Functions of Butterfly Genes Discussion

Functions of Butterfly Genes Discussion

The colorful canvas of the butterfly wing is an exceptional example of evolutionary innovation and adaptation. Compared with their forebears, whose wings wore patterns of black, brown, and gray, the Lepidoptera (butterflies and moths) evolved a more varied palette of pigmentation. With the capacity for complex color patterns, such as stripes and eyespots, wing coloration evolved a variety of functions, such as attracting mates and warning predators away. And yet, how exactly these ecologically important patterns develop and evolve has puzzled researchers for decades.

Now, using CRISPR to investigate gene function in butterfly wings, researchers have discovered that just a few genes are largely responsible for setting up the patterning throughout the wing. “The big insight: single genes can act as extremely discrete switches to completely change morphology,” says Bob Reed, associate professor of biology at Cornell University and coauthor on two recently published studies in PNAS about patterning the wings of Heliconius butterflies. “That was surprising, the extent to which they can completely change the entire color pattern in a very discrete way.” CRISPR is helping uncover not only genes responsible for ecologically important traits but also how gene networks are assembled from a mix of old and new parts.

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WING PATTERNS EVOLVE
The genes WntA and optix are among the most important players. They first came to the researchers’ attention through decades of previous work on the tropical Heliconius, or passion-vine, butterflies (1). In many locations in the New World tropics, multiple species in this genus co-occur; although they are distinct species and do not interbreed, they resemble each other so closely that they can be difficult to distinguish by eye. The species evolved a common warning coloration pattern to signal that they are poisonous, thus keeping predators at bay. As a result of this convergent mimicry, a predator has to recognize only a single warning pattern in any particular geographic location. Throughout its range, a given species might have 20 different geographically restricted color patterns.

More than a decade ago, researchers wanting to understand the origin of the basic pattern of red and yellow stripes and black splotches of most Heliconius species conducted genetic crosses to reveal the genetic basis of the patterns (2, 3). In a large team effort that involved many labs, they were able to map three genes with major effects that appeared to control color-pattern variations in the butterflies: WntA, optix, and cortex.

But, although researchers had genetic-mapping data, genome-wide association studies, and gene-expression data, they didn’t have experimental evidence that these particular genes were actually controlling color patterns and how. “Once CRISPR came along, we wanted to generate that proof to see exactly how these genes worked to control color patterns,” says Reed.

In their recent PNAS study (4), Reed and his colleagues showed that optix controls the red and yellow colors throughout the wing. When optix is knocked out, the wing patterns remain, but the wing loses intensity from red to orange to gold—it turns grayscale. The gene optix is ancestrally expressed in insect eyes, where it activates the expression of visual pigments. “So optix was recruited to the wings, and now it becomes possible to express the pigments of the eyes in the wings,” explains butterfly biologist Jeffrey Marcus, an associate professor at the University of Manitoba, who was not involved in the study.

Important information for writing discussion questions and participation

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Your initial discussion post should be a minimum of 200 words and response posts should be a minimum of 150 words. Be advised that I grade based on quality and not necessarily the number of words you post. A minimum of TWO references should be used for your initial post. For your response post, you do not need references as personal experiences would count as response posts. If you however cite anything from the literature for your response post, it is required that you cite your reference. You should include a minimum of THREE references for papers in this course. Please note that references should be no more than 5 years old except recommended as a resource for the class. Furthermore, for each discussion board question, you need ONE initial substantive response and TWO substantive responses to either your classmates or your instructor for a total of THREE responses. There are TWO discussion questions each week, hence, you need a total minimum of SIX discussion posts for each week. I usually post a discussion question each week. You could also respond to these as it would count towards your required SIX discussion posts for the week.

I understand this is a lot of information to cover in 5 weeks, however, the Bible says in Philippians 4:13 that we can do all things through Christ that strengthens us. Even in times like this, we are encouraged by God’s word that we have that ability in us to succeed with His strength. I pray that each and every one of you receives strength for this course and life generally as we navigate through this pandemic that is shaking our world today. Relax and enjoy the course!

Hi Class,

Please read through the following information on writing a Discussion question response and participation posts.

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Important information on Writing a Discussion Question

• Your response needs to be a minimum of 150 words (not including your list of references)
• There needs to be at least TWO references with ONE being a peer reviewed professional journal article.
• Include in-text citations in your response
• Do not include quotes—instead summarize and paraphrase the information
• Follow APA-7th edition
• Points will be deducted if the above is not followed

Participation –replies to your classmates or instructor

• A minimum of 6 responses per week, on at least 3 days of the week.
• Each response needs at least ONE reference with citations—best if it is a peer reviewed journal article
• Each response needs to be at least 75 words in length (does not include your list of references)
• Responses need to be substantive by bringing information to the discussion or further enhance the discussion. Responses of “I agree” or “great post” does not count for the word count.
• Follow APA 7th edition
• Points will be deducted if the above is not followed

• Remember to use and follow APA-7th edition for all weekly assignments, discussion questions, and participation points.
• Here are some helpful links
• The is a great resource