Name: Optimal Foraging: Foraging with Artificial Habitats and Prey - Concept
Uploaded: 2019-01-29T11:04:46.000Z
Duration: 3 min 37 s
Channel: JoVE

K12 Standards

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heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS4-2

Optimal Foraging

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Lab Manual Sub Articles

<p>Often in life, the things an individual needs may not be within immediate grasp. So, organisms need to forage. Foraging is defined simply as the process of searching for food or more generally resources. Although food is probably the first example that comes to mind, organisms must forage for other resources like shelter or mates and animals often go to great lengths to get what they need. However, the act of foraging itself requires energy. Essentially, individuals must balance burning calories with obtaining them. To put it simply, foraging requires a strategy. Ecologists created the optimal foraging theory to model the circumstances in which an organism meets the optimum balance between energy expended foraging, i.e., two acorn&#39;s worth and the potential energy it can acquire like six new acorns. </p>
<p>One characteristic of foraging is that resources are not always spread out evenly within a habitat. More typically, resources are contained in patches that foragers must move between. So how exactly should foragers navigate these patches of resources? In 1976, evolutionary ecologist Eric L. Charnov came up with the marginal value theorem or MVT to explain how organisms optimize their foraging. The MVT has five main predictions for optimal foraging. First, it states that foragers should capture more prey in patches with high prey density than in low prey density patches. Second, the theory predicts that foragers should spend more time hunting for resources in high prey density patches. Next, the forager should have a higher prey capture rate in dense environments with patches that are closely packed together than in sparse environments with patches that are spread further apart. The fourth prediction states that foragers will spend more time foraging in these dense environments than in sparse environments. Finally, a forager should leave a patch when the capture rate has declined to the average rate of all patches. And this is where a concept called giving up time or GUT comes in. To calculate the GUT simply subtract the time that the final prey item was acquired from the time that the individual leaves the patch. Therefore, the GUT should be the same for all of the patches a forager visits. </p>
<p>In this laboratory, you will complete foraging simulations in several different artificial resources patches and then perform calculations to gauge how your class performed as foragers and whether you adhered to the rules of the marginal value theorem.<br />
 </p>

