Junhu Su

Climate Change-Induced Range Expansion of a Subterranean Rodent: Implications for Rangeland Management in Qinghai-Tibetan Plateau.

Disturbances, both human-induced and natural, may re-shape ecosystems by influencing their composition, structure, and functional processes. Plateau zokor (Eospalax baileyi) is a typical subterranean rodent endemic to Qinghai-Tibetan Plateau (QTP), which are considered ecosystem engineers influencing the alpine ecosystem function. It is also regarded as a pest aggravating the degradation of overgrazed grassland and subject to regular control in QTP since 1950s. Climate change has been predicted in this region but little research exists exploring its impact on such subterranean rodent populations. Using plateau zokor as a model, through maximum entropy niche-based modeling (Maxent) and sustainable habitat models, we investigate zokor habitat dynamics driven by the future climate scenarios. Our models project that zokor suitable habitat will increase by 6.25% in 2050 in QTP. The predication indicated more threats in terms of grassland degradation as zokor suitable habitat will increase in 2050. Distribution of zokors will shift much more in their southern range with lower elevation compare to northern range with higher elevation. The estimated distance of shift ranges from 1 km to 94 km from current distribution. Grassland management should take into account such predictions in order to design mitigation measures to prevent further grassland degradation in QTP under climate change scenarios.

Habitat, diet, macronutrient, and fiber balance of Himalayan marmot (Marmota himalayana) in the Central Himalaya, Nepal

The Himalayan marmot (Marmota himalayana) occurs throughout the Himalayan alpine mountain ecosystem. We examined the characteristics of Himalayan marmot habitat, diet, and macronutrient consumption in the upper Mustang region of Nepal. Marmots inhabited warmer valleys close to water sources in areas between 2,900 and 4,800 m above sea level. Soil pH, organic matter, organic carbon, and phosphorus were not different in marmot use versus available habitat; however, potash levels significantly lower in marmot burrow habitat. Seventeen species of plants, including Primula spp., Potentilla fruticosa, Kobresia pygmaea, Anaphalis contorta, Lonicera spinosa, and Carex spp., were recorded in marmot scats over 3 seasons (summer 2010, autumn 2010, and spring 2011). Analysis showed a positive correlation between the total macronutrient content (dry matter protein + carbohydrate + fat) of plants and their occurrence in the diet. Analysis of the fiber and macronutrient balance of a limited number of plants consumed by marmots showed little difference between pre- and post-hibernation, but suggested that protein balance of foods was higher post-hibernation. Furthermore, relative frequency of plants in the diet did not reflect their abundance in the environment, suggesting active selection of plants high in total macronutrient concentration.

Phylogenetic relationships of extant zokors (Myospalacinae) (Rodentia, Spalacidae) inferred from mitochondrial DNA sequences

Abstract In this study, we use three mitochondrial markers, cytochrome b gene (Cyt b), NADH dehydrogenase subunit 4 (ND4) and control region (D-loop) to investigate the phylogenetic relationships of extant zokor species in Mysopalacinae. The phylogenetic tree constructed based on Cyt b strongly supports the monophyly genera Eospalax and Myospalax with E. fontanierii being the most ancient species in Eospalax. Further phylogenetic analyses of four species of Eospalax based on ND4 and D-loop sequences revealed two clades that correspond to two geographical distributions. The basal clade includes E. cansus which is mainly found on Loess Plateau (LP) and another clade including E. baileyi, E. smithii and E. rufescens that inhabits areas above 2000 m on Qinghai-Tibetan Plateau (QTP) and Qinling Mountains. Geographical events of QTP and LP may have played a major role in the diversification and evolution of Mysopalacinae.

Genetic diversity and demographic history of the endangered and endemic fish (Platypharodon extremus): implications for stock enhancement in Qinghai Tibetan Plateau

Release of captive bred individuals into the wild is now a conservation management approach to increase the depleted natural wildlife populations. Such method has been initiated for conservation of wild fish population on Qinghai Tibetan Plateau (QTP), a region of high level of species endemism. Platypharodon extremus is an endemic schizothoracine fish species and a dominated species in the plateau water ecosystem of the QTP in the past, it is now enlisted as an endangered species. However, phylogenetic and genetic information have not been previously considered in the ongoing stock enhancement program. In this study, genetic and demographic processes of the populations across the distribution of this species were assessed, using the mitochondrial DNA control region and Cyt-b. We found that all populations displayed low nucleotide diversity suggesting severe historical bottleneck events and high haplotype diversity indicating recent population expansion. Both the phylogenetic tree and the minimum spanning tree showed no significant genealogical structures corresponding to sampling locations. Population histories including bottleneck, exponential expansion and the absence of population structure indicate that demographic processes highly influenced genetic variation within and among populations of P. extreums. The data presented is consistent with a historical bottleneck and recent population expansion for all four populations based on several complementary analyses of the genetic data and inferred from demographic history (0.26 to 0.36 Mya). This genetic variation and demographic processes should become the baseline information for evaluating genetic effects of stock enhancement program and ongoing conservation decision making.

