No abstract

Rice blast is the most devastating plant disease in Japan. Our goal is to create new rice varieties which show enhanced resistance against blast, regardless of the race of blast. By an Agrobacterium-mediated transformation method, we reintroduced a rice class-I chitinase gene, Cht-2 or Cht-3, under the control of the enhanced CaMV 35S promoter and a hygromycin phosphotransferase gene, as a selection marker into the Japonica rice varieties Nipponbare and Koshihikari, which have retained the best popularity over a long period in Japan. In regenerated plants (R(0)), the Cht-2 product was found to accumulate intracellularly whereas the Cht-3 product was found to be targeted extracellularly. The transgenic rice plants which constitutively expressed either chitinase gene showed significantly higher resistance against the rice blast pathogen Magnaporthe grisea races 007.0 and 333. Both high-level expression of the chitinase and blast-resistance were stably inherited by the next generation in several lines.

According to classical sexual selection theory, complex multimodal courtship displays have evolved in males through female choice. While it is well-known that socially monogamous songbird males sing to attract females, we report here the first example of a multimodal dance display that is not a uniquely male trait in these birds. In the blue-capped cordon-bleu (Uraeginthus cyanocephalus), a socially monogamous songbird, both sexes perform courtship displays that are characterised by singing and simultaneous visual displays. By recording these displays with a high-speed video camera, we discovered that in addition to bobbing, their visual courtship display includes quite rapid step-dancing, which is assumed to produce vibrations and/or presumably non-vocal sounds. Dance performances did not differ between sexes but varied among individuals. Both male and female cordon-bleus intensified their dance performances when their mate was on the same perch. The multimodal (acoustic, visual, tactile) and multicomponent (vocal and non-vocal sounds) courtship display observed was a combination of several motor behaviours (singing, bobbing, stepping). The fact that both sexes of this socially monogamous songbird perform such a complex courtship display is a novel finding and suggests that the evolution of multimodal courtship display as an intersexual communication should be considered.

Estrildid finches are known for great interspecific diversity in the degree of elaboration in courtship dance, song and plumage coloration and also for the considerable sex differences in these traits within species. To study the evolution of multimodal sexual signaling in these taxa, we collected data on 85 species and analyzed them in a phylogenetic comparative study. As dances are often displayed in parallel with songs and include behavioral elements to emphasize coloration, they are likely to evolve non-independently of songs and plumage characteristics. Hence, we hypothesized that the degree of elaboration in dance would be associated with song and plumage ornamentation due to correlated responses between traits. Alternatively, each sexual signal may evolve independently of the others under the influence of different aspects of reproductive ecology or life history. Finally, because trait expression occurs in both males and females and can be caused by pleiotropic effects, we predicted correlated exaggerations of the traits between sexes as well. We found that courtship dance, song and plumage coloration evolve independently, as these traits were not correlated among species in either sex (i.e., the presence of female song was not related to female dance repertoire). However, we found evidence for correlated responses between the sexes, as species that have males with complex dances or colorful plumage also have females with exaggerated traits. Yet, selection factors acting on these traits were only partially shared between sexes. While coloration can be predicted by intraspecific brood parasitism and dance by body size in females, we were unable to reveal similar relationships in males. Our results indicate that different secondary sexual characters in Estrildid finches evolved under the influence of complicated selection factors, in which both correlated responses between sexes as well as independent selective mechanisms play roles.

Birdsong is an acoustic ornament. According to indicator models, a trait must be costly to act as an honest signal, but the potential costs of elaborate songs are still poorly understood. The developmental stress hypothesis suggests that learned song characteristics could be an honest indicator of early developmental conditions because the brain structures associated with learning songs are susceptible to early developmental stress, which could thus affect song development. Unlike previous studies of developmental stress that examined the effect of a stress hormone or restricted nutrition, we observed Bengalese finches under semi‐natural breeding conditions in captivity to investigate the relationship between early rearing conditions (e.g., brood size and sex ratio) and the subsequent variation in body size and song among individuals. Our results suggest that the early rearing environment directly affects body size and song complexity, whereas song output is determined mainly by body size. These results support the developmental stress hypothesis. Moreover, our findings are the first to show that developmental condition affects not only the number of note types but also the syntactical complexity of the song.

Chromosome banding patterns obtained by ammoniacal silver staining (Ag-AS) and alkaline Giemsa (CBG) have been analysed in several amphibian species of the genus Odontophrynus from South America. Ag-AS bands were found at secondary constrictions, mainly of chromosomes 4 and 11. The CBG technique revealed centromeric and telomeric constitutive heterochromatin on almost all chromosomes of these species. Moreover, intercalary bands were found at particular sites of several chromosomes. Some inter- and intra-population polymorphisms were found for the Ag-AS and C-banding patterns. The species variability in the number and position of the Ag-AS bands, known to be regions of active ribosomal cistrons, as well as the specific sites of intercalary heterochromatin, are used to discuss the possible evolutionary relationships among these species.

Social learning of vocalizations is integral to song inheritance in oscine passerines. However, other factors, such as genetic inheritance and the developmental environment, can also influence song phenotype. The relative contributions of these factors can have a strong influence on song evolution and may affect important evolutionary processes such as speciation. However, relative contributions are well-described only for a few species and are likely to vary with taxonomy. Using archived song data, we examined patterns of song inheritance in a domestic population of Java sparrows (Lonchura oryzivora), some of which had been cross-fostered. Six-hundred and seventy-six songs from 73 birds were segmented and classified into notes and note subtypes (N = 22,972), for which a range of acoustic features were measured. Overall, we found strong evidence for cultural inheritance of song structure and of the acoustic characteristics of notes; sons’ song syntax and note composition were similar to that of their social fathers and were not influenced by genetic relatedness. For vocal consistency of note subtypes, a measure of vocal performance, there was no apparent evidence of social or genetic inheritance, but both age and developmental environment influenced consistency. These findings suggest that high learning fidelity of song material, i.e., song structure and note characteristics, could allow novel variants to be preserved and accumulate over generations, with implications for evolution and conservation. However, differences in vocal performance do not show strong links to cultural inheritance, instead potentially serving as condition dependent signals.

Sexual traits (e.g. visual ornaments, acoustic signals, courtship behaviour) are often displayed together as multimodal signals. Some hypotheses predict joint evolution of different sexual signals (e.g. to increase the efficiency of communication) or that different signals trade off with each other (e.g. due to limited resources). Alternatively, multiple signals may evolve independently for different functions, or to communicate different information (multiple message hypothesis). We evaluated these hypotheses with a comparative study in the family Estrildidae, one of the largest songbird radiations, and one that includes many model species for research in sexual selection and communication. We found little evidence for either joint evolution or trade-offs between song and colour ornamentation. Some negative correlations between dance repertoire and song traits may suggest a functional compromise, but generally courtship dance also evolved independently from other signals. Instead of correlated evolution, we found that song, dance and colour are each related to different socio-ecological traits. Song complexity evolved together with ecological generalism, song performance with investment in reproduction, dance with commonness and habitat type, whereas colour ornamentation was shown previously to correlate mostly with gregariousness. We conclude that multimodal signals evolve in response to various socio-ecological traits, suggesting the accumulation of distinct signalling functions.