Properties of Populations
What are the differences between asexual and sexual reproduction?
Asexual - does not require the exchange of genetic material, the progeny are well adapted to environment, there is high potential for population growth BUT low genetic diversity
Sexual - exchange of genetic material between parents (via fusion of gametes), increase in genetic variation, and ensures an organism's genes will perpetuate BUT energetically costly to produce gametes and offspring
What is the difference between interspecific competition and intraspecific competition?
Interspecific competition is competition/interactions between organisms from DIFFERENT species.
Intraspecific competition is competition/interactions between members of the SAME species.
What does the term acclimation mean?
The change of function and tolerance of an organism that results in equilibration with new physiochemical conditions. It is an organism's response to changing environmental conditions.
What type of zonation do rocky shore intertidal ecosystems exhibit? Is this type of zonation found in other ecosystems?
Vertical
Yes- also found in salt marshes
On average, how much energy is transferred up the food chain (from one trophic level to the next)?
10%
What are some of the differences between r-selected and k-selected species?
R-selected - large # of offspring, high instantaneous mortality, no/little parental care, mature early, short life spans, good when environment is unpredictable, competition is lax
K-selected - small # of offspring, low instantaneous mortality, parental care, mature late, long life spans, good when environment is predictable, competition is fierce
What does "density-dependent" mean?
Any factor in the population that can change because of the population density (the number of organisms in an area).
Ex: at a high density, it is easier to find a mate but there is greater competition for resources
What is the difference between a regulator and a conformer? What category (regulator or conformer) do endotherms and ectotherms fall under? What about homeotherms and poikilotherms?
Regulator: An organism whose internal body temperature remains constant despite external temperature changes. -- Endotherms and Homeotherms
Conformer: An organism whose internal temperature changes to match the changing environmental temperature. -- Ectotherms and poikilotherms
List the 4 processes that shape ecological communities.
1. Speciation - the evolutionary origin of new species over many generations
2. Ecological Selection - environmental tolerances and interactions among species that predictably favor certain species under certain conditions
3. Dispersal - the movement of organisms among sites and regions
4. Ecological Drift - random fluctuations in species abundance
What is the difference between top-down and bottom-up control?
Top-down: Higher trophic levels control the biomass of lower trophic levels (Herbivores lessen the amount of autotroph biomass, but carnivores feed on herbivores to regulate autotroph populations)
Bottom-up: Resource availability controls the biomass of autotrophs (and therefore the biomass of all other higher trophic levels that rely on these producers)
What is "life history"? What are at least 2 examples of life history traits?
Life History is an organism's lifetime pattern of growth, development, and reproduction.
Examples include: type of reproduction (sexual vs. asexual), type of life cycle (simple vs. complex), number and size of offspring, parental investment, etc.
What are the signs (+/-/0) for mutualism, commensalism, predation, competition, and amensalism?
Mutualism: +,+
Commensalism: +,0
Predation/parasitism: +,-
Competition: -,-
Amensalism: -,0
What adaptations do homeotherms have to prevent heat loss to the environment? There are 2 major adaptations we discussed in class.
1. Insulation (like blubber) with a low thermal conductivity
2. Countercurrent heat exchange
What is the difference between a fundamental and a realized niche?
Fundamental: The full range of environmental conditions and resources an organism can possibly occupy and use.
Realized: The part of fundamental niche that an organism actually occupies. Can be the same size, smaller than, or larger than the fundamental niche.
Explain the Green World Hypothesis. How does it relate to marine environments?
Plants make up a significant portion of Earth’s biomass (Earth is dominated by photosynthetic organisms).
Plants make up most of the environment in terrestrial environments BUT there is an inverted pyramid for marine environments (animals and protists make up most of the marine biomass)
Why? Producers are single-celled and have the ability to reproduce rapidly – but this means their biomass will be consumed even quicker, leading to larger animal biomass in oceans.
What is the difference between Type I, Type II, and Type III survivorship curves?
Type I - low instantaneous mortality, fewer offspring, parental care for young
Type II - constant decline in survivorship; mortality rate remains constant
Type III - Low instantaneous mortality (due to production of a lot of offspring), many offspring, little/no parental care so life span is short
What are the 2 kinds of intraspecific competition? And what do they mean?
Exploitation competition: competing individuals do not interact directly with one another. Over time, one species dominates a habitat to preclude its use from competitors.
Interference competition: competing individuals directly interact with one another.
What are the 4 things an organism can do when challenged with low oxygen availability?
1. Reduce respiration and pumping rates
2. Switch to anaerobic metabolism
2. Decrease heart rate
3. Alter oxygen binding capacity of blood pigments
How does patch quality (source vs. sink) and number of patches influence extinction?
Quality- Sink habitats will have higher extinction rates (there is a negative growth rate), but they can be "rescued" by source habitats that have greater survival rates (there is a positive growth rate)
Number- Increased number of patches lowers the risk for regional extinction ("spread the risk"). Species and organisms can move between the patches/habitats as resource availability, disease, or competition change.
How does tertiary production differ in open ocean ecosystems vs. shelf ecosystems vs. upwelling systems?
Open ocean: Longer food chains (avg. 5 links) = low food chain efficiency = low tertiary production
Shelf: medium food chains (avg. 3 links) = medium food chain efficiency = semi-high tertiary production
Upwelling systems: shorter food chains (avg. 1.2 links) = higher food chain efficiency = most productive systems in aquatic ecosystems
What is the equation for exponential population growth? What does each variable represent/mean? What are the assumptions of this population growth model?
Equation: dN/dt = rN
Variables: r is exponential growth rate and N is population size
Assumptions: geographic closure, birth and death rates are constant, no age/stage structure, no time lags
What is the equation for logistic growth rate? What does each variable mean/represent? Why is it more realistic than exponential population growth?
Equation:dN/dt = rN(1-(N/K))
Variables: r is exponential growth rate, N is population size, and K is carrying capacity
It is more realistic because it incorporates carrying capacity to show that environmental pressures exist, and populations cannot grow unregulated.
Explain countercurrent heat exchange.
Warm blood from the heart enters an artery and flows outward to a cold extremity. As the warm blood flows, it diffuses heat to the nearby vein (which has blood flowing in the opposite direction back towards the heart). This diffusion causes the blood in the veins to warm, and therefore results in less heat loss at the end of the appendage.
What is the equation used to determine the probability of local persistence in a given year? What does each variable represent/mean?
Equation: r = 1 - e
Variables: r is probability of local persistence in a given year, e is probability of local extinction in a given year
What is the equation used to calculate trophic efficiency? What does each variable represent/mean?
Equation: P = BE^n
Variables: P is production at the highest level, B is primary production, E is food chain efficiency (unless given to you, assume it is 10% or 0.1), and n is number of links between trophic levels