Chorthippus Parallelus Research Articles

Females of the grasshopper Chorthippus parallelus (Zett.) do not remate for fresh sperm

The evolution of female multiple mating is still a largely debated field. Among the benefits that have been proposed to explain this risky behaviour is the replenishment of sperm reserves. Apart from an increase in total sperm number, it can be an expression of post-copulatory mate choice or can be directed towards the uptake of fresh sperm. Using fresh sperm for fertilization instead of sperm aged by storage in the female genital tract may avoid a lowered fertilization capacity, an increase in deleterious effects or a skewed offspring sex ratio. We investigated the influence of sperm age on female fitness in the grasshopper Chorthippus parallelus, a species where females mate multiply. After copulation, females store sperm over the course of weeks until fertilization. An average ejaculate of 250 000 spermatozoa exponentially declined with time within the female's spermatheca. The number of days since copulation better explained the variation in actual sperm number than the number of pods or eggs laid. We investigated differences in female fitness parameters in two treatments. In the first, females were mated only once, while in the second, females always had freshly ejaculated sperm available. Although in our experiment, multiply mated females had heavier offspring than singly mated females, egg number per pod, hatching and fertilization success, their composite effects and offspring sex ratio did not vary with respect to season or sperm age. We therefore reject the hypothesis that the reason for remating in females of this species is the uptake of fresh sperm.

The localization of mitochondrial sequences to chromosomal DNA in orthopterans

There is growing evidence that the integration of mitochondrial DNA sequences into nuclear and chloroplast genomes of higher organisms may be widespread rather than exceptional. We report the localization of 18S-25S rDNA and mitochondrial DNA sequences to meiotic chromosomes of several orthopteran species using in situ hybridisation. The cytochrome oxidase I (COI) sequence localizes to the centromeric and two telomeric regions of the eight bivalents of Chorthippus parallelus, the telomeric regions in Schistocerca gregaria and is present throughout the genome of Italopodisma sp. (Orthoptera: Acrididae). The control region of the mitochondrion and COI localize to similar chromosomal regions in S. gregaria. These data explain sequencing data that are inconsistent with the COI sequence being solely mitochondrial. The different nuclear locations of mtDNA in the different genera studied suggest that grasshopper mtDNA-like sequences have been inserted into the nuclear genome more than once in Acridid history, and there may have been different mechanisms involved when these events occurred in each of these species.Key words: Schistocerca gregaria, Italopodisma spp., Chorthippus parallelus, in situ hybridisation, mitochondrial DNA, genome organization.

Variation of Postembryonic Development Time and Number of Nymphal Instars on a Small Spatial Scale in Central European Grasshoppers (Caelifera: Acrididae)

The variation of postembryonic development time and number of nymphal instars of several species of central european grasshoppers were examined at 2 adjacent sites characterised by different sward conditions such as insolation and vegetation structure. In 5 out of 6 species of Gomphocerinae, 5 nymphal instars were developed in both sexes. But only at the site with higher heat supply, a few of the males have done so whereas the larger part passed through 4 instars. At both sites, however, 5 instars occurred at least in part of the females of these species. In Chorthippus mollis (Charpentier 1825), it became obvious that at the site with a higher heat supply, a higher percentage of the females passed through 5 instars. Only Chorthippus parallelus (Zetterstedt 1921) showed a constant number of 4 instars in the study area. In Chorthippus parallelus, a higher heat supply led to decreased nymphal development time. In Chorthippus mollis, however, the more frequent insertion of an additional nymphal instar led to a prolonged development time in the females. In the males, the effect of a small percentage of long cycle specimen was likely covered by the influence of the higher temperature. Thus, no clear difference between the 2 sites could be observed on the population level., The ecological significance of the variation of the postembryonic development is discussed with regard to the adapting of life cycles to seasonal environments. According to GRANT et al [1993] it is supposed that reaching a greater body size leads to a more increased fecundity compared with the advances of a longer season suitable for reproduction.

Reproductive potential of gamma‐irradiated males of the meadow grasshopper Chorthippus parallelus (Zetterstedt) (Orth., Acrididae)

Males of the meadow grasshopper Chorthippus parallelus were treated with five doses ranging from 0 (control) to 140 Gy of gamma irradiation. There was a negative correlation between irradiation dose and post‐treatment longevity. Individuals irradiated with the lowest dose lived, on average, longer than the controls. This was presumably not attributable to an energy allocation from tissue since at the time of death there were no dry weight differences. There was a negative correlation between irradiation dose and number of faecal pellets excreted in a period 6–9 days after treatment but not before. There were no negative correlations between irradiation dose and the time required to copulate, copulation duration and ejaculate size. The proportion of tail‐less sperm did not differ between the treatments.

