Chapter 23

Question 0

half-life

Answer 0

The time it takes for half of a given amount of a radioisotope to decay

Question 1

radiometric dating

Answer 1

A dating method that uses measurements of certain radioactive isotopes to calculate the absolute ages in years of rocks and minerals

Question 2

plate tectonics

Answer 2

The geological theory describing how Earth’s crust is broken into irregularly shaped plates of rocks that float on its semisolid mantle

Question 3

continental drift

Answer 3

The long-term movement of continents as a result of plate tectonics

Question 4

continuous distribution

Answer 4

A geographical distribution in which a species lives in suitable habitats throughout a geographical area

Question 5

disjunct distributions

Answer 5

A geographical distributions in which populations of the same species or closely related species live in widely separated locations

Question 6

Dispersal

Answer 6

The movement of organisms away from their place of origin

Question 7

Vicariance

Answer 7

The fragmentation of a continuous geographical distribution by nonbiological factors

Question 8

biotas

Answer 8

The total collection of organisms in a geographical region

Question 9

biogeographical realms

Answer 9

A major region of Earth that is occupied by distinct evolutionary lineages of plants and animals

Question 10

endemic species

Answer 10

A species that occurs in only one place on Earth

Question 11

convergent evolution

Answer 11

The evolution of similar adaptations in distantly related organisms that occupy similar environments

Question 12

biodiversity

Answer 12

The richness of living systems as reflected in genetic variability within and among species, the number of species living on Earth, and the variety of communities and ecosystems

Question 13

adaptive radiation

Answer 13

A cluster of closely related species that are each adaptively specialized to a specific habitat or food source

Question 14

adaptive zone

Answer 14

An environment or part of an environment that may be occupied by a group of species exploiting resources in a similar manner

Question 15

extinction

Answer 15

The death of the last individual in a species or the last species in a lineage

Question 16

background extinction rate

Answer 16

The average rate of extinction of taxa through time

Question 17

mass extinctions

Answer 17

The disappearance of a large number of species in a relatively short period of geological time

Question 18

phyletic gradualism hypothesis

Answer 18

The hypothesis that most morphological change occurs gradually over long periods of time

Question 19

punctuated equilibrium hypothesis

Answer 19

The evolutionary hypothesis that most morphological variation arises rapidly during speciation events in isolated populations at the edge of a species’ geographical distribution

Question 20

paedomorphosis

“child” “form/shape”

Answer 20

A common form of heterochrony in which juvenile characteristics are retained in a reproductive adult

Question 21

exaptation (preadaptation)

Answer 21

A trait that is adaptive in a context different from the context in which it originally evolved

Question 22

evolutionary development biology

Answer 22

A field of biology that compares the genes controlling the developmental processes of different animals to determine the evolutionary origin of morphological novelties and developmental processes

Question 23

homeotic genes

Answer 23

Any of the family genes that determines overall body plan (the structure of body parts) during embryonic development

Question 24

23.1

Answer 24

- Fossils are the parts of organisms preserved in sedimentary rocks or in oxygen-poor environments - The fossil record is incomplete because few organisms fossilize completely, because some organisms are more likely to fossilize than others, and because natural processes destroy many fossils - Fossils provide a relative dating system, the geological time scale, for the strata in which they occur. Radiometric dating techniques establish the absolute age of rocks and fossils - The fossil record provides data on change in morphology, biogeography, ecology, and the behavior of organisms

Question 25

What biological materials are the most likely to fossilize?

Answer 25

Hard parts, such as the shells or bones of animals, are the materials most likely to fossilize

Question 26

Why does the fossil record provide an incomplete portrait of life in the past?

Answer 26

The fossil record provides an incomplete portrait of life in the past because not all organisms are equally likely to form fossils; fossils do not form in all types of habitats; and fossils are often destroyed by processes and erosion

Question 27

What sorts of information can paleobiologist discern from the fossil record?

Answer 27

The fossil record provides information about the morphology of ancient organisms; how structures changed over time; and the proliferation and extinction of evolutionary lineages. It also offers indirect evidence about the behavior, ecology, and physiology of organisms that lived in the past.

Question 28

How did continental drift affect the geographical distribution of organisms?

Answer 28

Continental drift caused large-scale geographical separation of populations and lineages that subsequently evolved in isolation

Question 29

What effect glaciations have on sea level?

