5 Points of Natural Selection - Answer Key

5 Points of Darwin’s Natural Selection Read the following situations below and identify the 5 points of Darwin’s natural selection. 1) There are 2 types of worms: worms that eat at night (nocturnal) and worms that eat during the day (diurnal). The birds eat during the day and seem to be eating ONLY the diurnal worms. The nocturnal worms are in their burrows during this time. Each spring when the worms reproduce, they have about 500 babies but only 100 of these 500 ever become old enough to reproduce. a. What worm has natural selection selected AGAINST? diurnal worms nocturnal worms FOR? b. Darwin's 5 points: Identify the 5 points in the scenario above. Population has variations. There are 2 types of worms in the area (diurnal and nocturnal) Some variations are favorable. Birds do not eat nocturnal worms (nocturnal worms advantage) More offspring are produced than survive. 100 of the original 500 worms survive to reproduce Those that survive have favorable traits. More nocturnal worms survive and reproduce A population will change over time. Nocturnal worm population increases; diurnal worm population decreases 2) There are 3 types of polar bears: ones with thick coats, ones with thin coats and ones with medium coats. It is fall, soon to be winter. The temperatures are dropping rapidly and the bears must be kept warm, or they will freeze to death. Many of the bears have had 2 cubs each but due to the extreme temperatures, many mothers only have one cub left. a. What bear will natural selection select AGAINST? thin coats FOR? thick coats b. Darwin's 5 points: Identify the 5 points in the scenario above. Population has variations. There are 3 types of bears (thick, medium, and thin coats) Some variations are favorable. Thick coats provide warmth to survive (thick coat advantage) More offspring are produced than survive. Half of the total cubs born survive Those that survive have favorable traits. Bears with thicker coats have a higher survival rate A population will change over time. Survial rate of bears with thicker coats rises, population of bears with thin coats will gradually decrease 3) In ostriches, there are 2 types: ones that run fast and those that run slowly. The fast birds can reach up to 40 miles an hour. Jackals love to eat ostrich, and they can reach speeds of up to 35-40 miles per hour. A flock of ostrich will lay approximately 10 eggs (each mother only lays 1), but many rodents break into the eggs and eat the fetus before they hatch. a. What ostrich will natural selection select AGAINST? slow ostriches FOR? fast ostriches b. Darwin's 5 points: Identify the 5 points in the scenario above. Population has variations. There are slow and fast ostriches Some variations are favorable. Fast ostriches can out run the jackals (fast ostriches advantage) More offspring are produced than survive. Rodents eat the eggs before they hatch Those that survive have favorable traits. The fast ostriches can outrun the jackals A population will change over time. Fast ostriche population increases; slow ostriche population decreases 4) There are two types of rabbits: those that strictly eat grass and those that strictly eat berries and flowers. A drought occurs one year, and the plants have difficulty producing any extras (flowers, berries, etc.). They can only try and keep themselves green. The rabbits have had babies all year long but many are eaten by foxes or hawks. Due to the drought, many have starved to death. a. What rabbit will natural selection select AGAINST? Eat berries and flowers FOR? eat grass b. Darwin's 5 points: Identify the 5 points in the scenario above. Population has variations. There are 2 types of rabbits (eat grass and eat berries and flowers) Some variations are favorable. Rabbits that eat grass have food (grass eating advantage) More offspring are produced than survive. Babies are being eaten by predatos or starving Those that survive have favorable traits. The grass eating rabbits can eat the others cannot A population will change over time. The population of grass eating bunnies increases and the population of berry/flower eating bunnies decreases Living things that are well adapted to their environment survive and reproduce. Those that are not well adapted don’t survive and reproduce. An adaptation is any characteristic that increases fitness, which is defined as the ability to survive and reproduce. Over many generations heritable adaptive characteristics become more common in a population. This process is called evolution by natural selection. Evolution by natural selection takes place over many, many generations. Evolution by natural selection leads to adaptation within a population. The term evolution by natural selection does not refer to individuals changing, only to changes in the frequency of adaptive characteristics in the population as a whole .