Is asexual reproduction an evolutionary dead end in lichens?

2016 ◽  
Vol 48 (5) ◽  
pp. 559-580 ◽  
Author(s):  
Erin A. TRIPP
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Evolutionary Biology ◽  
Reproductive Mode ◽  
Phylogenetic Information ◽  
Statistical Framework ◽  
Evolutionary Innovation ◽  
Dead End ◽  
Sexual And Asexual Reproduction ◽  
Gains And Losses

AbstractClassical hypotheses in lichenology predict pairs of species in which sexual lineages are ancestral and long-lived evolutionarily and that these give rise to derived, evolutionarily transient asexual lineages. Extensive phylogenetic information generated over the last 20 years regarding relationships within and among various groups of lichens makes possible an investigation of polarity and lability in reproductive mode across diverse clades. To test the long-held hypothesis of asexual reproduction as an evolutionary dead end in lichens, existing phylogenetic data from 23 studies were utilized to reconstruct gains and losses of sexual and asexual reproduction in a model-based statistical framework. Summed across all studies, between 26–44 origins of asexual reproduction from sexual ancestors (forward transitions) and 14–25 origins of sexual reproduction from asexual ancestors (reverse transitions) were identified. However, the higher number of gains of asexual reproduction was concentrated in a relatively low number of clades (e.g. Dirina). The greater number of forward compared to reverse transitions is consistent with dogma in both lichenology and evolutionary biology, but nonetheless this study documents numerous reverse transitions, suggesting that asexual lineages represent a source for evolutionary innovation.

scholarly journals Ant queens adjust egg fertilization to benefit from both sexual and asexual reproduction

2011 ◽  
Vol 7 (4) ◽  
pp. 571-573 ◽  
Author(s):  
S. Aron ◽  
I. Timmermans ◽  
M. Pearcy
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Evolutionary Biology ◽  
Transmission Rate ◽  
Early Spring ◽  
Mating Period ◽  
Cataglyphis Cursor ◽  
Sexual And Asexual Reproduction ◽  
Over Time

An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of the ant Cataglyphis cursor maximize the transmission rate of their genes by regulating the proportion of fertilized and parthenogenetic eggs laid over time. Parthenogenetic offspring are produced in early spring, when workers raise the brood into sexuals. After the mating period, queens lay mostly fertilized eggs that will be reared as the non-reproductive caste.

scholarly journals Reproductive Strategies of the Seagrass Zostera japonica Under Different Geographic Conditions in Northern China

2020 ◽  
Vol 7 ◽  
Author(s):  
Shidong Yue ◽  
Xiaomei Zhang ◽  
Shaochun Xu ◽  
Yu Zhang ◽  
Peng Zhao ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Reproductive Strategies ◽  
Geographic Location ◽  
Dry Weight ◽  
Northern China ◽  
Shoot Density ◽  
Zostera Japonica ◽  
Sexual And Asexual Reproduction ◽  
Density And Biomass

Seagrasses form a unique group of submerged marine angiosperms capable of both sexual and asexual reproduction. The amounts of sexual and asexual reproduction differ within some species relying on geographic location and environmental factors. Here, we studied the reproductive strategies of different geographic Zostera japonica populations, S1 and S2 at Swan Lake lagoon (SLL), and H1 and H2 at Huiquan Bay (HQB), in northern China. The duration of flowering at SLL was longer than at HQB, whereas flowering initiation at HQB occurred earlier than at SLL. In addition, the timing of seed maturation at HQB occurred earlier than at SLL. The allocation to sexual reproduction at SLL was greater than at HQB. The maximum potential seed production was greatest at S1 (22228.52 ± 8832.46 seeds ⋅ m–2), followed by S2 (21630.34 ± 9378.67 seeds ⋅ m–2), H2 (7459.60 ± 1779.33 seeds ⋅ m–2), and H1 (2821.05 ± 1280.57 seeds ⋅ m–2). The seasonal changes in total shoot density and biomass were small at HQB. There was a relatively large number of overwintering shoots at HQB because of the higher average temperature during winter. The allocation to sexual reproduction was lower than at SLL, and no seedlings were observed at HQB during our study. Thus, the population of Z. japonica at HQB was maintained by asexual reproduction. Compared with HQB, the biomass of overwintering shoots at SLL was less than 30 g dry weight ⋅ m–2. The Z. japonica at SLL relied on asexual and sexual reproduction to maintain the population. The results show the necessity of understanding local reproductive strategies before starting restoration and management projects. The study provides fundamental information and guidance for the conservation and restoration of seagrass beds.

