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.

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.

Multivariate differentiation of parapatric and allopatric populations of threespine stickleback in the Sangan River watershed, Queen Charlotte Islands

1985 ◽  
Vol 63 (12) ◽  
pp. 2944-2951 ◽  
Author(s):  
T. E. Reimchen ◽  
E. M. Stinson ◽  
J. S. Nelson
Keyword(s):  
Discriminant Analysis ◽  
Reproductive Isolation ◽  
Gasterosteus Aculeatus ◽  
River System ◽  
Threespine Stickleback ◽  
Geographical Distance ◽  
Marine Waters ◽  
Meristic Characters ◽  
Allopatric Populations ◽  
Queen Charlotte Islands

A discriminant analysis was made of 17 morphometric and 10 meristic characters in the freshwater form (leiurus) of threespine stickleback (Gasterosteus aculeatus) from 16 localities in the Sangan River System on the Queen Charlotte archipelago and in the presumed ancestral form (trachurus) from a nearby locality in marine waters. While multivariate means were significantly different between trachurus and leiurus, there was even greater differentiation between the leiurus populations found in lakes, ponds, and streams, divergence which was independent of geographical distance between localities. Statistical removal of meristics, removal of body length, log transformation and size standardization of all morphometries did not substantially alter the discrimination of the populations. Two of the leiurus populations that overlap in a narrow zone appear to have achieved reproductive isolation.

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.

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 Spatial swarm segregation and reproductive isolation between the molecular forms of Anopheles gambiae

2009 ◽  
Vol 276 (1676) ◽  
pp. 4215-4222 ◽  
Author(s):  
Abdoulaye Diabaté ◽  
Adama Dao ◽  
Alpha S. Yaro ◽  
Abdoulaye Adamou ◽  
Rodrigo Gonzalez ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Anopheles Gambiae ◽  
Assortative Mating ◽  
Molecular Form ◽  
Mate Recognition ◽  
Spatial Segregation ◽  
Molecular Forms ◽  
Ecological Niches ◽  
Ecological Criteria ◽  
Underlying Mechanisms

Anopheles gambiae , the major malaria vector in Africa, can be divided into two subgroups based on genetic and ecological criteria. These two subgroups, termed the M and S molecular forms, are believed to be incipient species. Although they display differences in the ecological niches they occupy in the field, they are often sympatric and readily hybridize in the laboratory to produce viable and fertile offspring. Evidence for assortative mating in the field was recently reported, but the underlying mechanisms awaited discovery. We studied swarming behaviour of the molecular forms and investigated the role of swarm segregation in mediating assortative mating. Molecular identification of 1145 males collected from 68 swarms in Donéguébougou, Mali, over 2 years revealed a strict pattern of spatial segregation, resulting in almost exclusively monotypic swarms with respect to molecular form. We found evidence of clustering of swarms composed of individuals of a single molecular form within the village. Tethered M and S females were introduced into natural swarms of the M form to verify the existence of possible mate recognition operating within-swarm. Both M and S females were inseminated regardless of their form under these conditions, suggesting no within-mate recognition. We argue that our results provide evidence that swarm spatial segregation strongly contributes to reproductive isolation between the molecular forms in Mali. However this does not exclude the possibility of additional mate recognition operating across the range distribution of the forms. We discuss the importance of spatial segregation in the context of possible geographic variation in mechanisms of reproductive isolation.

No character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 849-852 ◽  
Author(s):  
B. N. Singh ◽  
Sujata Chatterjee
Keyword(s):  
Reproductive Isolation ◽  
Sexual Isolation ◽  
Character Displacement ◽  
Sympatric Populations ◽  
Allopatric Populations ◽  
Drosophila Bipectinata ◽  
Isolation Index ◽  
Drosophila Malerkotliana

To test whether character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana exists, the degree of sexual isolation was measured between their sympatric and allopatric populations. Although the isolation indices vary in different crosses, the average isolation index for sympatric populations is very close to that for allopatric populations. This shows no difference in the degree of sexual isolation between sympatric and allopatric populations of D. bipectinata and D. malerkotliana. Thus there is no evidence for the existence of character displacement for sexual isolation between these two closely related sympatric species.Key words: Drosophila bipectinata, Drosophila malerkotliana, sexual isolation, sympatric and allopatric populations.

scholarly journals The distribution of two morphological forms of Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae)

1985 ◽  
Vol 80 (2) ◽  
pp. 145-148 ◽  
Author(s):  
R. D. Ward ◽  
A. L. Ribeiro ◽  
L. Ryan ◽  
A. L. Falcão ◽  
E. F. Rangel
Keyword(s):  
Reproductive Isolation ◽  
Lutzomyia Longipalpis ◽  
Single Pair ◽  
Museum Collections ◽  
Southern Brazil ◽  
Eastern Area ◽  
Allopatric Populations ◽  
North Brazil ◽  
The One ◽  
Cuticular Structures

The males of the sandfly Lutzomyia longipalpis occur in two forms, one which bears a single pair of pale spots on tergite 4 and another in which an additional pair of spots characterizes tergite 3. Almost complete reproductive isolation between sumpatric populations of the two forms and between allopatric populations of the one-spot form has been reported (Ward et al., 1983). Micromorphological differences in cuticular structures on the spots have also been observed and may be sites of pheromone release (Lane & Ward, 1984). Detais of the known distribution of the two are based on the examination of new specimens captured in Brazil during 1982, as well as museum collections and specimens from other laboratories. Males with a single pair of pale spots have been found from Mexico to southern Brazil, whilst the two-spot form is found only from the state of Maranhão in North Brazil to Minas Gerais and the border with Paraguay. In the eastern area of Brazil the two forms occur sympatrically in some locations and separately in others.

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