Life‐cycle control of 13‐ and 17‐year periodical cicadas: A hypothesis and its implication in the evolutionary process

Periodical cicadas of the genus Magicicada exhibit a spectacular life-cycle phenomenon, with periodic mass emergence being observed every 13 or 17 years in the eastern United States. It is entirely unclear how their periodical life cycles are controlled. Here, I review previous knowledge and hypotheses about Magicicada life cycles and propose an integrated hypothesis of the life-cycle control mechanism, which includes critical body weight for adult metamorphosis, an internal 4-year clock, associated 4-year gate in 4 × n years of age for the timing of the metamorphosis decision, and genetic differences in growth rates between 13- and 17-year cicada nymphs (the former is faster). If the last (fifth) instar nymphs reach critical body weight in any of the 4-year gates (8, 12, 16, and 20 years of age, but not other years), they prepare for adult eclosion in the following year. The proposed hypothesis can explain the synchronized emergence of cicadas with varying growth trajectories in scheduled years (13 or 17 years of age) and the off-schedule emergence of some cicadas in 4 years earlier or later than the scheduled year, owing to their phenotypic plasticity that arises in response to large variations in the realized growth rate. The proposed hypothesis can also explain how evolutionary life-cycle shifts between 13- and 17-year cycles occur through phenotypic plasticity and selection on growth rate during climatic changes. It also facilitates understanding of the evolutionary mechanism of Maigicicada, which contains three species groups that are parallelly diverged into 13- and 17-year life cycles

Evaluation of Deep Learning-Based Monitoring of Frog Reproductive Phenology

カエルの鳴き声をAIで識別する --繁殖活動の高効率なモニタリング調査に向けて--. 京都大学プレスリリース. 2023-11-20.To evaluate the utility of a deep-learning approach for monitoring amphibian reproduction, we examined the classification accuracy of a trained model and tested correlations between calling intensity and frog abundance. Field recording and count surveys were conducted at two sites in Kyoto City, Japan. A convolutional neural network (CNN) model was trained to classify the calls of five anuran species. The model achieved 91–100% precision and 75–98% recall per species, with relatively lower performance on less abundant species. Computational experiments investigating the effects of the number and seasonality of the training samples showed that models trained on larger datasets from broader recording seasons performed better. Calling activity was high when males were abundant (Pearson's r = 0.45–0.66), although correlations between the calling activity and the number of pairs in amplexus were generally weaker. Our results suggest that deep learning is an effective tool for reconstructing the reproductive phenology of male anurans from field recordings. However, caution is required when applying to rare species and when inferring female reproductive activity

Evolutionary changes in gene expression profiles associated with the coevolution of male and female genital parts among closely related ground beetle species

[Background] The coevolutionary dynamics of corresponding male and female sexual traits, including genitalia, may be driven by complex genetic mechanisms. Carabus (Ohomopterus) ground beetles show correlated evolution in the size of their functionally corresponding male and female genital parts. To reveal the genetic mechanisms involved in the evolution of size, we investigated interspecific differences in gene expression profiles in four closely related species (two species each with long and short genital parts) using transcriptome data from genital tissues in the early and late pupal stages. [Results] We detected 1536 and 1306 differentially expressed genes (DEGs) among the species in males and 546 and 1959 DEGs in females in the two pupal stages, respectively. The DEGs were clustered by species-specific expression profiles for each stage and sex to identify candidate gene clusters for genital size based on the expression patterns among the species and gene ontology. We identified one and two gene clusters in females and males, respectively, all from the late pupal stage; one cluster of each sex showed similar expression profiles in species with similar genital size, which implies a common gene expression change associated with similar genital size in each sex. However, the remaining male cluster showed different expression profiles between species with long genital parts, which implies species-specific gene expression changes. These clusters did not show sex-concordant expression profiles for genital size differences. [Conclusion] Our study demonstrates that sex-independent and partly species-specific gene expression underlies the correlated evolution of male and female genital size. These results may reflect the complex evolutionary history of male and female genitalia

Evolutionary fine-tuning of background-matching camouflage among geographical populations in the sandy beach tiger beetle

カワラハンミョウの体色が生息地の砂色とよく一致することを解明 --場所ごとに異なる保護色の進化過程を明らかに--. 京都大学プレスリリース. 2020-12-17.Background-matching camouflage is a widespread adaptation in animals; however, few studies have thoroughly examined its evolutionary process and consequences. The tiger beetle Chaetodera laetescripta exhibits pronounced variation in elytral colour pattern among sandy habitats of different colour in the Japanese Archipelago. In this study, we performed digital image analysis with avian vision modelling to demonstrate that elytral luminance, which is attributed to proportions of elytral colour components, is fine-tuned to match local backgrounds. Field predation experiments with model beetles showed that better luminance matching resulted in a lower attack rate and corresponding lower mortality. Using restriction site-associated DNA (RAD) sequence data, we analysed the dispersal and evolution of colour pattern across geographical locations. We found that sand colour matching occurred irrespective of genetic and geographical distances between populations, suggesting that locally adapted colour patterns evolved after the colonization of these habitats. Given that beetle elytral colour patterns presumably have a quantitative genetic basis, our findings demonstrate that fine-tuning of background-matching camouflage to local habitat conditions can be attained through selection by visual predators, as predicted by the earliest proponent of natural selection

