Exam 6: Speciation and Phylogeny

The process where chance events can cause allele frequencies to fluctuate unpredictably from one generation to the next is called

What is not an example of sexual dimorphism?

Which of the following statements about plant speciation and hybridization is false?

Plant biologists estimate that ________ of living plant species are descendants of ancestors formed by polyploidy speciation.

After reading the paragraphs below, answer the question(s) that follow(s). The first fossil of Archaeopteryx, which lived about 150 million years ago, was found in the Solnhofen Quarry in Germany. Archaeopteryx has an interesting collection of characteristics that led to the hypothesis that it represented an evolutionary transition between modern-day birds and small bipedal dinosaurs. The fossil reveals the imprint of feathers, which connect Archaeopteryx to birds, although they don't present direct evidence of flight. Unlike birds, however, the fossil record reveals that Archaeopteryx had teeth, functional claws on the wings that may have been used for climbing trees or holding prey, and a long, bony tail. Birds have a fused collarbone, and this was found in Archaeopteryx also. However, there were differences in the structure of the sternum. In birds, the sternum is keeled (raised and slightly concave). The keel of the sternum serves as an attachment site for the flight muscles. Archaeopteryx had a flat sternum, similar to that found in reptiles. -The absence of a keeled sternum in Archaeopteryx suggests that this species

After reading the paragraphs below, answer the question(s) that follow(s). In 2004, scientists announced the discovery of the fossil remains of some extremely short early humans on the Indonesian island of Flores. The new species has been named Homo floresiensis. One hypothesis is that H. floresiensis evolved from Homo erectus, another early human species. How did a population of H. erectus become isolated on this remote island? Early humans constructed boats and rafts, so perhaps they were blown far off course by strong winds during a storm. H. erectus averaged almost 6 feet in height, but the remains show that adults of H. floresiensis were only about 3 feet tall. It's hypothesized that limited resources on this hot and humid island (only 31 square miles) exerted selection pressure and succeeding generations began to shrink in size. Small bodies require less food, use less energy, and are easier to cool than larger bodies. Evolution of small size in similar circumstances has been observed in many other species, but never before in humans. This find demonstrates that evolutionary forces operate on humans in the same way as on all other organisms. -If H. floresiensis could be shown to breed with H. erectus and the offspring were of normal size, one could conclude that

Modifying species by selecting and breeding individuals with desired traits over many generations is

After reading the paragraph below, answer the question(s) that follow(s). Desert pupfish live in springs of the American Southwest. Today there are about 30 species of pupfish, but they all evolved from a common Pleistocene ancestor. The southwestern United States was once much wetter than it is now, and the Pleistocene pupfish flourished over a wide geographic area. Over thousands of years, however, the Sierra Nevada mountain range was pushed upward by geological forces, blocking rainfall from the Pacific Ocean. As the large lakes dried up, small groups of pupfish remained in springs and pools fed by groundwater seepage. Now, although many of these small springs still have pupfish, each population has evolved to become very different from pupfish in other springs. -Individuals of the different pupfish species presumably would not mate with each other even if they were housed together. Which of the following is unlikely to be a possible reason for this?

Which mollusc has complex camera lens-type eyes?

Evolutionary biologists can put together a logical sequence of events on how a group of organisms evolved from a common ancestor by using all of the following methods except