scholarly journals Investigation of evolutionary effects on the relative frequency of sexual reproduction in freshwater diatoms

Phytotaxa ◽  
2013 ◽  
Vol 127 (1) ◽  
pp. 183 ◽  
Author(s):  
VIRGINIA M. CARD ◽  
MEEGEN CARRA
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Relative Frequency ◽  
Narrow Range ◽  
Size Class ◽  
Analysis Method ◽  
Costs And Benefits ◽  
Size Classes ◽  
Size Class Distribution ◽  
Sexual And Asexual Reproduction

There are substantial ecological and evolutionary costs to sexual reproduction and there is only a narrow range of conditions that favors the evolution of high rates of sexual reproduction in species that are capable of both sexual and asexual reproduction. Considering the evolutionary costs and benefits of sexual reproduction, it was hypothesized that the frequency of sexual reproduction relative to asexual reproduction in diatoms would be greater for attached pennates and lower for planktonic centrics. This was investigated by comparison of the size-class distributions of the attached pennate, Rhopalodia gibba (Ehrenberg) Müller 1895 and the planktonic centric Cyclotella meneghiniana Kützing 1844 collected from the littoral zone of Lake Phalen in St. Paul Minnesota, USA. Numerical combination of binomial functions was used to infer the number of significant occurrences of sexual reproduction contributing to the size-class distribution of each population, with the frequency of sexual reproduction relative to asexual reproduction inferred from the number of binomial curves contributing to the distribution. The size-class profile of C. meneghiniana was unimodal, dominated by a single peak at 12 µm, with additional contributing curves with peaks at 15 µm and 18 µm. The size-class profile of R. gibba was bimodal, dominated by peaks at 46 µm and 60 µm, with additional contributing curves with peaks at 36 µm, 73 µm, and 84 µm. The results of this investigation were robust with respect to difference between the species in sample size and number of size-classes, although the analysis method is sensitive to differences in the number of size-classes. The results supported the hypothesis, and demonstrate the principle that size-class analysis of diatom populations can be used to investigate evolutionary hypotheses about differences among taxa in the relative frequency of sexual and asexual reproduction.

Reproduction of Cnidaria

2002 ◽  
Vol 80 (10) ◽  
pp. 1735-1754 ◽  
Author(s):  
Daphne Gail Fautin
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Somatic Tissue ◽  
Class Level ◽  
Sexual And Asexual Reproduction ◽  
Analytical Tools ◽  
Reproductive Characters ◽  
Analytical Frameworks ◽  
Shed Light

