المؤلفون: Miura, Toru¹ (AUTHOR) miu@mmbs.s.u-tokyo.ac.jp, Maekawa, Kiyoto² (AUTHOR)

المصدر: Evolution & Development. Nov2020, Vol. 22 Issue 6, p425-437. 13p.

مصطلحات موضوعية: *TERMITES, *CASTE, *MILITARY personnel, *DEFENSIVENESS (Psychology), *SOCIAL evolution

مستخلص: Termites (Blattodea, Termitoidea, or Isoptera) constitute one of the major lineages of eusocial insects. In termite societies, multiple types of functional individuals, that is, castes, perform divisions of labors to coordinate social behaviors. Among other castes, the soldier caste is distinctive since it is sterile and exclusively specialized into defensive behavior with largely modified morphological features. Therefore, many of the previous studies have been focused on soldiers, in terms of ecology, behavior, and evolution as well as developmental and physiological mechanisms. This article overviews the accumulation of studies especially focusing on the developmental and physiological mechanisms underlying the soldier differentiation in termites. Furthermore, the evolutionary trajectories that have led the acquisition of soldier caste and have diversified the soldier characteristics in association with the social evolution are discussed. [ABSTRACT FROM AUTHOR]

المؤلفون: Hellemans, Simon¹ simon.hellemans@ulb.ac.be, Fournier, Denis¹, Hanus, Robert², Roisin, Yves¹

المصدر: Evolution & Development. Nov/Dec2017, Vol. 19 Issue 6, p253-262. 10p.

مصطلحات موضوعية: *TERMITES, *MORPHOMETRICS, *GENETICS, *NYMPHALIS, *QUEENS (Insects)

مستخلص: In termite species with asexual queen succession (AQS), parthenogenetically produced immatures mostly differentiate into secondary queens, called 'neotenics.' In order to elucidate the ontogenetic origin of neotenics in Cavitermes tuberosus (Termitidae: Termitinae), a neotropical termite with AQS, we investigated developmental pathways of offspring according to their sex and genetic origin using both morphometric and genetic tools. The caste system of C. tuberosus follows the classical pathway of Termitidae. After the first larval instar, there is a bifurcation between two developmental lines. The apterous line is composed of a second larval instar, several worker instars, presoldiers, and soldiers. Workers display a consistent male bias and soldiers are female-only. The nymphal line is composed of five nymphal instars and the imago stage. We highlight that neotenic queens derive from third and fourth instar nymphs displaying peculiar morphological traits, here termed 'aspirants,' most of which are produced by parthenogenesis. Aspirants are present in all nests and perform worker tasks while waiting for the queen's death to differentiate into neotenic queens. Aspirants can successfully be used to demonstrate the occurrence of parthenogenesis in termite species whose reproductive cores are difficult to access. [ABSTRACT FROM AUTHOR]

المؤلفون: Kaji, Tomonari¹, Keiler, Jonas², Bourguignon, Thomas³, Miura, Toru⁴

المصدر: Evolution & Development. Mar/Apr2016, Vol. 18 Issue 2, p78-88. 11p.

مصطلحات موضوعية: *TERMITES, *EVOLUTION research, *ANIMAL defenses, *ANIMAL morphology, *NASUTITERMES

مستخلص: SUMMARY The origins of evolutionary novelties are often deeply puzzling. They are generally associated with new functions that were absent in ancestors. The new functional configuration should arise via intermediate stages without any loss of function or impediment to the whole organism during the transitions. Therefore, understanding of the functional configurations of transitional states can shed light on how novel forms arise. Here we infer the evolutionary origin of a highly specialized termite defensive organ 'nasus' where different functions overlap in different structural configurations at intermediate evolutionary stages to ensure that each phase is functional. Soldiers of a nasutitermitine termite use reconfigured mandibular muscles to squirt a viscous secretion from a nozzle-like head projection (the nasus). This contrasts sharply with the primitive defensive strategy where mandibles are used to bite. MicroCT observations of soldiers of Nasutitermes takasagoensis and of species with the ancestral state ( Hodotermopsis sjostedti, Embiratermes neotenicus) revealed three different yet fully functional configurations in the transition from ancestral to novel state: (i) elevated hydrostatic pressure induced by contraction of mandibular muscles when biting gently oozes secretion from a gland; (ii) direct pressure on an enlarged gland arises from expansion of the mandibular muscles when biting; (iii) squirting in a piston-like manner by an inflated gland enveloped by highly modified mandibular muscles. Even a structure as exotic as the nasus therefore appears to have evolved with no loss of function at any stage. Such a functional approach, holds much promise for understanding the evolutionary origin of seemingly preposterous novel forms. [ABSTRACT FROM AUTHOR]

