Species and Allopatric Speciation

Cabej, Nelson R.

doi:10.1016/b978-0-12-415831-3.00018-5

Cited by 5 publications

(3 citation statements)

References 26 publications

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“…AFLPs revealed a slight differentiation between the two subspecies of Carex reuteriana , in congruence with their allopatric distribution ( Fig. 1 ), suggesting the importance of geographic speciation during their differentiation ( Cabej, 2012 ; Sobel, 2016 ). For the subspecies reuteriana , DAPC and BAPS analyses recovered a single genetic cluster likely due to gene flow between its populations, whilst for subspecies mauritanica two genetic clusters with geographical congruence were identified ( Figs.…”

Section: Discussionmentioning

confidence: 56%

Dramatic impact of future climate change on the genetic diversity and distribution of ecologically relevant Western Mediterranean Carex (Cyperaceae)

Benítez‐Benítez

Sanz-Arnal

Urbani

et al. 2022

PeerJ

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Anticipating the evolutionary responses of species to ongoing climate change is essential to propose effective management and conservation measures. The Western Mediterranean Basin constitutes one of the hotspots of biodiversity where the effects of climate change are expected to be more dramatic. Plant species with ecological relevance constitute ideal models to evaluate and predict the impact of climate change on ecosystems. Here we investigate these impacts through the spatio-temporal comparison of genetic diversity/structure (AFLPs), potential distribution under different future scenarios of climate change, and ecological space in two Western Mediterranean sister species of genus Carex. Both species are ecologically key in their riparian habitats, but display contrasting distribution patterns, with one widespread in the Iberian Peninsula and North Africa (C. reuteriana), while the other (C. panormitana) is a restricted, probably endangered, Central Mediterranean endemic. At present, we found a strong genetic structure driven by geography in both species, and lower values of genetic diversity and a narrower ecological space in C. panormitana than in C. reuteriana, while the allelic rarity was higher in the former than in C. reuteriana subspecies. Future projections predict an overall dramatic reduction of suitable areas for both species under all climate change scenarios, which could be almost total for C. panormitana. In addition, gene diversity was inferred to decrease in all taxa, with genetic structure reinforcing in C. reuteriana by the loss of admixture among populations. Our findings stress the need for a reassessment of C. panormitana conservation status under IUCN Red List criteria and the implementation of conservation measures.

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Section: Discussionmentioning

confidence: 56%

Dramatic impact of future climate change on the genetic diversity and distribution of ecologically relevant Western Mediterranean Carex (Cyperaceae)

Benítez‐Benítez

Sanz-Arnal

Urbani

et al. 2022

PeerJ

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“…The speciation mode of lineage splitting is the divergence of a single historical lineage into two or more descendent lineages (Coyne & Orr, 2004;Darwin, 1859;Mayr, 1963;Wu, 2001). In this speciation mode, the formation and maintenance of reproductive isolation (RI) is a complicated process that is determined by different evolutionary driving forces, such as natural selection, gene flow and random genetic drift (Cabej, 2012;Darwin, 1859;Mayr, 1959;Tavares et al, 2018;Wu, 2001). In the cichlid Astatotilapia calliptera, for example, adaptive divergence of shallowlittoral and deep-benthic ecomorphs was promoted by natural selection acting on candidate genes that are functionally related to traits under sexual selection, such as craniofacial development, the sensory system, hormone signaling and morphology (Carruthers et al, 2022;Malinsky et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Post‐hybridization introgression and natural selection promoted genomic divergence of Aegilops speltoides and the four S*‐genome diploid species