optimal foraging

<h4>Optimal Foraging</h4>
<p>Organisms must acquire and use resources in their environment to survive. While food is one of the primary resources organisms must search for, individuals also need to seek habitats, shelter, and mates. This process of searching for resources is known as foraging, which involves a series of costs and benefits. More specifically, acquiring a resource provides the organism with a benefit, however, searching and capturing the resource requires expenditure of time and energy. Thus, organisms adopt foraging strategies that maximize the net gain to an optimal level by providing the most benefit for the lowest cost.  Ecologists developed the &#8220;Optimal Foraging Theory&#8221; to model the situations under which an organism meets the optimum balance between foraging costs and benefits.</p>
<h4>The Marginal Value Theorem</h4>
<p>Resources are not uniformly distributed in the environment. For instance, in a forest ecosystem, it is much more likely to find species of trees clumped together rather than evenly distributed throughout the forest. This heterogeneity in resource availability creates &#8220;patches&#8221; of resources. Therefore, foragers must consider both the payoff of a patch as well as the distance between patches, thus the cost of moving to another patch. The Marginal Value Theorem (MVT) describes how optimal foragers utilize and move between patches of resources in their habitat <sup>1</sup>. There are five main predictions of the MVT: </p>
<ol class="references">
	<li>Foragers should capture more prey in patches of high prey density than patches of low prey density.</li>
	<li>Foragers should spend more time foraging in patches of high prey density than in those with low prey density.</li>
	<li>Foragers should have a higher prey capture rate in dense patches than those that are spread farther apart.</li>
	<li>Foragers should spend more time foraging in dense environments, where patches are clustered, than in sparse environments.</li>
	<li>Foragers should leave a patch when the capture rate has declined to the average rate of all the patches.</li>
</ol>
<p>The interval of time between when the last prey is captured and when the forager leaves the patch is known as the Giving-Up-Time, or GUT. In the context of the MVT, the GUT should be the same in all patches for each individual forager. This was tested in an experiment with black-capped chickadees in a large aviary foraging for mealworm hidden in artificial pine cones, where the birds had the same GUT for all types of patches, which was inversely related to the average capture rate for the entire environment <sup>2</sup>. </p>
<p>The longer an organism spends foraging, the more energy it spends, and the longer it exposes itself to predators and the elements, therefore developing an optimal foraging strategy for resource-acquisition is essential for most organisms. The principles of the MVT has many real-life applications to promoting diversity, conservation, and even human behavior.</p>
<h4>Optimal Foraging in a Changing Environment</h4>
<p>From the point of diversity and conservation, the MVT would predict that species can only exist if there are patches to adequately serve an organism&#8217;s energy needs, thus the availability and the distance between resources is important for organisms that depend on them for survival. Habitat loss, pollution, and other changes in the environment can interfere with an organism&#8217;s ability to forage optimally, therefore reducing its fitness. Thus, when habitats in an ecosystem are destroyed, patches or entire communities are removed. This removal limits the resources available to inhabitants of the rest of an ecosystem. Fewer patches with resources creates more intense competition and can eliminate certain species. This is particularly important for species under threat of extinction due to habitat loss who will be unable to meet their foraging needs if most of their habitat is destroyed. </p>
<p>Humans have developed sophisticated food storage to limit foraging needs, however there are many other instances in which foraging is necessary, such as searching for affordable housing, a well-paying job, or finding a suitable date among others. A recent study tested the predictions of the MVT using General Practitioners&#8217; information-seeking abilities. They found that general practitioners optimally foraged for information when diagnosing a patient; they moved between multiple information sources quickly, and utilized both high-density sources, such as the internet, and easily-attainable sources, including their colleagues frequently <sup>3</sup>. Similarly, Optimal Foraging Theory also applies to economics in how consumers shop, or &#8220;forage&#8221; for products and information when making a purchase <sup>4</sup>. These studies demonstrate how humans adhere to the predictions of optimal foraging theory in a variety of contexts.</p>
<h4>References</h4>
<ol>
	<li><strong>Charnov, E. L.</strong> ptimal foraging: the marginal value theorem. <em>Theoretical Population Biology. </em>1976, Vol. 9, (129-36).</li>
	<li><strong>John Krebs, John Ryan, Eric Charnov.</strong> Hunting by expectation or optimal foraging: A study of patch use by chickadees. <em>Animal Behaviour. </em>1974, Vol. 22, (953-64).</li>
	<li><strong>Mai Dwairy, Anthony C Dowell, Jean-Claude Stahl.</strong> The application of foraging theory to the information searching behaviour of general practitioners. <em>BMC Family Practice. </em>2011, Vol. 12, 90.</li>
	<li><strong>Wells, V.K.</strong> Foraging: an ecology model of consumer behaviour? <em>Marketing Theory. </em>2012, Vol. 2, 12 (117-136).</li>
</ol>

Optimal Foraging: Foraging with Artificial Habitats and Prey - Concept

Optimal Foraging
Organisms must acquire and use resources in their environment to survive. While food is one of the primary resources organisms must ...

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Learn how optimal foraging theory explains patch use, Giving-Up-Time, and the Marginal Value Theorem using chickadees, conservation, and human examples.

Patch Use in Optimal Foraging | JoVE K12

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New York State Science Learning Standards

Natural Selection and Evolution

HS-LS4-1.

Set up a high school foraging habitat patches activity with rice-filled buckets, pinto beans, and student roles to compare prey density and foraging behavior.

Foraging Habitat Patches Setup | JoVE K12

Explore a classroom foraging simulation with pinto beans, rice buckets, capture rate, giving-up time, scaled GUT, and Marginal Value Theorem graphs.

Foraging Choice and Patch Use | JoVE K12

<ul><li><a href="#" data-time="0.0">Simulating Foraging with Artificial Habitats and Prey
</a></li><li><a href="#" data-time="182">Results
</a></li></ul>