المؤلفون: Leniaud, Laurianne^1,2, Darrouzet, Eric¹, Dedeine, Franck¹, Ahn, Kiheung³, Huang, Zachary³, Bagnères, Anne-Geneviève¹ bagneres@univ-tours.fr

المصدر: Evolution & Development. Mar/Apr2011, Vol. 13 Issue 2, p138-148. 11p. 1 Diagram, 1 Chart, 4 Graphs.

مصطلحات موضوعية: *ONTOGENY, *TERMITES, *RETICULITERMES flavipes, *JUVENILE hormones

مصطلحات جغرافية: FRANCE

مستخلص: In termites, the capacity of workers to differentiate into neotenic reproductives is an important characteristic that deserves particular attention. To gain insight into the differentiation pathway, the potentialities of workers and the endocrinal changes during the formation of neotenics were compared in two sympatric termites, Reticulitermes flavipes and Reticulitermes grassei. After 1 year of development, 100% of R. flavipes worker groups produced neotenics against only 63% of R. grassei groups. The average production of female neotenics was significantly higher in R. flavipes worker groups compared with R. grassei groups and R. flavipes produced a greater proportion of female neotenics. Moreover, R. flavipes produced more offspring, not only because there were more females, but also because R. flavipes females were more productive. Moreover, the offspring produced by R. flavipes grew faster than the offspring of R. grassei. Both ecdysteroid and juvenile hormone (JH) titers varied significantly during the development of neotenics. The two species showed similar ecdysteroid titer variation patterns. However, the JH titer variation patterns strongly differed: in R. grassei, the concentration of JH increased in maturing neotenics then dropped in mature neotenics, whereas in R. flavipes, the level of JH was significantly higher than in R. grassei and remained constantly high in mature neotenics. Overall, these results suggest that these two species differ strongly in many life-history traits as well as in the physiological control of their caste differentiation system. Possible origins and mechanisms of such interspecific variations are discussed, as well as their evolutionary and ecological consequences. [ABSTRACT FROM AUTHOR]

المؤلفون: Korb, Judith¹ judith.korb@biologie.uni-osnabrueck.de, Hoffmann, Katharina¹, Hartfelder, Klaus²

المصدر: Evolution & Development. May/Jun2009, Vol. 11 Issue 3, p269-277. 9p. 1 Diagram, 1 Chart, 5 Graphs.

مصطلحات موضوعية: *TERMITES, *MATERIAL plasticity, *EMBRYOLOGY, *CRYPTOTERMES, *KALOTERMITIDAE, *JUVENILE hormones

مستخلص: Wood-dwelling termites are characterized by an extremely high and unique developmental flexibility that allows workers, which are immatures, to explore all caste options. The endocrine signatures underlying this flexibility are only vaguely understood. We determined juvenile hormone (JH) and ecdysteroid hemolymph titers during postembryonic development and in terminal instars of the drywood termite Cryptotermes secundus using field and laboratory colonies. Postembryonic development is characterized by a drop in JH titers at the transition from larval (individuals without wing buds) to nymphal (individuals with wing buds) instars. JH titers were low in winged sexuals and reproducing primary reproductives (<200 pg/μl) but were by an order of magnitude higher in neotenic replacement reproductives. The unique regressive molts of termites seem to be characterized by elevated JH titers, compared with progressive or stationary molts. Ecdysteroid titers were generally low in nymphal instars and in primary reproductives (<50 pg/μl). It was only during the third and fourth nymphal instars and in winged sexuals where some individuals showed elevated ecdysteroid titers. These results are the most comprehensive endocrinological data set available for any lower termite, with the potential to serve as baseline for understanding the extreme developmental flexibility underlying the evolution of social life in termites. [ABSTRACT FROM AUTHOR]

المؤلفون: Roux, Estelle A.¹, Roux, Maurice², Korb, Judith¹ judith.korb@biologie.uni-osnabrueck.de

المصدر: Evolution & Development. Jan/Feb2009, Vol. 11 Issue 1, p80-87. 8p. 1 Diagram, 4 Charts, 3 Graphs.

