You are an ecologist. Devise a method of estimating the number of great blue heron in Rhode Island.

You are an ecologist. Devise a method of estimating the number of great blue heron in Rhode Island.

Chapter 53 Population Ecology

Bioflix: population ecology

sn N  x © 2011 Pearson Education, Inc. • Mark-recapture method • Scientists capture, tag, and release a random sample of individuals (s) in a population • Marked individuals are given time to mix back into the population • Scientists capture a second sample of individuals (n), and note how many of them are marked (x) • Population size (N) is estimated by

AP biology test formula sheet

Patterns of dispersion within a population's geographic range. (a) Clumped (b) Uniform (c) Random

Table 53.1

© 2011 Pearson Education, Inc. Survivorship Curves • A survivorship curve is a graphic way of representing the data in a life table • The survivorship curve for Belding’s ground squirrels shows a relatively constant death rate

Figure 53.5 1,000 100 Number of survivors (log scale) Females 10 Males 1 0 2 4 6 8 10 Age (years)

© 2011 Pearson Education, Inc. • Survivorship curves can be classified into three general types • Type I: low death rates during early and middle life and an increase in death rates among older age groups • Type II: a constant death rate over the organism’s life span • Type III: high death rates for the young and a lower death rate for survivors • Many species are intermediate to these curves

Figure 53.6 1,000 I 100 II Number of survivors (log scale) 10 III 1 0 50 100 Percentage of maximum life span

© 2011 Pearson Education, Inc. Reproductive Rates • For species with sexual reproduction, demographers often concentrate on females in a population • A reproductive table, or fertility schedule, is an age-specific summary of the reproductive rates in a population • It describes the reproductive patterns of a population

Table 53.2

How would an ecologist determine change in population size over a given period of time? Devise a formula.

Population dynamics Births Deaths Deaths and emigrationremove individualsfrom a population. Births and immigrationadd individuals toa population. Immigration Emigration

Change in population size Immigrants entering population Emigrants leaving population   Births  Deaths  © 2011 Pearson Education, Inc. Per Capita Rate of Increase • If immigration and emigration are ignored, a population’s growth rate (per capita increase) equals birth rate minus death rate

© 2011 Pearson Education, Inc. • The population growth rate can be expressed mathematically as where N is the change in population size, t is the time interval, B is the number of births, and D is the number of deaths

© 2011 Pearson Education, Inc. • Births and deaths can be expressed as the average number of births and deaths per individual during the specified time interval B  bN D  mN where b is the annual per capita birth rate, m(for mortality) is the per capita death rate, and N is population size

dN  rmaxN dt © 2011 Pearson Education, Inc. Exponential Growth • Exponential population growth is population increase under idealized conditions • d means discrete, or over a short period of time • Under these conditions, the rate of increase is at its maximum, denoted as rmax • The equation of exponential population growth is

Figure 53.7 2,000 dNdt = 1.0N 1,500 dNdt = 0.5N Population size (N) 1,000 500 0 5 10 15 Number of generations

(K  N) dN  rmax N dt K © 2011 Pearson Education, Inc. The Logistic Growth Model • In the logistic population growth model, the per capita rate of increase declines as carrying capacity is reached • The logistic model starts with the exponential model and adds an expression that reduces per capita rate of increase as N approaches K

Table 53.3

Figure 53.9 Exponentialgrowth 2,000 dN dt = 1.0N 1,500 K = 1,500 Logistic growth 1,500 – N 1,500 dN dt ( ) Population size (N) = 1.0N 1,000 Population growthbegins slowing here. 500 0 0 5 10 15 Number of generations

Figure 53.UN03 K = carrying capacity Population size (N) K – N K dN dt ( ) = rmaxN Number of generations

Figure 53.10 180 1,000 150 800 120 Number of Daphnia/50 mL Number of Paramecium/mL 600 90 400 60 200 30 0 0 0 5 10 15 0 20 40 60 80 100 120 140 160 Time (days) Time (days) (b) A Daphnia population in the lab (a) A Paramecium population in the lab

Figure 53.15 When populationdensity is low, b > m. Asa result, the populationgrows until the densityreaches Q. When populationdensity is high, m > b,and the populationshrinks until thedensity reaches Q. Equilibrium density (Q) Birth or death rateper capita Density-independentdeath rate (m) Density-dependentbirth rate (b) Population density

Figure 53.16 100 80 60 % of young sheep producing lambs 40 20 0 200 300 400 500 600 Population size

Figure 53.18 50 40 30 20 10 0 2,500 2,000 1,500 1,000 500 0 Wolves Moose Number of moose Number of wolves 1955 1965 1975 1985 1995 2005 Year

© 2011 Pearson Education, Inc. © 2011 Pearson Education, Inc. • Hypothesis: The hare’s population cycle follows a cycle of winter food supply • If this hypothesis is correct, then the cycles should stop if the food supply is increased • Additional food was provided experimentally to a hare population, and the whole population increased in size but continued to cycle • These data do not support the first hypothesis

© 2011 Pearson Education, Inc. • Hypothesis: The hare’s population cycle is driven by pressure from other predators • In a study conducted by field ecologists, 90% of the hares were killed by predators • These data support the second hypothesis

Figure 53.19 Snowshoe hare 160 120 80 40 0 9 6 3 0 Number of lynx(thousands) Lynx Number of hares(thousands) 1850 1875 1900 1925 Year

© 2011 Pearson Education, Inc. • Hypothesis: The hare’s population cycle is linked to sunspot cycles • Sunspot activity affects light quality, which in turn affects the quality of the hares’ food • There is good correlation between sunspot activity and hare population size

Inquiry: How does food availability affect emigration and foraging in a cellular slime mold? EXPERIMENT Dictyosteliumamoebas Topsoil Bacteria 200 m Dictyostelium discoideum slug

Figure 53.21 ˚ Aland Islands EUROPE Occupied patch Unoccupied patch 5 km

Figure 53.22 7 6 5 4 3 2 1 0 Human population (billions) The Plague 8000 BCE 4000 BCE 3000 BCE 2000 BCE 1000 BCE 0 1000 CE 2000 CE

Figure 53.23 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 2009 Annual percent increase Projecteddata 1950 1975 2000 2025 2050 Year

Match the country with the age-structure pyramid: US, Italy, Afghanistan Afghanistan United States Italy Male Female Male Female Male Female Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 10 8 6 4 2 0 2 4 6 8 10 8 6 4 2 0 2 4 6 8 8 6 4 2 0 2 4 6 8 Percent of population Percent of population Percent of population

How do their growths compare? Futures Institute: Age-structure pyramids Afghanistan United States Italy Male Female Male Female Male Female Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 10 8 6 4 2 0 2 4 6 8 10 8 6 4 2 0 2 4 6 8 8 6 4 2 0 2 4 6 8 Percent of population Percent of population Percent of population

Futures Institute: Age-structure pyramids Rapid growth Afghanistan Slow growth United States No growth Italy Male Female Male Female Male Female Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 10 8 6 4 2 0 2 4 6 8 10 8 6 4 2 0 2 4 6 8 8 6 4 2 0 2 4 6 8 Percent of population Percent of population Percent of population

Conclusions? 60 50 40 30 20 10 0 80 60 40 20 0 Life expectancy (years) Infant mortality (deaths per 1,000 births) Indus-trializedcountries Less indus-trializedcountries Indus-trializedcountries Less indus-trializedcountries

You are an ecologist. Devise a method of estimating the number of great blue heron in Rhode Island.