Flightless birds on island often have relative on the mainland that can fly. The island species presumably evolved from fliers that, in the absences of predators, lost their ability to fly. Many island population of flightless birds are in decline because rats have been introduced to their previously isolated island habits. Despite current selection pressure in favor of flight, no flightless island bird species has regained the ability to fly. Why is this unlikely to happen?

Flightless birds on island often have relative on the mainland that can fly. The island species presumably evolved from fliers that, in the absences of predators, lost their ability to fly. Many island population of flightless birds are in decline because rats have been introduced to their previously isolated island habits. Despite current selection pressure in favor of flight, no flightless island bird species has regained the ability to fly. Why is this unlikely to happen?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter21: Microevolution: Genetic Changes Within Populations

Section: Chapter Questions

Problem 1ITD: Peter and Rosemary Grant of Princeton University have studied the ecology and evolution of finches...

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One of Darwin’s finches, the medium ground finch (Geospiza fortis), is found on the small island of Daphne Major. These finches are seedeating birds. A major drought occurred on the island in 1977. Following the drought, the average beak size of medium ground finches had increased about 3%–4%. Why might a drought lead to an evolutionary change in beak size? Propose a hypothesis and explain how you could go about testing it.
Peter and Rosemary Grant of Princeton University have studied the ecology and evolution of finches on the Galapagos Islands since the early 1970s. They have shown that finches with large bills (as measured by bill depth; see Figure) can eat both small seeds and large seeds, but finches with small bills can only eat small seeds. In 1977, a severe drought on the island of Daphne Major reduced seed production by plants. After the birds consumed whatever small seeds they found, only large seeds were still available. The resulting food shortage killed a majority of the medium ground finches (Geospizafortis) on Daphne Major; their population plummeted from 751 in 1976 to just 90 in 1978. The Grants research also documented a change in the distributions of bill depths in the birds from 1976 to 1978, as illustrated in the graphs to the right. In light of what you now know about the relationship between bill size and food size for these birds, interpret the change illustrated in the graph. What type of natural selection does this example illustrate? Source: P. R. Grant. 1986. Ecology and Evolution of Darwins Finches. Princeton University Press.
SCIENCE, TECHNOLOGY, AND SOCIETY Consider how the adaptive value of sea turtle migration has changed if, as a result of human activities, migration now puts sea turtles at greater risk than if they restricted their habitat to a single location. Discuss the possible evolutionary mechanisms by which the behavior of these species may (or may not) adapt to these environmental pressures. What conservation efforts should we take to increase the probability of successful migration?
Darwin’s finches have different beaks in terms of size and shape to be able to eat different food sources like insects, nectar, and seeds. Cactus finches have longer, more pointed beaks to probe cactus flowers compared to their relatives, the ground finches. If a plant disease killed a large portion of the cacti on the Galapagos islands, what would the future populations of finches look like in terms of beak size and shape? Use your knowledge of natural selection to determine which option is most likely. Ground finches would survive and pass on their shorter and wider beaks, so there would be a higher proportion of finches in future generations that have short and wide beaks. Ground finches would survive and pass on their beaks, but they would mate with the remaining cactus finches, creating a new hybrid that is somewhere between short versus long and narrow versus wide. Cactus finches would compete for food with ground finches and exhibit resource partitioning, so the beaks…
Pictured above is an Eurasian Owl, a species found in forests across Europe and Russia. Owls are a nocturnal, predatory bird that feeds on small rodents. Their wings are super-quiet as they flap and owls are known for their large eyes. Explain how natural selection acted upon owls to where all owls have the two aforementioned adaptations.
After the drought of 1977, researchers hypothesized that on the Galapagos Islands’ Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island? Why? * Increased variation in beak size and shape over time No answer No change in beak size and shape over time. Evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks. Evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks
1) Think back to the example of ovenbird evoluon in South America. Ovenbirds are a diverse family of small, insect-eang birds that live mainly in South America. Different ovenbird species have adapted to rocky ocean shorelines, snowy mountains, scorched deserts and tropical rainforests. Like finches, ovenbirds have a variety of beak sizes and shapes, an important indicator of food preference that makes them ideal for studying evoluon. In ovenbirds, "some [beaks] are long and down-curved, like a scythe, for probing into crevices in tree bark and others have short dagger-like bills." What conclusions did the researchers reach? A) ovenbirds are diverse because they do not share any common ancestors B) ovenbirds because successful because they are not native to the area and could easily colonize the area C) birds have different beaks that help them exploit different resources and avoid competition 2) One ant species from Africa is best at competing for space, but is worse at colonizing a…
Monarch butterflies and viceroy butterflies are both found in the United States and parts of Canada and Mexico. Monarch butterflies have a particular orange and black wing pattern and are toxic. Viceroy butterflies are non-toxic but have a very similar wing pattern to the monarch. Scientists have observed that attempted predation of viceroy butterflies is lower in regions that are also inhabited by monarch butterflies. Why would natural selection select for a non-poisonous butterfly with the same markings as a poisonous butterfly?
The rough-skinned newt, which lives in western North America, stores a poison in its skin and is avoided by predators. However, several populations of garter snakes have undergone one or a few mutations that enablethem to tolerate the toxin, and these snakes eat the newts with no ill effects. How has natural selection affected this predator–prey relationship? Based on what you have learned about evolutionary arms races, predict what may happen to the newts and the poison-resistant garter snakes over time.
A mile-wide river separates two rabbit populations for a million years. Over time, one population evolves long ears and is more active near dark, when they can hear predators coming but the predators can't easily see their ears sticking up above the grass. The other rabbit population evolves short ears and is more active in the middle of the day; it is harder to see, but also doesn't hear predators approaching as well. Eventually the river dries up, and the rabbits start encountering each other again. What do you predict will initially happen when the populations first start to meet? O rabbits will avoid hybridizing, since it is usually a mistake rabbits will interbreed and have offspring with intermediate ears that are visible during the day and not as good at hearing predators at night O rabbits will know not to mate with any that don't have their same "ear size" O rabbits will already show complete reproductive isolation after one million years and will ignore each other, having…
In birds of paradise that populate tropical rainforest ecosystems, bright colored beaks and feathers are commonly found. These phenotypes continue to persist, even though brightly colored birds are more easily seen by predators. Which of the following would best describe the reason behind the persistence of these phenotypes in birds of paradise?
You are surveying of the turtle species identifies several breeding populations in different habitats across the island. After a very warm summer of 2020, you observe that the hatchlings from low-elevation nests are mostly males, whereas hatchlings from higher elevations have an equal female-to-male sex ratio. As a bit more background, temperature influences the sex ratio in some turtle species, a phenomenon called temperature-sex determination (TSD). With this knowledge, you hypothesize this new turtle species exhibits TSD, and that eggs incubated at low elevations during the warm year experienced a high enough embryonic temperature to skew the sex ratio. To test this, you collect 20 newly laid eggs in early 2021 & take them back to the lab to conduct an experiment to test your hypothesis that this species exhibits TSD. Assume you know the average nest temperature in the wild, and you have access to multiple incubators Design an experiment to test the hypothesis that this turtle…