مصطلحات موضوعية: *GONADS, *TERMITES, *ALLOMETRY, *COLONIES, *BIOLOGICAL evolution

مستخلص: During development and evolution individuals generally face a trade-off between the development of weapons and gonads. In termites, characterized by reproductive division of labor, a caste evolved—the soldiers—which is completely sterile and which might be released from developmental trade-offs between weapons and testes. These soldiers are exclusively dedicated to defense. First, we investigated whether defensive traits are under selection in sterile termite soldiers using allometric analyses. In soldiers of the genus Cryptotermes phragmotic traits such as a sculptured and foreshortened head evolve rapidly but were also lost twice. Second, we compared the scaling relationships of these weapons with those in solitary insects facing a trade-off between weapons and gonads. Defensive traits consistently had lower slopes than nondefensive traits which supports the existence of stabilizing selection on soldier phragmotic traits in order to plug galleries. Moreover, soldier head widths were colony specific and correlated with the minimum gallery diameter of a colony. This can proximately be explained by soldiers developing from different instars. The scaling relationships of these termite soldiers contrast strikingly with those of weapons of solitary insects, which are generally exaggerated (i.e., overscaling) male traits. These differences may provide important insights into trait evolution. Trade-offs constraining the development of individuals may have been uncoupled in termites by evolving different castes, each specialized for one function. When individuals in social insect are “released” from developmental constraints through the evolution of castes, this certainly contributed to the ecological and evolutionary success of social insects. [ABSTRACT FROM AUTHOR]

المؤلفون: Wu, Tian, Dhami, Gurpreet K., Thompson, Graham J.

المصدر: Evolution & Development; Jan2018, Vol. 20 Issue 1, p3-16, 14p

مصطلحات موضوعية: GENE expression, INSECT genetics, SUBTERRANEAN termites, NYMPHS (Insects), RETICULITERMES flavipes, GENE ontology, RNA sequencing

مستخلص: In a termite colony, reproduction is typically monopolized by a small number of sexuals that are supported by reproductively altruistic soldiers and workers. We expect caste differentiation to be associated with clear‐cut differences in gene expression, and for these differences to reflect caste function and development. Here, we use RNA‐Sequencing to compare the gene expression profiles of sexual nymphs and two non‐reproductive helper castes (i.e., workers and soldiers) of the Eastern subterranean termite Reticulitermes flavipes. We found that of n = 93 genes that are strictly expressed as a function of caste, a majority (78%) show a soldier‐specific pattern. This conspicuous soldier‐bias in genome‐wide expression suggests that this defensively specialized caste is functionally well‐differentiated from both the reproductive and the other non‐reproductive caste of this species, despite a shared developmental program with workers. Gene ontology analysis supports the notion of functional specialization by soldiers, as soldier‐biased gene sets are enriched for novel biological processes. Whether this pattern reflects ancient or more recent bouts of selection for caste novelty at the gene‐regulatory level is not known, but because soldiers are sterile and thus have no direct fitness, any selection for novelty must have been mediated indirectly, through reproducing relatives. [ABSTRACT FROM AUTHOR]

: Copyright of Evolution & Development is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Legendre, Frédéric, Whiting, Michael F., Grandcolas, Philippe

المصدر: Evolution & Development; Mar/Apr2013, Vol. 15 Issue 2, p146-157, 12p, 1 Color Photograph, 3 Diagrams, 3 Charts

مصطلحات موضوعية: WORKER insects, PHYLOGENY, TERMITES, INSECT societies, EMBRYOLOGY, DIPLOIDY

مستخلص: SUMMARY Termites are highly eusocial insects with a caste polyphenism (i.e., discontinuous morphological differences between castes) and elaborated behaviors. While the developmental pathways leading to caste occurrence are well-known in many species, the evolutionary origin of these pathways is still obscure. Recent molecular phylogenetic studies suggest multiple independent origins of sterile castes in termites, reviving a 30 years old debate. We demonstrate here that diploid sterile castes ('true' workers) evolved several times independently in this group and that this caste was lost at least once in a lineage with developmentally more flexible workers called pseudergates or 'false' workers. We also infer that flexibility in post-embryonic development was acquired multiple times independently during termite evolution. We suggest that focusing on detailed developmental pathways in phylogenetic analyses is essential for elucidating the origin of caste polyphenism in termites. [ABSTRACT FROM AUTHOR]

: Copyright of Evolution & Development is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Nalepa, Christine A.

