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In all three cases, atmospheric concentrations of greenhouse gases have been increasing since we have been directly measuring them (1970s for CO2, 1980s for methane, and 1990s for nitrous oxide). For CO2, we can look further back than our measurement records by studying ice cores in Greenland and Antarctica, which show that current CO2 levels are much higher than the oscillations that occurred throughout the last ~800,000 years (which varied from ~180 to ~300 ppm, compared to today’s value of over 420 ppm).

The Principle of Allocation states that “each organism has a limited amount of energy that can be used for all life purposes” and that “energy allocated to one function cannot be applied to another function”. This means that organisms must make decisions about how to invest resources in different life functions (example: growth versus reproduction). The fact that an increased investment in one factor must be balanced by reduced investment in other factor(s) imposes trade-offs, whereby every decision has a benefit and a cost. 

We discussed three examples of this in class: root:shoot ratios, optimal foraging theory, and photosynthetic pathways

We discussed two examples of this in class: semelpartiy vs iteroparity and the tradeoff between offspring size and number.

Evolution relates to genetic changes in populations through time; ecology focuses on how species (and individuals) interact with one another and with the environment. These relate to one another in that ecological interactions can drive evolutionary changes, and genetic changes can influence or alter ecological interactions.

Species diversity (in terms of the D value) is a metric by which we compare diversity across ecosystems. The D value is calculated in respect to two important components: species richness (the number of species in the ecosystem) and species evenness (the similarity in relative abundance of each species). 

These terms are the two ‘ends’ of the continuum in how organisms regulate body temperature. Some species are fully ectothermic and regulate their body temperature behaviorally by relying on ecosystem temperatures. Endothermic organisms primarily regulate their temperature metabolically (though they will also often have some behavioral components as well). Remember that these are not hard categories, but exist more in a continuum, where some organisms may be primarily ectothermic, but occasionally perform some metabolic regelation to avoid extreme temperatures. 

Weather is the short-term, current conditions in the atmosphere while climate represents long term averages in conditions or patterns.

Rhizobia and mycorrhizae are similar in that they both form mutualisms with plant roots in which they provide below-ground nutrients to the plant and receive sugar from photosynthesis in return. They differ in that Rhizobia are bacteria, while mycorrhizae are fungi; Rhizobia associate only with legumes while mycorrhizae associate with all types of plants; and Rhizobia provide only nitrogen while mycorrhizae provide any/all below-ground nutrients the plant may require.

The fundamental niche is the abiotic conditions an organism can physiologically tolerate, and represents all the conditions under which the organism might be found. The realized niche incorporates biotic interactions, and represents where the organism will actually be found given its requirements for hosts/symbionts, or exclusion of some habitat by competition, predation, etc

The traits are listed on the lecture slide from the allocation lecture. Recognize that these exist on a continuum (meaning some organisms are ‘in the middle’ and are not fully K-selected or r-selected), additionally, some organisms have some traits that are very K-selected but also some traits that are very r-selected. These organisms can be difficult to ‘categorize’

These terms relate to osmoregulation, specifically which components of a system have higher or lower solute concentrations. Remember that these terms are comparisons – often the comparison is a cell or organism to its surrounding environment. For a marine organism, for example, the ocean environment is very salty, so the ocean is hypertonic (has higher solute concentrations) compared to the animal’s body and the animal’s body is hypotonic (has lower solute concentrations) compared to the ocean water. If two systems have equal solute concentrations, they are isotonic. 

Bergmann stated that body size of animals should be positively correlated with the temperature of the habitat in which they live, meaning that animals living in cold environments should generally be larger than animals living in warm environments (this should be applied within a taxonomic group. A bear will always be bigger than a bird, but Bergmann’s rule would predict that bears and birds in cold environments are bigger than bears and birds in warm environments). Allens’ rule is similar, but focuses on appendages. Given how easily limbs and appendages lose heat to the surrounding environment, Allen predicted that the length of limbs and appendages should be correlated with habitat temperature, with limbs being longer in warmer environments and shorter in colder environments. Both of these ‘rules’ apply principles of surface:area ratios and heat loss to predict what body shapes will be most suitable for different types of habitats.

Amphibians are especially sensitive to osmoregulatory issues since their skin is very permeable, which is why they are only found in freshwater or brackish (low salt) environments. Consequently, it is extremely difficult, to the point of virtually impossible for amphibians to disperse long distances across the ocean. The Hawaiian Island (among other island systems) are too far from other landmasses for amphibians to have been able to get to the islands unassisted. Amphibians that exist in the Hawaiian islands today were brought there by humans.