The availability of many types of plants and animals on earth refers to the diversity of life. There are many kinds of species, from plants to animals to insects to bacteria. However is significant that individuals are also of different species from each other. Therefore, this paper is entirely to discuss the causes of many different types of plants and animals on earth. The key aspects in this paper are speciation, dispersal, and species interactions. The community structure of species will also be discussed. In addition, the paper is to elaborate on key concepts and theories of the living world.

The existence of many types of plants animals on earth refers to species diversity or ecosystem diversity. Species diversity according to Wilson in his book ‘The Living World’, he denotes it as a result of speciation. Speciation refers to interbreeding between living organisms. For instance, insects of one species are mostly incapable of interbreeding of other species. However, he denotes that there may be emergence of a new species if there is an interbreeding between different species. The emergence of a new species thus leads to ecosystem change in structure and consumption of resources. Speciation is common in plants than in animals (Miller and Spoolman, 2011, pg. 371)

The neutral theory denotes that dispersal and speciation are a leading cause of ecosystem diversity. Dispersal is a critical aspect in species diversity as pt plays a key role in movement of different species from one place to the other. Longitudinal gradients give the difference in the number of species a given ecosystem can support. For instance, the tropical ecosystems have a wide range of species that gradually support luxuriant life. Species dispersal refers to the change of a species’ ecosystem. This may be as a result of high competition for available resources that may lead to extinction. Therefore, the species rehabilitates to a new ecosystem (Miller and Spoolman, 2011, pg. 111). Moreover, in the new ecosystem there is change in climate and maybe interbreeding resulting to rise in different species.

Species interaction is yet another cause of many kinds of plants and animals on earth, biological interaction. This refers to the ecosystem relation between species especially over resources and materials. There are various ways in which species in an ecosystem interact. Inhibition is one of the ways and involves equal competition over resources. Mutualism encompasses species interaction through co-existence over each other. A new species can emerge through competition if it overrules the ecosystem and interbreeds with other less significant species. Other forms of interaction include predation, inhibition, and commensalism (Miller and Spoolman, 2011, pg. 278).

The neutral theory suggests community structure or community assembly as a reason for addition of new species into an ecosystem. The dynamics of an ecosystem plays a considerable role in species diversity. Similarly, functioning species like trees in a forest are able to give to raise a new species of trees. This is because the forest assembly contain the tree family that can biologically reproduce. The community`s facilitation, for example, forest by agents of pollination and species interaction. The environment is an Agent of Selective Pressures referring to the phenomena that alter the fitness and functioning of an organism (Miller and Spoolman, 2011, pg. 301). The selective pressures may be climate change and diseases. This may lead to a rise of a new species of organism. The community structure thus imposes a significant contribution in new species introduction to the environment.

In conclusion, there are thousands of new species of plants and animals introduced on earth each year. This is due to the prevailing conditions and pressures within the organism` ecosystems. The result of new species can be observed from environmental selective pressures, speciation, species interactions, community structure and dispersal (Miller and Spoolman, 2011, pg. 89). Therefore, new species on earth is a continuous biological process resulting from the natural causes.

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