المصدر: Evolution & Development; Jan/Feb2010, Vol. 12 Issue 1, p95-105, 11p, 2 Diagrams

مصطلحات موضوعية: PHENOTYPIC plasticity, HYMENOPTERA, TERMITES, EMBRYOLOGY, PHYLOGENY, CRYPTOCERCUS, COCKROACHES, VERTEBRATES

مستخلص: Basal termites possess two developmental features that eusocial Hymenoptera lack: the majority of colony members are juveniles whose somatic and reproductive development is temporarily or permanently suspended, and individual development is characterized by extreme phenotypic plasticity. An examination of the literature indicates that the basis for these unique ontogenetic characters is not the prolongation of a pronymphal stage into postembryonic development, as recently suggested. Like other hemimetabolous insects, termites have three embryonic cuticles, and the pronymphal (EC3) cuticle is shed during or shortly after hatch. Nonetheless, a different developmental landmark, dorsal closure, occurs later during embryogenesis in termites than it does in their cockroach relatives, clearly indicating ontogenetic repatterning from an ancestral state. An alternate hypothesis for the origin of isopteran phenotypic plasticity becomes apparent if we remain focused on the phylogenetic and social context of termite evolution. Altricial development occurs in both vertebrate and invertebrate taxa, evolves in response to the parental environment, and is displayed by two distantly related, biparental, wood-feeding cockroaches, including Cryptocercus, the sister-group to termites. It is therefore likely the condition was present in subsocial termite ancestors, and played a complex, multidimensional role in the transition to eusociality. Most relevant to current arguments is that a shift in responsibility for the care of altricial dependents, from parents to the first nutritionally independent nymphs in the family (alloparents), resulted in the developmental stasis of alloparents at a relatively young age. Because early instar cockroaches are not metamorphically competent, these young alloparents would have provided a novel developmental template on which selection could act. [ABSTRACT FROM AUTHOR]

: Copyright of Evolution & Development is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Bourguignon, Thomas, Šobotník, Jan, Hanus, Robert, Roisin, Yves

المصدر: Evolution & Development; Nov/Dec2009, Vol. 11 Issue 6, p659-668, 10p, 2 Color Photographs, 2 Black and White Photographs, 1 Diagram, 2 Charts, 4 Graphs

مصطلحات موضوعية: SERRITERMITIDAE, BIOLOGICAL evolution, INSECT societies, WINGS (Anatomy), RHINOTERMITIDAE, INSECT sex ratio, TERMITES

مستخلص: The onset of a specialized (“true”) worker caste is a crucial step in the evolution of termite societies. Such workers, permanently excluded from wing development, repeatedly evolved from totipotent immatures, called “false” workers or pseudergates. In the family Rhinotermitidae, the presence of true workers and the level of specialization of this caste are highly variable, and key taxa illustrate transitional situations providing clues about worker evolution. Here we focused on the status of working immatures of Glossotermes oculatus, from the family Serritermitidae, now thought to represent either the sister-group of the Rhinotermitidae or a basal lineage nested within them. Contrary to previous assumptions, we show that the apterous immatures performing worker tasks in G. oculatus are the source of the single wing-budded nymphal instar preceding the alate. Consequently, they qualify as pseudergates rather than true workers. However, the sex ratio is strongly male biased in pseudergates and soldiers, which is a trait usually restricted to termites with true workers. We therefore argue that pseudergates of G. oculatus are close to a point where the species could easily shift toward the differentiation of a true worker caste, and that G. oculatus pinpoints a new possible route for the evolution of true workers from pseudergates. [ABSTRACT FROM AUTHOR]

: Copyright of Evolution & Development is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)