Ecosystems are made of a complex system of energy and nutrient transfers from one organism to another. Some of these transfers are in the form of predation: one organism eating another – while others are in the form of ecosystem engineering, an organism changing the environment around them. One major form of ecosystem engineering is niche creation, the process of an organism changing its environment to create a competitive advantage. In order for an organism to be considered as creating a niche, three things must be true: the organism must significantly modify its environment, those changes must affect other organisms’ survival, and those changes must lead to an evolutionary response in another organism. 1

One of the world’s most influential “niche constructors” - species known for changing the environment around them - is the earthworm, an organism found almost everywhere on the planet. Earthworms were originally aquatic organisms that were ill-equipped to survive on land. A scientist only concerned with evolution would predict that, in order to live on land, earthworms would have to significantly change. Earthworms didn’t change their physiology a great amount, however, instead, they changed the soil to make it more like the ocean in order to survive. Land with earthworms is less compacted, is more nutrient rich, and is better mixed than land without them, leading to monumental changes in the ecosystem.

To be considered true niche constructors, however, earthworms must change the environment in such a way as to alter the evolution of another species. One of the easiest ways to measure this effect on evolution is in the effect that the number of earthworms has on soil fertility, a measure of how hospitable an environment is to plant growth. Even the least fertile soil has around 62 worms per square meter, and as the number of worms increases so does soil fertility. As worms move through the different layers of soil, they eat, digest, and excrete massive amounts of organic matter. They leave their excretions behind in the form of nutrient-rich droppings known as casings. As these casings decompose, they release nutrients into the soil. This process not only moves nutrients from one layer of the soil to another but also converts the nutrients to forms that plants can absorb and process more easily. Because it is easier for plants to get the proper nutrients, plants don’t have to invest time and energy into making better root systems to gather nutrients. As a result, plants have, over time, lost some of these mechanisms – a form of evolution.

Without earthworms, modern land-based ecosystems would look very different. There is no way to predict the exact changes that would exist without earthworms, but it is easy to recognize earthworms’ impact. As research continues into the effect of earthworms, scientists are confident that it will show an even more complex picture of the earthworm’s contribution to the land-based ecosystem.

The author is considering the addition of the following table:

The table above outlines the unique ways in which several organisms have impacted their ecosystems to the benefit of other species.

Should the author make this addition?

The public’s perception of archaeologists has, for years, been colored by depictions of the profession in movie franchises like Indiana Jones, Tomb Raider, and The Mummy. However popular these movies are, they– like movies that depict any other profession – don’t necessarily reflect what archaeologists actually do. While fighting supernatural forces and foiling nefarious plans does make for a better movie, the primary work of archaeology is in research and preservation

The traditional view of archaeologists usually involves a college professor who spends much of his or her time digging and researching in ancient foreign libraries or a museum curator who works every day to preserve the artifacts the museum holds. While this view isn’t completely incorrect, it is incomplete, both in terms of the types of jobs available to archaeologists and in terms of the types of work within those jobs. For example, college professors may spend summers at dig sites, but much of their time is also spent writing grants, teaching students, and writing about their research projects. Additionally, although there are still many people who work in archaeology as professors and museum curators, the demand for these job far outstrips the number of positions available, making the positions difficult to acquire.

\[1\] The job of CRM archaeologists is to identify the potential cultural significance of a site and then document and preserve any artifacts of historical or cultural significance. \[2\] The surplus of people who want to work in archaeology has meant that the majority of archaeologists aren’t employed by universities or museums, but by construction companies and the government. 1 \[3\] Most archaeology positions in today’s economy are for what are referred to as a “cultural resource management” archaeologists, or CRM archaeologists, who are often involved in building projects as representatives of the state, Native American tribes, and historical societies. \[4\] While part of this analysis might involve starting a dig at the site in question to find relevant artifacts, much of this research process requires CRM archaeologists to consult historical records and talk to members of the community where the building process has been proposed.

At this point, the author is considering inserting the following graph.

Should the author make this addition here?

The public’s perception of archaeologists has, for years, been colored by depictions of the profession in movie franchises like Indiana Jones, Tomb Raider, and The Mummy. However popular these movies are, they– like movies that depict any other profession – don’t necessarily reflect what archaeologists actually do. While fighting supernatural forces and foiling nefarious plans does make for a better movie, the primary work of archaeology is in research and preservation

The traditional view of archaeologists usually involves a college professor who spends much of his or her time digging and researching in ancient foreign libraries or a museum curator who works every day to preserve the artifacts the museum holds. While this view isn’t completely incorrect, it is incomplete, both in terms of the types of jobs available to archaeologists and in terms of the types of work within those jobs. For example, college professors may spend summers at dig sites, but much of their time is also spent writing grants, teaching students, and writing about their research projects. Additionally, although there are still many people who work in archaeology as professors and museum curators, the demand for these job far outstrips the number of positions available, making the positions difficult to acquire.

\[1\] The job of CRM archaeologists is to identify the potential cultural significance of a site and then document and preserve any artifacts of historical or cultural significance. \[2\] The surplus of people who want to work in archaeology has meant that the majority of archaeologists aren’t employed by universities or museums, but by construction companies and the government. 1 \[3\] Most archaeology positions in today’s economy are for what are referred to as a “cultural resource management” archaeologists, or CRM archaeologists, who are often involved in building projects as representatives of the state, Native American tribes, and historical societies. \[4\] While part of this analysis might involve starting a dig at the site in question to find relevant artifacts, much of this research process requires CRM archaeologists to consult historical records and talk to members of the community where the building process has been proposed.

At this point, the author is considering inserting the following graph.

Should the author make this addition here?

The traditional view of archaeologists usually involves a college professor who spends much of his or her time digging and researching in ancient foreign libraries or a museum curator who works every day to preserve the artifacts the museum holds. While this view isn’t completely incorrect, it is incomplete, both in terms of the types of jobs available to archaeologists and in the types of work within those jobs. For example, college professors may spend summers at dig sites, but much of their time is also spent writing grants, teaching students, and writing about their research projects. Additionally, although there are still many people who work in archaeology as professors and museum curators, the demand for these jobs far outstrips the number of positions available, making the positions difficult to acquire. 1

The author is considering adding the following table to the end of this paragraph:

| | Construction Companies | Governmental Agencies | Museums | Universities | | | ------------------------- | --------------------- | ------- | ------------ | ------ | | Applicants | 14,138 | 12,415 | 9,884 | 15,232 | | Jobs Filled | 9,224 | 5,380 | 766 | 2,014 | | % of applicants hired | 65% | 43% | 8% | 13% |

The table above details the number of applicants for archaeology-related positions and the number of archaeology-related jobs filled for the year 2018 in the United States.

Should the author makes this addition?

One of the easiest ways to see the way that earthworms change their environment is in the effect that the number of earthworms has on soil fertility, a measure of how hospitable an environment is to plant growth. Even the least fertile soil has around 62 worms per square meter, and as the number of worms increases so does soil fertility. As worms move through the different layers of soil, they eat, digest, and excrete massive amounts of organic matter. They leave their excretions behind in the form of nutrient-rich droppings known as casings. As these casings decompose, they release nutrients into the soil. This process not only moves nutrients from one layer of the soil to another but also converts the nutrients to forms that plants can absorb and process more easily. 1

At this point the author is considering the addition of the following table.

Figure 1: Corn growth by worm count, rainfall, and temperature

(Adapted from a study of seven unique subclimates in the farmlands of Manitoba, Canada. Measurements were taken for the growing season of 2017, with average corn height measured as of September 1, 2017.)

Should the author make this addition?