scholarly journals Sexual isolation with and without ecological isolation in marine isopods J. albifrons and J. praehirsuta

2018 ◽  
Author(s):  
Ambre Ribardière ◽  
Elsa Pabion ◽  
Jérôme Coudret ◽  
Claire Daguin-Thiébaut ◽  
Céline Houbin ◽  
...  
Keyword(s):  
Gene Flow ◽  
Mate Choice ◽  
Free Choice ◽  
First Generation ◽  
Sexual Isolation ◽  
Relative Strength ◽  
Experimental Population ◽  
Species Pair ◽  
Ecological Isolation

AbstractSexual barriers associated with mate choice are nearly always found to be associated with some level of ecological isolation between species. The independence and relative strength of sexual isolation are thus difficult to assess. Here we take advantage of a pair of isopod species (Jaera albifrons and J. praehirsuta) that show sexual isolation and coexist in populations where they share the same microhabitat or not (i.e. without or with ecological isolation). Using no-choice trials and a free-choice experimental population, we estimated the strength of sexual isolation between J. albifrons and J. praehirsuta individuals originating from these different ecological contexts. We found that sexual isolation is strong in presence and absence of ecological isolation, but that it is asymmetric and fails to prevent gene flow entirely. First-generation post-zygotic barriers were low, and there was no sexual isolation within J. praehirsuta across habitats. The J. albifrons / J. praehirsuta species pair thus provides an example where the role of sexual isolation as a barrier to gene flow i) does not depend upon current ecological isolation, ii) seems to have evolved independently of local ecological conditions, but iii) is insufficient to complete speciation entirely on its own.

scholarly journals The role of copy-number variation in the reinforcement of sexual isolation between the two European subspecies of the house mouse

2020 ◽  
Vol 375 (1806) ◽  
pp. 20190540 ◽  
Author(s):  
Henry L. North ◽  
Pierre Caminade ◽  
Dany Severac ◽  
Khalid Belkhir ◽  
Carole M. Smadja
Keyword(s):  
Mate Choice ◽  
Copy Number Variation ◽  
Reproductive Isolation ◽  
House Mouse ◽  
Copy Number ◽  
Structural Changes ◽  
Sexual Isolation ◽  
Number Variation ◽  
Tandem Duplications

Reinforcement has the potential to generate strong reproductive isolation through the evolution of barrier traits as a response to selection against maladaptive hybridization, but the genetic changes associated with this process remain largely unexplored. Building upon the increasing evidence for a role of structural variants in adaptation and speciation, we addressed the role of copy-number variation in the reinforcement of sexual isolation evidenced between the two European subspecies of the house mouse. We characterized copy-number divergence between populations of Mus musculus musculus that display assortative mate choice, and those that do not, using whole-genome resequencing data. Updating methods to detect deletions and tandem duplications (collectively: copy-number variants, CNVs) in Pool-Seq data, we developed an analytical pipeline dedicated to identifying genomic regions showing the expected pattern of copy-number displacement under a reinforcement scenario. This strategy allowed us to detect 1824 deletions and seven tandem duplications that showed extreme differences in frequency between behavioural classes across replicate comparisons. A subset of 480 deletions and four tandem duplications were specifically associated with the derived trait of assortative mate choice. These ‘Choosiness-associated’ CNVs occur in hundreds of genes. Consistent with our hypothesis, such genes included olfactory receptors potentially involved in the olfactory-based assortative mate choice in this system as well as one gene, Sp110 , that is known to show patterns of differential expression between behavioural classes in an organ used in mate choice—the vomeronasal organ. These results demonstrate that fine-scale structural changes are common and highly variable within species, despite being under-studied, and may be important targets of reinforcing selection in this system and others. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers’.

scholarly journals Loss of sexual isolation in a hybridizing stickleback species pair

2013 ◽  
Vol 59 (5) ◽  
pp. 591-603 ◽  
Author(s):  
Alycia C. R. Lackey ◽  
Janette Wenrick Boughman
Keyword(s):  
Reproductive Isolation ◽  
Sexual Isolation ◽  
Distinct Species ◽  
Mate Preferences ◽  
Reproductive Barriers ◽  
Species Pair ◽  
Hybrid Swarm ◽  
Species Formation ◽  
Species Pairs

Abstract One approach to understand the importance of reproductive barriers to the speciation process is to study the breakdown of barriers between formerly distinct species. One reproductive barrier, sexual isolation, reduces gene flow between species through differences in mate preferences and mating signals and is likely important for species formation and maintenance. We measure sexual isolation in two limnetic-benthic threespine stickleback species pairs (Gasterosteus spp.). One species pair maintains strong reproductive isolation while the other species pair has recently collapsed into a hybrid swarm. We compare the strength of sexual isolation in the hybridizing pair to the currently isolated pair. We provide the first evidence that sexual isolation has been lost in the hybridizing pair and show furthermore that preferences females have for conspecific mates and the traits they use to distinguish conspecific and heterospecific males contribute to this loss. This work highlights the fragility of reproductive isolation between young species pairs and considers the role of sexual isolation in speciation.

