Evolution and selection what mechanisms lead to changes in the diversity of species on earth?

The answer is genetic drift and genetic shift. The former occurs when small changes occur in the genotype of a population that accumulates over time and changes the allelic frequency of the population. The latter (genetic shift) occurs abruptly and is usually caused by a bottleneck effect.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.

segmentation=endoskeleton=backbone=coelom=tissues