Answer 29

Sea levels fell whenever a large proportion of Earth's water was incorporated into glaciers

Question 30

Which type of geographical distribution requires no special explanation?

Answer 30

Continuous distribution requires no special explanations. Biologists infer that lineages with a continuous distribution simply occupy all or one part of their historical range

Question 31

Why do distantly related species that live in different biogeographical realms sometimes resemble each other?

Answer 31

Distantly related species that live in widely separated parts of the world may resemble each other because convergent evolution fosters similar adaptations to the environments they occupy.

Question 32

What factors might allow a population of organisms to occupy a new adaptive zone?

Answer 32

A population of organisms may occupy a new adaptive zone after the evolution of a key morphological innovation that allows it to use the environment in a unique way or after a once-successful group of organisms declines.

Question 33

What events apparently triggered the mass extinction at the end of the Permian period?

Answer 33

Huge volcanic eruptions triggered a chain of events that led to the mass extinction at the Permian period. These eruptions warmed the atmosphere and oceans enough to melt frozen undersea methane reserves. The methane entering the atmosphere warmed the climate even further, creating a "runaway greenhouse" effect.

Question 34

When did the first major adaptive radiation of animals occur?

Answer 34

The first major adaptive radiation of animals took place in the Cambrian era.

Question 35

Did the horse lineage undergo a steady increase in body size over its evolutionary history?

Answer 35

The horse lineage was highly branched, and it included some species that were larger and some that were smaller than their ancestors.

Question 36

What is the difference between the morphological change predicted by the phyletic gradualism hypothesis and the punctuated equilibrium hypothesis?

Answer 36

Phyletic gradualism predicts that morphological change is slow and steady, producing fossils with morphologies that are intermediate between the structures found in lower and higher strata. The punctuated equilibrium hypothesis predicts that the morphological changes occur rapidly as new species form and that most species experience little morphological change for long periods of time.

Question 37

What is the difference between allometry and heterochrony?

Answer 37

allometry refers to the differential growth of body parts. Heterochrony refers to changes in the timing of developmental events.

Question 38

What evidence suggests that many developmental control genes have been conserved by evolution?

Answer 38

Similar developmental control genes are present in a wide variety of animals, plants fungi, and prokaryotes. Their widespread distribution suggests that they were present in the ancestor of all these organisms and have been conserved through countless generations.

Question 39

What genetic factor is apparently responsible for the presence or absence of spines in stickleback fist?

Answer 39

The Pitx1 gene is expressed in fin buds that later produce spines, and it is not expressed in those that fail to produce spines.

Question 40

23.2

Answer 40

- Earth's crust is composed of plates of solid rock that float on semisold mantle. New crust is constantly generated and old crust is recycled. Currents in the mantle cause the continents to move over geological time. The breakup of the continents profoundly influenced biological evolution by separating populations and creating more shallow marine habitat - Continental movements caused variations in climate, the extent of glaciations, and sea levels. Asteroid impacts and volcanic eruptions have also influenced Earth's environment, sometimes triggering large-scale extinctions.

Question 41

23.3

Answer 41

- Disjunct distributions of species can be produced by dispersal and/or Vicariance. Dispersal results in a disjunct distribution when a new population is established on the far side of a barrier. Vicariance results in a disjunct distribution when external factors such as continental drift fragment the landscape. - Continental drift has created six major biogeographical realm, each with a character biota. - convergent evolution produces similar adaptations in distantly related species that live in similar environments.

Question 42

23.4

Answer 42

- adaptive radiation produces morphological diverse species within lineages increasing biodiversity. - extinction decreases species diversity. mass extinctions have occurred at least five times in the history of life. tectonic activity, climate change, and asteroid strikes are probable causes of mass extinction - biodiversity has increased repeatedly since life first evolved, partly in response to increased geographical separation of the continents and partly because complex interactions evolve among existing species.

Question 43

23.5

Answer 43

the horse lineage is complex and highly branched. It includes species of various sizes and diverse morphological adaptations -the tempo of morphological change varies among lineages. some exhibit a pattern of gradual change through time. other lineages confirm the predictions of the punctuated equilibrium hypothesis

Question 44

23.6

Answer 44

- morphological novelties can arise from evolutionary changes in the relative growth rates of body parts or in the timing of developmental events - evolutionary developmental biology-evo devo-examines how evolutionary changes in genes that regulate embryonic development can foster changes in body shape and form