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Comparative Chromosome Painting and NOR Distribution Suggest a Complex Hybrid Origin of Triploid Lepidodactylus lugubris (Gekkonidae).

Trifonov VA, Paoletti A, Caputo Barucchi V, Kalinina T, O'Brien PC, Ferguson-Smith MA, Giovannotti M - PLoS ONE (2015)

Bottom Line: Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs).The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals.The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia.

ABSTRACT
Parthenogenesis, unisexuality and triploidy are interesting but poorly studied phenomena occurring in some reptile species. The mourning gecko (Lepidodactylus lugubris) represents a complex of diploid and triploid parthenogenetic mostly all-female populations (males occur quite rarely) widely distributed in coastal areas of the Indian and Pacific Oceans. Here, we study karyotypes of a male and two female L. lugubris (LLU) triploid individuals (3n = 66) using comparative painting with Gekko japonicus, Hemidactylus turcicus and H. platyurus chromosome specific probes to visualize the homologous regions and to reveal genus specific rearrangements. Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs). Our results suggest that the karyotype of L. lugubris underwent a chromosome fission and a fusion after its divergence from a common ancestor of the Gekko-Hemidactylus group. The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals. It seems that three different bisexual populations might have contributed to the origin of this triploid parthenogenetic population. We postulate that the heterozygosity in NOR localization is maintained in the triploid clone studied by the absence of recombination as described in whiptail lizards. The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

No MeSH data available.


Related in: MedlinePlus

A scenario of karyotype evolution within Gekko-Lepidodactylus- Hemidactylus group.Stars indicate chromosome fissions and circles indicate chromosome fusions. The recurrent chromosome rearrangements are underlined. The tree is based on previously published data [19].
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pone.0132380.g007: A scenario of karyotype evolution within Gekko-Lepidodactylus- Hemidactylus group.Stars indicate chromosome fissions and circles indicate chromosome fusions. The recurrent chromosome rearrangements are underlined. The tree is based on previously published data [19].

Mentions: According to molecular phylogenies Lepidodactylus is more closely related to the genus Gekko [18] [19] than to Hemidactylus. However, we observed similar karyotypic features of L. lugubris and H. platyurus on the one hand, as well as two common fusions (GJA2p+GJA2q = HFR1p+HFR1q and GJA5pqprox+GJA5qdist = HFR2p+HFR2q) both in the Gekko lineage and in H. frenatus. Previously we suggested that the syntenies GJA2 = HFR1 and GJA5 = HFR2 were ancestral [14], and a recent paper of Pokorna et al [20] demonstrates the conservation of GJA2 and GJA1 syntenies across different families of Gekkota. This means that our suggestion about the ancestral state of the Gekko karyotype is still valid and high karyotype similarities between L. lugubris and H. platyurus on the one hand and between Gekko and H. frenatus on the other hand result from homoplasies. These homoplasies include frequent breakpoint reuse on ancestral elements homologous to GJA1, 2 and GJA5. Fissions of these chromosomes occurred independently in three gekkonid lineages–LLU, HPL and HTU (Fig 7).


Comparative Chromosome Painting and NOR Distribution Suggest a Complex Hybrid Origin of Triploid Lepidodactylus lugubris (Gekkonidae).

Trifonov VA, Paoletti A, Caputo Barucchi V, Kalinina T, O'Brien PC, Ferguson-Smith MA, Giovannotti M - PLoS ONE (2015)

A scenario of karyotype evolution within Gekko-Lepidodactylus- Hemidactylus group.Stars indicate chromosome fissions and circles indicate chromosome fusions. The recurrent chromosome rearrangements are underlined. The tree is based on previously published data [19].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492922&req=5

pone.0132380.g007: A scenario of karyotype evolution within Gekko-Lepidodactylus- Hemidactylus group.Stars indicate chromosome fissions and circles indicate chromosome fusions. The recurrent chromosome rearrangements are underlined. The tree is based on previously published data [19].
Mentions: According to molecular phylogenies Lepidodactylus is more closely related to the genus Gekko [18] [19] than to Hemidactylus. However, we observed similar karyotypic features of L. lugubris and H. platyurus on the one hand, as well as two common fusions (GJA2p+GJA2q = HFR1p+HFR1q and GJA5pqprox+GJA5qdist = HFR2p+HFR2q) both in the Gekko lineage and in H. frenatus. Previously we suggested that the syntenies GJA2 = HFR1 and GJA5 = HFR2 were ancestral [14], and a recent paper of Pokorna et al [20] demonstrates the conservation of GJA2 and GJA1 syntenies across different families of Gekkota. This means that our suggestion about the ancestral state of the Gekko karyotype is still valid and high karyotype similarities between L. lugubris and H. platyurus on the one hand and between Gekko and H. frenatus on the other hand result from homoplasies. These homoplasies include frequent breakpoint reuse on ancestral elements homologous to GJA1, 2 and GJA5. Fissions of these chromosomes occurred independently in three gekkonid lineages–LLU, HPL and HTU (Fig 7).

Bottom Line: Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs).The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals.The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia.

ABSTRACT
Parthenogenesis, unisexuality and triploidy are interesting but poorly studied phenomena occurring in some reptile species. The mourning gecko (Lepidodactylus lugubris) represents a complex of diploid and triploid parthenogenetic mostly all-female populations (males occur quite rarely) widely distributed in coastal areas of the Indian and Pacific Oceans. Here, we study karyotypes of a male and two female L. lugubris (LLU) triploid individuals (3n = 66) using comparative painting with Gekko japonicus, Hemidactylus turcicus and H. platyurus chromosome specific probes to visualize the homologous regions and to reveal genus specific rearrangements. Also, we applied a 28S ribosomal DNA probe and Ag-staining to detect nucleolus organizer regions (NORs). Our results suggest that the karyotype of L. lugubris underwent a chromosome fission and a fusion after its divergence from a common ancestor of the Gekko-Hemidactylus group. The NORs were found to be located on one out of three homologs on each of LLU8, LLU15 and LLU18, thus further confirming a hybrid origin of triploid individuals. It seems that three different bisexual populations might have contributed to the origin of this triploid parthenogenetic population. We postulate that the heterozygosity in NOR localization is maintained in the triploid clone studied by the absence of recombination as described in whiptail lizards. The pattern of NOR localizations and homologous regions in males and females, as well as the absence of other detectable karyotypic differences, suggest that males arise spontaneously in all female populations and do not arise from independent hybridizations with different species.

No MeSH data available.


Related in: MedlinePlus