• Endemic Species: Species native to a particular area. 🌲
• Alien Species: Species that humans bring to new places, either on purpose or by accident. Think of them like "unexpected tourists." 👽
• Invasive Species: Alien species that spread super fast and can sometimes cause chaos. Like that one friend who eats all the snacks at a party. 🍕
• Ecological Niche: It's like a species' job and address combined - where it lives and what it does there. 🏠+🛠️

• Density-Dependent Factors: Think of these as Mother Nature’s bouncers. 🚫 They make sure endemic species don’t get too crowded by limiting their population.
• Alien species & missing enemies: In their original home, they have pests and predators keeping them in check. But in their new area, those enemies might be missing. It’s like moving to a new city and realizing there's no one to tell you not to eat cake for breakfast! 🎂🌅
• When Aliens become Invaders: An alien species that grows super fast without controls becomes invasive. Imagine if everyone started playing their music loud in a quiet library! 🎶📚

If two species want the same "job" and "address" (ecological niche), eventually one will push the other out. Think of it like two people trying to be the lead singer in a band – eventually, only one can have the spotlight! 🎤