Research Article |
Corresponding author: Eduard Petitpierre ( eduard.petitpierre@uib.es ) Academic editor: Dorota Lachowska
© 2021 Eduard Petitpierre.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Petitpierre E (2021) The chiasmata systems of Scottish Chysolina latecincta (Demaison, 1896) (Coleoptera, Chrysomelidae). Comparative Cytogenetics 15(4): 339-343. https://doi.org/10.3897/CompCytogen.v15.i4.68309
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The meiotic systems of some Scottish individuals of the rare Chrysolina latecincta ssp. intermedia (Franz, 1938) have been analyzed from meiotic cells at diakinesis to study the types of chromosomal bivalents and the number and locations of their chiasmata. The mean number of unichiasmate was about two-thirds and that of bichiasmate bivalents about one-third. Most chiasmata were at distal positions and there were no pairwise statistically significant differences in the mean number of chiasmata and those of unichiasmate and bichiasmate bivalents between the three surveyed geographic sources of these Scottish individuals. However, pairwise significant differences were found in the mean number of proximal + interstitial chiasmata between Loch Etive (Argyllshire) and both Orkney and Shetland Islands individuals. The presumed higher values of genetic recombination due to the proximal + interstitial chiasmata with regard to the prevailing distal ones, might provide a slight selective advantage to the insular individuals against the more extreme climates of both islands compared with the Loch Etive site.
Coleoptera, chiasmata, Chrysomelidae, Chrysolina latecincta intermedia, meiosis
Chrysolina latecincta (Demaison, 1896) is a species distributed in western and central Europe from southern Norway to Spain and from Scotland to the Alps and Apennines (
One male individual from Orkney Islands, another one from Shetland Islands and two from Loch Etive, Argyllshire, in mainland Scotland, were chromosomally surveyed. The four samples of preserved testes in ethanol: glacial acetic acid (3:1) were sent to our laboratory at the University of Balearic Islands, in Palma de Mallorca, for their chromosomal analyses. We used a simple technique reported by
The observations and scoring of chiasmata were performed on cells at meiotic diakinesis in order to know the number of unichiasmate and bichiasmate bivalents and their locations as proximal, interstitial or distal, in each type of meiotic configurations, according with the drawings by
Number of each class of chiasma and mean values per cell in Scottish individuals of Chrysolina latecincta ssp. intermedia. pro. = proximal, int. = interstitial, nr. = number.
Islands | Loch Etive | Orkney Islands | Shetland Islands |
Cells scored | 75 | 11 | 29 |
bivalents scored | 825 | 121 | 319 |
bichiasmate bivalents | 254 (30.8%) | 42 (34.7%) | 106 (33.2%) |
unichiasmate bivalents | 570 (69.2%) | 79 (65.3%) | 213 (66.8%) |
total nr. of chiasmata | 1078 | 163 | 425 |
mean nr. of chiasmata | 14.373±0.117 | 14.818±0.157 | 14.60±0.162 |
nr. of distal chiasmata | 1038 (96.3%) | 143 (87.7%) | 392 (92.2%) |
mean nr. of distal chiasmata | x = 13.84±0.122 | x = 13.00±0.374 | x = 13.517±0.297 |
pro. + int. nr. of chiasmata | 40 (3.7%) | 20 (12.3%) | 33 (7.76%) |
mean pro.+ int. nr. of chiasmata | x = 0.533±0.089 | x=1.818±0.395 | x = 1.138±0.207 |
Pairwise comparisons for chiasma mean numbers between individuals from the three Scottish sites of Chrysolina latecincta ssp. intermedia. pro. = proximal, int. = interstitial.
Islands | Bichiasmate | Unichiasmate | Pro. + Int. | Distal | Total |
Loch Etive & Orkney Isl. | 0.872 | 1.398 | **3.000 *2.228 | *2.228 | 1.422 |
Loch Etive & Shetland Isl. | 0.845 | 1.321 | **3.563 1.022 | 1.022 | 1.433 |
Orkney Islands & Shetland Isl. | 0.370 | 0.506 | 1.453 1.122 | 1.022 | 0.492 |
From the total number of our 1265 studied bivalents in Ch. latecincta intermedia 68.2% were unichiasmate, mostly rod-shaped, and 31.8% bichiasmate, mostly ring-shaped (Table
The mean number of chiasmata per cell in Scottish Ch. latecincta were very similar in all studied individuals from the three sites, 14.4 to 14.8, due to the regular formation of a single chiasma in the seven smaller pairs of autosomes, and a varying number of one or two chiasmata in each of the four larger pairs (Table
The significant difference in the mean number of proximal + interstitial chiasmata between Loch Etive and both Shetland and Orkney Islands (Table
I would like thank to Dr. Michael Cox (Sussex, United Kingdom) who has sent me the preserved samples of Scottish Chrysolina latecincta intermedia and has given the mean year temperatures of the three surveyed sites. Drs. José Serrano (Murcia, Spain) and Dorota Lachowska-Cierlik (Kraków, Poland) have done a critical review in a first draft of this paper.