Interspecific relationships, which represent the interactions and coevolutionary behaviors between plants and other organisms in a habitat
[8]. Similar relationships exist in enterprise populations, including competition, cooperation, mutualism, parasitism, commensalism, etc.
[14]. These relationships have significant impacts on the enterprise populations and the entire business ecosystem. Numerous scholars focus on interspecific relationships between enterprise populations. Mathematical methods such as the logistic model and the Lotka–Volterra model are involved in studies on enterprise interspecific relationships to conduct quantitative research on enterprise populations
[15,16,17][15][16][17]. For e-cigarettes, a new industry that lacks data and research, it is necessary to characterize the relationship between the enterprise populations for future works. After years of development, a complete industrial chain, including upstream, midstream, and downstream, has been established in the Shenzhen e-cigarette industry. Relationships between enterprise populations along the industrial chain are complex. Mutualistic symbiosis exists behind their competition behaviors. Coevolution achieved by mutualism is an important relationship between enterprises in the business ecosystem, which is conducive to the stability and development of the whole ecosystem
[18]. Hence, this study focuses on interspecific relationships between different e-cigarette enterprise populations, especially their coevolution behavior achieved by mutualism.
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3. Niche Theory
A niche, which describes the roles, functions, and impacts of species in the environment, is a fundamental concept in ecological study. In the 1970s, niche theory was introduced in management science, and an “enterprise niche” was proposed by scholars
[19]. Quantities of literature explain the concepts of an enterprise niche. From the static level, an enterprise niche represents the space and environment occupied by enterprises
[12,20,21][12][20][21]. From the dynamic level, an enterprise niche is the capabilities of enterprises to engage in survival, development, and competition, in which core technological capability and manufacturing capability play vital roles
[22]. Recent literature combines both the static and dynamic attributes of enterprise niches. The former are the resources controlled by enterprises. The latter are the impacts enterprises have on the environment and the capabilities of enterprises for competition and development
[23].
The niches of organisms are often characterized by the niche breadth and overlap. For the niche breadth, different biological interpretations have been proposed by different ecologists
[24,25,26,27,28,29][24][25][26][27][28][29]. The niche breadth of a species can be estimated by measuring the uniformity of the distribution of individuals of that species in the resource matrix
[30]. According to this principle, Levins established Levins’ standardized niche breadth index for niche breadth metrics
[31]. Levins’ index was developed by other scholars from the perspectives of resource availability and resource matrixes
[30,32][30][32]. Additionally, varieties of niche measurement approaches were also proposed by follow-up researchers, such as Pielou’s index, Petraitis’ index, and Hurlbert’s index
[25,33,34,35,36][25][33][34][35][36]. Niche overlap is defined by previous literature from many perspectives, such as resource utilization, interspecific similarities, and interspecific encounter frequency
[25,30,37,38][25][30][37][38]. This study adopts niche overlap as the joint use of resources by two or more species
[30]. Approaches of niche overlap measurement include Pianka’s symmetrical niche overlap index, Levins’ asymmetrical niche overlap index, Hurlbert’s encounter-frequency-based niche overlap index, etc.
[25,31,39][25][31][39]. In addition to their widespread application in ecology, the niche breadth and overlap are also introduced by scholars in the evaluation of enterprise niches in recent years
[40,41,42,43,44,45][40][41][42][43][44][45].
As an emerging industry, the Shenzhen e-cigarette industry is at the peak of product R&D (research and development). Therefore, technological innovation plays a crucial role in enterprises’ development. Simultaneously, there is also a change in the market structure of the industry and competition between the enterprises is becoming increasingly fierce. With the intensification of competition, the environmental suitability and scalability of e-cigarette enterprises in the business ecosystem are also changing, that is, the enterprise niche is in variation. Technological innovation is important for e-cigarette enterprises to improve product quality, enhance the efficiency of resources’ utilization, and thus occupy favorable niches. For e-cigarette enterprises, the innovation-related niche breadth represents resources that they have occupied in different innovation orientations, and innovation-related niche overlap refers to resources jointly utilized by two enterprises.