Evolutionary history and colonization patterns of the wing dimorphic grasshopper Dichroplus vittatus in two Argentinean biomes

Natalia Rosetti,Maria Isabel Remis,Daniela Krohling

doi:10.1038/s41598-022-05162-6

Abstract

Quaternary climate oscillations and modification of the environment by humans have played an important role in shaping species distribution and genetic structure of modern species. Here, population genetic parameters were inferred from the analysis of 168 individuals belonging to 11 populations of the South American grasshopper, Dichroplus vittatus, distributed in two Argentinean Biomes (Grassland and Savanna), by sequencing a 543 bp of the mitochondrial COI gene. Overall, we detected considerable haplotype diversity and low nucleotide diversity. AMOVA analyses showed a significant degree of differentiation among Biomes and between populations. Two major mitochondrial lineages can be distinguished. The haplogroup containing the most common haplotype split 17,000 years BP while the haplogroup including the second most common haplotype has a divergence date of about 11,700 years. Approximate Bayesian Computation (ABC) analyses showed that the palaeodemographic scenario that best fitted our data is consistent with a hypothesis of divergence from an ancestral population and subsequent admixture with Grassland-Savanna (South–North) direction. Our results suggest that populations located in both Biomes would derive from a single ancestral population that colonized the region after the Last Glacial Maximum and Grassland would have a more ancestral origin than Savanna. Further, our results emphasize the importance of human-mediated dispersal in the reconfiguration of genetic diversity of species with potential pest capacity.

Highlights

The environment of South America changed dramatically between glacial and interglacial intervals in response to natural fluctuations in the Earth’s physical s ystem[1]
The places where species persist during glaciations have generally been described as r efugia[10].The way in which species are isolated within such refugia, and the timing and mode of expansion from them after the improvement of environmental conditions, have become highly important topics to get deeper insight into the evolutionary processes that shaped the current genetic diversity
A 543 bp fragment of the mitochondrial gene cytochrome oxidase I (COI) was sequenced from 168 samples of D.vittatus from 11 populations distributed in Central-West Argentina (Fig. 1)

Summary

Introduction

The environment of South America changed dramatically between glacial and interglacial intervals (ca. 100 ka. cycles for most of the Quaternary) in response to natural fluctuations in the Earth’s physical s ystem[1]. Cycles for most of the Quaternary) in response to natural fluctuations in the Earth’s physical s ystem[1] Climate change, such as Quaternary oscillations, as well as dispersal are two major factors determining the contemporary distribution and genetic diversity of o rganisms[1, 2]. Demographic events, such as stepping-stone e xpansion[3], human-related dispersal[4] and active m igration[5, 6] of species, blurred their distribution r anges[7]. The most relevant report proposed that this region is climatic and demographically unstable for an endemic s hrub[17]

Methods

Results

Conclusion