A phylogenetic study of the Mongolian Tree Pipit (Anthus trivialis, Linnaeus, 1758) population based on mitochondrial DNA (mtDNA) genes

Abstract

Our aim was to identify nucleotide polymorphisms, assess their distribution in haplotype diversity, and construct a phylogenetic tree by analyzing mtDNA markers of the Mongolian Tree Pipits(Anthus trivialis). We conducted this study using partial gene sequencesof mitochondrial marker genes, such as COI, Cyt-b, D-loop, andND2,to determine the genetic diversity of Mongolian Tree Pipits. We successfully amplified 2307 bp of the mitochondrial DNA fragments, including 469bp of COI, 435bp of Cyt-b, 554bp of D-loop and 846bp of ND2 from total 27 individuals of Mongolian (21) and Hungarian (6) populations of Anthus trivialis.The Hd value wasthe highest for ND2 (0.96) as compared with the other gene fragments in all populations, whileit was 0.94 in the Mongolian population. Moreover, the nucleotide diversity (Pi) ranged from 0.00234 to 0.004 in all population, it was observed that the Pi was between 0.00183 and 0.00376 in the Mongolian population. The phylogenetic tree based on combined mtDNA sequences revealed two mean clades.The probability value of the node supporting the posterior between these clades is 0.65,which suggests an indicative support in relationship between the two clades. Furthermore, phylogenetic analysis showed that Mongolian Tree Pipits do share common genetic characteristics with other populations and do not form distinct clusters.

Keyword: Population genetics, haplotype, Anthus trivialis, Phylogenetics, Cyt-b, ND2, D-loop, COI;

INTRODUCTION

The Tree Pipit (Anthus trivialis, Linnaeus, 1758) is a migratory bird belonging to the Motacillidae family within Passeriformes. This species faces significant challenges, particularly in Southeast Asian countries, where it has become a target of widespread hunting (Source). In recent years, the population of the Tree Pipit in Central Asia has experienced a notable decline, leading to its inclusion in the category of Globally Decreasing Populations according to the International Union for Conservation of Nature (IUCN) assessment for the year 2023 [1]. The genus Anthus, to which the Tree Pipit belongs, is a diverse group within the Motacillidae family, comprising 43 species. The Motacillidae family is recognized as one of the most widespread and species-rich families within Passeriformes, a testament to its members' ecological diversity and adaptability [2, 3]. The challenges associated with determining the exact genetic relationships between birds in genusAnthus, such as the Tree Pipit (Anthus trivialis), due to inconsistencies in appearance and plumage, are indeed significant. The genus Anthus encompasses a diverse group of bird species, and the variations in their external characteristics can make it challenging to establish a precise genetic relationship[4].

Acomprehensive classification involved identifying four major groups: the Small-Bodied African Group are predominantly found in the African regions and are characterized by smaller body sizes; the Old Continental Group, reflecting the historical continuity of relatively large species, are distributed across Asia, Africa, and Europe; the Palearctic Migratory Group consist of species undertaking migration within the Palearctic region encompassing Europe, Asia, and North Africa; and the New Continental Group comprises of species found in North, Central, and South America and represent the Anthus species that have colonized the Americas [5].The Tree Pipit (Anthus trivialis) predominantly inhabits the temperate regions of Eurasia.

The first study of the phylogeography of birds to determine the genetic basis of geographic location in birds established amethod based on mitochondrial DNA (mtDNA) [6], which initiated a method that explores the genealogical relationship of birds based on their geographical locations. The use of mtDNA in genetic and phylogeographic studies is widespread because of its high evolutionary intensity and minimal DNA degradation[7].Tree Pipit is a migratory egg-laying bird that is listed as a rare species in the Red Book of Mongolia. Therefore, it is necessary to conduct field and genetic research to determine the subspecies that are distributed in Mongolia.

In this study, we focused on elucidating the nucleotide sequence of specific genes within the mtDNA of Tree Pipit. Proceeding from, this premise, we focused on conducting a comparative genetic analysis of Mongolian Tree Pipits in relation to other global populations to determine if differences, any, exist at the subspecies level, thus contributing valuable insights into the population genetics of Tree Pipit.