Empirical and experimental data on cnidarian reproduction show it to be more variable than had been thought, and many patterns that had previously been deduced hold up poorly or not at all in light of additional data. The border between sexual and asexual reproduction appears to be faint. This may be due to analytical tools being insufficiently powerful to distinguish between the two, but it may be that a distinction between sexual and asexual reproduction is not very important biologically to cnidarians. Given the variety of modes by which it is now evident that asexual reproduction occurs, its ecological and evolutionary implications have probably been underestimated. Appropriate analytical frameworks and strategies must be developed for these morphologically simple animals, in which sexual reproduction may not be paramount, that during one lifetime may pass though two or more phases differing radically in morphology and ecology, that may hybridize, that are potentially extremely long-lived, and that may transmit through both sexual and asexual reproduction mutations arising in somatic tissue. In cnidarians, perhaps more than in any other phylum, reproductive attributes have been used to define taxa, but they do so at a variety of levels and not necessarily in the way they have conventionally been considered. At the species level, in Scleractinia, in which these features have been most studied, taxa defined on the basis of morphology, sexual reproduction, and molecular characters may not coincide; there are insufficient data to determine if this is true throughout the phylum. At the class level, transverse fission occurs in members of all three major taxa but is rare outside Scyphozoa, the group of which it is considered characteristic (pending more research, its absence in Cubozoa should be ascribed to poor knowledge). Understanding the role of transverse fission in the ecology and reproductive biology of hydrozoans and anthozoans could shed light on scyphozoan evolutionary history, and elucidating its morphogenesis in all groups is essential to determining if it is homologous across the classes. Only by comparing aspects of reproduction among cnidarians of various taxa will idiosyncratically adaptive strategies be distinguished from reproductive characters that reflect evolution and so are phylogenetically informative.

scholarly journals Sexual reproduction as bet-hedging

2017 ◽  
Keyword(s):  
Reproductive Success ◽  
Sexual Reproduction ◽  
Evolutionary Biology ◽  
De Novo ◽  
Geometric Mean ◽  
Arithmetic Mean ◽  
Bet Hedging ◽  
Sexual And Asexual Reproduction ◽  
Geometric Mean Fitness ◽  
Mean Fitness

AbstractIn evolutionary biology, bet-hedging refers to a strategy that reduces the variance of reproductive success at the cost of reduced mean reproductive success. In unpredictably fluctuating environments, bet-hedgers benefit from higher geometric mean fitness despite having lower arithmetic mean fitness than their specialist competitors. We examine the extent to which sexual reproduction can be considered a type of bet-hedging, by clarifying past arguments, examining parallels and differences to evolutionary games, and by presenting a simple model examining geometric and arithmetic mean payoffs of sexual and asexual reproduction. Sex typically has lower arithmetic mean fitness than asex, while the geometric mean fitness can be higher if sexually produced offspring are not identical. However, asexual individuals that are heterozygotes can gain conservative bet-hedging benefits of similar magnitude while avoiding the costs of sex. This highlights that bet-hedging always has to be specified relative to the payoff structure of relevant competitors. It also makes it unlikely that sex, at least when associated with significant male production, evolves solely based on bet-hedging in the context of frequently and repeatedly occupied environmental states. Future work could usefully consider bet-hedging in open-ended evolutionary scenarios with de novo mutations.

scholarly journals ASF1 activation PI3K/AKT pathway regulates sexual and asexual development in filamentous ascomycete

2021 ◽  
Author(s):  
Shi Wang ◽  
Xiaoman Liu ◽  
Chenlin Xiong ◽  
Susu Gao ◽  
Wenmeng Xu ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Signaling Pathway ◽  
Asexual Reproduction ◽  
Critical Role ◽  
Akt Signaling ◽  
Asexual Development ◽  
Akt Signaling Pathway ◽  
Filamentous Ascomycete ◽  
Sexual And Asexual Reproduction

