Darwins Natural Selection

Worksheet: Darwin’s Natural Select Read t selection. situations below and identify the 4 points of Darwi s n 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 FOR? Nocturnal worms b. What is the selective pressure? predation c. Darwin's 4 points: Identify the 4 points in the scenario above. Populations have variations. There are diurnal and nocturnal worms. More offspring are produced than survive. Of 500 born, 100 survive. Those that survive have favourable traits. Nocturnal worms survive because the birds don’t eat them. A population will change over time. Nocturnal worms will reproduce. The population will shift towards being nocturnal. 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. What is the selective pressure? temperature c. Darwin's 4 points: Identify the 4 points in the scenario above. Populations have variations. There are three types of bear coats More offspring are produced than survive Average ½ of cubs survive Those that survive have favourable traits. The bears that are surviving have thick coats to keep them warm A population will change over time. Over time, average coat thickness will increase 3) In ostriches, there are 2 types: ones that run fast and those hat run slowly. The fast birds can reach up to 40 mi n hour. Jackals love to eat ostrich, and they can reach sp of up to 35-40 miles per hour. A flock of ostrich will lay ~ 10 eggs ach mother only lays but many rodents break into the eggs d eat the fetus before they hatch. a. W ostrich will natural selection select AGAINST? Slow ones FOR? Fast ones b. W is the selective pressure? Predation c. D n's 4 points: Identify the 4 points in the scenario above. Populations have variations. There are slow and fast ostriches. More offspring are produced than survive. Many eggs are destroyed before hatching. Those that survive have favourable traits. Fast ostriches will survive A population will change over time. Average speed of ostriches will increase over time. 4) There are two types of rabbits: those that strictly eat grass and tho that strictly eat berries and flowers. A drought occurs one year, and 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? Berry eaters FOR? Grass eaters b. What is the selective pressure? Food supply c. Darwin's 4 points: Identify the 4 points in the scenario above. Populations have variations. There are two types of rabbits More offspring are produced than survive Many babies are eaten Those that survive have favourable traits. Grass eaters survive because they don’t starve A population will change over time. Over time, more grass-eating rabbits will be born 5) Bob believes that giraffes have long necks because they have stretched their necks to try and reach food that is high in trees. Since the parent had stretched its neck, it passed the long neck on to its offspring. b. Ryan believes that giraffes have long necks because the ones with long necks were able to reach the food, and those with short necks could not and died. The long necked giraffes reproduced, and soon all of the giraffes had long necks. a. Who thinks like Lamarck? Bob b. Who thinks like Darwin? Ryan c. Who disproved the idea of inheritance of acquired traits using tailless mice? Haeckl