Animals Population Growth Rate - Essay Example

Animals’ Population Growth Rate Affiliation Year Reproductive females Births Fecundity Total deaths Total populationGrowth rate 1974 19 2 0.105 2 73   1975 19 1 0.053 1 73 0.005 1976 20 8 0.400 0 73 0.005 1977 21 2 0.095 1 81 0.050 1978 18 3 0.167 2 82 0.011 1979 17 3 0.176 1 83 0.010 1980 16 1 0.063 3 85 0.015 1981 16 1 0.063 4 83 -0.005 1982 16 0 0.000 2 80 -0.010 1983 19 3 0.158 5 78 -0.005 1984 21 5 0.238 3 76 -0.006 1985 23 7 0.304 2 78 0.017 1986 25 4 0.160 1 83 0.032 1987 24 1 0.

042 1 86 0.015 1988 23 3 0.130 2 86 0.005 1989 28 2 0.071 3 87 0.010 1990 28 7 0.250 1 86 0.000 1991 27 3 0.111 2 92 0.033 1992 26 6 0.231 1 93 0.009 1993 27 2 0.074 4 98 0.027 1994 26 6 0.231 4 96 -0.004 1995 25 5 0.200 4 98 0.013 1996 23 0 0.000 6 99 0.009 1997 25 2 0.080 4 93 -0.022 1998 26 2 0.077 7 91 -0.005 1999 27 3 0.125 5 86 -0.020 2000 24 3 0.130 7 84 -0.005 2001 23       80 -0.016 Sum    0.168 Average 0.006 Std dev 0.02 Procedure for calculating 1975 growth rate Solution: r i= In(N1+1)/N1 In is the natural logarithm, N1 is the population size at the end of the year and N1 denominator is the population size at the beginning of the year.

r i= In( 73+1)/73 = In( 74)/73 =0.005 Sum = total summation of growth rates = 0.168 Average = mean of the growth rates = 0.168 ÷27 = 0.006 Standard deviation = Whereby N is the population size = 27(Number of years) Xi represent each value of data set starting with 0.005, 0.005, 0.050. 0.011…….. X with bar over it represent the mean of growth rate = 0.006 Standard deviation = = 0.02 2. The population rises by 0.

006 through this period. The average exponential growth was positive. 3. From the formula T(N) =2/S2in(1+S2N) +1 and r=0 The (N) value is 80 and S =0.02 T = 69 years. 4. As N rises, T(N) also escalate. That implies that as the population expands the probability of extinction decreases. Increase in the variation in the population reduces extinction time. 5. Initial population size S 10 100 1000 10000 0.05 10 79 436 1133 0.1 9 61 209 403 0.2 8 36 82 131 0.5 5 12 20 28 6. From the table the population size ranged from 73 to a high of 99 whales.

Assuming the value of standard deviation to be the same as of 0.02, then the estimated time to disappearance would be about 64 and 85 years respectively. 7. Small populations have a high chance of extinction as compared to a large population. This is because expected survival time always increases with the increase in population size. Alteration of the environment through human activities may reduce the carrying capacity of the habitat. The high number of predators in the habitat and imbalanced sex frequencies may also hinder the population growth.

Reference Taylor, M. & Plater, B. (2001). Population viability analysis for the southern resident population of the killer Whale. The Center For Biological Diversity. Retrieved from (http:// www.biologicaldiversity.org/swcbd/species/orca/pva.pdf).