Chromosomal differentiation through an Alpine hybrid zone in the grasshopper Chorthippus parallelus

Abstract The grasshopper Chorthippus parallelus is genetically differentiated over its range into at least five major geographical subdivisions. Two of these subdivisions, designated as subspecies, meet and form a hybrid zone in the Pyrenees. These subspecies differ for a wide range of morphological, behavioural and chromosomal characters, which vary clinally across the zone. A further geographical subdivision exists within Italy. Here we present the first evidence for chromosomal divergence between populations of the grasshopper north and south of the Alps. Across two Alpine cols (Col de Larche, between France and Italy; Passo de Resia, between Austria and Italy), these populations differ in both structural and functional components of the X-chromosome. Northern Alpine individuals possess an active nucleolar organizing region (NOR) at the distal end of the X-chromosome and an associated region of heterochromatin (C-band). Both these features are absent from individuals from the south of the Alps. However, all individuals examined carry distally located rDNA on the X-chromosome. Clinal transition was examined in the distal C-band in transects through the two cols. The cline centres are roughly coincident with the tops of the cols. Both clines were of similar widths (Col de Larche, 21.88 km; Passo de Resia, 24.05 km), and therefore much wider than those for an X-linked distal C-band in the Pyrenean hybrid zone. This suggests that there are different selective pressures on the cytogenetic characters in the Alps. The results are discussed in the context of the historical population dynamics of the species in relation to the climatic changes associated with the Pleistocene ice ages.

Costs and Benefits of Mating in the Grasshopper Chorthippus parallelus (Caelifera: Acrididae)

Fitness consequences of different levels of mating benefits, viz., (1) virgin, (2) seldom mated, (3) free mating chances with the same male throughout the female's life span, and (4) free mating chances with three males always offered, were investigated in female meadow grasshoppers Chorthippus parallelus. No differences among the treatments were apparent in egg number per pod, total egg number per female, and hatching success of larvae. Seldom-mated females had offspring with the heaviest average larval dry weight. We did not find costs of mating in terms of reduced female longevity and residual dry weight between the treatments.

MtDNA phylogeography and postglacial patterns of subdivision in the meadow grasshopper Chorthippus parallelus.

A 300 bp portion of the mitochondrial cytochrome oxidase subunit I (COI) gene was used to investigate the intraspecific genetic structure of the European meadow grasshopper Chorthippus parallelus. Levels of genetic subdivision between geographical regions in Europe were assessed using the KST statistic and revealed patterns indicative of the postglacial history of this organism. Northern European populations are shown to share a very recent common ancestor with, and hence originate from, a Balkan expansion. Genetic distances between these areas and both southern Italy and central Spain are shown to be approximately equal, even though only the Spanish form is recognized as a distinct subspecies. Distance estimates indicate that the common ancestor of the two subspecies lived more than one glacial cycle ago, and the refugial populations have probably been diverging in isolation for five or six glacial cycles (approximately equal to 550,000 years). Comparisons are made to the analysis of a similar data set using an anonymous nuclear DNA marker (Cooper et al., 1995). Although the structure revealed is generally very similar, differences in the location of transition zones between different genetic forms of C. parallelus may reflect the different historical assortment of these molecules.

MtDNA phylogeography and postglacial patterns of subdivision in the meadow grasshopper Chorthippus parallelus

A 300 bp portion of the mitochondrial cytochrome oxidase subunit I (COI) gene was used to investigate the intraspecific genetic structure of the European meadow grasshopper Chorthippus parallelus. Levels of genetic subdivision between geographical regions in Europe were assessed using the KST statistic and revealed patterns indicative of the postglacial history of this organism. Northern European populations are shown to share a very recent common ancestor with, and hence originate from, a Balkan expansion. Genetic distances between these areas and both southern Italy and central Spain are shown to be approximately equal, even though only the Spanish form is recognized as a distinct subspecies. Distance estimates indicate that the common ancestor of the two subspecies lived more than one glacial cycle ago, and the refugial populations have probably been diverging in isolation for five or six glacial cycles (≈550 000 years). Comparisons are made to the analysis of a similar data set using an anonymous nuclear DNA marker (Cooper et al., 1995). Although the structure revealed is generally very similar, differences in the location of transition zones between different genetic forms of C. parallelus may reflect the different historical assortment of these molecules.

