Insects have three thoracic (trunk) segments. While researchershave found insect fossils with pairs of wings on all threesegments, modern insects have wings or related structureson only the second and third segment. It turns out thatin modern insects, Hox gene products act to inhibit wingformation on the first segment. The treehopper insect (above)is somewhat of an exception. In addition to having wingson its second segment, the treehopper’s first segment has anornate helmet that resembles a set of thorns, which a recentstudy has found to be a modified, fused pair of “wings.” Thethorn-like structure helps to camouflage the treehopper intree branches, thus reducing its risk of predation. Explain howchanges in gene regulation could have led to the evolution ofsuch a structure.

Insects have three thoracic (trunk) segments. While researchershave found insect fossils with pairs of wings on all threesegments, modern insects have wings or related structureson only the second and third segment. It turns out thatin modern insects, Hox gene products act to inhibit wingformation on the first segment. The treehopper insect (above)is somewhat of an exception. In addition to having wingson its second segment, the treehopper’s first segment has anornate helmet that resembles a set of thorns, which a recentstudy has found to be a modified, fused pair of “wings.” Thethorn-like structure helps to camouflage the treehopper intree branches, thus reducing its risk of predation. Explain howchanges in gene regulation could have led to the evolution ofsuch a structure.

Biology Today and Tomorrow without Physiology (MindTap Course List)

5th Edition

ISBN:9781305117396

Author:Cecie Starr, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Christine Evers, Lisa Starr

Chapter11: Evidence Of Evolution

Section: Chapter Questions

Problem 1CT

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of this =rab or ditions ionary escen- se or 5. Describe two examples of vestigial structures that you can find among the Caminalcules. These are structures that have been reduced to the point that they are virtually useless. Ear muscles and the tail bones are examples of vestigial structures in our own species. Explain how vestigial structures provide clues about a species' evolutionary past. Illustrate your argument with vestigial structures found in humans or other real species.
A genetic change that caused a certain Hox gene to be expressedalong the tip of a vertebrate limb bud instead of farther backhelped make possible the evolution of the tetrapod limb.This type of change is illustrative of(A) the influence of environment on development.(B) paedomorphosis.(C) a change in a developmental gene or in its regulation thataltered the spatial organization of body parts.(D) heterochrony
Knowledge of the genomes of ancient homininsmight help us better understand not only the evolutionaryhistory of hominins, but also the traits that differ between usand our relatives—the traits that make us human. Our understandingof the functions of different genes is growing rapidly,so detailed comparisons of our genes to those present in, say,Neanderthals and Denisovans are very revealing. What do youthink are the functions most likely to be related to the geneticdifferences between us and our hominin relatives?
An evolutionary model of animal development explains how, O a.new genetic lines are produced less by modification than by unique mutation. O b.somites form as blocks of genes in cells randomly distributed throughout the body. OC.homeotic genes are found only in fruit flies, where they are responsible for odd placement of appendages. d. homeotic genes are not universal among animals. O e.animal body plans are constrained by existing structures in ancestral organisms.
. The upper forelimbs of humans and bats have fairly similarskeletal structures, whereas the corresponding bones inwhales have very different shapes and proportions. However,genetic data suggest that all three kinds of organisms divergedfrom a common ancestor at about the same time. Which ofthe following is the most likely explanation for these data?(A) Forelimb evolution was adaptive in people and bats, butnot in whales.(B) Natural selection in an aquatic environment resulted insignificant changes to whale forelimb anatomy.(C) Genes mutate faster in whales than in humans or bats.(D) Whales are not properly classified as mammals.
In many organisms, such as insects and flowering plants, morphological traits have been lost insome species due to the evolution of developmental arrest: growth and development cease,eliminating the final trait. The remaining tissuecan be remodeled or resorbed for other use.What does this observation suggest about thenature of mutations and adaptive evolution inthese cases?
Just as anatomical homology can lead to vestigial structuressuch as human wisdom teeth and the wings of flightlessbirds, genetic homology can lead to vestigial DNA sequences.For example, most mammal species produce an enzyme,L-gulonolactone oxidase, that catalyzes the last step in the productionof vitamin C. The species that produce the enzyme areable to do so because they all inherited the gene that encodesit from a common ancestor. Humans, however, do not produceL-gulonolactone oxidase, so we can’t produce vitamin C ourselvesand must consume it in our diets. But even though wedon’t produce the enzyme, our cells do contain a stretch of DNAwith a sequence very similar to that of the enzyme-producinggene present in rats and most other mammals. The human version,though, does not encode the enzyme (or any protein). Weinherited this stretch of DNA from an ancestor that we share withother mammal species, but in us, the sequence has undergonea change that rendered it nonfunctional. (The…
describe one way in which limb development in Acanthostega could differ from that in modern tetrapods (e.g., mouse, human) to generate this digit pattern. Your description must include the name of at least one specific gene and at least one basic cellular mechanism.
What are the genetic changes thatallow the repurposing of existing bodyparts during evolution? For example,how did bat wings evolve from arms?
Imagine that you have the DNA sequences fromthe intron of a gene in three species called A, B,and C. Species A and B are most closely related,while C is more distantly related. The sequencesof A and B differ by 18 base pairs, A and C differby 26 base pairs, and B and C differ by 28 basepairs. Fossils show that species A and B divergedabout 1.2 Mya, but there is no fossil evidence asto when the most recent common ancestor ofall three species lived. Use the genetic data toestimate that date. What assumptions are youmaking to get this estimate?
What are the most probable characteristics of the most recent com-mon ancestor of insects? What major lineages descended from it?
Birds are unique because they have modified forelimbs which serve as wings and a body covered in feathers. However, just having wings and feathers does not mean that an organism can fly (look at the ostrich and penguin!). Please discuss at least 3 of these additional characteristics/adaptations that are required in order for birds to fly.