Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae)
The grasshopper Dichroplus pratensis Bruner is polymorphic and polytypic for a complex Robertsonian system. In this species, centric fusions induce changes in number and position of chiasmata, and thus potentially affect intrachromosomal genetic recombination and genetic variability. Males and femal...
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| Format: | Article |
| Language: | English |
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Institute of Entomology, Biology Centre, Czech Academy of Science
2005-03-01
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| Series: | European Journal of Entomology |
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| Online Access: | https://www.eje.cz/artkey/eje-200501-0001_Variability_along_a_latitudinal_gradient_in_the_chiasma_frequency_and_morphological_characters_of_Dichroplus_pr.php |
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| author | Claudio J. BIDAU Dardo A. MARTÍ |
| author_facet | Claudio J. BIDAU Dardo A. MARTÍ |
| author_sort | Claudio J. BIDAU |
| collection | DOAJ |
| description | The grasshopper Dichroplus pratensis Bruner is polymorphic and polytypic for a complex Robertsonian system. In this species, centric fusions induce changes in number and position of chiasmata, and thus potentially affect intrachromosomal genetic recombination and genetic variability. Males and females, from 23 populations covering most of the geographic range of the species and spanning 22 degrees of latitude, were studied. We analyzed chiasma frequency in relation to variability in six exomorphological characters. The chromosomal polymorphisms of D. pratensis are widely geographically distributed, and show a central-marginal pattern, in which the central populations (those occupying the ecologically optimal habitats) have high mean frequencies of different fusions per individual (F) of up to F = 3.00 and total chiasma frequencies as low as XT = 8.98 per cell, while those near the margins of the distribution (central Patagonia and the Andes) have very low levels of chromosomal polymorphisms [down to F = 0.00 in most geographically marginal locations), monomorphic karyotypes and high chiasma frequencies (XT = 11.66, in the southernmost (Rada Tilly, 45°57´S) and XT = 12.01 in the northernmost population (Volcán, 23°55´S)]. Increasing chiasma frequencies towards the margins of the range are positively and significantly correlated with increasing levels of morphological variability. The decrease in fusion polymorphism and the consequent increase in genetic recombination (both inter- and intrachromosomal) in the marginal areas, is a result of natural selection favouring higher levels of variability, which could be adaptive in ecologically harsher and changing environments. |
| first_indexed | 2024-12-13T12:04:01Z |
| format | Article |
| id | doaj.art-4d1cee552a5346e78da972303705ac26 |
| institution | Directory Open Access Journal |
| issn | 1210-5759 1802-8829 |
| language | English |
| last_indexed | 2024-12-13T12:04:01Z |
| publishDate | 2005-03-01 |
| publisher | Institute of Entomology, Biology Centre, Czech Academy of Science |
| record_format | Article |
| series | European Journal of Entomology |
| spelling | doaj.art-4d1cee552a5346e78da972303705ac262022-12-21T23:47:01ZengInstitute of Entomology, Biology Centre, Czech Academy of ScienceEuropean Journal of Entomology1210-57591802-88292005-03-01102111210.14411/eje.2005.001eje-200501-0001Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae)Claudio J. BIDAU0Dardo A. MARTÍ1Laboratório de Zoologia de Vertebrados, Zoologia - DBAV-B-UERJ (Universidade do Estado do Rio de Janeiro), Rua São Francisco Xavier 524, Maracanã, Rio de Janeiro, RJ, 20550-900 Brazil; e-mail: bidau50@hotmail.comLaboratorio de Genética Evolutiva, Universidad Nacional de Misiones, Félix de Azara 1552, (3300) Posadas, Misiones, Argentina and Consejo Nacional de Investigaciones Científicas y Tecnológicas, Rivadavia 1917, (1033) Buenos Aires, ArgentinaThe grasshopper Dichroplus pratensis Bruner is polymorphic and polytypic for a complex Robertsonian system. In this species, centric fusions induce changes in number and position of chiasmata, and thus potentially affect intrachromosomal genetic recombination and genetic variability. Males and females, from 23 populations covering most of the geographic range of the species and spanning 22 degrees of latitude, were studied. We analyzed chiasma frequency in relation to variability in six exomorphological characters. The chromosomal polymorphisms of D. pratensis are widely geographically distributed, and show a central-marginal pattern, in which the central populations (those occupying the ecologically optimal habitats) have high mean frequencies of different fusions per individual (F) of up to F = 3.00 and total chiasma frequencies as low as XT = 8.98 per cell, while those near the margins of the distribution (central Patagonia and the Andes) have very low levels of chromosomal polymorphisms [down to F = 0.00 in most geographically marginal locations), monomorphic karyotypes and high chiasma frequencies (XT = 11.66, in the southernmost (Rada Tilly, 45°57´S) and XT = 12.01 in the northernmost population (Volcán, 23°55´S)]. Increasing chiasma frequencies towards the margins of the range are positively and significantly correlated with increasing levels of morphological variability. The decrease in fusion polymorphism and the consequent increase in genetic recombination (both inter- and intrachromosomal) in the marginal areas, is a result of natural selection favouring higher levels of variability, which could be adaptive in ecologically harsher and changing environments.https://www.eje.cz/artkey/eje-200501-0001_Variability_along_a_latitudinal_gradient_in_the_chiasma_frequency_and_morphological_characters_of_Dichroplus_pr.phpcentral-marginal distributionchiasmatadichropluslatitudinal gradientmorphological variabilityrecombinationrobertsonian translocation |
| spellingShingle | Claudio J. BIDAU Dardo A. MARTÍ Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae) European Journal of Entomology central-marginal distribution chiasmata dichroplus latitudinal gradient morphological variability recombination robertsonian translocation |
| title | Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae) |
| title_full | Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae) |
| title_fullStr | Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae) |
| title_full_unstemmed | Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae) |
| title_short | Variability along a latitudinal gradient in the chiasma frequency and morphological characters of Dichroplus pratensis (Orthoptera: Acrididae) |
| title_sort | variability along a latitudinal gradient in the chiasma frequency and morphological characters of dichroplus pratensis orthoptera acrididae |
| topic | central-marginal distribution chiasmata dichroplus latitudinal gradient morphological variability recombination robertsonian translocation |
| url | https://www.eje.cz/artkey/eje-200501-0001_Variability_along_a_latitudinal_gradient_in_the_chiasma_frequency_and_morphological_characters_of_Dichroplus_pr.php |
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