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?

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.

scholarly journals The relationship between intraspecific assortative mating and reproductive isolation between divergent populations

2012 ◽  
Vol 58 (3) ◽  
pp. 484-492 ◽  
Author(s):  
Daniel I. Bolnick ◽  
Mark Kirkpatrick
Keyword(s):  
Mate Choice ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Empirical Data ◽  
Gasterosteus Aculeatus ◽  
Threespine Stickleback ◽  
Darwin's Finches ◽  
Phenotypic Divergence ◽  
Darwin’S Finches ◽  
The Relationship

Abstract The term ‘assortative mating’ has been applied to describe two very different phenomena: (1) the tendency for individuals to choose phenotypically similar mates from among conspecifics; or (2) the tendency to prefer conspecific over hete-rospecific mates (behavioral reproductive isolation). Both forms of assortative mating are widespread in nature, but the relationship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics incidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin’s Finches (Geospiza spp). We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating.

Differences in male courtship in freshwater and marine sticklebacks (Gasterosteus aculeatus)

1983 ◽  
Vol 61 (2) ◽  
pp. 292-297 ◽  
Author(s):  
J. D. McPhail ◽  
D. E. Hay
Keyword(s):  
British Columbia ◽  
Assortative Mating ◽  
Gasterosteus Aculeatus ◽  
Threespine Stickleback ◽  
Male Courtship ◽  
First Response ◽  
Positive Assortative Mating ◽  
First Contact

Earlier studies indicated that the freshwater and marine forms of threespine stickleback (Gasterosteus aculeatus) in the Little Campbell River are genetically differentiated and that they do not mate randomly. In this study, we examine the possible contribution of male courtship to this positive assortative mating. Marine and freshwater sticklebacks were obtained from the Little Campbell River, southwestern British Columbia. Males were allowed to build nests in large aquaria and court females. The following courtship behaviours were recorded: zigzag bouts per minute, bites per minute, fanning bouts per minute, glueing, creeping through, and the male's first response. Freshwater males zigzag more, bite less, and glue more than marine males. The intensity of courtship in freshwater males depends on the form of female courted, whereas marine males do not alter their courtship with different forms of females. Freshwater males typically zigzag on first contact with a female, and marine males usually bite. This difference in male first response is independent of the type of female courted. Differences in male courtship provide a basis for positive assortative mating between the two forms of sticklebacks. We argue that selection should favour a male first response that signals genotype.

scholarly journals Assortative flocking in crossbills and implications for ecological speciation

2012 ◽  
Vol 279 (1745) ◽  
pp. 4223-4229 ◽  
Author(s):  
Julie W. Smith ◽  
Stephanie M. Sjoberg ◽  
Matthew C. Mueller ◽  
Craig W. Benkman
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Ecological Speciation ◽  
Central Question ◽  
Loxia Curvirostra ◽  
Call Type ◽  
Divergent Natural Selection ◽  
Contact Calls ◽  
Red Crossbills

How reproductive isolation is related to divergent natural selection is a central question in speciation. Here, we focus on several ecologically specialized taxa or ‘call types’ of red crossbills ( Loxia curvirostra complex), one of the few groups of birds providing much evidence for ecological speciation. Call types differ in bill sizes and feeding capabilities, and also differ in vocalizations, such that contact calls provide information on crossbill phenotype. We found that two call types of red crossbills were more likely to approach playbacks of their own call type than those of heterotypics, and that their propensity to approach heterotypics decreased with increasing divergence in bill size. Although call similarity also decreased with increasing divergence in bill size, comparisons of responses to familiar versus unfamiliar call types indicate that the decrease in the propensity to approach heterotypics with increasing divergence in bill size was a learned response, and not a by-product of calls diverging pleiotropically as bill size diverged. Because crossbills choose mates while in flocks, assortative flocking could lead indirectly to assortative mating as a by-product. These patterns of association therefore provide a mechanism by which increasing divergent selection can lead to increasing reproductive isolation.

scholarly journals Sexual selection on color and behavior within and between cichlid populations: Implications for speciation

2012 ◽  
Vol 58 (3) ◽  
pp. 475-483 ◽  
Author(s):  
Michael J. Pauers ◽  
Jeffrey S. Mckinnon
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Mate Preferences ◽  
Separate Experiment ◽  
Color Patterns ◽  
Male Behavior ◽  
Female Population ◽  
Different Color

Abstract Sexual selection is widely viewed as playing a central role in haplochromine cichlid speciation. Hypothetically, once divergent mate preferences evolve among populations of these fishes, reproductive isolation follows and the populations begin to behave as different species. Various studies have examined patterns of assortative mating among species and sometimes populations, but few have examined variation in directional preferences, especially among populations of the same species. We investigated mate choice behavior in two populations of Labeotropheus fuelleborni, a Lake Malawi endemic. We test whether mating preferences between populations are based on the same traits and in the same direction as preferences within populations. We examine the potential contributions of two classes of trait, color patterns and behaviors, to reproductive isolation. When females chose between either two males of their own population, or two from another, female preferences were generally similar (for the female population) across the two contexts. Mate choice patterns differed between (female) populations for a measure of color, but only modestly for male behavior. In a separate experiment we simultaneously offered females a male of their own population and a male from a different population. In these trials, females consistently preferred males from their own population, which were also the males that displayed more frequently than their opponents, but not necessarily those with color traits suggested to be most attractive in the previous experiment. Thus directional preferences for chroma and related aspects of color may be important when females are presented with males of otherwise similar phenotypes, but may play little role in mediating assortative mating among populations with substantially different color patterns. A preference for male behavior could play some role in speciation if males preferentially court same-population females, as we have observed for the populations studied herein.

