Introduction
A landscape is an intricate combination of distinct habitats, and each landscape feature may impact species' distribution and ecological process (Turner, 1989). Recognizing the effects of landscape features on organisms is of extreme importance for enhancing our fundamental knowledge of the environmental characteristics which shape population structure, assessing the size and boundaries of management units, and identifying populations requiring high-priority protection (Manel et al., 2003; Segelbacher et al., 2010). In urban areas, anthropogenic activities and constructions can disrupt the functional connectivity of wildlife among heterogeneous landscapes (Epps & Keyghobadi, 2015; Johnson & Munshi-South, 2017; Westekemper et al., 2021). Land use changes caused by human activities lead to significant habitat loss and fragmentation, making it one of the most influential threats to global wildlife and biodiversity in recent decades (Shochat et al., 2010). From a genetic perspective, highly isolated populations are more vulnerable to local extinction due to reduced fitness resulting from the accumulation of deleterious mutations and a loss of potential for adaptation to environmental change (Ellstrand & Elam, 1993; Lande, 1988).
 
Anthropogenic infrastructure, such as buildings and roads, can impede the gene flow of various species, especially of those not pre-adapted to urban environments or with limited dispersal capabilities (Fusco, Carlen, & Munshi-South, 2021; Montgelard et al., 2014). However, some empirical studies have indicated that specific land cover types in cities can act as corridors that facilitate gene flow and reduce population differentiation (Johnson & Munshi-South, 2017; Westekemper et al., 2021). For example, roads and railways are barriers to mongoose dispersal (Grilo, Bissonette, & Santos-Reis, 2009) but facilitate gene flow for foxes (Kimmig et al., 2020). In Felidae, human population density and highways disrupt cougars and tigers (Castilho et al., 2015; Yumnam et al., 2014). Anthropogenic impacts and various categories of roads also influence the movement of wildcats in Europe (Hartmann et al., 2013; Westekemper et al., 2021).
 
Identifying the relationship between landscape features and connectivity is crucial for effective conservation management and evaluating human impacts on endangered felids (Thatte et al., 2018; Yumnam et al., 2014). Anthropogenic climate change directly impacts wildlife behaviour, migration, reproduction, and foraging (LeDee et al., 2021; Wong & Candolin, 2015). In most scenarios, rising temperatures force wildlife to migrate to new habitats at higher altitudes and latitudes (Moritz et al., 2008; Sattar et al., 2021). Artificial barriers may impede such dispersal in human-disturbed areas characterized by fragmented patches (Fusco, Carlen, & Munshi-South, 2021). This makes it less likely for animals to disperse and adapt to climate change, especially for those with lower mobility, which can increase the risk of local extinction (LeDee et al., 2021; McLachlan, Hellmann, & Schwartz, 2007). Therefore, conservation strategies to mitigate human-induced population decline should also consider the long-term impact of climate change.    
 
In the present study, we investigated the landscape genetic connectivity and the demographic histories of Taiwan populations of Prionailururs bengalensis (Kerr, 1792). Prionailururs bengalensis is a small carnivore widely distributed throughout Southern, Eastern, and Southeast Asia and known for its ecological adaptability (Sunquist & Sunquist, 2017). Commensurate with its broad distribution, P. bengalensis has been classified into 12 accepted subspecies according to morphological differences, but this is currently under debate, and mitochondrial data support a reclassification into four species (Patel et al., 2017; Sunquist et al., 2009). Their adaptability is illustrated by their ability to inhabit diverse habitats, including rainforests, temperate forests, shrubland, and grassland (Sunquist & Sunquist, 2017). They are also characterized by their high tolerance to human disturbance and their ability to utilize various human-dominated habitats, including palm farms, orchards, and even semi-deserts (Rajaratnam et al., 2007; Sunquist & Sunquist, 2017). Given its high adaptability and large populations, P. bengalensis is categorized as of Least Concern (LC) by the International Union for Conservation of Nature (IUCN), implying a low risk of extinction (Ross et al., 2015). However, regardless of its large global population size, peripheral populations on islands of the Ryukyu Archipelago (e.g., Iriomotejima Island, Tsushima Island, and Taiwan) are at higher risk of local extinction relative to populations in continental Asia (Ian, 1979; Izawa et al., 2009; McCullough, 1974). Given their restricted habitat and small population sizes, leopard cats on Iriomotejima Island and Tsushima Island have been listed as Critically Endangered in the Red List of the Ministry of the Environment of Japan since 2007, and those in Taiwan have been listed as Endangered under Taiwan's Wildlife Conservation Act by the Council of Agriculture since 2009. The population sizes on these three islands have greatly declined over recent decades. Increased anthropogenic pressures may be the primary threat to the persistence of leopard cats in insular habitats (Chen et al., 2016; Izawa et al., 2009).   
 
