Final answer:
Between ferns and gymnosperms, a major reproductive change is the shift from spore production in ferns to the development of seeds in gymnosperms, along with a reduction of the gametophyte generation and independence from water for fertilization.
Step-by-step explanation:
A major change in reproduction from ferns to gymnosperms is the evolution from spore-based to seed-based reproduction. Ferns, which are part of a group known as seedless vascular plants, produce spores that germinate to form a free-living, independent gametophyte generation. These gametophytes produce flagellated sperm that require water to swim and fertilize the egg. In contrast, gymnosperms represent a significant evolutionary step in which the gametophyte generation is reduced and is no longer free-living, but rather exists as a microscopic entity within the structures of the sporophyte: the seeds and pollen.
Gymnosperms, like conifers, possess male and female cones where male gametes, or pollen grains, are spread by wind, negating the need for water in fertilization. This adaptation was crucial for the successful colonization of dry land. Essentially, gymnosperms' reproductive strategy includes the production of seeds, which enclose and protect the developing embryo, facilitating the distribution of offspring and enhancing survival in various environments.