scholarly journals Is Evolution of Mating Preferences Inevitable? Random Mating in the Multisex System of Tetrahymena thermophila

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Sujal S. Phadke ◽  
Lauren Cooper ◽  
Rebecca A. Zufall
Keyword(s):  
Theoretical Model ◽  
Mate Choice ◽  
Sex Ratio ◽  
Sexual Differentiation ◽  
Mating Systems ◽  
Tetrahymena Thermophila ◽  
Random Mating ◽  
Maximum Amount ◽  
Mating Preferences ◽  
Mechanistic Basis

Ciliate mating systems are highly diversified, providing unique opportunities to study sexual differentiation and its implications for mating dynamics. Many species of ciliates have multiple (>2) sexes. More sexes may mean more choice and an opportunity for evolution of preferential mating. We asked if the multiple sexes of the ciliate Tetrahymena thermophila mate preferentially among each other. We quantified pairing frequencies among four sexes of T. thermophila using experiments that allowed the sexes to compete as mating partners. We found that all sexes mated equally frequently among each other, that is, we found no evidence of preferential mating with respect to sex. This suggests that the “mate choice” in this ciliate is binary, between whether to form a pair or not and, in this regard, sex facilitates only self-/non-self-distinction. Thus, presence of multiple sexes does not necessarily result in the evolution of mating bias, which could decrease the maximum amount of mating that would otherwise be possible in a population. Our result of random mating verifies a key assumption in the theoretical model of sex ratio evolution in T. thermophila. Investigation into molecular differences between the sexes will be necessary to reveal the mechanistic basis of random mating among them.

Modeling Mating Patterns Given Mutual Mate Choice: The Importance of Individual Mating Preferences and Mating System

2003 ◽  
Vol 11 (03) ◽  
pp. 205-219 ◽  
Author(s):  
Carmen Bessa-Gomes ◽  
Jean Clobert ◽  
Stéphane Legendre ◽  
Anders Pape Møller
Keyword(s):  
Mate Choice ◽  
Sex Ratio ◽  
Mating System ◽  
Population Biology ◽  
Structured Populations ◽  
Operational Sex Ratio ◽  
Mating Preferences ◽  
Mating Patterns ◽  
Single Sex ◽  
Individual Mating

When we consider structured populations with sexual reproduction, the distribution of characters among mating pairs may influence the population biology, namely its dynamics and genetics. In the present paper, we propose a general framework to estimate the population mating patterns taking into account individual mating preferences and mating system, thus taking into account the inter- and intra-sexual interactions such as mate competition and mate choice. According to our results, mating patterns are not a direct reflection of mating preferences, but also depend upon the average sex ratio between individuals that are ready to mate at any given time (i.e., the Operational Sex Ratio, OSR). Therefore, mating patterns should be assessed not only in function of preferences, but also of OSR. It is then possible to distinguish three OSR regions: (1) the equilibrium OSR, where there is a predominance of assortative mating patterns due to differential access to mates (inter-sexual interactions); (2) the slightly biased OSR, where there is a high diversity of mating patterns and no clear predominance of inter- or intra-sexual interactions; and (3) the highly biased OSR where there is a predominance of mating patterns corresponding to single-sex uniform preferences and an increased influence of intra-sexual interactions. We hope that this approach may allow to further explore the interaction between OSR and mate choice, namely how such interaction may affect sexual selection and mate choice tactics.

Thresholds or Comparisons: Mate Choice Criteria And Sexual Selection in a Periodical Cicada, Magicicada Septendecim (Hemiptera: Cicadidae)

Behaviour ◽  
2004 ◽  
Vol 141 (6) ◽  
pp. 647-673 ◽  
Author(s):  
David Marshall ◽  
John Cooley
Keyword(s):  
Mate Choice ◽  
High Frequency ◽  
Mating Systems ◽  
Random Mating ◽  
Lek Mating ◽  
Periodical Cicadas ◽  
Fixed Threshold ◽  
Males And Females ◽  
Periodical Cicada ◽  
Rule Out

