Reduced hybrid viability is a barrier to speciation that occurs when

Extreme seasonal changes can be mitigated without long-distance moves by

Scientists investigated the role that beak depth plays in the ability of one species of seed-eating finch to reproduce. The scientists calculated the average beak depth of finches in mating pairs and then observed whether or not the pairs produced at least one offspring that survived to the next season. The data are represented in Figure 1. Figure 1. Beak depth and offspring survival in a species of finch Based on the data in Figure 1, which of the following best describes the concept illustrated?

Which of these is NOT considered a “behavior” in purely scientific terms?

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. Which of the following best describes the reproductive ability of C. elegans following the ARD introduced in the first experiment?

Researchers investigated the habitat preferences of two species of garter snakes, Thamnophis sirtalis and Thamnophis atratus. To create a choice chamber, the researchers built a meshed enclosure and positioned one end of the enclosure at the edge of a small pond. Zone I of the enclosure was located in the water, whereas zone IV of the enclosure was located 2–3 meters away from the water, as represented in the figure below. Snakes inside the enclosure were able to move freely between zones. From left to right, the zones are labeled 4 through 1. The side length of each square is 1 meter. A large semicircular shaded region, labeled “Pond,” completely covers square 1 and a very small part of square 2. The “Pond” region also extends beyond square 1 to the outside of the enclosure. In a series of experiments, the researchers introduced a single snake into zone IV of the enclosure at 7:00 A.M. The researchers recorded the location of the snake at six time points throughout the day. In a related experiment, the researchers introduced two snakes, one of each species, into the enclosure at the same time and observed the location of each of the two snakes at the same six time points as before. The researchers repeated both the one-snake and two-snake experiments using different individual snakes of each species. The results are presented in the table. The title of the table is ZONES MOST FREQUENTLY OCCUPIED BY GARTER SNAKES IN A MESHED ENCLOSURE. The top row contains the column labels, from left to right: column one, Time of Day; column two, Zone Most Frequently Occupied by T. atratus; column three, Zone Most Frequently Occupied by T. sirtalis; column four, Zone Most Frequently Occupied by T. Which of the following additions to the experimental design will best help test whether the observed habitat preferences were the result of competition between species?

Which statement is true regarding the structure of the chambered heart of a zebrafish?  ” A timeline at the top right spans from 100 to 600 million years ago. The phylogenetic tree shows branching relationships with colored lines representing different lineages. Tunicate branches off first at approximately 600 million years ago, shown with a black line. Amphioxus branches next at approximately 550 million years ago, also with a black line. Lamprey branches at approximately 500 million years ago with a magenta line extending to the present. A group of four fish species branches next, shown with light blue lines. Zebrafish, Medaka, Fresh Puffer, and Pufferfish all branch between approximately 450 and 400 million years ago. Clawed Frog branches at approximately 375 million years ago with a yellow-green line. Green Anole branches at approximately 325 million years ago, also with a yellow-green line. Chicken branches at approximately 300 million years ago. Opossum, Mouse, and Human branch as a group at approximately 200 million years ago, with orange lines extending to the present for all three species. On the left side, seven heart diagrams are arranged vertically corresponding to the organisms on the tree, showing increasing complexity from top to bottom. Black arrows point from each organism name to its corresponding heart structure. Each heart is illustrated with red chambers and blue blood vessels. The tunicate heart is a simple curved tube. The amphioxus heart is a tube with a knot-like structure in the middle. The lamprey heart shows two chambers with blue vessels at the top. The zebrafish through pufferfish group shares a heart with two atria at the top and a single large ventricle below. The clawed frog heart shows two atria and a partially divided ventricle. The green anole heart shows two atria at the top and a ventricle below with partial division. The chicken heart displays four distinct chambers with clear separation. The opossum, mouse, and human group shares a heart at the bottom with four chambers showing the most complex structure.”

Presence (+) or absence (-) of three derived characters Plant Species Derived Characters Vascular Tissue Seeds Flowers P + + + Q – – – R + + – S + + + T – – – U + – – W + – – The table above shows the presence (+) or absence (-) of three different derived characters (vascular tissue, seeds, and flowers) for several selected plant species. The cladogram below was created based on the information in the table to represent groups of related species. The presence of the derived characters is indicated with arrows. The figure presents a cladogram with the root of the main line at the bottom left and three equally spaced branches coming off the main line. From left to right, the branches are labeled as follows: “Species Group 1,” “Species Group 2,” and “Species Group 3.” Past the third branch, the upper right end of the main line is labeled “Species Group 4.” Three arrows are drawn pointing to the main line of the cladogram. The first arrow points to the main line midway between branch 1 and branch 2. The second arrow points to the main line midway between branch 2 and branch 3. The third arrow points to the main line midway between branch 3 and the end of the main line that is labeled 4. Group IV of the cladogram most likely includes which of the following species?

A group of populations that lives together an interacts with each other is called a(n) ______.

The figure below represents a food web in a particular ecosystem. Each letter represents a species. The arrows indicate the direction of energy flow. A is arranged at the bottom of the food web with decomposers on the right. The other letters are arranged from the far left above A, starting with E, then D up and to the right, then at the top of the web above A is C, with B to the right and lower than C, but above decomposer. The letter A has an arrow pointing up to D, an arrow pointing up to C and an arrow pointing to decomposer on the right. C has an arrow to decomposer. D has an arrow pointing left to E, an arrow pointing right to C, an arrow pointing right to B and an arrow pointing to decomposer. E has an arrow pointing to decomposer. C has an arrow pointing to decomposer. B has an arrow pointing to C and an arrow pointing to decomposer. Members of which species are most likely to be omnivorous?