The primary factor influencing the distribution of organisms is environmental conditions, which includes aspects like climate, temperature, and available resources such as water and nutrients. These conditions determine the habitat suitability for different species, affecting where they can survive and reproduce. Organisms adapt to their environments over time, allowing them to thrive under specific conditions while others may be excluded. Consequently, changes in environmental parameters—such as climate change or habitat degradation—can lead to significant shifts in species distributions, impacting biodiversity and ecosystem stability.