In a flock of birds, parents can raise small clutches on their own but can increase their clutch size if they have a helper. You want to see if altruistic behavior is likely to spread. To do this you observed a male bird that stayed at his birth nest for a year to help raise the offspring of his father and his stepmother (the original mother died) and then built his own nest the following year. You calculated direct fitness (cost) for the male bird by counting the number of offspring he produced in one year and multiplied it by ½ due to the relatedness between parents and offspring. To calculate his indirect fitness (benefit), you took the total number of offspring produced in his birth nest by his father and stepmother when he assisted them and multiplied it by ½. To determine if this altruistic behavior would spread you subtracted the cost from the benefit to determine whether it was greater than 1. What did you do wrong

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.

a. by using fur or clothes to trap heat energy near the body