Mixed Fortunes: Ancient Expansion and Recent Decline in Population Size of a Subtropical Montane Primate, the Arunachal Macaque Macaca munzala

Abstract

Quaternary glacial oscillations are known to have caused population size fluctuations in many temperate species. Species from subtropical and tropical regions are, however, considerably less studied, despite representing most of the biodiversity hotspots in the world including many highly threatened by anthropogenic activities such as hunting. These regions, consequently, pose a significant knowledge gap in terms of how their fauna have typically responded to past climatic changes. We studied an endangered primate, the Arunachal macaque Macaca munzala, from the subtropical southern edge of the Tibetan plateau, a part of the Eastern Himalaya biodiversity hotspot, also known to be highly threatened due to rampant hunting. We employed a 534 bp-long mitochondrial DNA sequence and 22 autosomal microsatellite loci to investigate the factors that have potentially shaped the demographic history of the species. Analysing the genetic data with traditional statistical methods and advance Bayesian inferential approaches, we demonstrate a limited effect of past glacial fluctuations on the demographic history of the species before the last glacial maximum, approximately 20,000 years ago. This was, however, immediately followed by a significant population expansion possibly due to warmer climatic conditions, approximately 15,000 years ago. These changes may thus represent an apparent balance between that displayed by the relatively climatically stable tropics and those of the more severe, temperate environments of the past. This study also draws attention to the possibility that a cold-tolerant species like the Arunachal macaque, which could withstand historical climate fluctuations and grow once the climate became conducive, may actually be extremely vulnerable to anthropogenic exploitation, as is perhaps indicated by its Holocene ca. 30-fold population decline, approximately 3,500 years ago. Our study thus provides a quantitative appraisal of these demographically important events, emphasising the ability to potentially infer the occurrence of two separate historical events from contemporary genetic data.

A tale of two forests: ongoing aridification drives population decline and genetic diversity loss at continental scale in Afro-Macaronesian evergreen-forest archipelago endemics

“…The DIYABC analysis detected a population decline ~2000-5000 generations ago, which could not be recovered with coalescent-based Bayesian skyline plots (Drummond et al, 2005;Mairal et al, 2015b). This is in agreement with observations that SSR markers detect more recent signals of genetic diversity than chloroplast DNA and AFLP markers (Chakraborty et al, 2014). Since the generation time of Canarina is not known precisely due to its tuberous habit (it can sometimes behave as a biennial or even show longer generation times), it is difficult to assign an absolute temporal framework for this decline; also, the time scale here differed slightly depending on the population.…”

Range-wide genetic structure and demographic history in the bat ectoparasite Cimex adjunctus

“…ABCs allow one to compare posterior probabilities of different demographic scenarios [62]. As per the method of [63], we input three scenarios in the analyses (for population sizes N A  > N 1  > N B ), mimicking an increase in effective population size from N 1 to N A at time t , a decrease in population size from N 1 to N B at time t , and finally constancy in population size at N 1 . Boundaries for N A , N B , N 1 and t priors are available in Table 5.…”

Multilocus phylogeny suggests a distinct species status for the Nepal population of Assam macaques (<i>Macaca assamensis</i>): implications for evolution and conservation

“… Node values represent RAxML percentage bootstrap probability. Inset shows geographical distribution of sinica- group species; source: M. leucogenys ( Fan et al, 2017 ); M. munzala ( Biswas et al, 2011 ; Chakraborty et al, 2014 ; Sarania et al, 2017 ), M. a. assamensis ( Minge et al, 2016 ; Zhou et al, 2011 ); NPAM ( Khanal et al, 2018a , 2019 ). …”