scholarly journals Mate choice enhances post-zygotic barriers to gene flow via ancestry bundling

2021 ◽  
Author(s):  
Pavitra Muralidhar ◽  
Graham Coop ◽  
Carl Veller
Keyword(s):  
Gene Flow ◽  
Mate Choice ◽  
Assortative Mating ◽  
Hybrid Zones ◽  
Genetic Introgression ◽  
Genetic Isolation ◽  
Common Features ◽  
Genome Wide ◽  
Zygotic Selection

Hybridization and subsequent genetic introgression are now known to be common features of the histories of many species, including our own. Following hybridization, post-zygotic selection tends to purge introgressed DNA genome-wide. While mate choice can prevent hybridization in the first place, it is also known to play an important role in post-zygotic selection against hybrids, and thus the purging of introgressed DNA. However, this role is usually thought of as a direct one: a mating preference for conspecifics reduces the sexual fitness of hybrids, reducing the transmission of introgressed ancestry. Here, we explore a second, indirect role of mate choice as a barrier to gene flow. Under assortative mating, parents covary in their ancestry, causing ancestry to be "bundled" in their offspring and later generations. This bundling effect increases ancestry variance in the population, enhancing the efficiency with which post-zygotic selection purges introgressed DNA. Using whole-genome simulations, we show that the bundling effect can comprise a substantial portion of mate choice's overall effect as a postzygotic barrier to gene flow, and that it is driven by ancestry covariances both between and within maternally and paternally inherited genomes. Using estimates of the strength of assortative mating in avian hybrid zones, we calculate that the bundling effect of mate choice may increase the amount of purging of introgressed DNA by 40-80%, contributing substantially to the genetic isolation of species.

Mate Choice, Speciation, and Hybridization

Mate Choice ◽  
2017 ◽  
Author(s):  
Gil G. Rosenthal
Keyword(s):  
Gene Flow ◽  
Mate Choice ◽  
Genetic Exchange ◽  
Mating Preferences ◽  
Individual Mating ◽  
The Relationship ◽  
Isolated Species ◽  
Geographically Isolated

This chapter reviews the ample literature on mate choice and speciation, as well as the more novel topic of mate choice and genetic exchange among species. It begins by discussing the widespread support for the intuitive predictions that mate choice should promote diversification among geographically isolated species, and that mate choice should evolve to minimize drastic loss of fitness through hybridization. The role of mate choice is more complicated when there is incomplete divergence between lineages; depending on their relationship to other traits under selection, mating preferences can act to accelerate speciation through reinforcement, but they can also act to increase gene flow between divergent lineages. Finally, the chapter addresses the relationship between individual mating decisions and hybridization between species.

scholarly journals What shapes the continuum of reproductive isolation? Lessons from Heliconius butterflies

2017 ◽  
Vol 284 (1856) ◽  
pp. 20170335 ◽  
Author(s):  
C. Mérot ◽  
C. Salazar ◽  
R. M. Merrill ◽  
C. D. Jiggins ◽  
M. Joron
Keyword(s):  
Gene Flow ◽  
Mate Choice ◽  
Reproductive Isolation ◽  
Hybrid Sterility ◽  
Wing Pattern ◽  
Key Factor ◽  
Comparative Results ◽  
Phylogenetic Divergence ◽  
The Continuum

The process by which species evolve can be illuminated by investigating barriers that limit gene flow between taxa. Recent radiations, such as Heliconius butterflies, offer the opportunity to compare isolation between pairs of taxa at different stages of ecological, geographical, and phylogenetic divergence. Here, we report a comparative analysis of existing and novel data in order to quantify the strength and direction of isolating barriers within a well-studied clade of Heliconius . Our results highlight that increased divergence is associated with the accumulation of stronger and more numerous barriers to gene flow. Wing pattern is both under natural selection for Müllerian mimicry and involved in mate choice, and therefore underlies several isolating barriers. However, pairs which share a similar wing pattern also display strong reproductive isolation mediated by traits other than wing pattern. This suggests that, while wing pattern is a key factor for early stages of divergence, it may become facultative at later stages of divergence. Additional factors including habitat partitioning, hybrid sterility, and chemically mediated mate choice are associated with complete speciation. Therefore, although most previous work has emphasized the role of wing pattern, our comparative results highlight that speciation is a multi-dimensional process, whose completion is stabilized by many factors.

scholarly journals Evidence for Initiation of Post-Zygotic Reproductive Isolation between Drosophila ananassae and D. pallidosa as Indicated by Reduction in the Fertility of Hybrid Males

2020 ◽  
Vol 12 (2) ◽  
pp. 41
Author(s):  
Roshni Singh ◽  
Bashisth Narayan Singh
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Sibling Species ◽  
Hybrid Sterility ◽  
Divergence Time ◽  
Sexual Isolation ◽  
Drosophila Ananassae ◽  
Species Pair ◽  
Hybrid Fertility ◽  
Species Pairs