Whole-genome resequencing reveals recent divergence of geographic populations of the dung beetle Phelotrupes auratus with color variation

Knowledge of population divergence history is key to understanding organism diversification mechanisms. The geotrupid dung beetle Phelotrupes auratus, which inhabits montane forests and exhibits three color forms (red, green, and indigo), diverged into five local populations (west/red, south/green, south/indigo, south/red, and east/red) in the Kinki District of Honshu, Japan, based on the combined interpretation of genetic cluster and color-form data. Here, we estimated the demographic histories of these local populations using the newly assembled draft genome sequence of P. auratus and whole-genome resequencing data obtained from each local population. Using coalescent simulation analysis, we estimated P. auratus population divergences at ca. 3800, 2100, 600, and 200 years ago, with no substantial gene flow between diverged populations, implying the existence of persistent barriers to gene flow. Notably, the last two divergence events led to three local populations with different color forms. The initial divergence may have been affected by climatic cooling around that time, and the last three divergence events may have been associated with the increasing impact of human activities. Both climatic cooling and increasing human activity may have caused habitat fragmentation and a reduction in the numbers of large mammals supplying food (dung) for P. auratus, thereby promoting the decline, segregation, and divergence of local populations. Our research demonstrates that geographic population divergence in an insect with conspicuous differences in traits such as body color may have occurred rapidly under the influence of human activity

Role of Sex-Concordant Gene Expression in the Coevolution of Exaggerated Male and Female Genitalia in a Beetle Group

Some sexual traits, including genitalia, have undergone coevolutionary diversification toward exaggerated states in both sexes among closely related species, but the underlying genetic mechanisms that allow correlated character evolution between the sexes are poorly understood. Here, we studied interspecific differences in gene expression timing profiles involved in the correlated evolution of corresponding male and female genital parts in three species of ground beetle in Carabus (Ohomopterus). The male and female genital parts maintain morphological matching, whereas large interspecific variation in genital part size has occurred in the genital coevolution between the sexes toward exaggeration. We analyzed differences in gene expression involved in the interspecific differences in genital morphology using whole transcriptome data from genital tissues during genital morphogenesis. We found that the gene expression variance attributed to sex was negligible for the majority of differentially expressed genes, thus exhibiting sex-concordant expression, although large variances were attributed to stage and species differences. For each sex, we obtained co-expression gene networks and hub genes from differentially expressed genes between species that might be involved in interspecific differences in genital morphology. These gene networks were common to both sexes, and both sex-discordant and sex-concordant gene expression were likely involved in species-specific genital morphology. In particular, the gene expression related to exaggerated genital size showed no significant intersexual differences, implying that the genital sizes in both sexes are controlled by the same gene network with sex-concordant expression patterns, thereby facilitating the coevolution of exaggerated genitalia between the sexes while maintaining intersexual matching

Contrasting effects of habitat discontinuity on three closely related fungivorous beetle species with diverging host-use patterns and dispersal ability

Understanding how landscape structure influences biodiversity patterns and ecological processes are essential in ecological research and conservation practices. Forest discontinuity is a primary driver affecting the population persistence and genetic structure of forest‐dwelling species. However, the actual impacts on populations are highly species‐specific. In this study, we tested whether dispersal capability and host specialization are associated with susceptibility to forest discontinuity using three closely related, sympatric fungivorous ciid beetle species (two host specialists, Octotemnus assimilis and O. crassus; one host generalist, O. kawanabei). Landscape genetic analyses and the estimation of effective migration surfaces (EEMS) method consistently demonstrated contrasting differences in the relationships between genetic structure and configuration of forest land cover. Octotemnus assimilis, one of the specialists with a presumably higher dispersal capability due to lower wing loading, lacked a definite spatial genetic structure in our study landscape. The remaining two species showed clear spatial genetic structure, but the results of landscape genetic analyses differed between the two species: while landscape resistance appeared to describe the spatial genetic structure of the specialist O. crassus, genetic differentiation of the generalist O. kawanabei was explained by geographic distance alone. This finding is consistent with the prediction that nonforest areas act more strongly as barriers between specialist populations. Our results suggest that differences in host range can influence the species‐specific resistance to habitat discontinuity among closely related species inhabiting the same landscape

Colorful patterns indicate common ancestry in diverged tiger beetle taxa: Molecular phylogeny, biogeography, and evolution of elytral coloration of the genus Cicindela subgenus Sophiodela and its allies.

