Iguana Decline In 1987, Martin Wikelski began a long-term study of marine iguanas in the Galápagos Islands. He marked iguanas on two islands—Genovesa and Santa Fe—and collected data on how their body size, survival, and reproductive rates varied over time. He found that because iguanas eat algae and have no predators, deaths usually result from food shortages, disease, or old age. In January 2001, an oil tanker ran aground and leaked a small amount of oil into the waters near Santa Fe. FIGURE 44.3 shows the number of marked iguanas that Wikelski and his team counted in their study populations just before the spill and about a year later.
FIGURE 44.3 Shifting numbers of marked marine iguanas on two Galápagos islands. An oil spill occurred near Santa Fe just after the January 2001 census (orange bars). A second census was carried out in December 2001 (green bars).
How much did the
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Biology: The Unity and Diversity of Life (MindTap Course List)
- Which of these following scenarios is caused by the Allee effect? Corals rely on external fertilization when gametes (sperm and eggs) are released into the sea in large quantities and have to meet at random chance. When coral densities drop due to coral bleaching and die back, external fertilization becomes inefficient, few zygotes form, and coral populations further decline or go extinct. After a big disturbance in forests, such as fire, many seeds germinate and seedlings compete for space, light and resources. K-selected species produce fewer, but larger seeds that are initially outnumbered by the numerous sEeds and resulting seedlings of r-selected species. The initial advantage of r-selected species of Occupying more locations and therefore by random chance also better locations, is later overcome by the K-selected species higher competitive ability. Therefore, for the first years to decades, r-selected species dominate areas that experienced severe disturbances, while in mature…arrow_forwardYou are surveying of the turtle species identifies several breeding populations in different habitats across the island. After a very warm summer of 2020, you observe that the hatchlings from low-elevation nests are mostly males, whereas hatchlings from higher elevations have an equal female-to-male sex ratio. As a bit more background, temperature influences the sex ratio in some turtle species, a phenomenon called temperature-sex determination (TSD). With this knowledge, you hypothesize this new turtle species exhibits TSD, and that eggs incubated at low elevations during the warm year experienced a high enough embryonic temperature to skew the sex ratio. To test this, you collect 20 newly laid eggs in early 2021 & take them back to the lab to conduct an experiment to test your hypothesis that this species exhibits TSD. Assume you know the average nest temperature in the wild, and you have access to multiple incubators Design an experiment to test the hypothesis that this turtle…arrow_forwardRed-billed oxpeckers feed almost exclusively on what they can collect from the skin of large African mammals. This includes ticks and other ectoparasites, but also dead skin and blood of the mammal. The attached image shows a red-billed oxpecker sitting on the back of a warthog with a tick in its bill. A recent study found that the depletion of African mammals due to habitat loss and hunting leads to declines in oxpeckers. Researchers were interested in whether the nature of the interaction between African mammals and oxpeckers was context-dependent. They compared the effect of removal of oxpeckers in two areas in which the number of ticks on the mammals differed. In area 2, stomach content data of oxpeckers showed they consumed ~400 ticks per day. Cows were infested experimentally with large numbers of tick larvae and then oxpeckers were introduced at different stages in the tick life cycle (larvae; nymph; adult). They counted the number of adult ticks that dropped off the…arrow_forward
- Red-billed oxpeckers feed almost exclusively on what they can collect from the skin of large African mammals. This includes ticks and other ectoparasites, but also dead skin and blood of the mammal. The attached image shows a red-billed oxpecker sitting on the back of a warthog with a tick in its bill. A recent study found that the depletion of African mammals due to habitat loss and hunting leads to declines in oxpeckers. Researchers were interested in whether the nature of the interaction between African mammals and oxpeckers was context-dependent. They compared the effect of removal of oxpeckers in two areas in which the number of ticks on the mammals differed. Given the data described in the introduction to this section, what effect do African mammals have on oxpeckers a) Positive b) negative c) neutralarrow_forward1) in the future there may be more than one species of ostrich ? True or false 2)There is evidence of gene flow in the cassowary ? True or falsearrow_forwardIn spadefoot toads there are two forms of the tadpoles: omnivores and carnivores. Environmental factors such as population density, oxygen concentration, and availability of food determine which form any particular tadpole takes. Consider the situation below. A single pair of toads produces a fertilized group of eggs in a pond. The pond dries a bit creating two separate ponds, one is deep and the other is shallow. All the tadpoles in the deep pond become omnivores and all the tadpoles in the deep pond become carnivores. There is a heavy rain and the ponds become connected again and the two groups of tadpoles mix together. The carnivores eat most of the omnivores and more of the carnivores become adult toads This is an example of Group of answer choices A. natural selection and evolution B. evolution only C. natural selection onlyarrow_forward