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Simulating Foraging with Artificial Habitats and Prey
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">NOTE: The foragers will hunt for prey represented by pinto beans in four buckets of rice with varying prey densities. Without knowing what these densities are, foragers must obtain as many prey items as possible in as little time as possible. 
</div></li><li data-sub-note-item="1-2"><div class="lab-step">HYPOTHESES: In this experiment, the experimental hypothesis could be that foragers will catch the most prey in the higher prey density bucket and also spend the most time foraging there.  The null hypothesis would then be that foragers will catch an equal number of prey in each bucket and that foragers will spend an equal amount of time foraging in each patch. 
</div></li><li data-sub-note-item="1-3"><div class="lab-step">To begin the foraging activity, record the names and role of each participant at the top of the student data collection sheet.  NOTE: Before starting the experiment, the forager is allowed to become familiar with the foraging process &#8211; the following steps are a practice round. 
</div></li><li data-sub-note-item="1-4"><div class="lab-step">The forager should kneel or sit in front of the average density bucket. 
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Once the timer says start, the forager may begin looking for the pinto beans representing the prey. The forager can spend as much time as they like foraging in this bucket. 
</div></li><li data-sub-note-item="1-6"><div class="lab-step">Once a prey item is located, the forager must signal that one has been found and place the prey in the cup next to the bucket.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Once they believe they have acquired most of the prey in the patch, they should tell the timer to stop the time and the practice round is over. 
</div></li><li data-sub-note-item="1-8"><div class="lab-step">To begin the simulation proper, the forager should sit or kneel in front of bucket A. 
</div></li><li data-sub-note-item="1-9"><div class="lab-step">The timer must be ready to start the stopwatch. 
</div></li><li data-sub-note-item="1-10"><div class="lab-step">The recorder should be ready to record the time each prey item is located, in addition to the time that the forager arrived at and left each bucket. 
</div></li><li data-sub-note-item="1-11"><div class="lab-step">When all parties are ready, the timer should start the stopwatch and say &#8220;start&#8221;,  and the forager should begin foraging. NOTE: The stopwatch will run through the rest of the round for buckets B and C.
</div></li><li data-sub-note-item="1-12"><div class="lab-step">As the forager signals finding pinto beans and places them in the cup next to the bucket, the timer should tell the recorder the time.
</div></li><li data-sub-note-item="1-13"><div class="lab-step">The recorder should then write the time in the student data collection sheet.  <a href="https://www.jove.com/CDNSource/lm/labs/34/Table_1_Optimal_foraging.xlsx" style="display:block;margin:20px;" target="_blank">Click Here to download Table 1</a>
</div></li><li data-sub-note-item="1-14"><div class="lab-step">Once the forager has decided to move on to the next bucket, they should tell the timer &#8220;done&#8221;, and begin moving to the next patch. 
</div></li><li data-sub-note-item="1-15"><div class="lab-step">The recorder should record the time the forager left and the time they arrived at bucket B in the student data collection sheet.
</div></li><li data-sub-note-item="1-16"><div class="lab-step">Repeat the same procedure for buckets B and C. Once the forager has completed the activity, it is time for the next forager to begin using the same procedure. 
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">Before performing any data analysis, review the data collection sheet and compile your individual data for captured prey, foraging time, and travel time for each bucket in your student calculations table. <a href="https://www.jove.com/CDNSource/lm/labs/34/Table_2_Optimal_foraging.xlsx" style="display:block;margin:20px;" target="_blank">Click Here to download Table 2</a>
</div></li><li data-sub-note-item="2-2"><div class="lab-step">After this, calculate your individual capture rate for each bucket by dividing the number of prey captured by the sum of the foraging time and travel time and record these values in your table. Individual capture rate =  Number of prey captured / (foraging time + travel time)
</div></li><li data-sub-note-item="2-3"><div class="lab-step">To calculate your Giving-Up-Time or a GUT for each bucket, subtract the time that the last prey item was acquired from the time you left the bucket.  GUT = time forager left bucket  -  time last prey item acquired
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Next, calculate the mean GUT for your foraging group and record the values in your table.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Finally, calculate your scaled GUT for each bucket by dividing the bucket GUT by your group&#39;s mean GUT. Scaled GUT =  Bucket GUT / Group mean GUT NOTE: The scaled GUT will allow class data to be pooled later on without differences in individual foragers skewing the data. 
</div></li><li data-sub-note-item="2-6"><div class="lab-step">The instructor should now compile the data into the classroom spreadsheet.  <a href="https://www.jove.com/CDNSource/lm/labs/34/Table_3_Optimal_foraging.xlsx" style="display:block;margin:20px;" target="_blank">Click Here to download Table 3</a>
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Plot a bar graph of the average number of prey collected in each bucket. On the x-axis, A should represent the low prey density bucket, B should represent the medium prey density bucket, and C the high prey density bucket. Plot the y-axis as the number of prey items caught. 
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Next, plot the graph of the class average scaled GUT, where the x-axis represents the buckets with varying levels of prey density and the y-axis shows the values for the average scaled GUT. 
</div></li><li data-sub-note-item="2-9"><div class="lab-step">Plot a third graph of the average time spent foraging in each bucket. 
</div></li><li data-sub-note-item="2-10"><div class="lab-step">Now review the Marginal Value Theorem (MVT) from the concepts video and examine the three graphs that you generated from your class data. Take note of whether the graphs conform to the predictions of MVT. 
</div></li></ul></li></ol>

