Opisthopappus
Landscape
SNP
Gene exchange
Introduction
Landscape ecology is an interdisciplinary scientific discipline that
focuses on spatial pattern and heterogeneity, and specifically their
characterization and description over time, their causes and
consequences (Francis et al., 2022; Wu, 2013). By using ecosystem
principles and system methods, landscape ecology mainly focuses on
landscape structure and function, landscape dynamic change and
interaction mechanism, landscape spatial pattern, structure
optimization, rational utilization and protection, and human management
(Jiang and Li, 2021; Li et al., 2021a). In recent years, more researches
have been conducted on land use, human experience and ecosystem services
(Hersperger et al., 2021; Lester et al., 2021; Song et al., 2017).
Nevertheless, with the constant climate changes and increasing human
activities, the landscape configuration of different regions is
continuously changing (Aylward et al., 2020; Wang et al., 2021c). This
change could affect the ecological and evolutionary processes of
organisms, and even ecosystems. During these processes, the organisms
begin to respond the habitat change caused by the landscape changes and
gradually adapt to and evolve in the changed landscapes (Fisher et al.,
2021; Wang et al., 2021b).
Landscape changes can result in the appearance or disappearance of
dispersal corridors for species or populations. Landscape factors would
affect population connectivity by correlating gene exchange. The
patterns of dispersal and gene exchange are key components shaping
population or species genetic structure and variation model over small
and large spatiotemporal scales (Polato et al., 2017). However, less is
known about the ecological role of migration or gene exchange.
Landscape-genetic approaches can infer landscape effects on dispersal
and migration by examining relationships between genetic differentiation
and landscape conditions among sampling locations (Anderson et al.,
2010; Savary et al., 2021).
Landscape genetics has been a constantly growing field that combines
population genetics, landscape ecology, and spatial analytical
techniques to quantify the effects of landscape on micro-evolutionary
processes. Recent studies have shown that about 80 % researches in
landscape genetics were focused on animals. In comparison, there were
only about 14.5 % reaearches were on plants, possibly because the
mechanism of plant pollen and seed propagation makes the study of gene
exchange at plant landscape-scale more complex than animals (Song et
al., 2017). However, the plant landscape genetic research is essential
for biodiversity because it can provide a powerful tool for protecting
important ecosystems, managing vegetation protection units, and
charactering the local adaptation and the evolution of species (De Kort
et al., 2021).
Taihang Mountains (N34°34’-40°43’, E110°14’-114°33’) is a vital mountain
range and geographical boundary in northern China, one of the second and
third stepped boundaries of China’s terrain, which stretches about 400km
from northeast to southwest (Shoubao et al., 2019; Wu, 2020). The
terrains of the Taihang Mountains are higher in the north and lower in
the south, and composed of a variety of rocks, cliffs, and many rivers,
which formed various and unique landscapes in the Taihang Mountains. In
Taihang Mountains, there are more than 1,290 wild species, of which 34
species were listed as a national priority protection species, and 23
species were rare and endangered plants. Thus, this mountain has already
been regarded as one ideal research site for many ecological researchers
(Wang, 2020). Nevertheless, most of the researches currently paid
attention to the geology, geomorphology, and culture on the Taihang
Mountains. There are few reports about the impact of the landscape
features on the plants in this area.
Opisthopappus genus only lives on the Taihang Mountains cliffs,
presenting excellent ecological, medicinal, and economic values.
Unfortunately, the individual number of this genus is decreasing mainly
due to artificial harvesting and has been listed as China’s national
II-protected plants. It contains two species: Opisopappustaihangensis and O. longilobus . O. taihangensismainly distributes in the south of the Taihang Mountains, covering Henan
and Shanxi provinces. O. longilobus mainly grows at northern of
the Taihang Mountains, including the border of Hebei province and Shanxi
Province (Wang et al., 2022).
Our wild investigation found that the shortest distance between O.
taihangensis and O. longilobus is only about 25 km in the
central areas of Taihang Mountains. However, the two species showed not
only morphologically but also genetically differences. The morphological
difference is mainly manifested in the leaves, whereas the morphologies
of flowers show little difference. According to the previous studies,
the populations of the two species could be clearly separated into two
groups with distinct genetic differentiation, which might be the
consequence of Opisthopappus ’s long-term adaptation to the
environment of Taihang Mountains(Lin et al., 2013). However, how do the
unique landscape features of Taihang Mountains affect the dispersal/
migration and differentiation of the two species? In addition, the
geographical and geomorphic topological structure caused by mountain
uplift often provides pathways for connectivity, gene exchange, and
expansion or contraction of species’ populations in its distribution
ranges (Hou et al., 2020). Previous studies found that there was a
limited gene exchange/flow between O. taihangensis and O.
longilobus (Ye et al., 2021). What landscape factors would prevent gene
exchange/flow between these two species, abiotic environmental factors,
biotic environmental factors, or conbimation of these factors? Is the
gene exchange pattern between Opisthopappus species a interplay
of landscape changes and species? These questions are still unanswered.
In this study, we combined the reduced representation genome data and
landscape characteristics of Taihang Mountains to analyze the genetic
characteristics of O. taihangensis and O. longilobus , to
reveal the potential gene exchange pattern among these two species, and
to analyze the effects of landscape factors and then explore the
possible interplay of landscape - species. The results would guide
scientific protection and utilization of Opisthopappus species
and play a theoretical clue for studying other species in the Taihang
Mountains.
Materials and Methods
2.1 Materials collection
The fieldwork had been approved by the Chinese government and
implemented following the People’s Republic of China laws. Each
participant had a letter of introduction from the College of Life
Sciences, Shanxi Normal University. The samples in this study were taken
along the Taihang Mountains from August to October and mainly covered
the distribution ranges of Opisthopappus species. The
elevation, longitude, and latitude information of each site were
recorded by GPS and shown in Table 1(Papadopulos et al., 2014).