Yangtze River, an insignificant genetic boundary in tufted deer (Elaphodus cephalophus): the evidence from a first population genetics study

Abstract

Great rivers were generally looked at as the geographical barrier to gene flow for many taxonomic groups. The Yangtze River is the third largest river in the world, and flows across South China and into the East China Sea. Up until now, few studies have been carried out to evaluate its effect as a geographical barrier. In this study, we attempted to determine the barrier effect of the Yangtze River on the tufted deer (Elaphodus cephalophus) using the molecular ecology approach. Using mitochondrial DNA control region (CR) sequences and 13 nuclear microsatellite loci, we explored the genetic structure and gene flow in two adjacent tufted deer populations (Dabashan and Wulingshan populations), which are separated by the Yangtze River. Results indicated that there are high genetic diversity levels in the two populations, but no distinguishable haplotype group or potential genetic cluster was detected which corresponded to specific geographical population. At the same time, high gene flow was observed between Wulingshan and Dabashan populations. The tufted deer populations experienced population decrease from 0.3 to 0.09 Ma BP, then followed by a distinct population increase. A strong signal of recent population decline (T = 4,396 years) was detected in the Wulingshan population by a Markov-Switching Vector Autoregressions(MSVAR) process population demography analysis. The results indicated that the Yangtze River may not act as an effective barrier to gene flow in the tufted deer. Finally, we surmised that the population demography of the tufted deer was likely affected by Pleistocene climate fluctuations and ancient human activities.

Effects of dispersal barriers and geographic distance on the genetic structure of a narrowly distributed frog in a spatially structured landscape

“…In this study, EBSP revealed that O. tormota experienced an effective population size expansion since 0.075 Mya and reached the largest population size around 0.017 Mya; this finding was also supported by the neutral tests, mismatch distribution analysis, and a star‐like network. The demographic expansion of O. tormota during this period is consistent with many species in East Asia, such as the Shangcheng stout salamander ( P. shangchengensis ; Pan et al ., ), Chinese bamboo partridge ( B. thoracica ; Huang et al ., ), Chinese hwamei ( Leucodioptron canorum ) (Li et al ., ), and tufted deer ( Elaphodus cephalophus ) (Sun et al ., ). This phenomenon has also been observed in species from mid‐latitude Europe, such as the Maltese wall lizard ( Podarcis filfolensis ; Salvi et al ., ) and Italian wall lizard ( P. siculus ; Senczuk et al ., ).…”

“…Compared with the drastic climate oscillations and glacial cycles in Europe and North America (Hewitt, ; Schmitt, ), there was a relatively mild Pleistocene climate and lack of ice sheets in many areas of East Asia (Rost, ; Weaver et al ., ; Ju et al ., ). East Asia has a mosaic of mountains lower than 2000 m. In this area, species generally exhibited two population dynamic patterns in response to Pleistocene climate change: population expansion and contraction for some biological groups (Huang et al ., ; Ding et al ., ; Sun et al ., ), or minor effects on the population demography of other species, such as spiny frogs ( Quasipaa boulengeri ) (Yan et al ., ).…”

“…Several hypotheses have been proposed to explain high genetic diversity, including historical levels of species genetic diversity, larger existing population sizes, longer generations, random mating, and lack of significant bottlenecks (Allentoft & O'Brien, 2010). East Asia is characterized by a mosaic of mountains and likely experienced a relatively mild Pleistocene climate (Rost, 1994;Weaver et al, 1998;Ju et al, 2007), which provided stable habitats and glacial refugia for species throughout their entire ranges (Li et al, 2009; 2010; Yan et al, 2013;Sun et al, 2016;Pan et al, 2019). The montane environmental and climatic conditions provided an opportunity for the accumulation of genetic diversity (Beniston, 2016).…”

“…During the last million years, climatic changes associated with Pleistocene glacial cycles are thought to have caused montane species to expand and contract along altitudinal and latitudinal gradients, which led to current species distributions and interpopulation gene flow patterns (Hewitt, 2004;Zhou et al, 2010;Ikeda et al, 2017). However, among different animal groups, the influence of Pleistocene climate cycles on population demographics varied (Hewitt, 2004;Schmitt, 2007;Yan, Luo & Wu, 2011;Wang et al, 2015;Sun et al, 2016;Pan et al, 2019). For example, many organisms that are sensitive to environmental changes retreated to southern regions and recolonized their original northern ranges in response to the severe Pleistocene climate fluctuations, especially in Europe and North America (Hewitt, 2004;Schmitt, 2007;Huang et al, 2010;Ding et al, 2011;Sun et al, 2016); in contrast, insensitive species have similar original and present-day ranges (Li et al, 2009;Huang et al, 2010;Salvi et al, 2014;Sun et al, 2016;Senczuk et al, 2017;Pan et al, 2019).…”

“…East Asia is characterized by a mosaic of mountains and likely experienced a relatively mild Pleistocene climate (Rost, 1994;Weaver et al, 1998;Ju, Wang & Jiang, 2007). The climatic conditions in East Asia led to major differences in the magnitude and timing of historical climate impact on population demography of species endemic to this area (Li et al, 2009;Huang et al, 2010;Yan et al, 2013;Sun et al, 2016;Pan et al, 2019). To further elucidate the impact of Pleistocene climate change on population fluctuations of East Asian species, especially amphibians with narrow distributions, further studies on population demography of montane species in this region are needed.…”