An isocline is a line on a graph that represents points where a particular variable, such as population density or temperature, remains constant. In ecology, isoclines are often used to illustrate the relationship between two species, showing where their growth rates are equal. This helps researchers understand how different species interact and coexist in an ecosystem. In mathematics, isoclines can be used in differential equations to visualize solutions. By plotting isoclines, one can identify the behavior of a system over time, making it easier to analyze stability and changes in variables. This concept is valuable in various fields, including biology, economics, and engineering.