Everything You Always Wanted to Know about Sexes

Whitfield, John

doi:10.1371/journal.pbio.0020183

Cited by 17 publications

(13 citation statements)

References 9 publications

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“…4), in line with recent work (Keightley and Otto 2006). In the establishment phase of sex, the twofold cost of sex would not have been relevantit seems likely that sex evolved before the separation of the sexes (Whitfield 2004), with males evolving to exploit the situation (Fisher 1930). The maintenance of sex, in which the twofold cost is applicable, is more complicated, and the advantages of sex may be buttressed by other effects, such as sexual selection (Siller 2001).…”

Section: Discussionmentioning

confidence: 66%

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Establishment of facultative sexuals

Paley

Taraskin

Elliott

2007

Naturwissenschaften

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The existence of sex is one of the major unsolved problems in biology. We use computer simulations to model conditions in which sex may first become established. We develop an individual-based population model and show that a hypothetical facultative sex gene can fix, provided that the initial cost is low. It is demonstrated that the equilibrium fitness in the population increases with increasing population size and decreasing mutation rate. The probability of the establishment of the sex gene is found not to be directly related to the fitness difference between the asexual and sexual populations. This change in fitness on changing the parameters of the model is investigated.

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Section: Discussionmentioning

confidence: 66%

“…The fixation of a hypothetical 'facultative sex gene' is examined in our simulated population. When sex initially evolved, there would have been no separate male and female (Whitfield 2004); separate sexes (and anisogamy) probably evolved later. There would have been initial costs to sex but this cost is unlikely to have been twofold.…”

Section: Introductionmentioning

confidence: 99%

Establishment of facultative sexuals

Paley

Taraskin

Elliott

2007

Naturwissenschaften

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“…In anisogamous species, in which one gamete class is normally larger than the other, this is typically the only possible stable scenario (Lessells et al, 2009). However, even among isogamous eukaryotes, the occurrence of two mating types is thought to be most common (Whitfield, 2004). Dictyostelids and their close rela-tives the myxogastrids are among the exceptions to this rule, along with certain ciliates and basidiomycete fungi (Hurst and Hamilton, 1992).…”

Section: Sex and Multiple Mating Typesmentioning

confidence: 99%

Sex and macrocyst formation in Dictyostelium

Bloomfield¹

2019

Int. J. Dev. Biol.

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Sex in Dictyostelia involves a remarkable form of cannibalism in which zygotes attract large numbers of surrounding amoebae and then ingest them. Before they are consumed, the attracted amoebae help the zygote by synthesising an outer wall around the aggregate that traps them inside and helps to protect the mature developed zygotic structure, the macrocyst. Competition between cells vying to contribute genetically to zygotes and through to the next generation seems likely to have promoted the evolution of several unusual features of dictyostelid sex: individual species often have more than two mating types, increasing haploid cells' chances of matching with a compatible partner, and fusion of many gametes to form transient syncytia allows cytoplasmic mixing and lateral transmission of mitochondrial genomes. This review will summarise recent advances in our understanding of mating-type determination, gamete fusion, and inheritance in Dictyostelium, and highlight the key gaps in our understanding of this fascinating set of phenomena.

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“…These represent many different combinations of “lifestyle choices” discussed in the review, and all are described in more detail in the main text. Photo credits: Macrostomum lignano , Dita Vizoso (Wikimedia Commons under CC‐BY‐SA‐3.0); Maritigrella crozieri , originally published in Lapraz et al () (reproduced under CC‐BY‐2.0); Pseudobiceros bedfordi , originally published in Whitfield () (Wikimedia Commons under CC‐BY‐2.5); Schmidtea mediterranea , Alejandro Sánchez Alvarado (Wikimedia Commons under CC‐BY‐SA‐2.5); Diplozoon paradoxum , public domain image (Wikimedia Commons); Schistocephalus solidus , Lukas Schärer; Echinococcus multilocularis , public domain image (Wikimedia Commons); Schistosoma mansoni , David Williams, public domain image (Wikimedia Commons). As noted in the figure, extensive genome and transcriptome data have recently become available for many of these model organisms (e.g.…”

Section: Lifestyle Choices Affecting Flatworm Reproductionmentioning

confidence: 99%

Exploring the sexual diversity of flatworms: Ecology, evolution, and the molecular biology of reproduction

Ramm

2016

Molecular Reproduction Devel

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SUMMARYFlatworms exhibit huge diversity in their reproductive biology, making this group an excellent model system for exploring how differences among species in reproductive ecology are reflected in the physiological and molecular details of how reproduction is achieved. In this review, I consider five key ''lifestyle choices'' (i.e., alternative evolutionary/developmental outcomes) that collectively encompass much of flatworm sexual diversity, beginning with the decisions: (i) whether to be freeliving or parasitic; (ii) whether to reproduce asexually or sexually; and (iii) whether to be gonochoristic (separate-sexed) or hermaphroditic. I then examine two further decisions involving hermaphroditism: (iv) outcrossing versus selfing and (v) the balance of investment into the male versus the female sex function (sex allocation). Collectively, these lifestyle choices set the basic rules for how reproduction occurs, but as I emphasize in the second part of the review, the reproductive biology of flatworms is also greatly impacted by the near-pervasive and powerful pressure of sexual selection, together with the related phenomena of sperm competition and sexual conflict. Exactly how this plays out, however, is strongly affected by the particular combination of reproductive strategies adopted by each species. A striking feature of flatworms . . . is the complexity and diversity of their reproductive systems.

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Everything You Always Wanted to Know about Sexes

Abstract: What defines a sex? Although we tend to think there are only two - males and females - there are many different ways to mix and match the attributes of sexes

Cited by 17 publications

References 9 publications

Establishment of facultative sexuals

Establishment of facultative sexuals

Sex and macrocyst formation in Dictyostelium

Exploring the sexual diversity of flatworms: Ecology, evolution, and the molecular biology of reproduction

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