Chapter 25 TEST

Adaptive radiation occurs within a single lineage. (Adaptive radiation occurs when a single lineage produces many descendant species.)

Mammals and reptiles in the post-dinosaur age. (Mammals and reptiles are not descended from a single lineage.)

True. (Convergent evolution occurs when selective pressures produced by similar conditions (such as habitat) favor the evolution of similar solutions.)

Trunk/ground. (These ecomorphs need long legs to jump from one broad perch to another.)

The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place. (This statement is true; the historical evidence of adaptive radiation on an island is recorded in the evolutionary history of the ecomorphs currently living on the island.)

Specific ecological niches. (Different species evolved in response to the selective pressures created by specific ecological niches on the islands.)

False. (The evolution of different ecomorphs is an example of disruptive selection. Each new ecomorph had characteristics that were ideal for a particular habitat, but as these characteristics developed, the lizards lost the ability to survive effectively in the other habitats on the island.)

Some stickleback populations became trapped in lakes that formed at the end of the last ice age. (Freshwater stickleback populations were established when marine populations became trapped in the freshwater lakes where they migrate to spawn annually. At the end of the last ice age, these lakes, formerly connected to the ocean, were cut off by retreating ice fields.)

1. In lakes with dragonfly larvae, pelvic spines can be disadvantageous, allowing the predatory larvae to grab the fish. 2. In lakes where there are no large predatory fish, there is no advantage to having pelvic spines. (Different environments can provide different selective pressures on an organism's morphology. In the threespine stickleback, pelvic spines provide a selective advantage in environments with large predatory fish but are a liability in environments with dragonfly larvae.)

To find the location of the gene(s) causing the difference between stickleback populations with and without spines. (Geneticists use crosses to map the location of genes.)

1. It occurred in a similar DNA region in freshwater stickleback populations all over the world. 2. It is found in a regulatory region (a "switch") upstream of the coding region of the Pitx1 gene. (Many mutations of evolutionary importance are found in regulatory regions. The gene remains intact, but the location of its expression changes—conveying a new phenotype without losing existing capabilities.)

The population of fish with pelvic spines that arrived in the lake at time B evolved a reduced pelvis over time (beginning at time C). (Having a reduced pelvis must have been advantageous for this ancient stickleback population, just as it is for many current freshwater stickleback populations.)

1. The fossil data show a pattern of evolution over long stretches of time. 2. If the same morphological changes occur in the fossil record as in living populations, we might deduce that the genetic mechanism discovered in the living populations might be responsible for the changes observed in fossils. 3. Genetic evidence reveals the precise molecular mechanism responsible for the change in pelvic structures in stickleback populations. 4. Data obtained by analyzing living fish in lakes show the selective pressures present in different environments. (Evolution repeats itself. The film uses three complimentary lines of evidence from field studies, molecular genetics, and fossil populations to show evolution of the same trait over and over again, across hundreds of thousands of years.)

the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules

India was a separate continent until 45 million years ago.

genetic drift

Yes, if the photoreceptor cells and simple eyes that preceded it were useful to the animals in which they arose. (In fact, such photoreceptors and simple eyes can be seen in many living animals. Read about the evolution of a complex eye.)

a change in a developmental gene or in its regulation that altered the spatial organization of body parts.

exaptation

are found in the deepest strata (Younger sediments are deposited over older sediments; thus, relatively older fossils are found in deeper strata than relatively younger fossils.)

prokaryotic (Prokaryotes originated a few hundred million years after Earth's crust cooled and solidified.)

used water as an electron source for photosynthesis (Oxygen began to accumulate in the atmosphere due to the action of photosynthetic cyanobacteria.)

1. It causes climate change, which puts selective pressure on organisms. 2. It causes changes in habitats, such as when large amounts of shallow marine habitat were lost in the formation of Pangaea. 3. It may cause an increase or decrease in competition among different species. (Continental drift affects organisms by changing the current environment in all of these ways. Organisms may have to adapt, move, or go extinct.)

they provide positional information in the embryo (Changes in Hox genes can have large effects on body plans in different organisms.)

"tinkering" with existing structures (Evolution, and in particular natural selection, can only select for the best available traits. Modifications to those traits are usually made in small, incremental steps, and new inventions are rare.)