4.1 Genetic diversity in C. hainanense
The genetic diversity of plants is usually influenced by their range,
longevity, reproductive systems, seed dispersal mechanisms, and
evolutionary history (Zhang et al., 2021; Nybom et al., 2004). SNP
variants are the most significant and extensive type of sequence
variation in plant genomes and can be easily identified by sequence
alignment (Fang et al., 2014). Our study yielded 477588 high-quality
SNPs through screening and filtering. C. hainanense has a wide
ecological population in the natural wild state, but the seeds require
high germination conditions in the natural environment, limiting the
population. The natural wild C. hainanense is distributed as
individuals in fragments in the natural tropical forest. So far, no
clusters of communities have been found, so the population density of
wild C. hainanense is very low, resulting in the population’s
weak stress resistance and reproductive ability. Population development
is long, and natural recovery is slow.
The genetic diversity of C. hainanense was low. The genetic
diversity of C. hainanense was low. The finding that the genetic
diversity of C. hainanense is low has significant implications
for the conservation and management of this species. C.
hainanense is a plant species native to Hainan Island in China. The low
genetic diversity, as indicated by the heterozygosity values ranging
from 10.79% to 14.55% with an average of 13.15%, suggests that this
species may be at risk for several reasons. Low genetic diversity can
reduce a species’ ability to adapt to environmental changes, such as
shifts in climate or the emergence of new diseases or pests. A more
genetically diverse population has a greater chance of possessing the
necessary genetic traits to survive and adapt to new challenges. With
low genetic diversity, there is an increased likelihood of inbreeding,
which can lead to inbreeding depression. This is a reduction in fitness
and overall health caused by the increased expression of harmful
recessive genes that become more prevalent in a closely related
population. Low genetic diversity can make a species more vulnerable to
extinction due to its reduced adaptability and potential for inbreeding
depression. When a species faces a new threat, it may not have the
genetic variation necessary to evolve and survive. Genetic diversity is
essential for maintaining the long-term stability and resilience of
ecosystems. A species with low genetic diversity might have a reduced
ability to fulfill its ecological role, which can negatively impact the
overall health and functioning of the ecosystem.
WPESP in nature can lead to an increase in inbreeding due to genetic
drift or bottleneck effects, which can lead to a decrease in population
genetic diversity, as well as a decrease in population fitness, leaving
populations unable to adapt to changing environments and facing
extinction (Theodorou, et al., 2015; Nayak, et al., 2010). Xu (2022)
reviewed the research on the genetic variation of 120 extremely small
populations of wild plants and found that only 10 of the 44 species
studied had low genetic diversity at the species level. They areAbies ziyuanensis, thaya argyrophylla, Firmiana danxiaensis,
Glyptostrobus pensili, Nyssa yunnanensis, Oreocharis mileensis,
Pinus squamata, Sinojackia huangmeiensis、Taxus contorta,
Vatica guangxiensis (Xu et al., 2022). At present, the distribution
area of C. hainanense is very narrow, and the population
collapse, dividing narrowly distributed may be less heritable than
widely dividing plant species due to inbreeding and genetic
drift(Setoguchi, et al., 2011; Zhang, et al., 2021). Low levels of
genetic diversity may impair the population’s ability to adapt to new
soil and photoperiodic environments during migration, thereby inhibiting
the population’s adaptive potential (Yang et al., 2018). In addition,
our field surveys showed that wild resources of C. hainanensewere affected by human activities, such as logging, which led to the
fragmentation of its habitat. Habitat fragmentation not only reduces the
number of plant populations but also increases the spatial isolation
between populations, directly or indirectly affecting species dispersal,
gene exchange between populations, and species interactions, and hinders
the maintenance of population genetic diversity (Aguilar et al., 2008).
The findings revealed that the distribution of C. hainanensepopulations is fragmented. Many native populations have been lost due to
fragmentation. Most of the C. hainanense populations were found
in protected areas. It also shows
human intervention in nature has extended into protected areas. There is
an urgent need to prevent the degradation of the remaining high-quality
forest ecosystems by protecting and restoring intact forests where
possible, as well as by paying attention to those forest landscapes
embedded in human modifications, such as those near logging fronts and
those near population centers.