Ecogeographic isolation: a reproductive barrier between species and between cytotypes in Houstonia (Rubiaceae)

Glennon, Kelsey L.; Rissler, Leslie J.; Church, Sheri A.

doi:10.1007/s10682-011-9539-x

Cited by 38 publications

(46 citation statements)

References 60 publications

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“…; Glennon et al. ). Divergence in response to discrete selection pressures across parapatric soil boundaries has received considerable attention (e.g., McNeilly and Antonovics ; Sambatti and Rice ; Wright et al.…”

Section: Discussionmentioning

confidence: 97%

Reproductive isolation and the maintenance of species boundaries in two serpentine endemic Jewelflowers

Christie

Strauss

2019

Evolution

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Speciation occurs when reproductive barriers substantially reduce gene flow between lineages. Understanding how specific barriers contribute to reproductive isolation offers insight into the initial forces driving divergence and the evolutionary and ecological processes responsible for maintaining diversity. Here, we quantified multiple pre‐ and post‐pollination isolating barriers in a pair of closely related California Jewelflowers (Streptanthus, Brassicaceae) living in an area of sympatry. S. breweri and S. hesperidis are restricted to similar serpentine habitats; however, populations are spatially isolated at fine‐scales and rarely co‐occur in intermixed stands. Several intrinsic postzygotic barriers were among the strongest we quantified, yet, postzygotic barriers currently contribute little to overall reproductive isolation due to the cumulative strength of earlier‐acting extrinsic barriers, including spatial isolation, and flowering time and pollinator differences. Data from multiple years suggest that pre‐pollination barriers may have different strengths depending on annual environmental conditions. Similarly, crossing data suggest that the strength of intrinsic isolation may vary among different population pairs. Estimates of total reproductive isolation in S. breweri and S. hesperidis are robust to uncertainty and variability in individual barrier strength estimates, demonstrating how multiple barriers can act redundantly to prevent gene flow between close relatives living in sympatry.

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Section: Discussionmentioning

confidence: 97%

Reproductive isolation and the maintenance of species boundaries in two serpentine endemic Jewelflowers

Christie

Strauss

2019

Evolution

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“…The divergence of ecotypes can eventually lead to speciation through the evolution of ecological reproductive isolation (Ramsey et al 2003; Kay 2006; Lowry et al 2008; Glennon et al 2012). Ecotypes generally differ in suites ( i.e.…”

mentioning

confidence: 99%

The Genetic Basis of Upland/Lowland Ecotype Divergence in Switchgrass (Panicum virgatum)

Milano

Lowry

Juenger

2016

G3 Genes|Genomes|Genetics

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The evolution of locally adapted ecotypes is a common phenomenon that generates diversity within plant species. However, we know surprisingly little about the genetic mechanisms underlying the locally adapted traits involved in ecotype formation. The genetic architecture underlying locally adapted traits dictates how an organism will respond to environmental selection pressures, and has major implications for evolutionary ecology, conservation, and crop breeding. To understand the genetic architecture underlying the divergence of switchgrass (Panicum virgatum) ecotypes, we constructed a genetic mapping population through a four-way outbred cross between two northern upland and two southern lowland accessions. Trait segregation in this mapping population was largely consistent with multiple independent loci controlling the suite of traits that characterizes ecotype divergence. We assembled a joint linkage map using ddRADseq, and mapped quantitative trait loci (QTL) for traits that are divergent between ecotypes, including flowering time, plant size, physiological processes, and disease resistance. Overall, we found that most QTL had small to intermediate effects. While we identified colocalizing QTL for multiple traits, we did not find any large-effect QTL that clearly controlled multiple traits through pleiotropy or tight physical linkage. These results indicate that ecologically important traits in switchgrass have a complex genetic basis, and that similar loci may underlie divergence across the geographic range of the ecotypes.

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“…However, the role of niche shift in polyploid establishment and persistence continues to be the subject of active debate. Divergence of habitat preferences between related diploid and polyploid taxa was detected in several studies (Parisod et al, 2010;Glennon et al, 2012;Manzaneda et al, 2012;McIntyre, 2012;Kol a r et al, 2013;Sonnleitner et al, 2016), including in Primula sect. Aleuritia (Theodoridis et al, 2013).…”

Section: Discussionmentioning

confidence: 92%

Do floral and niche shifts favour the establishment and persistence of newly arisen polyploids? A case study in an Alpine primrose

Casazza

Boucher

Minuto

et al. 2016

Ann Bot

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Background and Aims Polyploidization plays a key role in plant evolution. Despite the generally accepted 'minority-cytotype exclusion' theory, the specific mechanisms leading to successful establishment and persistence of new polyploids remain controversial. The majority of newly formed polyploids do not become established, because they are less common, have fewer potential mates or may not be able to compete successfully with co-occurring progenitors at lower ploidy levels. Changes in floral traits and ecological niches have been proposed as important mechanisms to overcome this initial frequency-dependent disadvantage. The aim of this study was to determine whether dodecaploids of the heterostylous P. marginata differ from their hexaploid progenitors in P. marginata and P. allionii for selected floral traits and ecological preferences that might be involved in establishment and persistence, providing a possible explanation for the origin of polyploidized populations.Methods Floral morphological traits and ecological niche preferences among dodecaploids and their hexaploid progenitors in P. marginata and P. allionii, all restricted to the south-western Alps, were quantified and compared Key Results Differences in floral traits were detected between dodecaploids and their closest relatives, but such differences might be too weak to counter the strength of minority cytotype disadvantage and are unlikely to enable the coexistence of different cytotypes. Furthermore, the results suggest the preservation of full distyly and no transition to selfing in dodecaploids. Finally, dodecaploids occur almost exclusively in environments that are predicted to be suitable also for their closest hexaploid relatives.Conclusions In light of the results, P. marginata dodecaploids have probably been able to establish and persist by occupying geographical areas not yet filled by their closest relatives without significant evolution in their climatic and pollination niches. Dispersal limitation and minority-cytotype exclusion probably maintain their current range disjunct from those of its close relatives.

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Ecogeographic isolation: a reproductive barrier between species and between cytotypes in Houstonia (Rubiaceae)

Cited by 38 publications

References 60 publications

Reproductive isolation and the maintenance of species boundaries in two serpentine endemic Jewelflowers

Reproductive isolation and the maintenance of species boundaries in two serpentine endemic Jewelflowers

The Genetic Basis of Upland/Lowland Ecotype Divergence in Switchgrass (Panicum virgatum)

Do floral and niche shifts favour the establishment and persistence of newly arisen polyploids? A case study in an Alpine primrose

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