Ecology test 1
What is the exotic fish species to New Zealand experiment?
A bunch of small-scale manipulative field studies Advantages - high controlled Also an algae experiment which was highly controlled too Did more of a large scale comparative field study - the value of both is that you can see whether what you're doing in the small-scale manipulative stuff is the same for large-scale real-world stuff
What is the definition of fitness?
Describes the success of individuals in the process of natural selection
What is a biome?
Description of the general types of life that are able to grow in an area
What is the Hubbard Brook Experiment?
Develop the small watershed technique to measure the input and out- put of chemicals from individual forest areas (small watersheds are called catchments) In their catchment studies, the Hubbard Brooks scientists measured the inputs of acids, nutrients, and other materials from the atmosphere Advantages - High level of realism Cons - Ethics (clearcutting area) Small sample size (lots of correlation but very little causation)
What drives climate?
Differential heating - effects rainfall patterns Interaction of the atmosphere with the oceans and with mountain ranges Local factors
What are advantages of Endotherms?
- Active over a broader range of conditions - Endurance
What are advantages of Ectotherms?
- Can survive/thrive on limited food / unpredictable food - More efficient at turning food into new biomass - Smaller / more elongated - can exploit areas an endotherm can't
Response Curves
Response Curve 1 Reproduction goes first, then Growth/Development, then Survival Performance vs. temperature Extreme conditions (either too hot or too cold) are lethal, but between the two extremes is a continuum of more favorable conditions Response Curve 2 Survival, Growth / Development, and Reproduction depends on the steepness of the curve Performance vs. cyanide concentration Condition may be lethal at only high intensities When the poison is absent or present at low concentrations, the organism may be unaffected, but there is a threshold above which performance may decrease rapidly: first reproduction, then growth, and finally survival Response Curve 3 Applies to conditions that are required by organisms at low concentrations but become toxic at high concen- trations. Performance vs. Salinity
What drives ocean currents?
Salt content Temperature of water Interactions of land masses Wind - Coriolis effect
What is parallel evolution?
Organisms diversify from a common ancestral line, and both inherited a common set of potentials and constraints
Contrast Parallel and Convergent Evolution
Parallel Evolution: Organisms diverging from a common ancestral line, and both inherited am common set of potentials and constraints (homologous structures - equivalent structure from a common ancestor) Convergent Evolution: When structures are analogous (similar in superficial form or function) This means that similar structures occur almost coincidentally. There are no common ancestors, just a pure coincidence that organisms evolved to be similar to each other (birds and bats) Placentals and Marsupials - a common ancestor somewhere way back when where they long since diverged Things are more complicated than what the book went into *Know analogous and homologous traits* - be careful and what common ancestor you're looking at
What is Canada's experimental lake study?
ELA was originally estab- lished in 1968 to study the problem of eutrophication in lakes: excess growth of algae and cyanobacteria as a result of excessive inputs of nutrients. A manipulative field experiment Advantages - Huge amount of realism Cons - Small sample size Not a lot of replication
Why is "survival of the fittest" a bad term to use?
First, we now know that survival is only part of the story: differential reproduction is often equally important. But more worryingly, even if we limit ourselves to survival, the phrase gets us nowhere. Who are the fittest?—those that survive. Who survives?—those that are fittest. (circular reasoning) An individual will survive better, reproduce more, and leave more descendants—it will be fitter—in some environments than in others. And in a given environment, some individuals will be fitter than others.
What is community ecology?
Focuses on questions such as what controls the diversity of species of in a given area
What is a population?
Functioning groups of individual organisms of the same species in a defined location.
What is a thermophile?
Heat loving bacteria Specialized fungi, bacteria, and archaea
Discuss the pros and cons of descriptive/comparative studies as opposed to manipulative/experimental studies of the same ecological phenomenon.
