Mitochondrial DNA control region sequencing of the critically endangered Hainan gibbon (Nomascus hainanus) reveals two female origins and extremely low genetic diversity

The Complete Mitochondrial Genome of Red Costate Tiger Moth (Aloa lactinea [Cramer, 1777]), and Phylogenetic Analyses of the Subfamily Arctiinae

BACKGROUND/OBJECTIVES

Aloa lactinea, class Insecta, order Lepidoptera, superfamily Noctuoidea, family Erebidae, and subfamily Arctiinae, is a polytrophic agricultural pest. However, there are still many sequences missing for Arctiinae from mitochondrial whole-genome sequences.

METHODS

In this study, we determined and analyzed the complete mitochondrial genome sequence of A. lactinea. Furthermore, based on the sequencing results, we used the Bayesian inference, maximum likelihood, and maximum reduction methods to analyze the phylogenies of 18 species of the Hypophora subfamily.

RESULTS

The mitochondrial genome was found to be a circular double-stranded DNA with a length of 15,380 bp and included 13 protein-coding genes (PCGS), 22 tRNA genes, 2 rRNA genes, and one control region. With the exception of tRNASer(AGC), all the tRNA genes could form conventional clover structures. There were 23 intergenic spacer regions with lengths of 1-52 bp and six gene overlaps with lengths of 1-8 bp. The control region was located between rrnS and tRNAMet genes and comprised 303 bp and an AT content of 74.25%.

CONCLUSIONS

The results showed that A. lactinea is closely related to Hyphantria cunea. Our results suggest that Syntomini is phylogenetically distinct from Arctiini and may warrant separate tribal status within Arctiinae. This study is dedicated to researching the mitochondrial genome and phylogenetic relationships of A. lactinea, providing a molecular basis for its classification.

Science-based suggestions to save the world's rarest primate species Nomascus hainanus

Conservation practices for extremely small populations must be grounded in solid science to prevent extinction. Hainan gibbon (Nomascus hainanus) is the world's rarest primate species; however, insufficient data on its habitat suitability and genetic status impede evidence-based decisions for habitat restoration. Here, we conducted a comprehensive analysis of Hainan gibbons' energy intake and expenditure, reproductive parameters, and genetic diversity based on field research (March 2021 to December 2022) and long-term historical data (2003 to 2024). By comparing our results with those of captive gibbons and other free-feeding captive primates, we found that Hainan gibbons can obtain sufficient energy for growth and reproduction in their existing habitats. Furthermore, we identified an additional D-loop haplotype indicating that the current population is more genetically diverse than previously thought. However, recently formed adult male-female pairs are increasingly related, signaling a high risk for inbreeding within this small population. Based on these findings, we highlight an urgent need to expand available habitat by building corridors.

Diverse grouping and mating strategies in the Critically Endangered Hainan gibbon (Nomascus hainanus)

Understanding flexibility in the social structure and mating strategies of the world's last remaining population (35 individuals) of wild Hainan gibbons (Nomascus hainanus) is critical for developing effective management plans to aid in their population recovery. Three of the five remaining Hainan gibbon groups (A, B, and C) currently live in a social unit characterized by two or three adult males, two reproducing adult females, and offspring. A fourth group (D) contains one adult male, two adult females, and offspring, and Group E contains a single adult male-adult female pair with a young infant. In this study, we describe observations of copulations between multiple resident males and one of the two resident females in Group C. Group C is best described as a small multi-male/multi-female group. We found that this breeding female (F2) solicited copulations from two resident adult males (M1 and M2) on the same day, and also mated with each of these two males on different days. Resident males were not observed to interrupt the mating pair. Although factors such as a biased adult sex ratio, severe population disruption, and habitat degradation can help explain variation in group composition and mating strategies in Hainan gibbons, we argue that there exists considerable mating system variability across gibbon species, and that this variability offers important insights into male and female Hainan gibbon group structure and reproductive strategies.

Recovery of Logged Tropical Montane Rainforests as Potential Habitats for Hainan Gibbon

As the world’s rarest ape, the main threat facing Hainan gibbon (Nomascus hainanus) is habitat degradation and loss caused by human disturbances. The insufficient area and continuous human disturbance in most of the existing habitats can hardly maintain the future recovery and development of the gibbon population. A large area of secondary tropical montane rainforest in recovery was retained in Bawangling National Nature Reserve after disturbance. Therefore, it is of great significance to study the recovery of these secondary forests for the protection and restoration of Hainan gibbon habitat. To explore the recovery of secondary tropical rainforests after different disturbances, and whether they have the potential to serve as the future habitats for Hainan gibbon, we calculated four dynamic indexes (including recruitment rate, mortality/loss rate, relative growth rate and turnover rate) of abundance and basal area for the total community and for food plants of Hainan gibbon based on data from two censuses of secondary forests recovered nearly 45 years after different disturbances (clear-cutting and selective-logging) and old-growth forest of tropical montane rainforest. The results are as follows: (1) There were no significant differences in recruitment rates, mortality rates and turnover rates of abundance and basal area between recovered clear-cutting forests, selectively logged forests and old-growth forests. (2) Abundance, basal area and species of small (1 < DBH ≤ 10 cm) and medium (10 ≤ DBH < 30 cm) food plants in the two disturbed forests were higher, while those of large food plants (DBH ≥ 30 cm) in the two forests were lower than in old-growth forests. (3) For the common food species occurring in all three kinds of communities, the relative growth rate of most small trees in clear-cutting forest was higher than that of old-growth forest. Our research demonstrates that the lack of large food plants is the key limiting factor for the development of the secondary mountain rainforest as habitats for Hainan gibbon at present. However, it has great potential to transform into suitable habitats through targeted restoration and management due to the high recruitment rate and relative growth rate of the small- and medium-sized food plants.