- Shrimp fishing off the coast of Georgia was closed in 2001, due to a drastic reduction in the shrimp population. Landings of blue crab plummeted in 2002 and 2003, as five years of drought and greatly reduced freshwater flow from underground aquifers led to increased salinity in coastal estuaries. These habitats between open ocean and fresh water are “nurseries” for many marine animals. Speculate about possible causes for the decline in shrimp and blue crab populations.arrow_forwardIguana Decline In 1987, Martin Wikelski began a long-term study of marine iguanas in the Galpagos Islands. He marked iguanas on two islandsGenovesa and Santa Feand collected data on how their body size, survival, and reproductive rates varied over time. He found that because iguanas eat algae and have no predators, deaths usually result from food shortages, disease, or old age. In January 2001, an oil tanker ran aground and leaked a small amount of oil into the waters near Santa Fe. FIGURE 44.3 shows the number of marked iguanas that Wikelski and his team counted in their study populations just before the spill and about a year later. FIGURE 44.3 Shifting numbers of marked marine iguanas on two Galpagos islands. An oil spill occurred near Santa Fe just after the January 2001 census (orange bars). A second census was carried out in December 2001 (green bars). Wikelski concluded that changes on Santa Fe were the result of the oil spill, rather than sea temperature or other climate factors common to both islands. How would the census numbers be different from those he observed if an adverse event had affected both islands?arrow_forwardIguana Decline In 1987, Martin Wikelski began a long-term study of marine iguanas in the Calapgos Islands. He marked iguanas on two islandsGenovesa and Santa Feand collected data on how their body size, survival, and reproductive rates varied over time. He found that because iguanas eat algae and have no predators, deaths usually result from food shortages, disease, or old age. In January 2001, an oil tanker ran aground and leaked a small amount of oil into the waters near Santa Fe. FIGURE 44.17 shows the number of marked iguanas that Wikelski and his team counted in their study populations just before the spill and about a year later. FIGURE 44.17 Shifting numbers of marked marine iguanas on two Galpagos islands. An oil spill occurred near Santa Fe just after the January 2001 census (orange bars). A second census was carried out in December 2001 (green bars). 3. Wikelski concluded that changes on Santa He were the result of the oil spill, rather than sea temperature or other climate factors common to both islands. How would the census numbers be different from those he observed if an adverse event had affected both Islands?arrow_forward
- if kelp population continues to decrease then how will sea otters, sea urchins, killer whales be affected ?arrow_forwardUse the survivorship curves (A, B, and C) shown on the graph below to answer the following three questions. kx A B с Age Which curve best describes survivorship in clams? (Clams have external fertilization and free-swimming larval stages.) Curve A Which curve best describes survivorship in mice? Curve C Which curve best describes survivorship in a species, such as humans, that invests a great deal in caring for the young over a very long period of time? Curve Barrow_forwardThe Two-Sided Attack on the Spiny Cactus The spiny cactus is a type of plant that lives in a desert environment. A population of spiny cact shows variation in the number of spines on their outer surfaces. The graph below shows the distribution of the number of spines before the introduction of collared peccaries and parasitic wasps. Spiny Cactus Organism Collared peccary (musk hog) Collared peccaries and parasitic wasps are two organisms that were introduced to the ecosystem in which the spiny cactus population lives. The chart describes the relationship between the spiny cacti and these two organisms Parasitic wasp 100- o 70 80 90 100 110 120 130 Number of Spines Organisms Introduced into the Ecosystem C2022 Iluminate Education, Inc. Relationship with Spiny Cactus Plants They eat spiny cactus plants that have a small number of spines. They lay eggs at the base of cactus spines. When the eggs hatch, the emerging grubs dig into the interior of the cactus. and eat the inner pulp of the…arrow_forward
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