Microhabitat Analysis of three Fen-grassland Grasshopper species (Acrididae: Gomphocerinae)

Based on an individual data recording of 13 biotic and abiotic microhabitat variables, the microhabitat of 3 sympatric and coexisting fen-grassland grasshoppers was analyzed. The investigated species were closely related Chorthippus albomarginatus Degeer 1773, Chorthippus montanus Charpentier 1825, and Chorthippus parallelus Zetterstedt 1821 (Acrididae: Gomphocerinae). The application of Principal Components Analysis combined 70.4% of the recorded data to 3 main factors: (a) Perch height in the vegetation and its density, (b) leaf canopy, and (c) microclimate, describing the microhabitat of the 3 species in a sufficient way. Supported by 3 ecological standard calculations, the results show a finely tuned microhabitat utilization, confirming a strategy of competition avoidance of the 3 species in case of coexistence. Even on microhabitat scale Ch montanus is stenoecious, whereas Ch albomarginatus and Ch parallelus are euryecious. Thus, the species' macrohabitat requirements are continued in the microhabitat.

The insect cytochrome oxidase I gene: evolutionary patterns and conserved primers for phylogenetic studies.

Insect mitochondrial cytochrome oxidase I (COI) genes are used as a model to examine the within-gene heterogeneity of evolutionary rate and its implications for evolutionary analyses. The complete sequence (1537 bp) of the meadow grasshopper (Chorthippus parallelus) COI gene has been determined, and compared with eight other insect COI genes at both the DNA and amino acid sequence levels. This reveals that different regions evolve at different rates, and the patterns of sequence variability seems associated with functional constraints on the protein. The COOH-terminal was found to be significantly more variable than internal loops (I), external loops (E), transmembrane helices (M) or the NH2 terminal. The central region of COI (M5-M8) has lower levels of sequence variability, which is related to several important functional domains in this region. Highly conserved primers which amplify regions of different variabilities have been designed to cover the entire insect COI gene. These primers have been shown to amplify COI in a wide range of species, representing all the major insect groups; some even in an arachnid. Implications of the observed evolutionary pattern for phylogenetic analysis are discussed, with particular regard to the choice of regions of suitable variability for specific phylogenetic projects.

The sequence and structure of the meadow grasshopper (Chorthippus parallelus) mitochondrial srRNA, ND2, COl, COll ATPase8 and 9 tRNA genes

The nucleotide sequence of the mitochondrial ND2, COI, COII, ATPase8, srRNA and nine tRNA genes have been sequenced from two individual of the meadow grasshopper Chorthippus parallelus. Comparisons are made to other insects for which the same regions are completely sequenced. Percentage A + T is found to be relatively low in C. parallelus though consistent with that of the other Orthopteran, Locusta migratoria. The relative number of substitutions observed in the different protein-coding genes was analysed between pairs of insect species sharing different levels of relatedness. A clear change in this rate was observed between the within-genus and between-genera comparisons. This change is interpreted in terms of the functional constraints acting on these four different genes. The patterns seem to result from an early saturation of COI and COII genes with synonymous substitutions, and a tolerance of ND2 and ATPase8 function to high levels of amino acid replacements. This analysis highlights a need for further sequence studies and comparisons between taxa of different levels of divergence in order to understand the patterns of mtDNA evolution on which many evolutionary investigations are based.

A hybrid zone between two subspecies of Chorthippus parallelus. X‐chromosome variation through a contact zone

SummaryTwo grasshopper subspecies, Chorthippus parallelus parallelus (Cpp) and Chorthippus parallelus erythropus (Cpe), meet along the Pyrenees where they hybridize and produce a hybrid zone. A contact zone located in the Col de Portalet has been analyzed for the distribution of chromosome markers on the sex (X) chromosome in pure and hybrid populations. C‐banding allowed us to distinguish both pure subspecific forms and recombinant forms, and to demonstrate their different frequencies through the contact zone. Interestingly, the distal C‐band (P) on the X chromosome that characterizes Cpp individuals occurs at very high frequency through the zone and then drops sharply, close to where pure Cpe populations are found. A novel interstitial C‐band (H) has been found, probably derived from that characterizing Cpe individuals (E). This marker band is only present in hybrid populations. These data are discussed in the light of the dynamics of the hybrid zone.

Patterns of DNase I sensitivity in the chromosomes of the grasshopper Chorthippus parallelus (Orthoptera).

We have analysed the patterns of DNase I/nick translation in the chromosomes of the grasshopper Chorthippus parallelus erythropus. Sites of preferential DNase I-nicking were concentrated at the distal chromosome regions, thus showing the non-uniform DNase I sensitivity of different chromosome domains. Among centromeric C-bands, the heterochromatin of metacentric and acrocentric chromosomes differed with respect to their DNase I resistance.

Postglacial expansion and genome subdivision in the European grasshopper Chorthippus parallelus.

A noncoding nuclear DNA marker sequence (Cpn1-1) was used to investigate subdivision in the grasshopper Chorthippus parallelus and deduce postglacial expansion patterns across its species range in Europe. Investigation of the spatial distribution of 71 Cpn1-1 haplotypes and estimation of levels of genetic differentiation (KST values) between populations and geographic regions provided evidence for subdivision of C. parallelus into at least five major geographic regions and indicated that the French form of C. parallelus originated after range expansion from a Balkan refugium. Further evidence for subdivision of C. parallelus between Italy and northern Europe suggests that the Alps may have formed a significant barrier to gene flow in this grasshopper.

