Evolution, Niche and Biodiversity-Why The Dinosaurs Died Off:

From a scientific point of view, evolution is the study of genetic change within a species, nothing more and nothing less.

Biodiversity is the mapping of variation of organisms within a geographic area, biomes or even on the entire plant. A good way to look at the definition of biodiversity is to think about humans. Humans inhabit nearly every geographic area of the earth. The biodiversity of the human organism is measured on a global scale/region. In comparison, the biome of an endemic species of the Galapagos would be the Galapagos Island where the organism resides.

Biogeography is the study of the spatial relationships between the organism and their environment, or the characteristics of their environment that enable the organism to thrive but restrict the colonization of the organism outside of the geographic biome.

The dinosaurs are a broad group of organisms that range in size from tiny to extremely large. Some were terrestrial, some were aerial, some resided only in the waters and some survived in both the waters and on land. In short, we are talking about a very wide set of bio-diversification within the known species of dinosaur.

This article is going to look at the dinosaur, their niche habitats, the evolution of species (not dinosaurs), the destruction of the dinosaurs, and the impact of change within biomes.

A habitat is a environmental area that a species of organism lives in. It is the natural and physical relationship between the organism and the environment and the subsequent relationship between the two. A niche is defined as what an organism does within its habitat, when it does it, how it does it, and why it does it. "It" being the variable of activity. What does the organism eat? Where does the organism sleep? What are the geographic barriers that prevent the organism form colonizing elsewhere? What are the elements of the niche that make the organism dependent upon the niche or habitat?

Organisms that share habitat must compete for resources found within that habitat. This is how and why specialization of niche occur. The larger the organism the more resources it takes for the organism to survive. Compare for example the dietary intake of an average human to the dietary intake of parakeet. Not only are the two diets very different there is a vast difference in the amount of food that is eaten each day by both species. Humans and parakeets could live within the same habitat because both develop separate niches or methods of utilizing resources within that habitat. Humans typically do not eat the same seeds as the parakeet, though they may eat the parakeet, the parakeet on the other hand does not eat the same foods as the human. Both are utilizing different resources with the habitat and those differences help to define the niche of each species.

The Mesozoic era, which occurred for roughly 185 million years, is known as the age of reptile. This is because reptiles were the primary organism (vertebrates) to inhabit both the land and the oceans. The Mesozoic period is snuggled in between Permian-Triassic event and the Cretaceous-Paleogene event. Both events are documents as mass extinction events within the geological record.

The number of dinosaur species that inhabited the earth was vast. For the pure sake of simplification lets just say there were diversified species that inhabited the waters, the land and the sky. Development of niche within each of these ecosystems was complex and overlapping. The general food pyramid would include a vast majority of plant eaters, a lesser number of dinosaurs that ate both plants and animals and an even smaller percentage of pure carnivores. This has to do with how much resource it takes to survive not only within a niche but within the biological functions of every day life. It takes a lot to feed a T-Rex and a lot to feed a brontosaurus. This means that to feed a T-Rex, the landscape had to be rich in plant life because what did the T-Rex eat? Brontosaurus... well.. smaller herbivore, omnivore and the occasional carnivore. So the niche of the T-Rex included everyone as a food source but the niche of the Brontosaurus was specifically made up of plants. Two dinosaurs, two different and non-competing food sources, both Extinct.

We have mentioned that there were a great many different species of dinosaurs. Each with its own function and niche within the environment and habitat. If we leave the dinosaurs for a bit and we look at species that are isolated within a biome we begin to see how species specialize and adapt to the niche. An isolated biome has very limited amounts of resources. What happens in this case is the number of resources have to be shared by all the species and those species that survive and thrive develop a method of utilizing more of the resources available or utilizing resources that other species can not use.

