Since Western and Eastern meadowlarks are similar in appearance, one could assume that both are members of the same species. However, the Western meadowlark sings a song that is distinct from the Eastern meadowlark, preventing the two from mating. Therefore, one could also assume that Western and Eastern meadowlarks each represent their own species. Identify which concepts characterize both assumptions.

Figure 47.6 Scientists measured the relative abundance ot fern spores above and below the K-Pg boundary in this reck sample. Which of the following statements most likely represents their findings? An abundance of fern spores from several species was found below the K-Pg boundary, but none was found above. An abundance of fern spores from several species was found above the K-Pg boundary, but none was found below. An abundance of fern spores was found both above and below the K-Pg boundary, but only one species was found below the boundary , and many species were found above the boundary. Many species of fern spores were found both above and below the boundary, but the total number of spores was greater below the boundary.

Match the terms with the most suitable description. ____ data a. ifthen statement ____ probability b. unique type of organism ____ species c. experimental results ____ hypothesis d. testable explanation ____ prediction e. measure of chance ____ producer f. makes its own food

Which two extinction risks may be a direct result of the pet trade? climate change and exotic species introduction habitat loss and overharvesting overharvesting and exotic species introduction habitat loss and climate change

Which term describes the process whereby toxic substances increase along trophic levels of an ecosystem? biomassification biomagnification bioentropy heterotrophy

Tree Rings Reveal Droughts El Malpais National Monument, in west central New Mexico, has pockets of vegetation that have been surrounded by lava fields for about 3,000 years, so they have escaped wildfires, grazing animals, agricultural activity, and logging. Henri Grissino-Mayer generated a 2,129-year annual precipitation record using tree ring data from living and dead trees in this park (FIGURE 27.22). FIGURE 27.22 Annual precipitation record for 2,129 years, inferred from compiled tree ring data in El Malpais National Monument, New Mexico. Data were averaged over 10-year intervals; the graph correlates with other indicators of rainfall collected in all parts of North America. PDSI, Palmer Drought Severity Index: 0, normal rainfall; increasing numbers mean increasing excess of rainfall; decreasing numbers mean increasing severity of drought. A severe drougt contributed to a series of catastrophic dust storms that turned the midwestern United States into a "dust bowl" between 1933 and 1939. Around a.d.770, the Mayan civilization began to suffer a massive population loss, particularly in the southern lowlands of Mesoamerica. The El Malpais tree ring data show a drought during that time. Was it more or less severe than the Dust Bowl drought in 19331939?

Mountain gorillas are a highly endangered primate species, with 800 or so individuals surviving in the two remaining populations. A recent sampling of mountain gorilla genomes revealed a very low level of genetic diversity. Explain why a decline in genetic diversity often accompanies a decline in population size.

Testing Biological Control Biological control agents are used to battle red imported fire ants. Researchers have enlisted the help of Thelohania solenopsae, a natural enemy of the ants. This microsporidian (Section 23.4) is a parasite that infects ants and shrinks the ovaries of the colony's egg-producing female (the queen). As a result, a colony dwindles in numbers. Are these biological controls useful against imported fire ants? To find out, USDA scientists treated infested areas with either traditional pesticides or pesticides plus biological controls (both flies and the parasite). The scientists left some plots untreated as controls. FIGURE 45.16 shows the results. FIGURE 45.16 A comparison of two methods of controlling red imported fire ants. The graph shows the numbers of red imported fire ants over a 28-month period. Orange triangles represent untreated control plots. Green circles are plots treated with pesticides alone. Black squares are plots treated with pesticide and biological control agents (parasitoid flies and a microsporidian parasite). How did population size in the control plots change during the first four months of the study?

Bruce Ames and his colleagues have pointed out that although detailed toxicological analysis has been conducted on synthetic chemicals, almost no information is available about the mutagenic or carcinogenic effects of the toxins produced by plants as a natural defense against fungi, insects, and animal predators. Tens of thousands of such compounds have been discovered, and he estimates that in the United States adults eat about 1.5 g of these compounds each daylevels that are approximately 10,000 times higher than those of the synthetic pesticides present in the diet. For example, cabbage contains 49 natural pesticides and metabolites, and only a few of these have been tested for their carcinogenic and mutagenic effects. a. With the introduction of new foods into the U.S. diet over the last 200 years (mangoes, kiwi fruit, tomatoes, and so forth), has there been enough time for humans to develop resistance to the mutagenic effects of the toxins present in those foods? b. The natural pesticides present in plants constitute more than 99% of the toxins we eat. Should diet planning, especially for vegetarians, take into account the doses of toxins present in the diet?

Testing Biological Control Biological control agents are used to battle red imported fire ants. Researchers have enlisted the help of Thelohania solenopsae, a natural enemy of the ants. This microsporidian (Section 23.4) is a parasite that infects ants and shrinks the ovaries of the colony's egg-producing female (the queen). As a result, a colony dwindles in numbers. Are these biological controls useful against imported fire ants? To find out, USDA scientists treated infested areas with either traditional pesticides or pesticides plus biological controls (both flies and the parasite). The scientists left some plots untreated as controls. FIGURE 45.16 shows the results. FIGURE 45.16 A comparison of two methods of controlling red imported fire ants. The graph shows the numbers of red imported fire ants over a 28-month period. Orange triangles represent untreated control plots. Green circles are plots treated with pesticides alone. Black squares are plots treated with pesticide and biological control agents (parasitoid flies and a microsporidian parasite). How did population size in the two types of treated plots change during this same interval?