Sexual and asexual reproduction is ubiquitous in eukaryotes. PI3K/AKT signaling pathway can modulate sexual reproduction in mammals. However, this signaling pathway modulating sexual and asexual reproduction in fungi is scarcely understood. SeASF1, a SeH4 chaperone, could manipulate sexual and asexual reproduction of Stemphylium eturmiunum. SeDJ-1, screened from SeΔasf1 transcriptome, was confirmed to regulate sexual and asexual development by RNAi, of which the mechanism was demonstrated by detecting transcriptional levels and protein interactions of SeASF1, SeH4 and SeDJ-1 by qRT-PCR, and Y2H, Co-IP and Pull-down, respectively. SeASF1 coupling SeH4 bound SeDJ-1 to arouse the sexual and asexual activity. In S. eturmiunum genome, SeDJ-1 was upstream while SeGSK3 was downstream in PI3K/AKT signaling pathway. Moreover, SeDJ-1 interacted with SePI3K or SeGSK3 in vivo and in vitro. Significantly, SeDJ-1 or SePI3K could effectively stimulate sexual activity alone, but SePI3K could recover the sexual development of SiSeDJ-1.SeDJ-1-M6 was a critical segment for interaction of SeDJ-1 with SePI3K. SeDJ-1-M6 played a critical role in irritating sexual reproduction in SiSePI3K, which further uncovered the regulated mechanism of SeDJ-1. SeASF1 coupling SeH4 motivates SeDJ-1 to arouse SePI3K involved in sexual reproduction. Thus, SeASF1 can activate PI3K/AKT signaling pathway to regulate sexual and asexual development in filamentous ascomycete.

scholarly journals Flood disturbance affects morphology and reproduction of woody riparian plants

2021 ◽  
Author(s):  
Sarah Fischer ◽  
Joe Greet ◽  
Christopher Walsh ◽  
Jane Catford
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Woody Plants ◽  
Riparian Forest ◽  
Good Condition ◽  
Riparian Forests ◽  
Flood Disturbance ◽  
Riparian Plants ◽  
Flood Regime ◽  
Sexual And Asexual Reproduction

Abstract Riparian forests are structured and maintained by their hydrology. Woody riparian plants typically adapt to the local flood regime to maximise their likelihood of survival and reproductive success. Understanding how extant trees form and reproduce in response to flood disturbance is crucial for predicting vegetation changes and informing restoration. Working in a temperate evergreen riparian forest, we aim to determine whether disturbance-based responses of plants found in other ecosystems also typify woody plants in riparian forests where disturbances are non-lethal, annual events. Using plant surveys and 20-year modelled hydrological data, we examined whether i) the morphology (main stem diameter, height, crown width, crown extent, stem leaning) and ii) reproduction type (sexual and asexual reproduction) and extent of three dominant woody species (Eucalyptus camphora, Leptospermum lanigerum and Melaleuca squarrosa) vary with flood regime (flood frequency and flood duration); and iii) whether different morphology is associated with different reproductive strategies. Increased flooding generally resulted in increased stem numbers and greater stem leaning – morphologies associated with asexual reproduction – of our study species. More frequent flooding also reduced plant size and sexual reproduction in E. camphora. Sexual reproduction in the studied species was more common in taller plants with single, more upright stems in good condition. Flexible morphology and plastic reproductive strategy may constitute an adaptation to mild or chronic disturbance in floodplains. Our findings suggest that woody plants respond to physical disturbance in consistent ways regardless of the nature of the disturbance – be it fires, hurricanes or floods.

Interactions between population growth and sexual reproduction in the viviparous monogenean Gyrodactylus turnbulli Harris, 1986 from the guppy, Poecilia reticulata Peters

Parasitology ◽  
1989 ◽  
Vol 98 (2) ◽  
pp. 245-251 ◽  
Author(s):  
P.D. Harris
Keyword(s):  
Population Growth ◽  
Sexual Reproduction ◽  
Population Size ◽  
Asexual Reproduction ◽  
Population Biology ◽  
Poecilia Reticulata ◽  
Seminal Receptacle ◽  
Potential Importance ◽  
Sexual And Asexual Reproduction ◽  
First Time