AbstractMany insects possess life history characteristics that make them unlikely to use the kinds of relative mate choice criteria implicit in theoretical discussions of leks; thus, many insect mating aggregations are treated differently, as 'swarms' or 'choruses.' Yet periodical cicadas (Magicicada spp.) seem strong candidates for participating in lek mating systems. We present a series of observations and experiments designed to reveal whether there are mating biases in periodical cicadas and whether any biases are most consistent with flexible ('best-of-N 'choice) or fixed (threshold choice) mating criteria. We rule out postcopulatory choice by demonstrating that most females mate once, after which they become sexually unreceptive. In our study, patterns of mating success among actively chorusing males are indistinguishable from random mating, and we uncover no consistent differences between unmated and mated males on the basis of size and song pitch, two criteria that have been associated with Magicicada mating biases in other contexts. Because our results are most consistent with a fixed-threshold choice mechanism, we suggest that Magicicada mating aggregations do not function in a manner similar to vertebrate leks even though they fulfill Bradbury's (1981) lek criteria. Instead, features of Magicicada behavior suggesting female selectivity may arise incidentally from males' and females' unequal tendencies to mate multiply, the resulting superabundance of sexually receptive males, and the high frequency at which females are courted at the onset of mating readiness.

scholarly journals Mating preferences can drive expansion or contraction of major histocompatibility complex gene family

2020 ◽  
Vol 287 (1921) ◽  
pp. 20192706
Author(s):  
Piotr Bentkowski ◽  
Jacek Radwan
Keyword(s):  
Major Histocompatibility Complex ◽  
Gene Family ◽  
Random Mating ◽  
Major Histocompatibility Complex Gene ◽  
Major Histocompatibility ◽  
Mating Preferences ◽  
Histocompatibility Complex ◽  
Mhc Diversity ◽  
Mechanistic Basis

Major histocompatibility complex (MHC)-based mating rules can evolve as a way to avoid inbreeding or to increase offspring immune competence. While the role of mating preference in shaping the MHC diversity in vertebrates has been acknowledged, its impact on individual MHC diversity has not been considered. Here, we use computer simulations to investigate how simple mating rules favouring MHC-dissimilar partners affect the evolution of the number of MHC variants in individual genomes, accompanying selection for resistance to parasites. We showed that the effect of such preferences could sometimes be dramatic. If preferences are aimed at avoiding identical alleles, the equilibrium number of MHC alleles is much smaller than under random mating. However, if the mating rule minimizes the ratio of shared to different alleles in partners, MHC number is higher than under random mating. Additionally, our simulations revealed that a negative correlation between the numbers of MHC variants in mated individuals can arise from simple rules of MHC-disassortative mating. Our results reveal unexpected potential of MHC-based mating preferences to drive MHC gene family expansions or contractions and highlight the need to study the mechanistic basis of such preferences, which is currently poorly understood.

scholarly journals Dynamics of the sex ratio in Tetrahymena thermophila

2018 ◽  
Author(s):  
Guangying Wang ◽  
Kai Chen ◽  
Jing Zhang ◽  
Xuefeng Ma ◽  
Shanjun Deng ◽  
...  
Keyword(s):  
Population Genetics ◽  
Sex Ratio ◽  
Mating Systems ◽  
Tetrahymena Thermophila ◽  
Mating Types ◽  
Eukaryotic Lineage ◽  
Single Sex ◽  
Theoretical Predictions ◽  
The Impact ◽  
Insight Into

AbstractSex is often hailed as one of the major successes in evolution, and in sexual organisms the maintenance of proper sex ratio is crucial. As a large unicellular eukaryotic lineage, ciliates exhibit tremendous variation in mating systems, especially the number of sexes and the mechanism of sex determination (SD), and yet how the populations maintain proper sex ratio is poorly understood. Here Tetrahymena thermophila, a ciliate with seven mating types (sexes) and probabilistic SD mechanism, is analyzed from the standpoint of population genetics. It is found based on a newly developed population genetics model that there are plenty of opportunities for both the co-existence of all seven sexes and the fixation of a single sex, pending on several factors, including the strength of natural selection. To test the validity of predictions, five experimental populations of T. thermophila were maintained in the laboratory so that the factors that can influence the dynamics of sex ratio could be controlled and measured. Furthermore, whole-genome sequencing was employed to examine the impact of newly arisen mutations. Overall, it is found that the experimental observations highly support theoretical predictions. It is expected that the newly established theoretical framework is applicable in principle to other multi-sex organisms to bring more insight into the understanding of the maintenance of multiple sexes in a natural population.

