30. Refer to the figure shown here. Which of the following would have been a selective agent or pressure that could lead to the reduction in hindlimbs through time? Present 10 MYA 20 MYA 30 MYA 40 MYA 50 MYA 60 MYA- Modern toothed whales The reduced hind limbs of Rodhocetus kasrani could not have alded it in walking or swimming. Rodhocetus swam with an up-and-down motion, as do modern whales. Hypothetical mesonychid skeleton Ambulocetus natans probably walked on land (as do modern sea lions) and swam by flexing its backbone and paddling with its hind limbs (as do modern otters).

30. Refer to the figure shown here. Which of the following would have been a selective agent or pressure that could lead to the reduction in hindlimbs through time? Present 10 MYA 20 MYA 30 MYA 40 MYA 50 MYA 60 MYA- Modern toothed whales The reduced hind limbs of Rodhocetus kasrani could not have alded it in walking or swimming. Rodhocetus swam with an up-and-down motion, as do modern whales. Hypothetical mesonychid skeleton Ambulocetus natans probably walked on land (as do modern sea lions) and swam by flexing its backbone and paddling with its hind limbs (as do modern otters).

Biology: The Unity and Diversity of Life (MindTap Course List)

14th Edition

ISBN:9781305073951

Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Chapter25: Animal Evolution- The Chordates

Section: Chapter Questions

Problem 1CT: In 1798, a stuffed platypus specimen was delivered to the British Museum. Reports that it laid eggs...

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. 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.
Exaptations are traits that: a. prepare some organisms for future environmental changes. b. appear in lineages as a result of an adaptive radiation. c. evolve in anticipation of a species future needs. d. are useful in new situations before natural selection alters them for a new function. e. occur in animals, but not in plants.
The position where a spinal cord enters the skull provides evidence about whether a fossil species __________. a. was nocturnal b. was carnivorous c. walked upright d. all of the above
The 3.6-million-year-old footprints left by bipedal walkers in Tanzania were probably made by _______. a. australopiths b. Neanderthals c. modem human d. Homo enctus
In 1798, a stuffed platypus specimen was delivered to the British Museum. Reports that it laid eggs created much confusion. To modem biologists, a platypus is clearly a mammal. It has fur and the females produce milk. Young animals have typical mammalian teeth that are replaced by hardened pads of the bill as the animal matures. Why do you think modem biologists can more easily accept that a mammal can have some reptilelike traits than scientists who were considering this animal in the late 1700s?
All of the following data types can be used as evidence of shared ancestry except similarities in _______. a. amino acid sequences b. embryonic development c. DNA sequences d. fossil morphologies e. form due to convergent evolution
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?
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.
A skull of Homo Neanderthalensisis tested using carbon14. Palaeontologists are wondering about whether the Neanderthal was living at the same time as Homo sapiens, known to be living in the same area 45 000 years ago. Measurements shown the original amount of carbon-14 isotope present in the skull when Neanderthal died is only 1.56%. A) How old is the Neanderthal fossil? B) Could this Neanderthal have been living with Homo sapiens in this area at the same time?
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?
Taphonomy tells us ab0ut preservati0n biases in the fossil rec0rd. What kind of biases affect 0ur understanding 0f the large animals 0f the Triassic, Jurassic, and Cretaceous? (a short list with explanations or 2-3 short paragraphs) need help asap, thank you in advance
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.