Optimal Foraging: Foraging with Artificial Habitats and Prey - Procedure

Simulating Foraging with Artificial Habitats and Prey
ExpandNOTE: The foragers will hunt for prey represented by pinto beans in four buckets of rice with ...

<p>First, the instructor will explain the activity. The foragers will hunt for prey represented by pinto beans in four buckets of rice with varying prey densities. Without knowing what these densities are, foragers must obtain as many prey items as possible in as little time as possible.</p><p>In this experiment, the experimental hypothesis could be that foragers will catch the most prey in the higher prey density bucket and also spend the most time foraging there. The null hypothesis would then be that foragers will catch an equal number of prey in each bucket and that foragers will spend an equal amount of time foraging in each patch. To begin the foraging activity, record the names and role of each participant at the top of the student data collection sheet.</p><p>Before starting the experiment, the forager is allowed to become familiar with the foraging process. The forager should kneel or sit in front of the average bucket. Once the timer says start, the forager may begin looking for the pinto beans representing the prey.</p><p>The forager can spend as much time as they like foraging in this bucket. Once a prey item is located, the forager must signal that one has been found and place the prey in the cup next to the bucket. Once they believe they have acquired most of the prey in the patch, they should tell the timer to stop the time and the practice round is over.</p><p>The forager should sit or kneel in front of bucket A.The timer must be ready to start the stopwatch. The recorder should be ready to record the time each prey item is located in addition to the time that the forager arrived at and left each bucket. When they are ready, the timer starts the stopwatch and says start and the forager begins foraging.</p><p>The stopwatch will run through the rest of the round for buckets B and C.As the forager signals finding pinto beans and places them in the cup next to the bucket, the timer should tell the recorder the time. The recorder can then write the time in the student data collection sheet. Once the forager has decided to move on to the next bucket, they should tell the timer done and begin moving to the next patch.</p><p>The recorder should record the time the forager left and the time they arrived at bucket B in the student data collection sheet. Repeat the same procedure for buckets B and C.Once the forager has completed the activity, it is time for the next forager to begin using the same procedure. Before performing any data analysis, review the data collection sheet and compile your individual data for captured prey, foraging time, and travel time for each bucket in your student calculations table.</p><p>After this, calculate your individual capture rate for each bucket by dividing the number of prey captured by the sum of the foraging time and travel time and record these values in your table. To calculate your Giving-Up-Time or a GUT for each bucket, subtract the time that the last prey item was acquired from the time you left the bucket. Next, calculate the mean GUT for your foraging group and record the values in your table.</p><p>Finally, calculate your scaled GUT for each bucket by dividing the bucket GUT by your group's mean GUT. The scaled GUT will allow class data to be pooled later on without differences in individual foragers skewing the data. Now the instructor will compile the data into the classroom spreadsheet.</p><p>Now plot the following bar graph. First plot the average number of prey collected in each bucket. On the x-axis, A represents the low prey density bucket, B represents the medium prey density bucket, and C represents the high prey density bucket.</p><p>The y-axis shows the number of prey items caught. Next, plot the graph of the class average scaled GUT. Again, the x-axis represents the buckets with varying levels of prey density.</p><p>The y-axis shows the values for the average scaled GUT. Finally, plot the graph of the average time spent foraging in each bucket. Now review the Marginal Value Theorem or MVT from the concepts video that describes how foragers should optimally utilize resources and move between patches in their habitat.</p><p>Now look at the three graphs that you generated from your class data. Do the graphs conform to the predictions of MVT? Do any of the graphs disagree with the theorem?</p>

