scholarly journals Distribution of facial resemblance in romantic couples suggests both positive and negative assortative processes influence human mate choice

2019 ◽  
Author(s):  
Iris Jasmin Holzleitner ◽  
Kieran J. O'Shea ◽  
Vanessa Fasolt ◽  
Anthony J Lee ◽  
Lisa Marie DeBruine ◽  
...  
Keyword(s):  
Mate Choice ◽  
Assortative Mating ◽  
Control Sample ◽  
Facial Appearance ◽  
Romantic Couples ◽  
Physical Similarity ◽  
Disassortative Mating ◽  
Face Shape ◽  
Positive Assortative Mating ◽  
Facial Similarity

Previous research suggests that humans show positive assortative mating, i.e. tend to pair up with partners that are similar to themselves in a range of traits, including facial appearance. Facial appearance can function as a cue to genetic similarity and plays a critical role in human mate choice. Evidence for positive assortative mating for facial appearance has largely come from studies showing people can match pictures of couples’ faces at levels greater than chance and that facial photographs of couples are rated to look more similar than those of non-couples. However, interpreting results from matching studies as evidence of positive assortative mating for facial appearance is problematic, since this measure of perceived compatibility does not necessarily reflect actual physical similarity, and may be orthogonal to, or even negatively correlated with, physical similarity. Even if participants are asked to rate facial similarity directly, it remains unclear which, if any, face shape cues contribute to an increased perception of similarity in romantic couples. Here we use a shape-based assessment of facial similarity to show that the median similarity of long-term couples’ face shapes is only slightly greater than that of an age-matched control sample. Moreover, this was driven by the most similar 40% of couples, while the most dissimilar 20% of couples actually showed disassortative mating for face shape when compared to the control sample. These data show that a simple measure of central tendency obscures variability in the extent to which couples display assortative or disassortative mating for face shape. By contrast, a more fine-grained analysis that considers the distribution of variation across couples in the extent to which they resemble each other suggests that both positive and negative assortative processes influence human mate choice.

scholarly journals No evidence of positive assortative mating for genetic quality in fruit flies

2019 ◽  
Vol 286 (1912) ◽  
pp. 20191474
Author(s):  
Nathaniel P. Sharp ◽  
Michael C. Whitlock
Keyword(s):  
Sexual Selection ◽  
Assortative Mating ◽  
Genetic Variance ◽  
Genetic Load ◽  
Fruit Fly ◽  
Genetic Quality ◽  
Mating Patterns ◽  
Disassortative Mating ◽  
Deleterious Alleles ◽  
Positive Assortative Mating

In sexual populations, the effectiveness of selection will depend on how gametes combine with respect to genetic quality. If gametes with deleterious alleles are likely to combine with one another, deleterious genetic variation can be more easily purged by selection. Assortative mating, where there is a positive correlation between parents in a phenotype of interest such as body size, is often observed in nature, but does not necessarily reveal how gametes ultimately combine with respect to genetic quality itself. We manipulated genetic quality in fruit fly populations using an inbreeding scheme designed to provide an unbiased measure of mating patterns. While inbred flies had substantially reduced reproductive success, their gametes did not combine with those of other inbred flies more often than expected by chance, indicating a lack of positive assortative mating. Instead, we detected a negative correlation in genetic quality between parents, i.e. disassortative mating, which diminished with age. This pattern is expected to reduce the genetic variance for fitness, diminishing the effectiveness of selection. We discuss how mechanisms of sexual selection could produce a pattern of disassortative mating. Our study highlights that sexual selection has the potential to either increase or decrease genetic load.

scholarly journals Positive assortative mating between recently described sympatric morphs of Icelandic sticklebacks

2006 ◽  
Vol 2 (2) ◽  
pp. 250-252 ◽  
Author(s):  
Gudbjörg Á Ólafsdóttir ◽  
Michael G Ritchie ◽  
Sigurdur S Snorrason
Keyword(s):  
Mate Choice ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Gasterosteus Aculeatus ◽  
Sympatric Speciation ◽  
Threespine Stickleback ◽  
Positive Assortative Mating ◽  
Important Character ◽  
Nest Type ◽  
Sympatric Morphs

Recently, models of sympatric speciation have suggested that assortative mating can develop between sympatric morphs due to divergence in an ecologically important character. For example, in sympatric pairs of threespine stickleback ( Gasterosteus aculeatus L.) size-assortative mating seems to be instrumental in reproductive isolation. Here, we examine courtship behaviour and assortative mating of newly described sympatric stickleback morphs in Lake Thingvallavatn, Iceland. We find that the two morphs show strong positive assortative mating. However, the mechanism involved in mate choice does not seem to be as straightforward as in other similar systems of sympatric stickleback morphs and may involve variation in nest type.