Let's say the ecological phenomenon is whether the amount of nitrogen pollution placed onto the landscape in snow, rain, dust, and gases affects the diversity of grassland communities. The hypothesis of the phenomenon is that more nitrogen pollution lowers biodiversity by comparing diversity in many different grasslands that receive different inputs of nitrogen pollution from the atmosphere. Using the comparative field observation approach, the diversity of the broad leaved herbs is lower when nitrogen pollution is greater, but the diversity of the grasses increases with increasing nitrogen pollution. The scatter among the relationships are great, but the relationship is still significant. The scatter is due to many other factors across the landscape, such as the type of soil or other climate variables, along with other pollution disturbances. Instead of relying on the comparative field observational approach, one could conduct a manipulative field experiment to test the hypothesis that nitrogen pollution affects biodiversity. The results from this experiment shows a very pronounced effect of increasing nitrogen supply on biodiversity after four years of nitrogen addition. This experiment actually has an advantage over the comparative field observation study because confounding variables such as soil type and climate are held constant between treatments, which explains the tighter relationship between nitrogen and biodiversity. The cons of this experiment are that there was only one type of soil experimented on, one type of climate and disturbance history, along with a fairly limited amount of time. This means that the results of this experiment might not apply to other areas and/or to longer time scales. Overall, both manipulative and comparative studies are important to ecology, and ecologists have the potential to gain confidence in their understanding of nature when the conclusions of these two studies have similar answers.
How does the rate and timing of environmental change affect species?
Mainly negatively affects species Climatization vs. acclimation
What is a manipulative field experiment?
Manipulative experiments alter levels of a predictor variable (or factor), and then measures how one or more variables respond to these alterations. These results are then used to test cause-and-effect. In the lab - highly controlled and relatively cheap
What is diapause?
Metabolic activity is massively reduced
What causes the rainshadow effect?
Mountains - what side is wet and what side is dry depends on the dominant wind direction
What are observational study advantages?
One is able to capture the complexity of the real world that they wouldn't be able to recreate ini the lab A great launching point for experimental studies where lots of hypotheses are being made Really good at giving information you can use to generate hypotheses - background information used to create experiments You can generate mathematical models
What is an induced chemical?
Produced only in response to damage itself, and hence with lower fixed costs to the plants.
Proximate vs Ultimate explanation
Proximate - explanation of what is going on here and now Ultimate - explanation via evolutionary terms
How would global warming effect ocean currents?
Remove salinity gradient from the arctic - water doesn't sink like it would've before Southern flow deep through Atlantic stops - upwellings have a lack of nutrients Is the conveyer belt going to stop? Or slowdown that it dramatically changes the features of the oceans?
What are the four foundational propositions or truths upon which evolution by natural selection is built?
The first established truth is that individuals that make up a population of a species are not all the same. (Phenotypically and genotypically) The second established truth is that some of the variation between individuals of a population is heritable, meaning it has a genetic basis and can be passed down from generation to generation. The third fundamental truth is that all populations have the potential to grow too big to effect the environment negatively, but most individuals die before they can reproduce, and if they do reproduce, they do so at a less than maximum rate. This means that in each generation, those in a population are only a subgroup of those that might have arrived there from a previous generation. Lastly, different ancestors leave a different number of descendants, meaning they don't all contribute equally to the next generations. So, those that contribute most have the greatest influence on heritable characteristics in the next generations.
What is industrial melanism?
The phenomenon in which black or blackish forms of species of moths and other organisms have come to dominate populations in industrial areas.
What is ecological succession?
The successive and continuous colonization of a site by certain species populations, accompanied by the local extinction of others - may be studied over a period
What is the biosphere?
The totality of all of life interacting with the physical environment at the scale of the entire planet
What is the definition of a autotroph?
Their major resources are photosynthetic radiation, water, nutrients, and carbon dioxide. These autotrophs (also known as primary producers) assemble carbon dioxide, water, and nutrients into complex molecules (carbohydrates, fats, proteins, nucleotides, etc.) and then package them into cells, tissues, organs, and whole organisms
Thermophilic microbes grow at higher or lower temperatures?
They are temperature loving microbes that grow at much higher temperatures
What do ecologists do?
They describe, explain, and predict
What is a constitutive chemical?
They tend to be produced even in the absence of herbivore attack
What are acidophiles?
