top-rated free essay

Mass Extinction

By chhiiaa02 Jul 22, 2013 750 Words
Extinction and Evolution
Ecology helps us understand the importance of mass extinction in evolution, and it also helps us understand some of the causes of extinction. Ecological niche is one of the most important concepts to understand. An animal or plant lives in a certain place is active at a particular times, and eats certain things; all these factors describe its ecological niche.

Our environment is parted into millions of ecological niches, each that represents a probable home for life. Taking advantage of new opportunities are what animals and plants will always try to do, so they will always try to make a home in an empty niche. To specify, only one animal or plant can have a certain niche. When two different organisms try to take the same niche they will compete for the same resources, and one will always try to out-compete the other. When the species is extinct and there is an empty niche, there will be a race to fill it. Mass extinctions open up a swarm of niches, and there is evolutionary explosion as animals and plants adapt to fill the vacant homes.

As we all know the environment of the Earth is always changing which might have led to some niches being destroyed, making the species that have took it to extinction. A fall of sea level might lead to loss of shallow seas, so the species that made the niche in shallow seas home might become extinct, or evolve into forms adapted to the new environment. On the other hand, if two continents crash to form one, larger continent, then the niches of two continents can merge, no longer separated by a barrier. This leads to competition between the two species for the same niche, and can cause the extinction of one.

The dinosaurs did not survive on Earth. How is it that mammals and many birds did? Of course millions of species and thousands of types lower in the phylogenetic tree survived as well even though millions more went extinct. The basic rule of evolution is that the fittest organisms (species) will differentially survive and produce, thus out competing the less fit. But fitness is in place to the conditions of the environment and niche of the species. The continents have always been shifting. The local ecologies have always been changing, sometimes speedily, more often gradually. The more rapid changes are the ones that stress species and provide the major distinguishing forces that do the selecting. And then some species are more able to operate under the changed conditions and compete against rivals for the niches available more magnificently.

The End-Cretaceous Event appears to have been an equally unexpected one by physical and climatic criteria. The usual current hypothesis holds that the event was activated by an asteroid of enough mass slamming into the Yucatan around 65 mybp. Recent evidence adds strength to this hypothesis. The cataclysm had global effect, what is now called a nuclear winter-like wonder that so brutally changed Earth's climate that the food sources for the dinosaurs died back dramatically, therefore the dinosaurs were no longer fit. Selection did the rest. Punctuated equilibrium has been presented as a ranked theory of evolution. Supporters of punctuated equilibrium see speciation as analogous to mutation and the replacement of one species by another as analogous to natural selection. This is called species selection. Speciation adds new species to the species pool just as mutation adds new alleles to the gene pool. Species selection favors one species over another just as natural selection can favor one allele over another. Evolutionary trends within a group would be the result of selection among species, not natural selection acting within species Many species of mammals and birds also went extinct. But no dinosaurs other than birds survived. Several hypotheses have been progressive to explain this occurrence as well. Between them have been the general average sizes of birds and mammals, which were much smaller than the average dinosaur and that size difference plus metabolic energetics gave smaller birds and mammals an advantage. Other hypotheses involve the fact that most mammals, at the time, were burrowers so might have been protected from the harsher features of the climate changes.

* * *


Cite This Document

Related Documents

  • Mass Extinctions Research Task

    ...Mass Extinctions What is the biological significance of mass extinctions? PART A You are living in the 23rd century. All knowledge of scientific things have been hidden from the human race by evil dictators during the last 2 generations of humans. One brilliant scientist, Albert Einstein the 16th, has rebelled against the dictators. He ...

    Read More
  • The Role Od Extinction in Evolution

    ...The Role of Extinction in Evolution In contrast to the opposite phenomenon, speciation. This is surprising in view of the special importance Darwin attached to extinction, and because the number of species extinctions in the history of life is almost the same as the number of originations; present-day biodiversity is the result of a trivial s...

    Read More
  • The Significance of Mass Extinctions

    ...Question 1 How significant are mass extinctions to living organisms? Mass extinctions are very important events to the living organism. When mass extinction happens, it will create huge impact toward the world, negative or positive. For the conservation biologist, they usually think this is a great loss. On the other hand, from the evolutiona...

    Read More
  • Mass Extinction

    ...Extinction is the end of an organism or group of taxa.  Extinctions occur when a species becomes unfit for survival in its natural habitat usually to be replaced by another, better-suited species. An organism becomes ill-suited for survival because its environment is changed or because its relationship to other organisms is altered as stated fr...

    Read More
  • Causes of Animal and Plant Extinction, and Its Effects on Humans

    ... Animals and Plants Extinctions causes and effects on human Nowadays , animal extinction is a broad issue, one that involves the habitats and environments where other species live and interact with one another . Only a minority of people are concerned with extinction in today痴 society, while others might argue that it is a sma...

    Read More
  • Mass Extinction

    ...Physical Geology Essay Assignment: Mass Extinctions Topic: The Cretaceous - Tertiary extinction Submitted by Suhaidee Yusoh ID No. 15240 Petroleum Geosciences UNIVERSITI TEKNOLOGI PETRONAS The Cretaceous-Tertiary extinction 1. Introduction Fastovsky, D.E. and Weishampel, D.B., 2005 defined the mass extinction “Mass extinctions involve lar...

    Read More
  • Mass Extinctions on the Earth

    ...Intro: Sixty-five million years ago, some phenomenon triggered mass extinctions on the lands and in the oceans so profound that they define the geological boundary between the older Mesozoic Era, often called the "Age of Reptiles," and the modern Cenozoic Era, the "Age of Mammals." On a finer scale, the extinctions define the boundary between th...

    Read More
  • The Cretaceous – Tertiary Boundary (K-T) Extinction

    ...ABSTRACT Several mass extinctions have occurred during the Earth's history. The Cretaceous – Tertiary Boundary (K-T) Extinction caused the loss of at least three-quarters of all species known at that time including the dinosaurs. The cause of this mass extinction is a controversial subject among scientists but the fossil evidence of it's occur...

    Read More

Discover the Best Free Essays on StudyMode

Conquer writer's block once and for all.

High Quality Essays

Our library contains thousands of carefully selected free research papers and essays.

Popular Topics

No matter the topic you're researching, chances are we have it covered.