Courtship Feeding and Mate Choice in Thynnine Wasps (Hymenoptera, Tiphiidae)

1987 ◽  
Vol 35 (5) ◽  
pp. 451 ◽  
Author(s):  
J Alcock ◽  
DT Gwynne
Keyword(s):  
Body Weight ◽  
Mate Choice ◽  
Assortative Mating ◽  
Courtship Feeding ◽  
Positive Assortative Mating ◽  
Males And Females

Females of two species of thynnine wasps, Megalothynnus klugii and Macrothynnus sp., attract mates while perched upright on vegetation close to the ground. When given an experimental choice between two females of different sizes, males of M. klugii carry off and copulate with the larger female significantly more often than they do the smaller one. No such preference was exhibited by males of Macrothynnus sp. Females of both species resist being removed from their calling perches and large males succeed more often than small ones in carrying away very large females. Despite mechanisms allowing a preference for large partners by both males and females in M. klugii, there is no evidence, in nature, of positive assortative mating according to body weight in this species. Various conditions, especially a scarcity of fertilisable females, may severely limit the choice of mates by males of these wasps.

scholarly journals Divergent Selection and Then What Not: The Conundrum of Missing Reproductive Isolation in Misty Lake and Stream Stickleback

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Katja Räsänen ◽  
Matthieu Delcourt ◽  
Lauren J. Chapman ◽  
Andrew P. Hendry
Keyword(s):  
Mate Choice ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Gasterosteus Aculeatus ◽  
Common Garden ◽  
Adaptive Divergence ◽  
Apparent Lack ◽  
Divergent Natural Selection ◽  
Inlet Stream ◽  
Positive Assortative Mating

In ecological speciation, reproductive isolation evolves as a consequence of adaptation to different selective environments. A frequent contributor to this process is the evolution of positive assortative mate choice between ecotypes. We tested this expectation for lake and inlet stream threespine stickleback (Gasterosteus aculeatus) from the Misty system (Vancouver Island, Canada), which show strong genetically based adaptive divergence and little genetic exchange in nature. This, and work on other stickleback systems, led us to expect positive assortative mating. Yet, our standard “no-choice” laboratory experiment on common-garden fish revealed no evidence for this—despite divergence in traits typically mediating assortative mating in stickleback. These results remind us that divergent natural selection may not inevitably lead to the evolution of positive assortative mate choice. The apparent lack of strong and symmetric reproductive barriers in this system presents a conundrum: why are such barriers not evident despite strong adaptive divergence and low gene flow in nature?

Nonrandom mate choice by females of Drosophila pseudoobscura: a case of outbreeding avoidance?

1985 ◽  
Vol 63 (2) ◽  
pp. 334-339 ◽  
Author(s):  
R. Harmsen ◽  
L. R. McKay
Keyword(s):  
Mate Choice ◽  
Assortative Mating ◽  
Female Choice ◽  
Mating Success ◽  
Alternative Explanation ◽  
Random Mating ◽  
Drosophila Pseudoobscura ◽  
Positive Assortative Mating ◽  
Set Up ◽  
Different Strains

Relative mating success of genetically different males of Drosophila pseudoobscura was measured with five female strains using an experimental set-up consisting of a mating chamber containing 20 females of one strain and a total of 20 males of two different strains. No evidence was found indicating negative assortative mating, neither of the direct type, nor of the "rare male" type. Some strains, however, displayed strong positive assortative mating, as males of the same strain as the females were significantly more successful in obtaining copulations than were males of another strain present in the mating chambers. Deviations from random mating can be interpreted as the result of some males possessing higher levels of "vigour," but an alternative explanation is favoured, one involving female choice. Experimental results do indicate that the orange-eyed mutant flies, used as one of the male strains in all experiments, did have a relatively low level of courtship vigour, but not low enough to account for more than a small fraction of the differential mating success observed in some of the experiments.

scholarly journals Sexual Size Dimorphism and Positive Assortative Mating in Alpine Choughs (Pyrrhocorax graculus)

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 553-556 ◽  
Author(s):  
Anne Delestrade
Keyword(s):  
Sample Size ◽  
Assortative Mating ◽  
Body Condition ◽  
Sexual Size Dimorphism ◽  
Morphological Characters ◽  
Positive Trend ◽  
Tarsus Length ◽  
Size Dimorphism ◽  
Positive Assortative Mating ◽  
Larger Sample

Abstract The degree of sexual size dimorphism in a number of different morphological characters was examined in a social corvid, the Alpine Chough, using measurements taken on 178 males and 144 females. A small amount of size dimorphism appeared in all morphological characters, and weight was the most dimorphic character. To identify if Alpine Choughs mate assortatively, measurements of mates were compared in 76 pairs. A positive assortative mating was found on tarsus length, and a small positive trend is suggested between body condition of partners, but that needs to be confirmed with a larger sample size.

scholarly journals Marry Your Like: Assortative Mating and Income Inequality

2014 ◽  
Vol 104 (5) ◽  
pp. 348-353 ◽  
Author(s):  
Jeremy Greenwood ◽  
Nezih Guner ◽  
Georgi Kocharkov ◽  
Cezar Santos
Keyword(s):  
Income Inequality ◽  
Assortative Mating ◽  
Household Income ◽  
The United States ◽  
Census Bureau ◽  
United States Census ◽  
United States Census Bureau ◽  
Positive Assortative Mating ◽  
High Level ◽  
Married Female

Has there been an increase in positive assortative mating? Does assortative mating contribute to household income inequality? Data from the United States Census Bureau suggests there has been a rise in assortative mating. Additionally, assortative mating affects household income inequality. In particular, if matching in 2005 between husbands and wives had been random, instead of the pattern observed in the data, then the Gini coefficient would have fallen from the observed 0.43 to 0.34, so that income inequality would be smaller. Thus, assortative mating is important for income inequality. The high level of married female labor-force participation in 2005 is important for this result.

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