They thrive in environments that are highly acidic
What is an annual species?
Those that complete a whole generation from seed to adult through to seeds again within a year - tend to be good at increasing in abundance rapidly in relatively empty habitats
What is a perennial?
Those that live for several or many years and may not reproduce in their early years - are slower to establish but more persistent once they do
How is geographic variation affected by natural selection and migration?
Too much migration results in not a lot of geographic variation No migrations results in a buildup of geographic variation Natural selection and migration affect geographic variation almost oppositely The characteristics of a population will separate from each other only if there is enough heritable variation on which natural selection can act, and only if the forces of said selection favoring separation are strong enough to counter the mixing of individuals from different sites. Two populations will not separate completely if their members are continually migrating between them, mating and mixing their genes
What is a comparative field experiment?
We explicitly compare the same sort of data from many different sites.
What questions do ecologists ask?
What determines where a species occurs on the earth? How does that species respond as a level of individuals? Why here and not there? What determines how abundant they are? How are species affecting the environment? How does life change? How does that change how nutrients cycle?
What is meant when an ecological niche is described as an n-dimensional hypervolume.
When niches were first being adapted as a modern concept, there was usually only one dimension being examined to define an organisms needs and tolerances, such as the optimal temperature of an organism. Although many realized that there are a lot more dimensions to consider for the niche of a specific species, such as pH, wind speed, or even water flow. Thus, the more modern concept of a niche is multidimensional. Some niches are two-dimensional or three-dimensional, but most consider now a niche to be a "n-dimensional hypervolume" where n is the number of dimensions that make up the niche. This concept was proposed by Hutchinson in 1957, and is the most modern concept of a niche.
What is convergent evolution?
When the structures are analogous (similar in super- ficial form or function) but not homologous (derived from an equivalent structure in a common ancestry) Same function but not genetically linked (marsupials and placentals)
Explain, referring to a variety of specific organisms, how the amount of water in different organisms' habitats may define either the conditions for those organisms, or their resource level, or both.
Whether something is a resource or condition is based on perspective Desert mouse vs. swamp mouse with water Desert mouse - condition Swamp mouse - resource Harsh environment, Benign environment, and Extreme Environment These are relative terms - it depends on the organism Organisms don't sense the environment the way we (humans) do Antarctic Penguin in a jungle - extreme environment Extreme/Harsh Environment: Any environment in which a species will have trouble existing Benign Environment: Any environment a species will thrive These aren't really good definitions though
What are some of the major factors affecting the confidence we can have in our conclusions when doing ecological studies?
You want to know the confidence you have in conclusions Sample Size Time Confounding variables controlled? How variable is the data? Confidence in a representative sample Strength of relationship Experimental design - want to account for variation and limit the unknown variability so we can see a real effect
Whta is a niche?
A summary of an organisms tolerances and requirements
What is intraspecific competition?
Competition between indi- viduals of the same species.
What is exploitation?
Competitors interact only indirectly through their shared resources
What is a community?
Consist of all the species populations present in a defined location
What are 'common garden' and 'reciprocal transplant' experiments? Why are they so useful in ecological studies?
A common garden experiment is when plants from different populations are exposed to a common environment. This eliminates any influence of contrasting immediate environments. For example, the high and low elevation plants of the Arabis fecunda species in western Montana is a kind of common garden experiment the book discusses. This type of experiment eliminates any influence of contrasting immediate environments, and also helps ecologists study aspects of plants and animals that is impossible to observe in nature. If you get different results of populations it doesn't mean you have local adaptation, you just know the groups are different. Reciprocal transplant experiments compare whether organisms have evolved to become specialized to life in their local environment. This basically means this type of experiment tests the match between organisms and their environment. Ecologists can compare a species or populations performance when they are grown in their original habitat with their performance out of their original habitat. This is sometimes difficult in animals because if they don't like their transplanted habitat, they can just run away. Reciprocal transplant experiments are a good way of detecting local adaptations, but not all populations are perfectly adapted to their local environments. In this experiment, each individual is to be translated, but some are pulled out and put back into the same environment they came from and others are pulled out and put in a completely different environment that they came from. This is essential because only then can you distinguish the effects of local adaptation from any effects of translocation in its own right
What is a 'natural field experiment'? Why are ecologists eager to take advantage of them?