We investigated the phylogenetic relationships among tiger beetles of the subtribe Cicindelina (=Cicindela s. lat.; Coleoptera: Cicindelidae) mainly from the Oriental and Sino-Japanese zoogeographic regions using one mitochondrial and three nuclear gene sequences to examine the position of the subgenus Sophiodela, currently classified in the genus Cicindela s. str., their biogeography, and the evolution of their brilliant coloration. The subgenus Sophiodela was not related to the other subgenera of Cicindela s. str. but was closely related to the genus Cosmodela. In addition, the Oriental genus Calochroa was polyphyletic with three lineages, one of which was closely related to Sophiodela and Cosmodela. The clade comprising Sophiodela, Cosmodela and two Calochroa species, referred to here as the Sophiodela group, was strongly supported, and most species in this clade had similar brilliant coloration. The Sophiodela group was related to the genera Calomera, Cicindela (excluding Sophiodela) and Cicindelidia, and these were related to Lophyra, Hipparidium and Calochroa, except species in the Sophiodela group. Divergence time estimation suggested that these worldwide Cicindelina groups diverged in the early Oligocene, and the Sophiodela group, which is found in the Oriental and Sino-Japanese zoogeographic regions, in the mid Miocene. Some components of the elytral pattern related to maculation and coloration in the Cicindelina taxa studied contained weak, but significant, phylogenetic signals and were partly associated with habitat types. Therefore, the brilliant coloration of the Sophiodela was related to both phylogeny and habitat adaptation, although the function of coloration needs to be studied

Die Folgen des Libyen-Konflikts für Afrika: Gräben zwischen der AU und dem Westen, Destabilisierung der Sahelzone

Der Bürgerkrieg und die Nato-Intervention in Libyen haben Auswirkungen auf Afrika und die europäische Afrikapolitik, denen bislang zu wenig Aufmerksamkeit geschenkt wurde. Kurz- und mittelfristig droht eine weitere Destabilisierung der Sahelzone. Der im Januar 2012 neu ausgebrochene Konflikt im Norden Malis ist eine direkte Folge des libyschen Bürgerkriegs, ebenso wie die Rückkehr von Kämpfern aus Libyen und die Zunahme des Waffenschmuggels. Außerdem hat der Libyen-Konflikt neue Hindernisse für regionale Kooperation im Sahel aufgetürmt. Nicht minder gravierend sind die mittel- und langfristigen internationalen Folgen der Nato-Intervention. Sie hat Streit zwischen afrikanischen und westlichen Staaten verursacht, der die oft beschworene »Partnerschaft auf Augenhöhe« als deklaratorische Politik zu entblößen droht. Auch innerhalb der Afrikanischen Union hat der Umgang mit der Krise Spannungen hervorgerufen, die die Handlungsfähigkeit der Organisation nach innen wie außen beeinträchtigen werden. Aus diesen Gründen muss deutsche und europäische Afrikapolitik auf mehreren Ebenen reagieren. Europa muss seinen Ansatz für den Sahel modifizieren, denn bisher wollte die EU vor allem die Sicherheitskräfte in der Region stärken. Dies geht nicht nur an den eigentlichen Problemen vorbei, sondern könnte Auseinandersetzungen sogar befeuern und regionale Kooperation erschweren. Stattdessen sollte die EU weit mehr Gewicht auf die Förderung regionaler Anstrengungen legen sowie Libyen und Algerien entschlossener in ihre Sahel-Strategie einbeziehen. Für Europa wird eine funktionsfähige AU in Zukunft noch wichtiger werden. Deutschland und die EU sollten sich daher bemühen, die politischen Gräben zuzuschütten, die der Umgang mit dem Libyen-Konflikt aufgerissen hat. (Autorenreferat

(electronic) Mitochondrial DNA, Early Online: 1-2 !

Abstract This study reported the 15,435 bp-long complete mitochondrial genome of the relict Epiophlebia superstes (Odonata, Epiophlebiidae), an enigmatic dragonfly of the paraphyletic 'Anisozygoptera' possessing characteristics similar to members of both extant odonate suborders, the Zygoptera and the Anisoptera. This mitogenome comprises the common set of 37 genes and an A þ T-rich control region, and has a gene arrangement identical to those of all available odonates. The genome contains three non-coding inter-genic spacers (s1-s3), which occurs in all of other known odonates, but it lacks the inter-genic spacer s5 typically found in the Anisoptera. This result suggests that E. superstes possesses a mitogenmic organization more closely related to that of the Zygoptera than that of the Anizoptera