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BackgroundIndividual organisms may exhibit phenotypic plasticity when they acclimate to different conditions. Such plastic responses may facilitate or constrain the adaptation of their descendant populations to new environments, complicating their evolutionary trajectories beyond the genetic blueprint. Intriguingly, phenotypic plasticity itself can evolve in terms of its direction and magnitude during adaptation. However, we know little about what determines the evolution of phenotypic plasticity, including gene expression plasticity. Recent laboratory-based studies suggest dominance of reversing gene expression plasticity—plastic responses that move the levels of gene expression away from the new optima. Nevertheless, evidence from natural populations is still limited.ResultsHere, we studied gene expression plasticity and its evolution in the montane and lowland populations of an elevationally widespread songbird—the Rufous-capped Babbler (Cyanoderma ruficeps)—with reciprocal transplant experiments and transcriptomic analyses; we set common gardens at altitudes close to these populations’ native ranges. We confirmed the prevalence of reversing plasticity in genes associated with altitudinal adaptation. Interestingly, we found a positive relationship between magnitude and degree of evolution in gene expression plasticity, which was pertinent to not only adaptation-associated genes but also the whole transcriptomes from multiple tissues. Furthermore, we revealed that genes with weaker expressional interactions with other genes tended to exhibit stronger plasticity and higher degree of plasticity evolution, which explains the positive magnitude-evolution relationship.ConclusionsOur experimental evidence demonstrates that species may initiate their adaptation to new habitats with genes exhibiting strong expression plasticity. We also highlight the role of expression interdependence among genes in regulating the magnitude and evolution of expression plasticity. This study illuminates how the evolution of phenotypic plasticity in gene expression facilitates the adaptation of species to challenging environments in nature.

Characteristics of egg surfaces serve as recognition cues that allow avian hosts to detect and reject foreign eggs in brood parasitism. The blunt egg pole hypothesis suggests that the blunt egg pole is an essential signal in parasitic egg recognition. In the present study, eggs of Yellow-bellied Prinia (Prinia flaviventris) were painted with black spots at either the blunt or sharp egg pole to determine and compare the responses of different populations exposed to brood parasitism (parasitized population) or not (non-parasitized population). These results supported the above hypothesis and showed that the parasitized population displayed a higher rate of rejection of eggs with blunt pole-painted spots than with sharp pole-painted spots. In contrast, the non-parasitized population accepted all experimental eggs, which may be related to decreased egg recognition resulting from low exposure to brood parasitism.

Nest-dismantling behavior in birds is considered a fitness-maximizing adaptive behavior. Here, we compared nest-dismantling behavior and associated predation rates and nest characteristics in yellow-bellied prinia (Prinia flaviventris) on mainland China and the island of Taiwan during the breeding season from 2010 to 2014. Our results indicated that the proportion of individuals showing nest-dismantling behavior was higher on the island than on the mainland (29.3 vs. 0.8%). Nest-dismantling behavior was most frequent at the peak of the breeding season and mainly involved removing the upper halves of the nests and reusing the materials to construct new nests. The time taken to dismantle old nests and use the materials to build new ones was shorter than the time needed to build completely new nests. Nest predation, fidelity to the nest site, distance between old and new nests, and the costs of searching for nest materials could influence nest-dismantling behavior. Our results suggested that saving time and energy searching for new nest materials was the primary motivation behind nest-dismantling behavior in yellow-bellied prinia.

Tail autotomy incurs energetic costs, and thus, a trade-off in resource allocation may lead to compromised immunity in lizards. We tested the hypothesis that tailless lizards will favor constitutive innate immunity responses over an energetically costly inflammatory response. The influence of fasting and colorful ornamentation was also investigated. We experimentally induced tail autotomy in the lizard Eutropis multifasciata and found that inflammation was suppressed by tail loss, but not further affected by fasting; the suppressive effect of colorful ornamentation was manifested only in males, but not in females. Constitutive innate immunity was not affected by any of these factors. As expected, only costly inflammation was compromised, and a less expensive constitutive innate immunity might be favored as a competent first-line defense during energetically demanding periods. After considering conventional trade-offs among tail regeneration and reproduction, further extending these studies to incorporate disease risk and how this influences escape responses to predators and future reproduction would make worthwhile studies.

