Food Webs During Mass Extinction

“A minority disputes this theory, arguing that other events-such as volcanic eruptions, sea-level changes or a series of impacts-were to blame for the spectacular loss of species that occurred at the transition between the Cretaceous and Tertiary periods…”

The organisms found in temperate forest ecosystem are trees: producers, plants: producers, insects: consumers and decomposers, squirrels: consumers, deer: consumers, bears: consumers, foxes: consumers, and birds: which consumers and decomposers. The rewards of this biodiversity are the survival of life is certain and will maintain to live in connection with the organism. Essential nutrients are supplied by plant life eaten by herbivores that are then eaten by carnivores, which keep the food chain going. Producers, consumers, and decomposers are the major three categories of organisms found in the temperate forest system. Producers consists of trees,

The scale and pace of change is dramatic; for example, the extinction of species is occurring at around 100-fold pre-human rates4. The population sizes of vertebrate species have, on average, declined by half over the last 45 years5. More than 2.3 million km2 of primary forest has been felled since 20006. About

The question of what caused the extinction of megafauna during the Late Pleistocene period is one that archaeologists have struggled to answer for decades, but why should it matter? Discovering with certainty the cause of megafaunal extinction would

8. The periods in which there were mass extinctions are Permian – volcanic eruptions which spewed lava and put CO2 into the air which warmed the climate an estimated 6 degrees Celsius. The resulting of oxygen deficiency. And Cretaceous – asteroid or comet

-Reintroduction of a top predator lowered the number of over grazing herbivores, leaving a more stable amount of food for many species of herbivores.

In the book The Sixth Extinction written by Elizabeth Kolbert there are a lot of examples that are going on in the world today and also examples of things that started when the first human being was around. This book talks about how we are in the sixth mass extinction, and that is caused by humans. Overall the book goes chapter by chapter and talks about the different mass extinctions there have been, and how they were caused, but also the book talks about different species that have gone extinct and the reasons why. For example the book talks about golden frogs that are located in Panama and how they were seen everywhere located in El Valle de Anton, but they suddenly started disappearing. They were disappearing because of a chytrid fungis cause by humans, when humans travel they were bring this fungis to different places, this ended up killing the frogs (Chapter 1, Kolbert). That is just one example, but throughout the book Kolbert talks about different extinctions like this and what caused them.

Earth’s vegetation and animal life are all part of an intricate “web” of essential relations in which both cannot survive without the other. According to Campbell’s Biology textbook, The transfer of food energy up the trophic levels is referred to as a food chain. This chain usually begins with plants, (primary producers), then herbivores, (primary consumers), to carnivores (secondary, tertiary and quaternary consumers), and finally decomposers. When one part of the chain is low in population, the species above it are likely to be negatively affected and will likely drop in population as well. In order to show how delicate this web is, and how human activity has affected this system, Carson describes a small food chain in which sagebrush

The concept of species going extinct was not always accepted as fact. It wasn’t until the discovery of the American mastodon that the concept of extinction was even considered. With the discovery of the bones, When the bones were discovered, many theories were constructed, such as that the bones were actually from multiple creatures, or that this was simply an undiscovered species and hadn’t been found. The discovery of other mysterious, lost species led to the concept of extinction, and the idea that the mammoth was indeed a species that, while it once was prevalent, no longer roamed the Earth. In chapter three, Kolbert writes about her visit to Iceland in which she learned about the loss of the great auk, a three foot tall bird reminiscent of a large penguin or puffin. She then proceeds to write the tragedy of the great auks, that being that they were regularly hunted and killed. The final moments of the great auk’s species can be tracked down, as they were captured and sold and their only egg was broken. The concept of human-caused extinctions wasn’t new, as Darwin wrote about how the Galápagos tortoises were dying out very rapidly due to overhunting. The extinction of species stems from events that drastically affect them, be them environmental changes to human

The overkill thesis may be after all a bogus clarification of the late pleistocene extinction with humans as the main driving force behind it, namely due to excessive over-hunting. Two things which may go against Martin’s idea of overkill is the assumption that the animals too small or environmentally

Species within food webs are interconnected in many complex ways that may not be visible to those who are not actively studying these relationships. As a result, modifying one level of the food web can cause unintended consequences when the entire food web is into taken account. Hoping to protect their crops, the ranchers were justified in their actions: their motive to remove prairie dogs from the area was driven by their need to yield a greater amount of crops, not by a malice to eradicate a species.

Dinosaur extinction: An analysis of events and theories that possibly led to the dinosaurs' demise.

It’s clear that a great extinction is coming from the evidence of the destruction of other species around us. The choices made by the human race have too often negatively affected the surrounding species. Tracy Wilson, the site director for HowStuffWorks.com, in an article for Animal Planet, states that

Scientists abase their extinction theories off one of commonly known piece of information: that there was a change in climate around the time of the K-T boundary. Both major theories support this idea, and both believe that something blocked out the Sun for many months. This stopped the photosynthesis in plants, the base of the food chain. Without plants, the food chain was majorly affected. A domino effect happened, and one species died out after another. Eventually all species of dinosaurs died out. Scientists know that there was a global climatic change, but are not sure how it happened.

This final blow would have sent earth into a nuclear winter. According to this theory, dust caused by the asteroid collision disrupted plant growth by blocking out the sunlight needed for photosynthesis for nearly a year. A chain reaction occurred as plants died off, so did the herbivores relying on the plants, and then the carnivores that relied on the herbivores. Around 75% of species became extinct, including dinosaurs, mammals, giant marine lizards, fish, birds, and insects. Meanwhile, seawater flooded around 40% of the world’s continents ("Mass Extinctions").