Why are Darwin's Finches important? They are important because they show how a species will evolve genetically as a means of natural selection. Natural selection is the process by which species thrive or do not thrive within their niche. Those that are not able to adapt to the niche die off because they are not able to obtain enough resource from the niche to survive. This means on a genetic level that those organisms within a species that can adapt, consumer more of the resources and their genes are passed on through reproduction. As a result the gene pool becomes enriched with the genes of successful species and the species that can not adapt to the changing environment die off. As a result, the genetic code of the species changes so that eventually you have a new species. With Darwin's finches, this is shown through the comparison of the birds that were found on the isolated islands and those birds found on mainland. Both were the same at one time but through isolated biome one set changed or adapted. This is the crux of evolution. With the dinosaurs, natural selection occurred as a means of normal control of non-isolated niche and not as a means of evolutionary change... for the most part.

As mentioned earlier, the Mesozoic Era sits between two mass extinction periods. The end of one period enabled the dinosaur to flourish and the beginning of the other caused their rapid extinction. Or did it? There are many theories about what happened to the dinosaurs but through scientific examination, many of those theories have been proven to be false. Below is the process by which the theory of massive Tsunami caused the extinction of the dinosaurs is proven to be false. Have a look.

What is uncovered here in terms of evidence is the geologic record of not one asteroid impact, but two. The span of time separating the two impacts are millions of years. If we go back and look at species dependency on niche, then we can begin to see how the first impact changed the ecosystem on a great and rapid manner. So within the span of time following the first impact, you would see massive changes in temperature, plant life, and other factors that allow the organisms to survive within their niche. Through natural selection, some of those organisms may have survived the rapid change in environment and began the process of genetic evolution. Those species that can adapt, live to survive, while those species that can not adapt die off and become extinct.

The time that is needed for genetic evolution can be as short as a generation or as long as a millions of years. Following the first impact specialization of species may certainly have occurred within the dinosaur population as with all the other organism of that time period. Those species that survived would have had 300 thousand years between the impact of the first meteorite and the second to adapt.

Following the first impact, we would see massive destruction of niche environment and substantial disruption of the ecosystem within the biosphere, hydrosphere, atmosphere, geosphere. The times they are a changing! The problem here is that the time frame is immediate and the disappearance of resources devastating. There is no time for genetic evolution to occur (for most species) and the dinosaurs began to die off and go extinct. The recovery period that the earth must have gone through would have allowed those dinosaurs that survived the first impact to begin the process of adaptation to the new environments. It seems logical that while some species were going extinct, others were beginning to thrive. A great change within the balance of organisms likely occurred. Without time, genetic evolution can not occur.

The K-T Line provides a geological record for what is probably the cause of the extinction of the dinosaurs. The second impact is what finished off the dinosaurs, but the inevitable is already written. Even without the second asteroid and the devastation that its impact, the fossil record suggests that the earths terrestrial changes were already causing extinction. Whether or not those geological changes were the result of the first impact or just part of the natural development of the global environment, it is not known.

Regardless, of which impact, there is fossil evidence of the mass destruction of niche. With the destruction of niche environment the available resources available become next to nothing. It is likely that the impact caused the earths vegetation to die. This means the the plant eating dinosaurs have nothing left to eat and they die off and go extinct too. Since the carnivorous dinosaurs, which eat the plant eating dinosaurs, die off as the plant eaters go extinct. The massive changes prevent genetic evolution because there is not time for change. The impact force caused massive change almost instantaneously. The factors that affect biodiversity and biogeology also changed instantly. Niches were wiped out, specialization became obsolete as the environment changed.

While evolution occurs on a genetic basis it requires time. Specialization through adaptation is the result of changes within genetic attributes of species from generation to generation. Extinction may occur over time or suddenly. What happened to the dinosaurs was a series of massive changes within their environments and their niche. Not everything became extinct as the dinosaurs died off. Smaller creatures that required less resource survived and then adapted to fill the niche as the changes in the environment created new resources. The process is much the same as Darwin would later discover with his finches. Adaptation is the key but it requires time. As I close out this hub I will leave you with this final video...