Final answer:
The mechanism that enables traits to pass unchanged across generations is the inheritance of genetic material, DNA, a concept clarified by Gregor Mendel. Mendel's work overturned the incorrect blending theory of inheritance, showing that distinct traits are passed down without blending, a principle of discontinuous variation.
Step-by-step explanation:
The mechanism for continuity that allows traits to pass unchanged across generations is the inheritance of genetic material, specifically DNA. Gregor Mendel's foundational work on genetics, which went largely unnoticed during his lifetime, clarified the process by which traits are passed down. Unlike the previously held belief in the blending theory of inheritance, Mendel established that traits are inherited in distinct classes and maintain their distinctness across generations, a concept known as discontinuous variation. This is contrary to continuous variation, where many genes work together, making offspring appear as a 'blend' of parental traits.
The continuity of traits across generations relies on stable genetic material within cells. When genes are passed from parents to offspring, they ensure that species continue with specific characteristics, maintaining distinction and continuity amongst species. Mutations or changes in these genetic messages lead to evolution over time.