Biology subjects

Yang, M.-M.

Publications and source records attributed to Yang, M.-M..

7 recordsLinked to original sources

bioRxiv2025

The kin-selected context of duelling in horned aphids: cooperation or conflict?

In one-on-one (dyadic) contests in group-living animals, relatedness is of potentially critical importance in determining the relative value of the resources for which the individuals are fighting. We investigated the function of dyadic contests over access to a food resource (plant phloem) in the horned aphid Astegopteryx bambusae, by observing competing aphids in the field and genotyping them with microsatellite markers. Each aphid colony consists of a small number of clones, creating levels of relatedness that can be both high and variable. The contests involve only low costs in terms of time or injury. Our results indicate that there is no kin-discrimination in the duelling pairs of aphids. Genetic relatedness between duelling pairs did not differ significantly from that of randomly selected pairs and showed no association with contest duration or outcome. The mean relatedness between a duelling pair was 0.79 {+/-} 0.12 (mean {+/-} SD, N = 75), with 56% (42/75) of duels occurring between clonal pairs. We suggest that the duels in these Astegopteryx aphids are not an aggressive fight for resources between different genotypes, but rather a low-cost method by which the aphids assess each others reproductive value. 83% (50/60) of the contests between aphids of different ages were won by the aphid that was older, and therefore of greater reproductive value, providing an indirect fitness benefit for the losing younger individual. Younger nymphs, when attacked by older aphids, yield feeding sites altruistically and gain inclusive fitness benefits: this provides a compelling selective context for the evolution of the young, rather than old, altruistic soldiers that are observed in the open colonies of many cerataphidine species.

ecology↗

bioRxiv2022

Eusocial evolution without a nest: kin structure of social aphids forming open colonies on bamboo

Living in nests is an almost universal feature of eusocial animals. In some aphids, however, sterile soldier castes have evolved in open colonies without a nest. To clarify the factors promoting the evolution of eusociality in these colonies, we used newly developed microsatellite markers to compare the kin structure of the open colonies of two aphid species on bamboo: the non-eusocial colonies of Astegopteryx bambucifoliae and the eusocial colonies of Pseudoregma alexanderi on Dendrocalamus latiflorus. Our samples, from over 1,000 hectares, contained 99 clones of A. bambucifoliae and 19 of P. alexanderi. Clonal mixing occurred in both species: average pairwise relatedness within a colony was 0.54 in A. bambucifoliae and 0.71 in P. alexanderi. Each clone of A. bambucifoliae occurred in a unique location, whereas those of P. alexanderi occurred in multiple locations and more than 90% of individuals came from just four clones. There was significant genetic variation among different colonies in the same clump (stem-cluster) in A. bambucifoliae but not in P. alexanderi, indicating that P. alexanderi colonies in a single clump are genetically homogenized, functioning as a large colony. In P. alexanderi, the proportion of sterile soldiers to normal first-instar nymphs was significantly different across the four clones. Our results indicate that the lack of input of migrants from the primary host and feeding on a large, stable host plant are important ecological factors that might favour the evolution of eusociality, enabling the production of genetically homogenised, large, and long-lived colonies. After eusociality evolves on the secondary host, the optimal strategy of soldier production might vary between different clones. Significance StatementNest-living has often been considered to be a necessary condition for the evolution of eusociality. In a small number of aphid species, however, sterile soldier castes have evolved in open colonies without a nest. To understand why these aphids are unique, we examined the kin structure and genetic relatedness of individuals within eusocial and non-eusocial open colonies of two aphid species on bamboo. We found that clonal mixing occurred in both species, but the eusocial colonies are more genetically homogenized, functioning as a large colony. Our results suggest that ecological conditions that promote genetically homogenized, large and long-lived colonies are important for the evolution of eusociality in these aphids. We propose that the open colonies of social aphids provide an ideal model system in which to study the evolution of altruism.

evolutionary biology↗

bioRxiv2022

Seasonal polyphenism underlies the origin of a sterile caste in aphids

The origin of a sterile caste among eusocial animals has been a fundamental but still unresolved problem in understanding the evolution of biological complexity. At the origin of a sterile caste, recruitment of pre-existing plasticity may lead to produce physiologically, morphologically and behaviorally distinct caste phenotypes. Here, we provide convincing evidence that preexisting seasonal polyphenism has been recruited to generate a sterile soldier caste in host-alternating social aphids. We demonstrate that sterile soldier nymphs of Colophina aphids resemble those of monomorphic defensive nymphs produced in a different host-plant generation. Notably, the two morphs in the basal species show the closest similarity in morphology and gene expression among all morph pairs. Moreover, their evolutionary phenotypic changes along the phylogeny of four Colophina species are significantly correlated positively. These results suggest that they may share the common regulatory mechanisms of development, which underpin the heterochronic expression of monomorphic defenders on the different host plant leading to the evolution of a novel soldier phenotype. We further demonstrate that the monomorphic defenders can increase their inclusive fitness by killing predators eggs on a seasonally different host plant. Taken together, our findings suggest that preexisting plasticity that can gain indirect fitness benefits facilitates the early evolution of a sterile caste.

evolutionary biology↗

bioRxiv2021

Whole-genome sequencing of Chinese native goat offers biological insights into cashmere fiber formation