scholarly journals Gamete-mediated mate choice: towards a more inclusive view of sexual selection

2018 ◽  
Vol 285 (1883) ◽  
pp. 20180836 ◽  
Author(s):  
Jukka Kekäläinen ◽  
Jonathan P. Evans
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sperm Competition ◽  
Female Choice ◽  
Mating Systems ◽  
Molecular Level ◽  
Evolutionary Significance ◽  
Random Interactions ◽  
Physiological Processes ◽  
The Everyday

‘Sperm competition’—where ejaculates from two or more males compete for fertilization—and ‘cryptic female choice’—where females bias this contest to suit their reproductive interests—are now part of the everyday lexicon of sexual selection. Yet the physiological processes that underlie these post-ejaculatory episodes of sexual selection remain largely enigmatic. In this review, we focus on a range of post-ejaculatory cellular- and molecular-level processes, known to be fundamental for fertilization across most (if not all) sexually reproducing species, and point to their putative role in facilitating sexual selection at the level of the cells and gametes, called ‘gamete-mediated mate choice’ (GMMC). In this way, we collate accumulated evidence for GMMC across different mating systems, and emphasize the evolutionary significance of such non-random interactions among gametes. Our overall aim in this review is to build a more inclusive view of sexual selection by showing that mate choice often acts in more nuanced ways than has traditionally been assumed. We also aim to bridge the conceptual divide between proximal mechanisms of reproduction, and adaptive explanations for patterns of non-random sperm–egg interactions that are emerging across an increasingly diverse array of taxa.

scholarly journals MATE CHOICE AND HUMAN STATURE: HOMOGAMY AS A UNIFIED FRAMEWORK FOR UNDERSTANDING MATING PREFERENCES

Evolution ◽  
2010 ◽  
Author(s):  
Alexandre Courtiol ◽  
Michel Raymond ◽  
Bernard Godelle ◽  
Jean-Baptiste Ferdy
Keyword(s):  
Mate Choice ◽  
Unified Framework ◽  
Mating Preferences

scholarly journals EVOLUTION OF INTERACTIONS IN FAMILY-STRUCTURED POPULATIONS: MIXED MATING MODELS

Genetics ◽  
1980 ◽  
Vol 96 (1) ◽  
pp. 275-296
Author(s):  
Richard E Michod
Keyword(s):  
Mating System ◽  
Mating Systems ◽  
Random Mating ◽  
Additive Model ◽  
Multiplicative Model ◽  
Structured Populations ◽  
Mixed Mating ◽  
Genotypic Distribution ◽  
Individual Fitness ◽  
Recessive Genes

ABSTRACT The effect of inbreeding on sociality is studied theoretically for the evolution of interactions between siblings in certain mixed mating systems that give rise to inbreeding: sib with random mating and selfing with random mating. Two approaches are taken. First, specific models of altruism are studied for the various mating systems. In the case of the additive model, inbreeding facilitates the evolution of altruistic genes. Likewise, for the multiplicative model this is usually the case, as long as the costs of altruism are not too great. Second, the case of total altruism, in which the gene has zero individual fitness but increases the fitness of associates, is studied for a general fitness formulation. In this case, inbreeding often retards the ability of such genes to increase when rare, and the equilibrium frequency of those recessive genes that can increase is totally independent of the mating system and, consequently, of the amount of inbreeding. It appears from the results presented that inbreeding facilitates most forms of altruism, but retards extreme altruism. These results stem from the fact that inbreeding increases the within-family relatedness by increasing the between-family variance in allele frequency. In most cases this facilitates altruism. However, in the case of total altruism, only heterozygotes can pass on the altruistic allele, and inbreeding tends to decrease this heterozygote class. In either case, the important effect of inbreeding lies in altering the genotypic distribution of the interactions.