et al. 2023

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SUMMARYUnderstanding how different driving forces have promoted biological divergence and speciation is one of the central issues in evolutionary biology. The Triticum/Aegilops species complex contains 13 diploid species belonging to the A‐, B‐ and D‐lineages and offers an ideal system to address the evolutionary dynamics of lineage fusion and splitting. Here, we sequenced the whole genomes of one S‐genome species (Aegilops speltoides) of the B‐lineage and four S*‐genome diploid species (Aegilops bicornis, Aegilops longissima, Aegilops sharonensis and Aegilops searsii) of the D‐lineage at the population level. We performed detailed comparisons of the five species and with the other four representative A‐, B‐ and D‐lineage species. Our estimates identified frequent genetic introgressions from A‐ and B‐lineages to the D‐lineage species. A remarkable observation is the contrasting distributions of putative introgressed loci by the A‐ and B‐lineages along all the seven chromosomes to the extant D‐lineage species. These genetic introgressions resulted in high levels of genetic divergence at centromeric regions between Ae. speltoides (B‐lineage) and the other four S*‐genome diploid species (D‐lineage), while natural selection is a potential contributor to divergence among the four S*‐genome species at telomeric regions. Our study provides a genome‐wide view on how genetic introgression and natural selection acted together yet chromosome‐regionally divided to promote genomic divergence among the five S‐ and S*‐genome diploid species, which provides new and nuanced insights into the evolutionary history of the Triticum/Aegilops species complex.

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“…Such results would be expected given the large geographic distance between Knapp et al (2012) and my collection sites. This distance is likely linked to a longer separation time from a common ancestor and different selection pressures, both of which increase the possibilities for genetic divergence (Cabej, 2012).…”

Section: Taxonomic Identificationmentioning

confidence: 99%

A Symbiosis Between a Dark Septate Fungus, an Arbuscular Mycorrhiza, and Two Plants Native to the Sagebrush Steppe

Carpenter¹

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Plant roots form symbioses with various fungi, including arbuscular mycorrhizae (AMFs) and dark septate endophytes (DSEs). The symbiosis between plants and AMFs has been extensively studied and is generally considered to be mutualistic. Much less is known about the symbiosis between plants and DSE. In sagebrush habitats, DSEs are common, but their effects on the vegetation are unclear. As a first step to study these effects, I isolated and cultured a DSE from the roots of the shrub Artemisia tridentata. Based on partial sequences of five genes and phylogenetic analyses, the isolated fungus was a non-described species within the Darksidea or a closely related sister group. Subsequently, I performed experiments in vitro and in potted plants to determine the effect of the isolated DSE on root tissue integrity, colonization by the AMF Rhizophagus irregularis, and plant biomass. These experiments were conducted in two plant species, A. tridentata and the native grass Poa secunda. Plants were exposed to one of four treatments: no inoculation (-AMF-DSE), inoculation with the DSE isolate (-AMF+DSE), inoculation with R. irregularis (+AMF-DSE), and inoculation with both fungi (+AMF+DSE). Microscopic observations revealed that the DSE hyphae grew along the root surface and penetrated epidermal and cortical cells without damage to them. In A. tridentata, the hyphae also reached the stele. For both species, total DSE colonization in the –AMF+DSE treatment was similar to that in the +AMF+DSE treatment, indicating the presence of AMF did not alter DSE colonization. Inoculation with DSE did not affect total AMF colonization of A. tridentata; however, it increased total colonization of P. secunda from 16.9 (+5.6%) in the +AMF-DSE treatment to 42.6 (+2.9%) in the +AMF+DSE treatment. Also, in both species, the presence of the DSE more than doubled the frequency of AMF intraradical storage structures, which consisted of vesicles plus intraradical spores. These results suggest that via increases in AMF colonization, DSE could lead to a beneficial effect on the host plants. However, neither on its own nor through co-inoculation with AMF, did the DSE isolate affect plant biomass. Thus, under the two conditions tested, the symbiosis was commensalistic. Further work is needed to evaluate the symbiosis in settings that better mimic the natural environment.

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Species and Allopatric Speciation

Cited by 5 publications

References 26 publications

Dramatic impact of future climate change on the genetic diversity and distribution of ecologically relevant Western Mediterranean Carex (Cyperaceae)

Dramatic impact of future climate change on the genetic diversity and distribution of ecologically relevant Western Mediterranean Carex (Cyperaceae)

Post‐hybridization introgression and natural selection promoted genomic divergence of Aegilops speltoides and the four S*‐genome diploid species

A Symbiosis Between a Dark Septate Fungus, an Arbuscular Mycorrhiza, and Two Plants Native to the Sagebrush Steppe

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