Homologous Versus Antithetic Alternation of Generations and the Origin of Sporophytes

Haig, David

doi:10.1007/s12229-008-9012-x

Cited by 34 publications

(33 citation statements)

References 50 publications

(57 reference statements)

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“…Beard believed that the alternation of asexual (sporophyte) and sexual (gametophyte) generations of plants had its counterpart in an alternation of asexual (larval) and sexual (adult) stages in animals. Plant and animal life cycles differed in that the transition from asexual to sexual forms was accompanied by a halving of chromosome number in plants but occurred without chromosome reduction in animals (analogous to aposporous development in plants) [43]. The chorion was the 'larval' generation of mammals.…”

Section: Trophoblast and The Subversion Of Extrinsic Defencesmentioning

confidence: 99%

Maternal–fetal conflict, genomic imprinting and mammalian vulnerabilities to cancer

Haig

2015

Phil. Trans. R. Soc. B

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Antagonistic coevolution between maternal and fetal genes, and between maternally and paternally derived genes may have increased mammalian vulnerability to cancer. Placental trophoblast has evolved to invade maternal tissues and evade structural and immunological constraints on its invasion. These adaptations can be co-opted by cancer in intrasomatic selection. Imprinted genes of maternal and paternal origin favour different degrees of proliferation of particular cell types in which they reside. As a result, the set of genes favouring greater proliferation will be selected to evade controls on cell-cycle progression imposed by the set of genes favouring lesser proliferation. The dynamics of stem cell populations will be a particular focus of this intragenomic conflict. Gene networks that are battlegrounds of intragenomic conflict are expected to be less robust than networks that evolve in the absence of conflict. By these processes, maternal–fetal and intragenomic conflicts may undermine evolved defences against cancer.

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Section: Trophoblast and The Subversion Of Extrinsic Defencesmentioning

confidence: 99%

Maternal–fetal conflict, genomic imprinting and mammalian vulnerabilities to cancer

Haig

2015

Phil. Trans. R. Soc. B

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“…The green algae, however, are heterogeneous and include taxa in which one or the other or both generations are multicellular, so inferences about the origin of the embryophyte life cycle depend on which group of green algae is sister to the embryophytes ( Haig, 2008 ;Niklas and Kutschera, 2009 ). Evidence from ultrastructural, biochemical, and molecular data supports the view that the charophycean green algae (including the Charales, Coleochaetales, and other groups) are closely related to the embryophytes, and so their life cycles are informative about the ancestral condition in embryophytes.…”

Section: Relationships Among Bryophyte Groups and The Evolution Of Emmentioning

confidence: 99%

Bryophyte diversity and evolution: Windows into the early evolution of land plants

Shaw

Szövényi

Shaw

2011

American J of Botany

185

136

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The "bryophytes" comprise three phyla of plants united by a similar haploid-dominant life cycle and unbranched sporophytes bearing one sporangium: the liverworts (Marchantiophyta), mosses (Bryophyta), and hornworts (Anthocerophyta). Combined, these groups include some 20000 species. As descendents of embryophytes that diverged before tracheophytes appeared, bryophytes offer unique windows into the early evolution of land plants. We review insights into the evolution of plant life cycles, in particular the elaboration of the sporophyte generation, the major lineages within bryophyte phyla, and reproductive processes that shape patterns of bryophyte evolution. Recent transcriptomic work suggests extensive overlap in gene expression in bryophyte sporophytes vs. gametophytes, but also novel patterns in the sporophyte, supporting Bower's antithetic hypothesis for origin of alternation of generations. Major lineages of liverworts, mosses, and hornworts have been resolved and general patterns of morphological evolution can now be inferred. The life cycles of bryophytes, arguably more similar to those of early embryophytes than are those in any other living plant group, provide unique insights into gametophyte mating patterns, sexual conflicts, and the efficacy and effects of spore dispersal during early land plant evolution.

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“…In the early part of the 20th century the origin of land plants was debated in the form of two opposing theories: antithetic alternation (or interpolation) theory vs. the homologous alternation (or transformational) theory (Haig, 2008). Based on the ideas of Celakovsky (1874), Bower (1908Bower ( , 1935 proposed that the embryophytes originated through the interpolation of a de novo sporophytic generation between preexisting fertile gametophytic phases.…”

Section: The Antithetic Theory and The Asynchronous Origin Of Embryopmentioning

confidence: 99%

Thalloid carbonaceous incrustations and the asynchronous evolution of embryophyte characters during the Early Paleozoic

Strother

2010

International Journal of Coal Geology

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Homologous Versus Antithetic Alternation of Generations and the Origin of Sporophytes

Abstract: Published Version

Cited by 34 publications

References 50 publications

Maternal–fetal conflict, genomic imprinting and mammalian vulnerabilities to cancer

Maternal–fetal conflict, genomic imprinting and mammalian vulnerabilities to cancer

Bryophyte diversity and evolution: Windows into the early evolution of land plants

Thalloid carbonaceous incrustations and the asynchronous evolution of embryophyte characters during the Early Paleozoic

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