Biodiversity types. Genetic Diversity| Species Diversity | Ecosystem Diversity.

Researchers generally accept three levels of biodiversity:1- genetic Biodiversity., 2-species Biodiversity., and 3-ecosystem Biodiversity. These levels are all interrelated yet distinct enough that they can be studied as three separate components. Some researchers believe that there are fewer or more levels than these, but the consensus is that three levels is a good number to work with. Most studies, either theoretical or experimental, focus on the species level, as it is the easiest to work on both conceptually and in practice. The following parts will cover all levels of diversity, though examples will generally use the species level.

1- Genetic diversity is the variety present at the level of genes. Genes, made of DNA (right), are the building blocks that determine how an organism will develop and what its traits and abilities will be. This level of diversity can differ by alleles (different variants of the same gene, such as blue or brown eyes), by entire genes (which determine traits, such as the ability to metabolize a particular substance), or by units larger than genes such as chromosomal structure. 

 Genetic diversity can be measured at many different levels, including population, species, community, and biome. Which level is used depends upon what is being examined and why, but genetic diversity is important at each of these levels. 

2- Species Diversity. Species are well known and are distinct units of diversity. Each species can be considered to have a particular "role" in the ecosystem, so the addition or loss of single species may have consequences for the system as a whole. Conservation efforts often begin with the recognition that a species is endangered in some way, and a change in the number of species in an ecosystem is a readily obtainable and easily comprehensible measure of how healthy the ecosystem is.  Biodiversity studies typically focus on species. They do so not because species diversity is more important than the other two

 3-Ecosystems Diversity: Ecosystem-level theory deals with species distributions and community patterns, the role and function of key species, and combines species functions and interactions. The term "ecosystem" here represents all levels greater than species: associations, communities, ecosystems, and the like. Different names are used for this level and it is sometimes divided into several different levels, such as community and ecosystem levels; all these levels are included in this overview. This is the least-understood level of the three described here due to the complexity of the interactions. Trying to understand all the species in an ecosystem and how they affect each other and their surroundings while at the same time being affected themselves, is extremely complex.
One of the difficulties in examining communities is that the transitions between them are usually not very sharp. A lake may have a very sharp boundary between it and the deciduous forest it is in, but the deciduous forest will shift much more gradually to grasslands or to a coniferous forest. This lack of sharp boundaries is known as "open communities" (as opposed to "closed communities," which would have sudden transitions) and makes studying ecosystems difficult, since even defining and delimiting them can be problematic.
Some researchers think of communities as simply the sum of their species and processes, and don't think that any of the properties found in communities are special to that level. Many others disagree, claiming that many of the characteristics of communities are unique and cannot be extrapolated from the species level. Examples of these characteristics include the levels of the food chain and the species at each of those levels, guilds (species in a community that are functionally similar), and other interactions.