In contrast to previous reports, our data suggest that neither type nor position of intragenic mutations in the LIS1 gene allows an unambiguous prediction of the phenotypic severity. Furthermore, patients presenting with mild cerebral malformations such as subcortical band heterotopia or cerebellar hypoplasia should be considered for genetic analysis of the LIS1 gene.

Orthoptera have some of the largest genomes of all insects. At the same time, the architecture of their genomes remains poorly understood. Comparative cytological data across a wide range of taxa, even for basic parameters such as chromosome number, may provide important insights into the evolution of these genomes and help answer the question of why some species attained such large sizes. We collected and compiled more than 1,000 records of chromosome numbers of 339 genera (13.8% of 2,452 known genera) and 769 species (6.2% of 12,250 known species) of Caelifera, the suborder of Orthoptera that includes those taxa with short antennae. Within the family Acrididae, most of the records come from the subfamilies Oedipodinae (N = 325), Melanoplinae (N = 192) and Gomphocerinae (N = 254). Out of the 621 investigated species of Acrididae, 459 (73.9%) shared a chromosome number of 2n♂ = 23. Chromosome numbers of 2n♂ = 17 (12.2%) and 2n♂ = 21 (9.9%) were less common. The remaining 4.0% of species exhibited different chromosome numbers between 2n♂ = 8 (6 + XY) and 2n♂ = 27. Plotted on a phylogenetic tree, our results confirm that chromosome numbers, especially in the largest grasshopper family Acrididae, are highly conserved with a basic count of 2n♂ = 23 (22 + X0), sometimes reduced to, e.g., 2n♂ = 17 (16 + X0) in some genera of the slant-faced grasshopper subfamily Gomphocerinae. Species with divergent chromosome numbers occur in many of the groups we studied, but are not a systematic trait and have evolved multiple times independently. Our study supports the view that chromosome numbers are much more stable across the investigated Caelifera compared to Ensifera, the second suborder of Orthoptera that includes the long antennae bush crickets and crickets. Our results significantly extend our knowledge on the diversity of this character in Caelifera.

No abstract

Mitochondrial gene order has contributed to the elucidation of evolutionary relationships in several animal groups. It generally has found its application as a phylogenetic marker for deep nodes. Yet, in Orthoptera limited research has been performed on the gene order, although the group represents one of the oldest insect orders. We performed a comprehensive study on mitochondrial genome rearrangements (MTRs) within Orthoptera in the context of mitogenomic sequence-based phylogeny. We used 280 published mitogenome sequences from 256 species, including three outgroup species, to reconstruct a molecular phylogeny. Using a heuristic approach, we assigned MTR scenarios to the edges of the phylogenetic tree and reconstructed ancestral gene orders to identify possible synapomorphies in Orthoptera. We found all types of MTRs in our dataset: inversions, transpositions, inverse transpositions, and tandem-duplication/random loss events (TDRL). Most of the suggested MTRs were in single and unrelated species. Out of five MTRs which were unique in subgroups of Orthoptera, we suggest four of them to be synapomorphies; those were in the infraorder Acrididea, in the tribe Holochlorini, in the subfamily Pseudophyllinae, and in the two families Phalangopsidae and Gryllidae or their common ancestor (leading to the relationship ((Phalangopsidae + Gryllidae) + Trigonidiidae)). However, similar MTRs have been found in distant insect lineages. Our findings suggest convergent evolution of specific mitochondrial gene orders in several species, deviant from the evolution of the mitogenome DNA sequence. As most MTRs were detected at terminal nodes, a phylogenetic inference of deeper nodes based on MTRs is not supported. Hence, the marker does not seem to aid resolving the phylogeny of Orthoptera, but adds further evidence for the complex evolution of the whole group, especially at the genetic and genomic levels.The results indicate a high demand for more research on patterns and underlying mechanisms of MTR events in Orthoptera.

Aiolopusstrepens Croatia GBORT991-15 N.a.

The genus Thalpomena Saussure comprises nine species and four subspecies and is largely endemic to the Atlas Mountains (North Africa). Here, we used an evolutionary taxonomic approach to differentiate the species of the genus Thalpomena and to reconstruct their biogeographic history. Phylogenetic tree reconstruction based on five molecular markers revealed four distinct clades within the genus Thalpomena. These are not fully in line with the current taxonomy but rather seem to represent lineages defined by their distribution and hind wing banding patterns. All lineages are geographically separated and can be distinguished based on genetic, morphometric and ecological modelling data. Ancestral area reconstruction suggests an origin of the species in the southern regions of the Atlas Mountains (High Atlas to Aures Mountains). Molecular clock analysis promotes the glacial refugia theory, supporting the origin of Thalpomena in the Pliocene, followed by diversification events in the Pleistocene.

Animal genomes vary widely in size, and much of their architecture and content remains poorly understood. Even among related groups, such as orders of insects, genomes may vary in size by orders of magnitude–for reasons unknown. The largest known insect genomes were repeatedly found in Orthoptera, e.g., Podisma pedestris (1C = 16.93 pg), Stethophyma grossum (1C = 18.48 pg) and Bryodemella holdereri (1C = 18.64 pg). While all these species belong to the suborder of Caelifera, the ensiferan Deracantha onos (1C = 19.60 pg) was recently found to have the largest genome. Here, we present new genome size estimates of 50 further species of Ensifera (superfamilies Gryllidea, Tettigoniidea) and Caelifera (Acrididae, Tetrigidae) based on flow cytometric measurements. We found that Bryodemella tuberculata (Caelifera: Acrididae) has the so far largest measured genome of all insects with 1C = 21.96 pg (21.48 gBp). Species of Orthoptera with 2n = 16 and 2n = 22 chromosomes have significantly larger genomes than species with other chromosome counts. Gryllidea genomes vary between 1C = 0.95 and 2.88 pg, and Tetrigidae between 1C = 2.18 and 2.41, while the genomes of all other studied Orthoptera range in size from 1C = 1.37 to 21.96 pg. Reconstructing ancestral genome sizes based on a phylogenetic tree of mitochondrial genomic data, we found genome size values of >15.84 pg only for the nodes of Bryodemella holdereri / B. tuberculata and Chrysochraon dispar / Euthystira brachyptera. The predicted values of ancestral genome sizes are 6.19 pg for Orthoptera, 5.37 pg for Ensifera, and 7.28 pg for Caelifera. The reasons for the large genomes in Orthoptera remain largely unknown, but a duplication or polyploidization seems unlikely as chromosome numbers do not differ much. Sequence-based genomic studies may shed light on the underlying evolutionary mechanisms.

No abstract