We reconstructed a molecular phylogeny for all four species of the wren-babbler genus Pnoepyga and added a comparative analysis of their territorial songs. The genus is divided into two species pairs which can also be distinguished by ecological and bioacoustic features. One species pair, Pnoepyga albiventer and P. formosana, occupies the higher forested mountain elevations of the Sino-Himalayas and Taiwan and shares broad-banded songs with a marked element-type variation. The second species pair, Pnoepyga pusilla and P. immaculata, occupies median and low mountain elevations of the Sino-Himalayas, continental Southeast Asia, and the Sunda region and has characteristic narrow-banded whistled songs. Intraspecific variation of molecular and bioacoustic markers in P. albiventer was conspicuous among individuals from Nepal and those from the Chinese provinces of Sichuan and Hubei. A third distinct genetic lineage of P. albiventer was found in Myanmar. We suggest that the Chinese form be ranked as a separate species Pnoepyga mutica Thayer & Bangs, 1912.

We developed six new microsatellite markers containing tetranucleotide repeat motifs (GATA/CTAT) for Lanyu scops owl (Otus elegans botelensis) from an enriched partial library. All these loci are polymorphic and conform to Hardy–Weinberg equilibrium. We cross-species tested these and 12 other microsatellite primer pairs previously developed from O. elegans on four other species of owls (O. lettia, O. spilocephalus, O. scops, and Ninox scutulata). Results showed that the degree of polymorphism decreased with increasing phylogenetic distance to O. elegans. Most loci (66.7, 83.3, and 100%) were polymorphic in the three Otus owls but only five (27.8%) were polymorphic in N. scutulata. These microsatellites should be very useful genetic markers in studying the mating system, population genetics, and conservation of other little studied Old World Otus owls.

We isolated and characterized nine polymorphic microsatellite loci from a partial genomic library enriched for tetranucleotide repeats in the hoopoe (Upupa epops). A panel of up to 34 adult individuals with unknown relationship was used to characterize polymorphism of these loci. The number of alleles per locus ranged from 5 to 11 and the observed heterozygosity of each locus ranged from 0.250 to 0.853. Only one locus deviated from Hardy–Weinberg equilibrium, with the excess of homozygote. By using five of the nine loci, we conducted paternity analysis on a population of hoopoe on Kinmen Island. The probability of false parent exclusion is 0.984 for the set of loci. In 20 clutches containing parents and juveniles, only one young was sired by extra-pair copulation. In addition to paternity analysis, these microsatellite markers should be useful in population studies for this widely distributed species.

Background Adaptive divergence driven by environmental heterogeneity has long been a fascinating topic in ecology and evolutionary biology. The study of the genetic basis of adaptive divergence has, however, been greatly hampered by a lack of genomic information. The recent development of transcriptome sequencing provides an unprecedented opportunity to generate large amounts of genomic data for detailed investigations of the genetics of adaptive divergence in non-model organisms. Herein, we used the Illumina sequencing platform to sequence the transcriptome of brain and liver tissues from a single individual of the Vinous-throated Parrotbill, Paradoxornis webbianus bulomachus, an ecologically important avian species in Taiwan with a wide elevational range of sea level to 3100 m. Results Our 10.1 Gbp of sequences were first assembled based on Zebra Finch (Taeniopygia guttata) and chicken (Gallus gallus) RNA references. The remaining reads were then de novo assembled. After filtering out contigs with low coverage (P. w. bulomachus genome. Of 7,779 contigs retained for a top-hit species distribution analysis, the majority (about 86%) were matched to known Zebra Finch and chicken transcripts. We also annotated 6,365 contigs to gene ontology (GO) terms: in total, 122 GO-slim terms were assigned, including biological process (41%), molecular function (32%), and cellular component (27%). Many potential genetic markers for future adaptive genomic studies were also identified: 8,589 single nucleotide polymorphisms, 1,344 simple sequence repeats and 109 candidate genes that might be involved in elevational or climate adaptation. Conclusions Our study shows that transcriptome data can serve as a rich genetic resource, even for a single run of short-read sequencing from a single individual of a non-model species. This is the first study providing transcriptomic information for species in the avian superfamily Sylvioidea, which comprises more than 1,000 species. Our data can be used to study adaptive divergence in heterogeneous environments and investigate other important ecological and evolutionary questions in parrotbills from different populations and even in other species in the Sylvioidea.