Many crustaceans (for example, lobsters, shrimps, and crayfish) use their tails toswim, but crabs have reduced tails that curl under their shells and are not used inswimming. This condition is an example of what evidence of evolution? *A homologous structureNatural selectionConvergent evolutionno answerA vestigial structureWhich of the following evidence most strongly supports the common origin of alllife on Earth? *no answerUniversality of the genetic codeUse of energy to power cellular activitiesReproductionO Heritability of genetic variation

Many crustaceans (for example, lobsters, shrimps, and crayfish) use their tails to swim, but crabs have reduced tails that curl under their shells and are not used in swimming. This condition is an example of what evidence of evolution? * A homologous structure Natural selection O Convergent evolution

Many crustaceans (for example, lobsters, shrimps, and crayfish) use their tails to swim, but crabs have reduced tails that curl under their shells and are not used in swimming. This condition is an example of what evidence of evolution? * A homologous structure Natural selection O Convergent evolution

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

Chapter15: Animal Evolution

Section: Chapter Questions

Problem 4CT

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House sparrows (Maya) were introduced to North America in 1852. Since that time thesparrows have evolved different characteristics in different locations. Sparrow populations inthe north are larger-bodied than sparrow populations in the south. This divergence inpopulations is probably at least partly a result of natural selection: larger-bodied birds canoften survive lower temperatures than smaller-bodied birds can. Colder weather in the northmay select for larger-bodied birds. What type of evolution based on natural selectionaccounts for this observation? Explain your answer.
Recent reconstructions of evolutionary history are often dependenton assigning divergence in terms of changes in amino acid ornucleotide sequences. For example, a comparison of cytochromec shows 10 amino acid differences between humans and dogs,24 differences between humans and moths, and 38 differencesbetween humans and yeast. Such data provide no information asto the absolute times of divergence for humans, dogs, moths, andyeast. How might one calibrate the molecular clock to an absolutetime clock? What problems might one encounter in such acalibration?
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?
The diversity of modern vertebrates was shaped in partby mass extinctions. The most severe extinction eventwe know of occured at the border between the Permianand Triassic periods about 250 million years ago. Anestimated 96 percent of the marine species and 70 percentof land species disappeared in what is sometimes called“The Great Dying.” The cause of this mass extinctionremains under investigation. Suggested causes includean asteroid impact, extreme volcanic activity, or a sudden release of carbon dioxide from deposits on the sea floor. Which groups of vertebrates were present when this mass extinction event occurred? Which evolvedafterward?
WRITE ABOUT A THEME: Organization You have seenmany examples of how form fits function at all levels of thebiological hierarchy. However, we can imagine forms thatwould function better than some forms actually found innature. For example, if the wings of a bird were not formedfrom its forelimbs, such a hypothetical bird could fly yet alsohold objects with its forelimbs. In a short essay (100–150words), use the concept of “evolution as tinkering” to explainwhy there are limits to the functionality of forms in nature.
Full or partial limblessness has evolved many times invertebrates (snakes, lizards, manatees, whales). Do youexpect the mutations that occurred in the evolution oflimblessness to be in the coding or noncoding sequencesof toolkit genes? Why?
DNA-sequencing studies for a gene in two closely relatedspecies produce the following numbers of sites that vary:Synonymous polymorphisms 50Nonsynonymous polymorphisms 20Synonymous species differences 18Nonsynonymous species differences 2Does this result support neutral evolution of the gene?Does it support an adaptive replacement of aminoacids? What explanation would you offer for theobservations?
EVOLUTION CONNECTION Darwin suggested looking at aspecies’ close relatives to learn what its ancestors may havebeen like. Explain how his suggestion anticipates recentmethods, such as phylogenetic bracketing and the use ofoutgroups in cladistic analysis.
EVOLUTION CONNECTION Living members of a vertebratelineage can be very different from early members of the lineage,and evolutionary reversals (character losses) are common. Giveexamples that illustrate these observations, and explain theirevolutionary causes.
The elaborate tail of the peacock (Pavo cristatus) is approximately 120 cm to 150 cm long, while the tail ofthe peahen is quite short. The long tail reduces the male bird’s ability to maneuver and fly and makes him moreconspicuous to predators. Suggest at least one reason why this cumbersome structure has not been eliminatedby natural selection.
A scientist is attempting to a cladogram that shows the evolutionary closeness of three organisms in relation to humansAfter doing DNA analysis, they that the organisms share the following percentages of DNA Organism A and humans share 85% of their DNA Organismn and humans share 80% of their DNA Organism and humans share 90% of their DNA Based on informationwhich order should they go on the cladogram ( related to most related ?
. Some scientists vigorously rejected Darwin’sideas when On the Origin of Species was published. Richard Owen (1860), perhaps the mostrespected biologist in England, wrote (amongmany other objections): “Are all the recognisedorganic forms of the present date, so differentiated, so complex, so superior to conceivableprimordial simplicity of form and structure,as to testify to the effects of Natural Selectioncontinuously operating through untold time?Unquestionably not. The most numerous livingbeings … are precisely those which offer suchsimplicity of form and structure, as best agrees…with that ideal prototype from which…vegetableand animal life might have diverged.” Howmight Darwin, or you, argue against Owen’slogic?