Semiconservative replication was not the only model of DNA replication proposed during the mid-1950s, however. In fact, two other prominent hypotheses were put also forth: conservative replication and dispersive replication.
Main idea. Aquatic ecosystems are grouped based on abiotic factors such as water flow, depth,distance from shore, salinity, and latitude. Freshwater ecosystems. The major freshwater ecosystems include ponds, lakes, streams,rivers, and wetlands.
In these next sections, we will look at how communities interact with a few other abiotic factors: the essential chemicals water, carbon, nitrogen, and phosphorous. Water is perhaps the most important component of any ecosystem. All living organisms need water to grow and survive. In an ecosystem, water cycles through the atmosphere, soil, rivers, lakes, and oceans. Some water is stored deep in the earth. Surface water, on the other hand, is the source that sustains life on land. In many cases, water also structures the physical habitat of an ecosystem. Polar bears, for example, rely on ocean ice in order to successfully hunt and capture seals.