothetic biogeographic processes in shaping the patterns of present-day species distributions. Here we investigate evolutionary biogeography of mangroves in the Indo-West Pacific (IWP) and western Atlantic-East Pacific (AEP) regions using a large sample of populations of Rhizophora (the most representative mangrove genus) and a combination of chloroplast and nuclear DNA sequences and genome-wide ISSR markers.ResultsOur comparative analyses of biogeographic patterns amongst Rhizophora taxa worldwide support the hypothesis that ancient dispersals along the Tethys Seaway and subsequent vicariant events that divided the IWP and AEP lineages resulted in the major disjunctions. We dated the deep split between the Old and New World lineages to early Eocene based on fossil calibration and geological and tectonic changes. Our data also provide evidence for other vicariant processes within the Indo-West Pacific region in separating conspecific lineages of SE Asia and Australia-Pacific at the Oligocene-Miocene boundary. Close genetic affinities exist between extant Fijian and American lineages; East African and Australian lineages; and Australian and Pacific lineages; indicating relatively more recent oceanic long-distance dispersal events.ConclusionsOur study demonstrates that neither vicariance nor dispersal alone could explain the observed global occurrences of Rhizophora, but a combination of vicariant events and oceanic long-distance dispersals can account for historical diversification and present-day biogeographic patterns of mangroves.

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“…In addition to these structures, it is now evident that some unimodal hybrid zones may be entirely or largely composed of F1 hybrids, while other hybrid zones are trimodal, containing both parents and mainly F1s. The absence or low frequency of later generation hybrids in these hybrid zones is not surprising when F1s are sterile (e.g., Moccia et al, 2007;Lo, 2010;Twyford et al, 2015), but is unexpected when F1s are fully fertile as documented in several studies (e.g., Milne et al, 2003;Christe et al, 2016). The absence of post-F1 hybrids where F1s are fertile has been attributed to their reduced postzygotic, extrinsic fitness in ecotones relative to F1s, causing them to be outcompeted (Milne et al, 2003), or to a lower intrinsic fitness relative to F1s caused by expression of Bateson-Dobzhansky-Muller (BDM) incompatibilities and/or breakdown of coadaptive gene complexes following recombination .…”

Section: Structure Of Hybrid Zonesmentioning

confidence: 99%

Plant speciation across environmental gradients and the occurrence and nature of hybrid zones

Abbott

2017

J of Sytematics Evolution

131

140

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Environmental gradients are very common and many plant species respond to them through adaptive genetic change. This can be a first step along a continuum of change that leads ultimately to the origin of fully reproductively isolated forms, i.e., 'biological species'. Before complete reproductive isolation is achieved, hybrid zones may form between divergent lineages either through primary intergradation or secondary contact. Here, I review the literature on plant hybrid zones between native species and highlight: mode of origin (primary intergradation versus secondary contact); distribution among plant families, genera and life form; type and genotypic composition related to strength and type of reproductive isolation between parental lineages; nature of prezygotic and postzygotic reproductive barriers; level and direction of gene flow; and the stability of hybrid zones in the face of climate change. The total number of plant hybrid zones detected in a literature search was surprisingly small (137). This was the case even for areas of the world with a long history of research into plant evolution, ecology and systematics. Reasons for this are discussed, including the possibility that plant hybrid zones are naturally rare in the wild. Only for a few hybrid zones have attempts been made to distinguish between formation by primary intergradation or secondary contact, and it is assumed that most hybrid zones originate through secondary contact. From the limited information available, it appears that plant hybrid zones may frequently move in response to climate change, but long-term studies are required to confirm this.

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Testing hybridization hypotheses and evaluating the evolutionary potential of hybrids in mangrove plant species

Cited by 33 publications

References 100 publications

Genomic Markers Reveal Introgressive Hybridization in the Indo-West Pacific Mangroves: A Case Study

Genomic Markers Reveal Introgressive Hybridization in the Indo-West Pacific Mangroves: A Case Study

Phylogeographic pattern of Rhizophora (Rhizophoraceae) reveals the importance of both vicariance and long-distance oceanic dispersal to modern mangrove distribution

Plant speciation across environmental gradients and the occurrence and nature of hybrid zones

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