Exam 23: Broad Patterns of Evolution

One explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation.When they had become sufficiently large,these extensions became useful for gliding through the air,and selection later refined them as flight-producing wings.If this hypothesis is correct,modern insect wings could best be described as

Many species of snakes lay eggs.However,in the forests of northern Minnesota where growing seasons are short,only live-bearing snake species are present.This trend toward species that perform live birth in a particular environment is an example of

The loss of ventral spines by modern freshwater sticklebacks is due to natural selection operating on the phenotypic effects of Pitx1 gene

The history of continental drift on Earth has

Records of extinctions on the planet indicate that

What is true of the fossil record of mammalian origins?

A difficulty in presenting evidence for a sixth mass extinction is

What is critical to understand about the following statement? Eyes could not have evolved over time,part by part,because for the eyeball to function at all,it needs all of its parts working together.

The existence of evolutionary trends,such as increasing body sizes among various horse species,is evidence that

Which of these fly organs,as they exist in current fly populations,best fits the description of an exaptation?

Hox genes are a group of related genes that

Which statement about the atmosphere and life on Earth is correct?

Which effect of continental drift would allow scientists to track the history of life on the planet?

The major evolutionary episode corresponding most closely in time with the formation of Pangaea was the

In the 5 to 7 million years that the hominid lineage has been diverging from its common ancestor with the great apes,dozens of hominid species have arisen,often with several species coexisting in time and space.As recently as 30,000 years ago,Homo sapiens coexisted with Homo neanderthalensis.Both species had large brains and advanced intellects.The fact that these neurological traits were common to both species is most easily explained by which of the following?

Which group of tetrapods had the first examples of specialized teeth?

Figure 23.3 -According to the theory of seafloor spreading,oceanic islands,such as the Hawaiian Islands depicted in Figure 23.3,form as oceanic crustal plates move over a stationary "hot spot" in the mantle.Currently,the big island of Hawaii is thought to be over a hot spot,which is why it is the only one of the seven islands that has active volcanoes.What should be true of the island of Hawaii? 1)Scientists in search of ongoing speciation events are more likely to find them there than on the other six islands. 2)Its species should be more closely related to those of nearer islands than to those of farther islands. 3)It should have a rich fossil record of terrestrial organisms. 4)There is a good chance of finding endemic species on this island. 5)On average,it should have fewer species per unit surface area than the other six islands.

Which event stimulated the rapid development of eukaryotes?

If we visualize the time that has passed since the origin of our solar system and Earth,or about 4.6 billion years,as a one-hour clock,then out of one hour,multicellular eukaryotes have been present on the planet for about

The following questions refer to this hypothetical situation. A female fly,full of fertilized eggs,is swept by high winds to an island far out to sea.She is the first fly to arrive on this island and the only fly to arrive in this way.Thousands of years later,her numerous offspring occupy the island,but none of them resembles her.There are,instead,several species,each of which eats only a certain type of food.None of the species can fly,for their flight wings are absent,and their balancing organs (in other words,halteres)are now used in courtship displays.The male members of each species bear modified halteres that are unique in appearance to their species.Females bear vestigial halteres.The ranges of all of the daughter species overlap. -If these fly species lost the ability to fly independently of each other as a result of separate mutation events in each lineage,then the flightless condition in these species could be an example of