Variation III: Social Environment and Epigenetics

Mate Choice ◽  
2017 ◽  
Author(s):  
Gil G. Rosenthal
Keyword(s):  
Mate Choice ◽  
Social Interactions ◽  
Social Environment ◽  
Sexual Maturity ◽  
Horizontal Transmission ◽  
Epigenetic Modifications ◽  
Older Individuals ◽  
Mating Preferences ◽  
Sources Of Variation ◽  
Sexually Mature

This chapter focuses on social interactions, in the broadest sense, as sources of variation in mate choice and mating preferences. These interactions can be divided into three categories corresponding to when they are specified and which individuals are involved. The first includes effects that are determined before birth and transmitted vertically from parents: epigenetic modifications to the genome and the fetal or embryonic environment. The second includes influences between birth and sexual maturity, when the phenotypes of parents and/or other sexually mature, older individuals (oblique transmission) direct the development of preferences in choosers. Experience with courters and choosers after sexual maturity, or experience with other juveniles that shapes subsequent preferences, constitutes peer (horizontal) transmission.

Variation in Preferences and Choices: General Considerations

Mate Choice ◽  
2017 ◽  
Author(s):  
Gil G. Rosenthal
Keyword(s):  
Mate Choice ◽  
Social Variables ◽  
Mating Preferences ◽  
Important Constraint ◽  
Underlying Mechanisms

This chapter provides an overview of variation in mating preferences, focusing on the repeatability of mate choice. Variation in mate choice and mating preferences can arise from differences within and between individuals in any of the mechanisms used to sense, perceive, and evaluate courter signals before, during, and after mating, and in the mechanisms they use to sample and choose among mates. Preferences frequently covary with traits not directly involved with mate choice. These patterns of covariation, among preferences and between preferences and other traits, may arise either from properties internal to choosers, like shared underlying mechanisms or statistically associated genetic underpinnings, or from correlations among environmental and social variables that shape preferences. These correlations represent an important constraint on the directions in which preferences can evolve.

Reproductive qualities of the Ayrshire cows depending on the different reasons for culling

2021 ◽  
Vol 1 (3) ◽  
pp. 60-70
Author(s):  
S. V. Anistenok ◽  
◽  
O. V. Tulinova ◽  
Keyword(s):  
Sex Ratio ◽  
Dairy Cattle ◽  
Maximum Amount ◽  
Data Set ◽  
The Third ◽  
Gynecological Diseases

In order to increase the number of replacement young animals and the terms of productive use, the dynamics of reproductive qualities of the first calving cows in the period from 2009 to 2016 and those who survived to the 5th calving (n=36 164) was analyzed. The data set is divided into groups of cows of different age of culling: Clvn – the group leaving after the n-th calving, Lclv – the group by the last calving with reasons for their culling: LP – low productivity, G&I – gynecological diseases and infertility, U – udder diseases, L – limb diseases. The following calving results in proportions were taken into account: Ab – abortions, Sb – stillborns, B – bulls, H – heifers, Mo – multiple offspring. It was revealed that the smallest proportion of cull animals at the first calving (9,2%), and the largest – at the third (27,1%) with a tendency to increase after Clv2 and Clv3 calving by 6,2 and 7,3% and, conversely, decrease at the age of 5th calving by 11.2%. It was found that the share of Ab in the studied sample in cows Clv1 is lower (from 0,10 to 0,60%) than Lclv (from 0,30 to 0,60%), and on Sb, on the contrary, indicators are higher for Clv1 (from 4,47 to 5,10%). There is a tendency for the sex ratio to shift towards B: their share in the offspring by Clv1 ranges from 48,3% in 2010 to 51,4% in 2016, and H from 45,2% in 2014 to 47,3% in 2010. The greatest losses in the breeding of dairy cattle are caused by culling for G&I cows, the share of which has decreased in recent years from 42.9% in 2009 to 32.0% in 2016 in Lclv and from 58,8 to 45,7%, respectively, by Clv1, and the share of analogues for Clv2 and Clv3 calving is significantly lower (40,5 and 36,2%, respectively). In this group of cull animals Clv2 and Clv3, the Ab is the second in value (on average, 0.54 with fluctuations from 0,51 to 0,65%, respectively). For active and effective reproduction of the herd, it is necessary to keep the maximum amount of heifers from Clv1 for introduction into the herd and to reduce losses from G&I.

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