Genetic Structure and Demographic History of the Endangered and Endemic Schizothoracine Fish Gymnodiptychus pachycheilus in Qinghai-Tibetan Plateau

The endangered schizothoracine fish Gymnodiptychus pachycheilus is endemic to the Qinghai-Tibetan Plateau (QTP), but very little genetic information is available for this species. Here, we accessed the current genetic divergence of G. pachycheilus population to evaluate their distributions modulated by contemporary and historical processes. Population structure and demographic history were assessed by analyzing 1811-base pairs of mitochondrial DNA from 61 individuals across a large proportion of its geographic range. Our results revealed low nucleotide diversity, suggesting severe historical bottleneck events. Analyses of molecular variance and the conventional population statistic FST (0.0435, P = 0.0215) confirmed weak genetic structure. The monophyly of G. pachycheilus was statistically well-supported, while two divergent evolutionary clusters were identified by phylogenetic analyses, suggesting a microgeographic population structure. The consistent scenario of recent population expansion of two clusters was identified based on several complementary analyses of demographic history (0.096 Ma and 0.15 Ma). This genetic divergence and evolutionary process are likely to have resulted from a series of drainage arrangements triggered by the historical tectonic events of the region. The results obtained here provide the first insights into the evolutionary history and genetic status of this little-known fish.

Examining object recognition and object-in-Place memory in plateau zokors, Eospalax baileyi

Recognition memory is important for the survival and fitness of subterranean rodents due to the barren underground conditions that require avoiding the burden of higher energy costs or possible conflict with conspecifics. Our study aims to examine the object and object/place recognition memories in plateau zokors (Eospalax baileyi) and test whether their underground life exerts sex-specific differences in memory functions using Novel Object Recognition (NOR) and Object-in-Place (OiP) paradigms. Animals were tested in the NOR with short (10min) and long-term (24h) inter-trial intervals (ITI) and in the OiP for a 30-min ITI between the familiarization and testing sessions. Plateau zokors showed a strong preference for novel objects manifested by a longer exploration time for the novel object after 10min ITI but failed to remember the familiar object when tested after 24h, suggesting a lack of long-term memory. In the OiP test, zokors effectively formed an association between the objects and the place where they were formerly encountered, resulting in a higher duration of exploration to the switched objects. However, both sexes showed equivalent results in exploration time during the NOR and OiP tests, which eliminates the possibility of discovering sex-specific variations in memory performance. Taken together, our study illustrates robust novelty preference and an effective short-term recognition memory without marked sex-specific differences, which might elucidate the dynamics of recognition memory formation and retrieval in plateau zokors.

Complete mitochondrial genome of the Gansu zokor, Eospalax cansus (Rodentia, Spalacidae)

Mysopalacinae (zokors) is a group of fossorial rodents for which the taxonomy has yet to reach consensus. Furthermore, due to their fossorial lifestyle, little is known about their ecology. Molecular data are important to elucidate such aspects. In this paper, the complete mitochondrial DNA genome of Gansu zokor (Eospalax cansus) of the type found in Lintan, China was determined. The genome is 16,354 bp in length and consists of 13 protein-coding genes, 22 tRNA genes, two ribosomal RNA genes, and two main non-coding regions (the control region and the origin of the light strand replication), the gene composition and order of which are similar to most other mammals. The overall base composition is T 30.0%, C 24.2%, A 33.5%, and G 12.3%, with an A+T bias of 63.5%. These mitogenome sequence data are potentially important for evolutionary, population genetic, and ecological studies of the Mysopalacinae.

Function‐related Drivers of Skull Morphometric Variation and Sexual Size Dimorphism in a Subterranean Rodent, Plateau Zokor (Eospalax baileyi)

Abstract Sexual dimorphism is prevalent in most living organisms. The difference in size between sexes of a given species is generally known as sexual size dimorphism (SSD). The magnitude of the SSD is determined by Renschs rule where size dimorphism increases with increasing body size when the male is the larger sex and decreases with increasing average body size when the female is the larger sex. The unique underground environment that zokors (Eospalax baileyi) live under in the severe habitat of the Qinghai‐Tibetan Plateau (QTP) could create SSD selection pressures that may or may not be supported by Renschs rule, making this scientific question worthy of investigation. In this study, we investigated the individual variation between sexes in body size and SSD of plateau zokors using measurements of 19 morphological traits. We also investigated the evolutionary mechanisms underlying SSD in plateau zokors. Moreover, we applied Renschs rule to all extant zokor species. Our results showed male‐biased SSD in plateau zokors: The body‐ and head‐related measurements were greater in males than in females. Linear regression analysis between body length, body weight, and carcass weight showed significant relationships with some traits such as skull length, lower incisor length, and tympanic bulla width, which might support our prediction that males have faster growth rates than females. Further, the SSD pattern corroborated the assumption of Renschs rule in plateau zokors but not in the other zokor species. Our findings suggest that the natural underground habitat and behavioral differences between sexes can generate selection pressures on male traits and contribute to the evolution of SSD in plateau zokors.

Abundance and characteristics of microsatellite markers in Gansu zokor (Eospalax cansus), a fossorial rodent endemic to the Loess plateau, China

1College of Grassland Science, Gansu Agricultural University, Key Laboratory of Grassland Ecosystem of Ministry of Education, Pratacultural Engineering Laboratory of Gansu Province, Lanzhou 730070, People’s Republic of China 2Gansu Agricultural University-Massey University Research Centre for Grassland Biodiversity, Gansu Agricultural University, Lanzhou 730070, People’s Republic of China 3Lanzhou Vocational Technology College, Lanzhou 730070, People’s Republic of China 4Institute for Applied Ecology, University of Canberra, Bruce ACT 2601, Australia 5Ecological Genetics Laboratory, Landcare Research, Private Bag 92170, Auckland, New Zealand 6Institute of Natural Sciences, Massey University, North Shore Mail Centre 0632, Auckland, New Zealand