Population Growth

Q: Exponential growth

A: used when generation time does not equal the unit of time. Shows unrestricted growth with constant rates of increase.

Q: geometric growth

A: used when generation time equals the unit of time (no overlapping generations). Shows unrestricted growth with constant rates of increase.

Q: λ (lambda)

A: =finite multiplication rate.

Q: r

A: =per capita rate of increase.

Q: Know the geometric equation for projecting population size:

A: Nt=NoλT, where N= population size, t = unit of time, and 𝜆= finite multiplication rate.

Q: Know the exponential equation for projecting population size:

A: Nt=Noert where N= population size, t= unit of time, r= per capita rate of increase, and e = the base of natural logarithms.

Q: Explain the logistic (sigmoid) growth curve.

A: The logistic growth curve shows a lag phase (slow growth), followed by a phase of exponential growth (unlimited resources, no competition), then an inflection point beyond which population growth slows, and then deceleration, until the carrying capacity (K) is reached.

Q: What is meant by the carrying capacity of an ecosystem?

A: It is the maximum number of individuals an ecosystem can sustain, determined by the most limiting resource.

Q: Malthusian (r-selected) species

A: have a high reproductive rate, are small, short-lived, have little protection of offspring, disperse rapidly into unstable environments, and fluctuate greatly in population.

Q: Logistic (K-selected) species

A: have a low reproductive rate, are large, have protection of offspring, are competitive in stable environments, and attain and maintain a population at or near carrying capacity.

Q: What influences the vulnerability of species to becoming extinct?

A: Influenced by distribution (geographic range), habitat specificity, local population size, degree of genetic variation, generation time, ability to migrate, and reproduction capability.

Q: How has mankind accelerated the extinction rate?

A: Through excessive hunting, introduction of alien species, and altering habitats.

Q: Density-dependent factors that regulate population growth

A: factors affecting a population in proportion to its size, greater size=greater affect

Q: Density-independent factors that regulate population growth

A: factors affecting a population in the same proportion (%) no matter the size, more climatic factors