Zhibin Zhang - Interests and Research#

Dr. Zhang’s research interests focus on studying impacts of global change on population and community dynamics of animals and their interactions with plants and microbes, and looking for novel methods or strategies for pest control or biodiversity conservation. Using long-term historical records or monitoring data, Dr. Zhang have made important contributions in revealing the scale-dependent effects of global change on population dynamics of animals or diseases and species interaction by integrating the ecological studies from local to global scale, and from monotonic to non-monotonic regimes. Dr. Zhang also made important progresses in revealing the behavioral and molecular mechanisms of population regulation of small rodents and in developing new techniques and strategies for sustainable pest management or biodiversity conservation.

Dr. Zhang has made important contributions in promoting the international cooperation among global zoologists and the development of integrative zoology. Dr. Zhang played a key role in founding the International Society of Zoological Sciences (ISZS) (http://www.globalzoology.org/dct/page/1) and its official journal, Integrative Zoology (http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1749-4877); in launching the International Conference of Rodent Biology and Management (ICRBM), International Symposium of Integrative Zoology (ISIZ) (http://www.globalzoology.org/dct/page/70021) , International program of Biological Consequences of Global Chang (BCGC) (http://www.globalzoology.org/dct/page/70004).

Global change and population dynamics

Using long-term data, Dr. Zhang and his colleagues found that the ecological effects of climate might be non-monotonous, depending upon the studying scales. Using historical data of 1,910-y-long time series of outbreaks of Oriental migratory locusts (Locusta migratoria manilensis) in ancient China, they found occurrences of locust plague and drought/floods were positively associated with low temperature (Stige et al. 2007; Zhang et al. 2009; Tian et al. 2011), expanding the conventional view that climate warming benefits locust occurrences. Using the spatial and temporal human plague records in China from 1850 to 1964, they found plague occurrences were positively related to precipitation in dry region but negatively related to precipitation in wet region in China (Xu et al. 2011), expanding the conventional view that wet climate benefits plague prevalence. Using nearly 100-yr historical data, they found temperature showed indirect and negative effect on lynx populations, and recent global warming attributed to the successive decline of lynx populations in Canada through increased rainfall in summer season (Yan et al. 2013). Using data over the past two millennia, they found both human impact and climate cooling caused range contraction of large mammals in China (Li et al. 2015). Using fossil data covering past 50,000 yrs, they found rapid global warming was the predominant factor driving the total extinction of mammoths and rhinos in frigid zones from the Late Pleistocene and Early Holocene, while humans were the predominant factor causing the extinction or major extirpations of elephants, rhinos, deer and horses in the Holocene (Wan and Zhang 2017).

Dr. Zhang and his colleagues found that global climate factors such as El Nino/Southern Oscillation (ENSO), Northern Atlantic Oscillation (NAO) and global temperature might be important in driving or modifying population dynamics or cycles of many biological populations, such as locusts (Zhang and Li 1999), Brandt’s voles (Zhang et al. 2003), Yangtze voles (Zhang et al 2010), rodent-borne plague (Zhang et al. 2007) in China; lynx in Canada (Yan et al. 2013) and lemming and voles in Europe (Zhang 2001). They revealed multiple pathways of these global climate factors through local climate and trophic webs on plague occurrences (Xu et al. 2015) and population dynamics of small rodents (Jiang et al. 2011) in grasslands ecosystems, and lynx populations in Canada (Yan et al. 2013). They found global climate factors may play an important role in modifying the famous 10-yr cycles of snow hare and lynx in Canada (Yan et al. 2013) which is widely believed to be driven by the prey-predator interactions. These findings expanded our conventional views on the ecological effects of climate on animals from local to global scales.

Dr. Zhang and his colleagues found that human disturbances could impose significant impacts on population dynamics of small rodents. Using large human plague dataset in China, they proposed a novel method (Nearest Neighbour Approach, NNA) which is able to deal with both short- and long-distance transmissions of diseases, and found the presence of major roads, rivers and coastline accelerated the spread of plague and shaped the transmission patterns (Xu et al., 2015). Using over 300-month data which they collected in their long-term research station in the North China Plain, they found agricultural irrigation in breeding season reduced the positive and direct effect of climate warming on population dynamics of the Chinese striped hamster (Cricetulus barabensis) in non-breeding season in northern China plain (Yan et al. 2013). Increased agricultural flood irrigation resulted in steady decline of population and their body mass of both the Chinese striped hamster and the Greater long-tailed hamster (Tscherskia triton) (Yan and Zhang 2014). Using large-scale enclosures, they found that successive grazing attributed to sustained population decline of Brandt’s voles (Lasiopodomys brandtii) in Inner Mongolia grasslands, through reducing both food quantity and quality (Li et al., 2016).