In the past, P. bengalensis was documented inhabiting natural habitats at low altitudes in Taiwan (Chen, 1956; Horikawa, 1931). However, adverse anthropogenic impacts constituting depletion of natural habitat (e.g. vehicle collisions, pesticide poisoning) as well as disease transmission and attacks from invasive mammals have resulted in a severe population decline since the 1970s (Ian, 1979; McCullough, 1974), eliciting concerns for population sustainability (Chen et al., 2019; Pei, 2008). Despite a relatively high tolerance to human disturbance and degraded habitats, leopard cats now appear to be limited to fragmented broad-leafed forests and abandoned orchards at altitudes lower than 1,500 m a.s.l in Western Taiwan (Chen et al., 2016; Pei, 2008). Radiotelemetry has demonstrated that leopard cats in Taiwan alter their hunting and resting behaviours to avoid anthropogenic infrastructure and areas with high human density (van der Meer et al., 2023), suggesting that human activity may have impacted their dispersal and connectivity. Nevertheless, the assumptions of population decline and discontinuity due to anthropogenic impacts have never been investigated using genetic analyses in Taiwan. Integrating mitochondrial and nuclear genetic information provides an opportunity to test hypotheses generated from radiotracking studies, which is critical for evaluating the conservation status of leopard cats in Taiwan and informing strategies to ensure their long-term persistence.
 
In landscape genetic studies, it is challenging to interpret how contemporary landscapes and historical demographic processes influence the genetic structure and gene flow due to the time lag problem (Bolliger, Lander, & Balkenhol, 2014; Epps & Keyghobadi, 2015), which refers to the time lag between the emergence of a landscape feature and when the impacts could be genetically detectable (Epps & Keyghobadi, 2015). Various molecular markers and approaches have been used to assess the effects of contemporary landscapes and historical events on genetic structures at different timescales (Epps & Keyghobadi, 2015), with one such approach being to combine genetic markers displaying different mutation rates (Pérez‐Espona, McLeod, & Franks, 2012). To address this issue, we combined nuclear microsatellites and mitochondrial sequences to unravel the historical and current factors influencing the genetic variation of focal species. 
 
As the only extant felids in Taiwan, leopard cats may play a crucial role as apex predators, contributing to ecosystem stability and trophic cascades (Pace et al., 1999; Terborgh et al., 1999). The conservation of leopard cats may also benefit the protection of local habitats and other species as an umbrella species. Our study is the first to focus on the individual-based landscape genetics of P. bengalensis on a subtropical island, aiming to identify fine-scale genetic boundaries among landscapes (Kierepka & Latch, 2015). Based on geographic distances and potential barriers (i.e., urban areas and mountain ridges) that may disrupt the connectivity of leopard cats in Taiwan, we also defined three geographic populations, i.e., Northern, Central, and Southern groups (Fig. 1). To comprehensively evaluate the conservation status of P. bengalensis in Taiwan, we performed population-based analyses on pre-defined populations based on known physical boundaries to assess population admixture, genetic diversity, and gene flow. We used 12 simple sequence repeats (SSRs) and mitochondrial cytochrome b (cytb) sequences to tackle the following population genetic objectives of leopard cats in Taiwan:
a) To depict population discontinuity, diversity, and gene flow to identify population boundaries and potential corridors.
b) To describe demographic history and assess the impacts of anthropogenic and natural landscape features responsible for population discontinuities.
c) To predict the influence of climate change on shifting distribution and to identify populations vulnerable to local extinction.