There are several barriers to preclude the gene flow between diverging populations. On the basis of their temporal nature, these can be broadly categorized into two forms: pre- and post-zygotic. Post-zygotic reproductive isolation can manifest in the form of reductions in hybrid fertility. Keeping this fact in view, in the present study, we studied sterility in hybrids of D. ananassae and D. pallidosa. Surprisingly a distinguishable pattern of infertility was found in the hybrids. This pattern, referred to as Haldane’s rule, is often observed in hybrids of recently diverged populations or species. Reduction in the fertility of hybrids provides the clue of incipient kind of post-zygotic reproductive isolation in these two sibling species. This is the first report of hybrid sterility in this species pair. However, hybrid sterility is not very prominent especially when compared to that of other species pairs with the similar divergence time. Thus, on the basis of our results, we conclude that either sexual isolation between these sibling species is sufficient and does not require the aid of post-zygotic isolation to preclude gene flow or rate of divergence between D. ananassae and D. pallidosa is very slow in comparison to other species pair or even races of some species.

scholarly journals What shapes the continuum of reproductive isolation? Lessons from Heliconius butterflies

2017 ◽  
Author(s):  
C. Mérot ◽  
C. Salazar ◽  
R. M. Merrill ◽  
C. Jiggins ◽  
M. Joron
Keyword(s):  
Gene Flow ◽  
Mate Choice ◽  
Reproductive Isolation ◽  
Hybrid Sterility ◽  
Habitat Isolation ◽  
Wing Pattern ◽  
Key Factor ◽  
Comparative Results ◽  
Phylogenetic Divergence

AbstractThe process by which species evolve can be illuminated by investigating barriers that limit gene flow between taxa. Recent radiations, such as Heliconius butterflies, offer the opportunity to compare isolation between pairs of taxa at different stages of ecological, geographic and phylogenetic divergence. We carry out a comparative analysis of existing and novel data in order to quantify the strength and direction of isolating barriers within a well-studied clade of Heliconius. Our results highlight that increased divergence is associated with the accumulation of stronger and more numerous barriers to gene flow. Wing pattern is both under natural selection for Müllerian mimicry and involved in mate choice, and therefore underlies several isolating barriers. However, pairs which share a similar wing pattern, also display strong reproductive isolation mediated by traits other than wing pattern. This suggests that, while wing pattern is a key factor for early stages of divergence, it is not essential at a higher level. Additional factors including habitat isolation, hybrid sterility and chemically-mediated mate choice are associated with complete speciation. Therefore, although most previous work has emphasised the role of wing pattern, our comparative results highlight that speciation is a multidimensional process, whose completion is stabilized by many factors.

Rapid evaluation of FDG imaging alternatives using head-to-head comparisons of full ring and gamma camera based PET scanners –

2002 ◽  
Vol 41 (05) ◽  
pp. 208-213 ◽  
Author(s):  
L. M. Haslinghuis-Bajan ◽  
L. Hooft ◽  
A. van Lingen ◽  
M. van Tulder ◽  
W. Devillé ◽  
...  
Keyword(s):  
Methodological Quality ◽  
Gamma Camera ◽  
First Generation ◽  
Prospective Evaluation ◽  
First Approximation ◽  
Variable Head ◽  
Malignant Lesions ◽  
The Impact ◽  
Pet Scanners

SummaryAim: While FDG full ring PET (FRPET) has been gradually accepted in oncology, the role of the cheaper gamma camera based alternatives (GCPET) is less clear. Since technology is evolving rapidly, “tracker trials” would be most helpful to provide a first approximation of the relative merits of these alternatives. As difference in scanner sensitivity is the key variable, head-to-head comparison with FRPET is an attractive study design. This systematic review summarises such studies. Methods: Nine studies were identified until July 1, 2000. Two observers assessed the methodological quality (Cochrane criteria), and extracted data. Results: The studies comprised a variety of tumours and indications. The reported GC- and FRPET agreement for detection of malignant lesions ranged from 55 to 100%, but with methodological limitations (blinding, standardisation, limited patient spectrum). Mean lesion diameter was 2.9 cm (SD 1.8), with only about 20% <1.5 cm. The 3 studies with the highest quality reported concordances of 74-79%, for the studied lesion spectrum. Contrast at GCPET was lower than that of FRPET, contrast and detection agreement were positively related. Logistic regression analysis suggested that pre-test indicators might be used to predict FRPET-GCPET concordance. Conclusion: In spite of methodological limitations, “first generation” GCPET devices detected sufficient FRPET positive lesions to allow prospective evaluation in clinical situations where the impact of FRPET is not confined to detection of small lesions (<1.5 cm). The efficiency of head-to-head comparative studies would benefit from application in a clinically relevant patient spectrum, with proper blinding and standardisation of acquisition procedures.

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