31. More than two-thirds of that growth can be ascribed to a natural increase resulting from high fertility and birthrates. 32. To prevent the natural increase of a species by adverse modification of habitat suitable for expansion assuredly impairs breeding. 33. Natural increase of the population together with immigration from the south led to the settlement also in mountain areas.34. In Mexico, Alvarez said he believed that the number of conversions heavily outweighed the rate of natural increase among members. 35. The natural increase in Europe's population is slowing and may start a steep decline within a few decades, researchers say. 36. Nonetheless, the rate of natural increase shew to be a more important component of the population growth in that period. 37. Population : 123, 337, 822 ( 2000 estimate ); average annual rate of natural increase : 2 . 6 percent. 38. By purchase and natural increase , the number of slaves had risen to 133 at the time of the 1860 census. 39. Slavery in the United States became, more or less, self-sustaining by natural increase among the current slaves and their descendants. 40. Net migration to the county between 2002 and 2006 was 48, 000, with a natural increase of 33, 000 people.