Cashmere evolved naturally in the goat, and almost all breeds of goat can produce more or less cashmere fibers. However, the genetic alterations underlying cashmere trait selection are still unclear.We sequenced 120 Chinese native goat including two cashmere goat breeds (Ujumain, Chaidamu) and six ordinary goat breeds (Jining Gray, Matou, Guizhou Black, Jintang Black, Yunnan Black Bone, Chengdu Brown). The genome-wide selective sweep of cashmere goat and ordinary goat revealed a novel set of candidate genes as well as pathways, such as Nuclear factor kappa-B and Wnt Signaling pathways. Of them, the LHX2 gene regulating hair follicle development, was evident from the strongest selection signal when comparing the Uhumqin cashmere goat and ordinary goat. Interestingly, we identified a 582bp deletion at 367 kb upstream of LHX2 with higher frequency in cashmere goats and their ancient relatives. This mutation probably rises along the breeding procedures, and is putatively responsible for cashmere production and diameter, as revealed by association studies. Luciferase assay shows that the deletion, which acts as an insulator, restrains the expression of LHX2 by interfering its upstream enhancers.Our study discovers a novel insulator of the LHX2 involved in regulating cashmere production and diameter, which would be beneficial to understanding hair follicle development and regeneration. Our findings also provide new insights into the genetic formation of cashmere, and facilitate subsequent molecular breeding for cashmere goat improvement.

genomics↗

bioRxiv2021

Extrachromosomal DNA is associated with chromothripsis events and diverse prognoses in gastric cardia adenocarcinoma

Extrachromosomal DNA plays an important role in oncogene amplification in tumour cells and poor outcomes across multiple cancers. However, the function of extrachromosomal DNA in gastric cardia adenocarcinoma (GCA) is very limited. Here, we investigated the availability and function of extrachromosomal DNA in GCA from a Chinese cohort of GCA using whole-genome sequencing (WGS), whole-exome sequencing (WES), and immunohistochemistry. For the first time, we identified the ecDNA amplicons present in most GCA patients, and found that some oncogenes are present as ecDNA amplicons in these patients. We found that oncogene ecDNA amplicons in the GCA cohort were associated with the chromothripsis process and may be induced by accumulated DNA damage due to local dietary habits in the geographic region. Strikingly, we observed diverse correlations between the presence of ecDNA oncogene amplicons and prognosis, where ERBB2 ecDNA amplicons correlated with good prognosis, EGFR ecDNA amplicons correlated with poor prognosis, and CCNE1 ecDNA amplicons did not correlate with prognosis. Large-scale ERBB2 immunohistochemistry results from 1668 GCA patients revealed that there was a positive correlation between the presence of ERBB2 and prognosis in 2-7-year survival; however, there was a negative correlation between the presence of ERBB2 and prognosis in 0-2-year survival. Our observations indicate that the presence of ERBB2 ecDNA in GCA patients may represent a good prognosis marker.

genomics↗

bioRxiv2021

Defensive nymphs in the water-repellent gall of the social aphid Colophina monstrifica (Hemiptera: Aphididae: Eriosomatinae)

The aphid Colophina monstrifica forms woolly colonies with sterile soldiers on the secondary host Clematis uncinata in Taiwan. However, the gall or primary-host generation of C. monstrifica has not been found to date. We successfully induced galls of the species on trees of Zelkova serrata through attaching its eggs onto the trees, and also found a few naturally formed galls on another Z. serrata tree. The identity of the aphids was confirmed by examining their morphology and mitochondrial DNA sequences. First- and second-instar nymphs in the galls exhibited attacking behavior toward artificially introduced moth larvae. Observations with a scanning electron microscope revealed that the gall inner surface was densely covered with minute trichomes. This indicates the water repellency of the inner surface, and strongly suggests that young nymphs of C. monstrifica dispose of honeydew globules outside the gall, as known in the congener C. clematis.

zoology↗

bioRxiv2019

Vibrational behavior of psyllids (Hemiptera: Psylloidea): functional morphology and mechanisms

Vibrational behavior of psyllids was first documented more than six decades ago. Over the years, workers have postulated as to what the exact signal-producing mechanisms of psyllids might be but the exact mechanism has remained elusive. The aim of this study is to determine the specific signal-producing structures and mechanisms of the psyllids. Here we examine six hypotheses of signal-producing mechanisms from both previous and current studies that include: wing vibration, wing-wing friction, wing-thorax friction, wing-leg friction, leg-abdomen friction, and axillary sclerite-thorax friction. Through selective removal of possible signal producing structures and observing wing-beat frequency with a high-speed video recorder, six hypotheses were tested. Extensive experiments were implemented on the species Macrohomotoma gladiata Kuwayama, while other species belonging to different families, i.e., Trioza sozanica (Boselli), Mesohomotoma camphorae Kuwayama, Cacopsylla oluanpiensis (Yang), and Cacopsylla tobirae (Miyatake) were also examined to determine the potential prevalence of each signal-producing mechanism within the Psylloidea. Further, scanning electron microscopy (SEM) was used to examine possible rubbing structures. The result of high speed photography showed that wing-beating frequency did not match the dominant frequency of vibrational signals, resulting in the rejection of wing vibration hypothesis. As for the selective removal experiments, the axillary sclerite-thorax friction hypothesis is accepted and wing-thorax friction hypothesis is supported partially, while others are rejected. The SEM showed that the secondary axillary sclerite of forewing bears many protuberances that would be suitable for stridulation. In conclusion, the signal-producing mechanism of psyllids involves two sets of morphological structures. The first is stridulation between the axillary cord and anal area of the forewing. The second is stridulation between the axillary sclerite of the forewing and the mesothorax.

animal behavior and cognition↗