Divergence in cuticular hydrocarbons between parapatric subspecies of the meadow grasshopper, Chorthippus parallelus (Orthoptera, Acrididae)

Abstract Two subspecies of the grasshopper Chorthippus parallelus (Orthoptera; Acrididae) meet and form a hybrid zone in the Pyrenees. Here we investigate whether the subspecies differ in the blend of cuticular hydrocarbons. Such differences may function as chemical signals, being detected via contact chemoreception and used during mate choice as in other insects. Gas chromatography shows that the subspecies have diverged in the composition of their cuticular hydrocarbons. This difference between subspecies exists over and above variation in cuticular hydrocarbons among individual populations. The majority of the difference can be attributed to the relative amounts of a small group of compounds present in the cuticle. The possible consequences of this chemical divergence for mating encounters between the subspecies are discussed.

A hybrid zone between two subspecies of the grasshopper Chorthippus parallelus along the Pyrenees: the west end

The grasshopper Chorthippus parallelus (Cp) has two distinct subspecies which meet along the Pyrenees forming a hybrid zone. As Cp is rarely found above 2000 m, the contact between the two subspecies must occur through valleys crossing the Pyrenees perpendicularly or at both ends of the mountain ridge. The contact zones in two valleys have already been studied in detail, Col de Porta-let (Central Pyrenees) and Col de la Quillane (Eastern Pyrenees), and this paper analyses the structure of the contact zone at the western end of the Pyrenees. The study has been carried out using different chromosome markers obtained by C-banding and silver staining, both related to the sex chromosome. Although the structure of this contact zone, analysed using these two markers, is similar to that of the contact zones occurring in other valleys, it is much wider and some remarkable peculiarities in the shapes of the clines have been detected. Additionally, hybrid-related sex chromosome markers detected in Portalet have not been found in the present sample.

Nuclear DNA introgression across a Pyrenean hybrid zone between parapatric subspecies of the grasshopper Chorthippus parallelus.

Two parapatric subspecies of the European grasshopper Chorthippus parallelus meet along the Pyrenees and form a hybrid zone. A nuclear DNA sequence marker (cpnl-1), involving the presence or absence of a 5 bp insertion, was found to differentiate between the two subspecies along either side of the High Pyrenees but further electrophoretic and sequence analyses revealed that considerable mixing of the subspecific genomes had occurred towards the western and eastern ends of the Pyrenees. The cline for this marker was relatively narrow in two adjoining western central high cols (Peyrelue: 9.7 km and Portalet: 13.3 km) but was significantly wider in another central high col towards the east (Quillane: 42.3 km), indicating that a different combination of forces has been operating on this locus in different regions of the Pyrenees.

Variation in cuticular hydrocarbons across a hybrid zone in the grasshopperChorthippus parallelus

Two subspecies of the meadow grasshopper Chorthippus parallelus form a hybrid zone across the mountains of the Pyrenees. The subspecies differ, amongst several other traits, in the composition of their cuticular hydrocarbons. These compounds are thought to be involved in chemical communication during courtship. Here we report that cuticular hydrocarbon composition differs between the sexes and that a narrow cline for cuticular hydrocarbons separates the subspecies. The cline centre is displaced 15 km north of the majority of clines reported for other characters. This unusual lack of coincidence is discussed with reference to its possible causes and its consequences for the sexual communication system of Chorthippus parallelus .

Divergence in Morphology and Mating Signals, and Assortative Mating Among Populations of Chorthippus parallelus (Orthoptera: Acrididae)

Divergence in Morphology and Mating Signals, and Assortative Mating Among Populations of Chorthippus parallelus (Orthoptera: Acrididae)

DIVERGENCE IN MORPHOLOGY AND MATING SIGNALS, AND ASSORTATIVE MATING AMONG POPULATIONS OF CHORTHIPPUS PARALLELUS (ORTHOPTERA: ACRIDIDAE).

Three geographically widely separated populations of the grasshopper Chorthippus parallelus (Orthoptera: Acrididae) have been examined for morphological divergence, divergence in characteristics of the acoustic sexual signals of males, and assortative mating. Significant assortative mating existed between two of the three pairwise combinations of populations in multiple-choice tests. This may be caused by divergence in three of the four acoustic signal parameters measured. The populations also differed in morphology, including characters associated with signal production. The results are discussed in relation to theories for the origin of premating isolation, and it is argued that the observed divergence has developed rapidly, possibly indicating the action of selection. However, this selection could not have been caused by interactions with closely related taxa.