SUMMARYMating was observed in populations of Gyrodactylus turnbulli from guppies. Copulation took place between older (post-1st birth) flukes and resulted in the insemination of spermatozoa into the seminal receptacle. New-born flukes, and flukes which had only recently given birth for the first time (in which the penis was absent or developing), were never inseminated. Flukes were promiscuous, copulating with several partners in succession. The occurrence of mating was related to the size, age and crowding of the G. turnbulli population, taking place most frequently when the parasites were most densely crowded upon the peduncle of the fish on days 5 and 6 of the infection. Maximum population size was positively correlated with the number of flukes initiating an infection. As a result, mating began earlier, and continued for longer in populations founded by several parasites rather than those begun by single flukes. These observations are discussed with respect to the population biology of G. turnbulli: it is likely that sexual and asexual reproduction alternate, with sex being important only during phases of epidemic population growth. The significance of sex in gyrodactylids is discussed, and the potential importance of continuous sexual reproduction in G. turnbulli infections on cultivated guppies is noted.

scholarly journals The frequency of sex in fungi

2016 ◽  
Vol 371 (1706) ◽  
pp. 20150540 ◽  
Author(s):  
Bart P. S. Nieuwenhuis ◽  
Timothy Y. James
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Population Genetic ◽  
Mixed Mode ◽  
Molecular Mechanisms ◽  
Costs And Benefits ◽  
Ancient Asexual ◽  
Sexual And Asexual Reproduction ◽  
Almost All ◽  
Huge Variation

Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’.

scholarly journals To sex, or not to sex ... Structures and strategies of reproduction in the family Umbilicariaceae (Lecanorales, Ascomycetes)

Sommerfeltia ◽  
1991 ◽  
Vol 3 (s3) ◽  
pp. 1-52
Author(s):  
G. Hestmark
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Ecological Factors ◽  
Reproductive Mode ◽  
Distribution Patterns ◽  
Life History Strategies ◽  
Ecological Performance ◽  
Fungal Partner ◽  
The Family ◽  
Strategy Types

Abstract This is a study of the evolution and ecology of reproduction in the family of lichen-forming fungi U mbilicariaceae comprising the two genera Umbilicaria and Lasallia. Members of this family exhibit a variety of reproductive structures and strategies. The fungal partner of the symbiosis may reproduce by sexually generated ascospores, asexual thalloconidia, or both. Propagules reproducing the intact symbiosis include asexual isidia, soredia, thallyls, phyllidia and schizidia. The algal partner - unicellular Pseudotrebouxia (Chlorophyceae) - reproduces by asexual autospores when in symbiosis, and in addition zoospores and aplanospores in pure culture. In about half of the species in Umbilicariaceae the fungal partner can only reproduce sexually - it is exclusively teleomorphic. In these species, apparently, the option of asexual reproduction has not been presented by evolution. In the taxa where this option has been presented, the forces of ecology and evolution seem to favour this option. Although no tax.on with asexual reproduction appears to have dispensed with sexuality altogether, the allocation to sexual reproduction tends to decrease and the resources are translocated to asexual reproduction. Different taxa represent progressive stages in this de-evolution of sex. In some of these cases sex is correlated with geographical distribution patterns or ecological factors such as high humidity or high population density and sib-competition. The latter observation supports the ‘Tangled Bank’ hypothesis for the maintenance of sex, as well as ESS models for reproductive allocations in heterocarpic plants. In some cases exclusively teleomorphic tax.a co-exist with morphologically virtually identical but mainly asexual (anamorphic) taxa, suggesting that a difference in reproductive mode may have led to speciation. Associated with different propagule types are a number of other traits with consequences for the ecological performance of the species. These sets of correlated traits constitute strategies of reproduction, the core sets of specific life-history strategies. Three ‘pure’ reproductive strategies are tentatively distinguished in the Umbilicariaceae, depending on whether the propagule is sexually or asexually generated and whether it is symbiotic or not. The asexual propagules are close-dispersed while sexual propagules are more far-dispersed. A comparative study of the performance of representatives of the three strategy types in two glacier forelands shows that the sexually reproducing species are the fastest colonizers. The need to re-establish symbiosis at target site appears to be no great obstacle to sexual reproduction by ascospores.

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