<ul><li><a href="#" data-time="0.0">Setting up the Foraging Habitat Patches
</a></li></ul>

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Setting up the Foraging Habitat Patches
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">Print a student data collection sheet for each student to record data.  NOTE: Students will work in groups of three for this activity. For any given round, one student will forage, one student will record data and another student will run the stopwatch. 
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Choose a location for the foraging activity to take place. An open field is ideal for this activity but a hallway will suffice provided another location is not available. 
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Label four five-gallon buckets as A, B, C and Average. 
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Fill each bucket with 15 to 30 pounds of rice. Make sure the amount of rice is the same in each bucket. 
</div></li><li data-sub-note-item="1-5"><div class="lab-step">For the bucket labeled A mix in six pinto beans. This represents the low prey density.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">For the bucket labeled B mix in 16 pinto beans. This represents the medium prey density.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">For the bucket labeled C mix in 26 pinto beans. This represents the high prey density.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">Finally, for the bucket labeled average mix in 16 pinto beans. This represents the average prey density. 
</div></li><li data-sub-note-item="1-9"><div class="lab-step">To distribute the buckets, place buckets A and average at the start of the foraging area five paces apart from each other.
</div></li><li data-sub-note-item="1-10"><div class="lab-step">Walk 25 paces away from the first two buckets and place bucket C. 
</div></li><li data-sub-note-item="1-11"><div class="lab-step">Then walk 10 paces to the right or left of C and place the final bucket, B. 
</div></li><li data-sub-note-item="1-12"><div class="lab-step">Place an empty cup next to each bucket &#8211; these will stay with the bucket, and the instructor must mix the pinto beans back into the rice after each forager has finished the course.  NOTE: The average bucket should always be placed at the start but for variety or convenience the buckets can be arranged in different ways or at different distances or prey items and numbers can be varied. 
</div></li></ul></li></ol>

<div class="section-question"><h4 class="question-sect">What is foraging?</h4><p>Foraging is the process of searching for resources including food, shelter, and mates. 
</p></div><div class="section-question"><h4 class="question-sect">What does Optimal Foraging Theory model? </h4><p>Optimal Foraging Theory models the circumstances in which an organism meets the optimum balance between expending energy to forage and acquiring resources from foraging. 
</p></div><div class="section-question"><h4 class="question-sect">How are resources spread out within a habitat?</h4><p>Generally, resources are not spread out evenly in a habitat. Resources are usually contained in &#8220;patches&#8221; that foragers must move between.  
</p></div><div class="section-question"><h4 class="question-sect">What are the five predictions of Marginal Value Theorem?</h4><p>First, foragers should capture more prey in patches with high prey density. Second, foragers should spend more time foraging in high prey density patches. Third, foragers should have a higher prey capture rate in dense environments. Fourth, foragers will spend more time foraging in dense environments. Finally, a forager should leave a patch when the capture rate has declined to the average rate of all patches. 
</p></div><div class="section-question"><h4 class="question-sect">How do you calculate the Giving Up Time (GUT)?</h4><p>To calculate the GUT, subtract the time that the final prey item was acquired from the time the forager leaves the patch.
</p></div>

Optimal Foraging: Foraging with Artificial Habitats and Prey - Prep

Setting up the Foraging Habitat Patches
ExpandPrint a student data collection sheet for each student to record data.  NOTE: Students will work in groups ...

<p>Print a student data collection sheet for each student to record data. Students will work in groups of three for this activity. For any given round, one student will forage, one student will record data and another student will run the stopwatch.</p><p>Choose a location for the foraging activity to take place. An open field is ideal for this activity but a hallway will suffice provided another location is not available. Label four five-gallon buckets as A, B, C and Average.</p><p>Fill each bucket with 15 to 30 pounds of rice. Make sure the amount of rice is the same in each bucket. For the bucket labeled A mix in six pinto beans.</p><p>This represents the low prey density. For the bucket labeled B mix in 16 pinto beans. This represents the medium prey density.</p><p>For the bucket labeled C mix in 26 pinto beans. This represents the high prey density. Finally, for the bucket labeled average mix in 16 pinto beans.</p><p>This represents the average prey density. To distribute the buckets, place buckets A and average at the start of the foraging area five paces apart from each other. Walk 25 paces away from the first two buckets and place bucket C.Then walk 10 paces to the right or left of C and place the final bucket B.Place an empty cup next to each bucket.</p><p>The cup stays with the bucket and the instructor must mix the pinto beans back into the rice after each forager has finished the course. The Average bucket should always be placed at the start but for variety or convenience the buckets can be arranged in different ways or at different distances or prey items and numbers can be varied. Once the activity has been completed by a forager the instructor should mix the pinto beans back into the bucket for the next round.</p><p>Please take time to review the material list and the student protocol video to be fully prepped for the lab.</p>

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Some of Mendel&#8217;s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A ...

