Nico Tinbergen conducted an experiment with three-spined stickleback fish in which he discovered that during the breeding season, male stickleback fish would respond very agressively to any red model introduced nearby or inside the tank–even red models not shaped like fish at all, incuding red cars driving by the window! Tinbergen showed that it is the red color of an intruding male’s belly that provokes an agressive response in the breeding male, preventing the intruder from coming near the stickleback’s nest area. This type of response is called a

Diapause is the interruption of an organism’s life cycle in response to the environmental cues. The soil nematode Caenorhabditis elegans is capable of entering entering adult reproductive diapause (ARD) when food is scarce. In C. elegans, individuals normally become reproductively mature 2 days after hatching and remain fertile for 18 days. They reproduce either by self-fertilization or by mating with another individual. In an investigation, researchers examined the survival and reproductive success of female C. elegans who were without food for 0-30 days. Groups of C. elegans were held in ARD for different numbers of days before reintroduction of food. Average brood sizes (average number of offspring per adult) were determined following either self fertilization or mating with a well-fed males. The results are shown in Figure 1. There are tick marks on the horizontal axis labeled from left to right: 0, 3 through 15 in increments of 2, and 30, with a break indicated between 15 and 30. The vertical axis has evenly spaced tick marks labeled from 0 to 450 in increments of 50. There are two bars on each of the tick marks on the horizontal axis. In each pair, the unshaded bar represents self-fertilized and the shaded bar represents mated. Each bar also shows an error bar. From left toright, the data are as follows. All numbers are approximate. 0 days: self-fertilized, 260, error bar from 255 to 265; mated, 375, error bar from 325 to 420. 3 days: self-fertilized, 190, error bar from 185 to 200; mated, 245, error bar from 240 to 250. 5 days: self-fertilized, 120, error bar from 115 to 125; mated, 150, error bar from 140 to 170. 7 days: self-fertilized, 75, error bar from 70 to 80; mated, 125, error bar from 120 to 130. 9 days: self-fertilized, 50, error bar from 49 to 51; mated, 110, error bar from 95 to 115. 11 days: self-fertilized,40, error bar from 38 to 41; mated, 120, error bar from 110 to 130. 13 days: self-fertilized, 25, error bar from 24 to 26; mated, 100, error bar from 90 to 110.15 days: self-fertilized, 10, error bar from 9 to 11; mated, 125, error bar from 120 to 130. 30 days: self-fertilized, 5, error bar from 3 to 7; mated, 45, error bar from 35 to 50. The caption on the figure reads: Figure 1. Mean brood sizes plus or minus two times the standard error of the mean after different times in A R D. Individual C. elegans were held in A R D and subsequently allowed to reproduce either via self-fertilization (unshaded bars) or by mating with well-fed males (shaded bars). Figure 1. Mean brood sizes ± SEg after different times in ARD. Individual C. elegans were held in ARD and subsequently allowed to reproduce either via self-fertilization (unshaded bars) or by mating with well-fed males (shaded bars). In a second experiment, individuals were held in ARD without food for 0-30 days and monitored for average survival times following reintroduction of food (Figure 2). There are tick marks on the horizontal axis labeled from left to right: 0, 3 through 15 in increments of 2, and 30, with a break indicated between 15 and 30. The vertical axis has evenly spaced tick marks labeled 0 to 30 in increments of 5. Each bar shows an error bar. From left to right, the data are as follows. All numbers are approximate. 0 days: 18, error bar from 15 to 21. 3 days: 15, error bar from 12 to 18. 5 days: 18, error bar from 15 to 22. 7 days: 19, error bar from 17 to 23. 9 days: 19, error bar from 16 to 23. 11 days: 17, error bar from 14 to 20. 13 days: 16, error bar from 12 to 20. 15 days: 19, error bar from 16 to 23. 30 days: 22, error bar from 18 to 24. The caption on the figure reads: Figure 2. Mean survival plus or minus two times the standard error of the mean following different times in A R D. Individual C. elegans were held in A R D and subsequently given access to food, whereupon their survival times were determined. Figure 2. Mean survival ± SEg following different times in ARD. Individual C. elegans were held in ARD and subsequently given access to food, whereupon their survival times were determined. The average brood size per mated individual upon reintroduction of food following 30 days of ARD is closest to which of the following?

Population Census Level Population 4 4 3 360 2 780 1 5,782 In a simple ecosystem, a census of the population in four successive trophic levels was taken as shown above. If level 1 is composed of photosynthetic autotrophs, then the trophic level with 780 individuals will most likely represent ______.

Behavioral isolation is a reproductive barrier that refers to

A sign stimulus is a stimuli that elicits an instinctive response in an animal. Which of the following is NOT an example of a sign stimulus?

Natural selection acts on ______, but its mechanism is at the level of ______ and their ability to reproduce.

In animals, foraging behaviors include: (select all that apply)

The following is a food web for a meadow habitat that occupies 25.6 km2. The primary producers’ biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km2. The bottom level has Meadow Grasses, the middle level has Deer, Rabbit and Vole, and the top level has Coyote and Hawk. On the bottom, Meadow Grasses has three arrows pointing to the middle level. One arrow points to Deer on the left, one arrow points to Rabbit in the middle, and one arrow points to Vole on the right. The middle level has arrows pointing to the top level. There are arrows pointing from both Deer and Rabbit to Coyote, and arrows from both Rabbit and Vole pointing to Hawk. Developers have approved a project that will permanently reduce the primary producers’ biomass by 50 percent and remove all rabbits and deer. Which of the following is the most likely result at the completion of the project?

The levels are labeled roman numeral one, roman numeral 2, roman numeral 3, and roman numeral 4.Each tropic level is represented by a rectangle and an image of an organism. From bottom to top, trophic level one shows a flower and a rectangle with a large area. Trophic level 2 shows a grasshopper and a rectangle with approximately half the area of the trophic level one rectangle.Tropic level 3 shows a mouse and a rectangle with approximately half the area of the tropic level 2 rectangle. Tropic level 4 shows a hawk and a rectangle with approximately half the area of the trophic level 3 rectangle. Assume there are 50,000 joules (J) of energy available in trophic level II in the figure. According to the conventional model of energy flow in ecosystems, which of the following statements correctly describes the flow of energy in the system?

The process of one species replacing another in a recently disrupted community is called ______.