Food Webs & Production and Biogeography Lecture Notes

Flashcards covering biogeography patterns, island biogeography experiments, global diversity mechanisms, food web structure, and energy transfer efficiencies.

Equilibrium theory of island biogeography

A theory used to find equilibrium species richness by looking for the intersection of the immigration and extinction rate curves.

Simberloff & Wilson 1969

An experimental test of Island Biogeography Theory where 6 small mangrove islands were fumigated to kill all insects to observe recolonization.

Species-Area Curve formula

$S = cA^z$, where $S$ is the number of species, $c$ is a constant, $A$ is the area of the habitat, and $z$ is the slope of increase.

Log-transformed Species-Area Curve

$\ln S = \text{ln } c + z \times \text{ln } A$, where $c$ is the y-intercept and $z$ is the slope of increase.

Global Diversity Pattern

The trend where most taxa show the highest species diversity in the tropics and the lowest diversity at the poles.

Mechanism # 1 for Global Diversity

The tropics have the most energy and less abiotic stress, which allows more species and more trophic levels to exist.

Mechanism # 2 for Global Diversity

The tropics are the largest and oldest land mass, providing more time and more space for opportunities for speciation.

Mechanism # 3 for Global Diversity

Higher speciation rates in the tropics occur due to stronger biotic interactions, constant feedback, and coevolution leading to a possibly-infinite number of niches.

Food Web

A system that organizes species based on trophic or energetic interactions, determined by what they eat and what eats them.

Primary Producers (Autotrophs)

Organisms at the first trophic level, such as plants or detritus, that provide the energetic base for the ecosystem.

Primary Consumers (Herbivores)

Organisms at the second trophic level that consume primary producers or detritus.

Secondary Consumers

Carnivores at the third trophic level that feed on herbivores (primary consumers).

Communities

Groups of interacting species that occur together at the same place and time.

Ecosystems

The organisms in an area along with the abiotic materials and energy with which they interact.

Second Law of Thermodynamics

The principle that conversion of heat to work is not perfect; energy is lost during transfer, so available energy decreases with each trophic level.

Consumption efficiency ($E_c$)

The ratio of biomass ingested by consumers ($I_n$) to the available plant biomass ($P_{n-1}$), calculated as $E_c = \frac{I_n}{P_{n-1}}$.

Assimilation efficiency ($E_a$)

The ratio of biomass that consumers assimilate by digestion ($A_n$) to the biomass ingested by consumers ($I_n$), calculated as $E_a = \frac{A_n}{I_n}$.

Production efficiency ($E_p$)

The ratio of new consumer biomass ($P_n$) to the biomass that consumers assimilate ($A_n$), calculated as $E_p = \frac{P_n}{A_n}$.

Ecological efficiency ($E_e$)

The conversion efficiency of energy from one trophic level to the next level, equal to $E_c \times E_a \times E_p$ or $\frac{P_n}{P_{n-1}}$.