Law of Segregation

When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 ...

Law of Independent Assortment

While Mendel&#8217;s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how ...

Test Cross

Alleles are different forms of the same gene. Humans and other diploid organisms inherit two alleles of every gene, one from each parent.

An allele is ...

Chi-square Analysis

The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an ...

Pedigree Analysis

Overview

A pedigree is a diagram displaying a family&rsquo;s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or ...

Nature and Nurture

Many human characteristics, like height, are shaped by both nature&mdash;in other words, by our genes&mdash;and by nurture, or our environment. For ...

Probability Laws

Overview

The probability of inheriting a trait can be calculated using the sum and product rules. The sum rule is used to calculate the probability of ...

background-and-environment-affect-phenotype

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as ...

Multiple Allele Traits

The Concept of Multiple Allelism

Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, ...

X and Y Chromosomes

Among mammals, the gender of an organism is determined by the sex chromosomes. Humans have two sex chromosomes, X and Y. Every human diploid cell has 22 ...

Chromosomal Theory of Inheritance

In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of ...

The Y Chromosome Determines Maleness

The Y chromosome is a sex chromosome&#160;found in several vertebrates and mammals, including humans. In addition to 22 pairs of autosomes, the human ...

Non-nuclear Inheritance

Most DNA resides in the nucleus of a cell. However, some organelles in the cell cytoplasm⁠&mdash;such as chloroplasts and mitochondria⁠&mdash;also ...

The Ratio of X Chromosome to Autosomes

In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined ...

Incomplete Dominance

Gregor Mendel&#39;s work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid ...

X-linked Traits

In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be ...

Lethal Alleles

Agouti: A Lethal Allele
Lucien Cu&#233;not discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is ...

Sex-linked Disorders

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological ...

Epistasis

In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence ...

X-Inactivation

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, ...

Polygenic Traits

When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered ...

Dosage Compensation

In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one ...

Pleiotropy

Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause ...

Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring. [Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.]

HS-LS3-1

genome-size-and-the-evolution-of-new-genes

Genome Size and the Evolution of New Genes

Gene Families

Gene Evolution - Fast or Slow?

types-of-genetic-transfer-between-organisms

Types of Genetic Transfer Between Organisms

What is Meiosis?

Meiosis I

Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of ...

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for ...

Meiosis vs. Mitosis

Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, ...

Crossing over

Nondisjunction

Replication in Eukaryotes

Overview

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high ...

Proofreading

Synthesis of new DNA molecules starts when DNA polymerase links nucleotides together in a sequence that is complementary to the template DNA strand. DNA ...

Mismatch Repair

Overview

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires ...

Nucleotide Excision Repair

Overview

Exposure to mutagens can damage DNA and result in bulky lesions that distort the double-helix structure or impede proper transcription. Damaged ...

Cancer Prevention

Several factors can increase the risk of cancer in an individual. About 50% of cancer cases can be prevented by adopting a healthy lifestyle, regular ...

cancers-originate-from-somatic-mutations-in-a-single-cell

Cancers Originate from Somatic Mutations in a Single Cell

Cancer arises from mutations in the critical genes that allow healthy cells to escape cell cycle regulation and acquire the ability to proliferate ...

DNA Distortion and Damage
Cells are regularly exposed to mutagens&#8212;factors in the environment that can damage DNA and generate mutations. UV ...

comparing-copy-number-variations-and-snps

Comparing Copy Number Variations and SNPs

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist ...

Make and defend a claim based on evidence that inheritable genetic variations may result from (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and or (3) mutations caused by environmental factors. [Clarification Statement: Emphasis is on using data to support arguments for the way variation occurs.] [Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.]

HS-LS3-2

Optimal Foraging

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Optimal Foraging

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