Species interaction, stability and coexistence

Dr. Zhang and his colleagues proposed the concept that species interaction might be non-monotonous, and it might play an important role in maintaining diversity and stability (Zhang 2003). They found that specific non-monotonic interactions (e.g. dome-shaped or satiated function) could promote species coexistence or persistence of complex ecological networks (Zhang 2003; Yan et al. 2014), providing an alternative mechanism in resolving the biodiversity-stability paradox. They developed an unique method of seed tagging (Zhang and Wang 2001; Xiao et al. 2006) or combing it with IR camera tracking method (Zhao et al. 2016, Gu et al. 2017) to study interactions between seeds and rodents in various forest ecosystems of China. They found rodents quantified the both positive (through seed scatter hoarding) and negative (through seed consumption and seed ladder-hoarding) effects of rodents on seed regeneration of forests, and found this largely depended on the seed availability of rodents. High rodent abundance would cause failure of seeding establishment (Li and Zhang 2003), while seed masting would promote seeding establishment (Li and Zhang 2007) or seed survival (Xiao et al. 2013). They found function traits of seeds (i.e. seed coat thickness, tannin, protein, fat and starch) and animal (body size) played a significant role in the formation of mutualism-predation interaction and network structure of the seed-rodent dispersal system (Chang and Zhang 2014; Wang et al. 2014; Zhang et al. 2015).

They found some interesting co-evolutionary mechanisms between seeds and rodents in forests. Rapid germination of non-dormant seeds is one adaptation strategy plants have evolved to counter seed predation by rodents. They found Pallas’s squirrels (Callosciurus erythraeus) have evolved behaviors that prevent or slow the seed germination process through seed embryo removal of non-dormant acorns in subtropical forest of Sichuan (Xiao et al. 2009). While in tropical rain forest of Yunnan, they found rodents had the capacity of seed pruning to non-dormant seeds; interestingly, they found that the non-dormant seeds of Pittosporopsis kerrii Craib had a high regeneration capacity to counter for seed pruning by rodents (Cao et al. 2011). In an oak–squirrel system in a subtropical forest, they found a positive frequency-dependent selection on germination phenotype (dormancy, i.e., delayed germination vs. nondormancy, i.e., immediately germinating) in the two white oaks (Quercus aliena and Quercus serrata) under predation of Pe`re David’s Rock squirrel (Sciurotamias davidianus) (Xiao et al. 2010). They found the display of hoarding behavior in Siberian chipmunks (Tamias sibiricus) in temperate forest of northeast China was associated with increased cell proliferation in the hippocampus and this increase occurred in a brain region-specific manner (Pan et al. 2013), providing the molecular evidence that mutualistic interaction of scatter hoarding by rodents is an adaptive behavior.

Behavioral and molecular evidences of population regulation

Intrinsic factors, such as social, physiological and genetic factors, are also important in regulating population density of animals. Little is known as to how genetic diversity is associated with long-term population dynamics, and whether genetic bottlenecks or genetic resilience occur in fluctuating populations of small rodents. Using DNA markers, they found genetic diversity of the Greater long-tailed hamster (Tscherskia triton) in the North China Plain was positively associated with population density; bottleneck effect was detected in some low-density years, demonstrating an obvious genetic resilience and capacity for recovery in this species (Dong et al. 2010; Xu et al. 2013).

Social rank of dominant or subordinate counterparts is a very important mechanism in population regulation of small rodents. Neuropeptides oxytocin (OT) and vasopressin (AVP) play a significant role in the regulation of social behaviors of rodents. They found distinct patterns of neuronal activation associated with agonistic encounters in a behavior-specific manner in male Greater long-tailed hamsters by using Fos-immunoreactive staining (Fos-ir) (Pan et al. 2010). By using immunoreactive (ir) staining of OT and AVP, they found social species (Brandt’s voles, Mongolia gerbils) showed different densities of OT-ir cells and AVP-ir cells in the specific regions of brain from that of solitary species (Greater long-tailed hamsters, Striped hamster). These data supported the hypothesis that species-specific patterns of central OT and AVP pathways might underlie species differences in social or solitary patterns of rodents (Xu et al. 2010; Wang et al. 2013).

Sustainable pest management

Fertility control is an alternative non-lethal method in the management of rodents, but high efficiency and cost-effective methods are still lacking. The most common approach was through the use of steroid hormones which often face problems of poor palatability and repeated baiting. Dr. Zhang and his colleagues found that quinestrol and levonorgetrel or their mixture, which are women contraceptives, had great potential in fertility control of wild rodents. They found a single baiting of quinestrol, levonorgestrel or their mixture at a very low dosage in baits (10-50 ppm) in field condition could significantly reduce the breeding of wild rodents (Zhang et al 2004, Liu et al. 2011; Zhang 2015). Dr. Zhang proposed that mating system would affect the efficiency of fertility control of animals because infertile individuals would compete for mating with normal ones (Zhang 2000). This was supported by a study by Liu et al. (2012). Both compounds were shown to be decomposed quickly under field conditions, with half-lives of 5-16 days in soils and less than 3 days in water. Non-target effects on birds appear to be minimal (Qu et al. 2015). The high efficiency of quinestrol and levonorgetrel or their mixture in fertility control of wild rodents have been widely proved by many other laboratories in China (Zhang et al. 2015) and in Tanzania (Apia et al. 2017). Official registration of these compounds for fertility control of rodents has been started.

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