Symmetrical and asymmetrical sexual isolation among laboratory strains of Drosophila ananassae

1985 ◽  
Vol 27 (4) ◽  
pp. 405-409 ◽  
Author(s):  
Bashisth N. Singh ◽  
Sujata Chatterjee
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Sexual Isolation ◽  
Drosophila Ananassae ◽  
Isofemale Lines ◽  
Male Choice ◽  
Positive Assortative Mating ◽  
Different Strains ◽  
Assortive Mating

Male-choice experiments using five isofemale lines of Drosophila ananassae originating from different localities were performed to study sexual isolation within the species. In most of the crosses homogamic matings outnumber heterogamic ones, and deviation from randomness is statistically significant in 11 of 20 crosses. This provides evidence for positive assortative mating within D. ananassae. Isolation indices range from −0.057 to 0.555. Eleven positive isolation indices are significantly greater than zero. Both types of sexual isolation, symmetrical and asymmetrical, have been observed among different strains. Thus the present results clearly indicate that the laboratory strains of D. ananassae have developed behavioural reproductive isolation as a result of genetic divergence.Key words: Drosophila, assortive mating, sexual selection, behaviour.

scholarly journals Gut microbiomes and reproductive isolation in Drosophila

2017 ◽  
Vol 114 (48) ◽  
pp. 12767-12772 ◽  
Author(s):  
Philip T. Leftwich ◽  
Naomi V. E. Clarke ◽  
Matthew I. Hutchings ◽  
Tracey Chapman
Keyword(s):  
Reproductive Isolation ◽  
Assortative Mating ◽  
Gut Microbiome ◽  
Experimental Studies ◽  
Gut Bacteria ◽  
Evolutionary Significance ◽  
Direct Role ◽  
General Role ◽  
Positive Assortative Mating

Experimental studies of the evolution of reproductive isolation (RI) in real time are a powerful way in which to reveal fundamental, early processes that initiate divergence. In a classic speciation experiment, populations of Drosophila pseudoobscura were subjected to divergent dietary selection and evolved significant positive assortative mating by diet. More recently, a direct role for the gut microbiome in determining this type of RI in Drosophila melanogaster has been proposed. Manipulation of the diet, and hence the gut microbiome, was reported to result in immediate assortative mating by diet, which could be eliminated by reducing gut microbes using antibiotics and recreated by adding back Lactobacillus plantarum. We suggest that the evolutionary significance of this result is unclear. For example, in D. melanogaster, the microbiome is reported as flexible and largely environmentally determined. Therefore, microbiome-mediated RI would be transient and would break down under dietary variation. In the absence of evolutionary coassociation or recurrent exposure between host and microbiome, there are no advantages for the gut bacteria or host in effecting RI. To explore these puzzling effects and their mechanisms further, we repeated the tests for RI associated with diet-specific gut microbiomes in D. melanogaster. Despite observing replicable differences in the gut microbiomes of flies maintained on different diets, we found no evidence for diet-associated RI, for any role of gut bacteria, or for L. plantarum specifically. The results suggest that there is no general role for gut bacteria in driving the evolution of RI in this species and resolve an evolutionary riddle.

scholarly journals Assortative mating, sexual selection and their consequences for gene flow in Littorina

2020 ◽  
Author(s):  
Samuel Perini ◽  
Marina Rafajlović ◽  
Anja M. Westram ◽  
Kerstin Johannesson ◽  
Roger K. Butlin
Keyword(s):  
Sexual Selection ◽  
Gene Flow ◽  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Small Male ◽  
Mating Pattern ◽  
Barrier Effects ◽  
Divergent Natural Selection ◽  
Coastal Marine

AbstractWhen divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple-effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail, Littorina saxatilis, occur in North Atlantic rocky-shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size-assortative mating has previously been documented. Here, we analyze the mating pattern in L. saxatilis with respect to size in intensively-sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment.

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.

Observations of asymmetric reproduction along a morphocline of the blackspotted stickleback, Gasterosteus wheatlandi

1993 ◽  
Vol 71 (7) ◽  
pp. 1477-1479 ◽  
Author(s):  
Suzanne G. Ayvazian
Keyword(s):  
Reproductive Isolation ◽  
Assortative Mating ◽  
Gasterosteus Aculeatus ◽  
Nest Construction ◽  
Mating Types ◽  
Allopatric Populations ◽  
Motivational States ◽  
Behavioral Cues

Assortative mating has been documented within the Gasterosteus aculeatus complex. The outcome of laboratory mating trials between individuals from allopatric populations of the blackspotted stickleback, Gasterosteus wheatlandi, is reported. A total of 70 intra- and inter-population mating trials between individuals from Massachusetts and Connecticut were conducted between 1984 and 1987. The results showed differences in the proportion of successful matings, measured as nests constructed, eggs deposited, and young produced. Although intrapopulation mating trials yielded the greatest proportion of nests, eggs, and young, mating did not proceed beyond nest construction between males from Massachusetts population and females from Connecticut population. These results suggest asymmetric reproductive isolation between this mating combination, as all other mating types produced offspring. Further research is necessary to resolve questions concerning differences in motivational states and reproductive behavioral cues.

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