A natural field experiment is an unplanned experiment that ecologists take advantage of in a situation where either natural events or human-controlled events map out to learn something about ecological processes. I think the best advantage a natural field experiment poses to ecologists is the fact that they can use past records from years ago (that already exist) to help form a conclusion from the experiment. When ecologists have to plan an artificial manipulation experiment, the results of said experiment could take decades to accumulate, which isn't ideal. A natural field experiment thus helps ecologists save time (decades) to form conclusions about ecological processes because they can use resources that already exist
What is the Asian vulture experiment?
A rapid decline in these vultures were quickly noticed by people One group of people, the Parsees, were even more intimately affected, because their religion calls for the dead to be taken in daylight to a special tower (dakhma) where the body is stripped clean by vultures within a few hours. It took scientists a few years to find a common element in the deaths of otherwise healthy birds-each had suffered from visceral gout followed by kidney failure. Vultures dying of visceral gout contained residues of the drug diclofenac. Then it was confirmed that carcasses of domestic animals treated with diclofenac were lethal to captive vultures. Diclofenac, a non-steroidal anti-inflammatory drug developed for human use in the 1970s, had only recently come into common use as a veterinary medicine in Pakistan and India. Thus, a drug that benefited domestic mammals proved lethal to the vultures that fed on their bodies. An observational study Used mathematical modeling to determine a conclusion Challenge: All the variables are estimated (can change whole model if messed up) A messy process Don't intelligently weigh all the data
Explain why different species of algae, with different surface to volume ratios, will dominate in different aquatic ecosystems having different nutrient levels.
Algal cells have no roots, and they can actually acquire nitrogen and phosphorus right across their cell surfaces. In ocean waters where nutrient concentrations are very low, very small algal species dominate because smaller cells have a greater surface area to volume ratio, and so the small size of the algal species can maximize the rate of nutrient uptake across the surface area of the cell per volume of cell. In aquatic ecosystems where nutrient concentrations are higher, larger algal cells with a lower surface area to volume ratio thrive. These cells have more chlorophyll per volume of cell, and can therefore photosynthesize and grow quicker, and less surface area per volume is needed for adequate nutrient uptake.
Describe the various ways in which animals use color to defend themselves against attacks by predators.
An animal may be less obvious to a predator if it matches its background, or even possesses a pattern that disrupts its outline or resembles an inedible feature of its environment. An example of this crypsis is the green coloration of many grasshoppers and caterpillars. Cryptic animals may be very enjoyable to eat, but their morphological traits and color reduce the likelihood that they will be seen and eaten. In contrast to cryptic animals, noxious or dangerous animals often advertise themselves by bright distinct colors and patterns. An example of this would be the monarch butterfly, who has very bright and distinct colors, but is poisonous to mammals and birds because as caterpillars they feed on milkweeds containing cardiac glycosides. The last type of way animals use color to defend themselves is mimicry. These animals adopt memorable body patterns of distasteful prey, and thus deceives predators because the predator will believe the mimic is the distasteful species. An example of mimicry would be the viceroy butterfly mimicking the monarch butterfly, so that when a blue jay learns to avoid the monarch butterflies, they will also avoid the viceroys even though they are not toxic.
What are mimics?
An organism that looks just like another organism that is dangerous Monarch butterfly and viceroy butterfly
What are vital rates?
An organisms Survival Growth Reproduction
Applied ecology vs Fundamental 'pure' ecology
Applied Ecology - Seek to understand the distribution, abundance, and productivity of organisms in order to apply that knowledge for their own benefit. Fundamental Ecology - A pure and applied science
What are resources?
Are consumed by organ- isms in the course of their growth and reproduction. - can be used up Resources of life: Water Oxygen Energy Nutrients (C H O N P) Space to exist Organisms may compete with each other to capture a share of a limited resource.
What factors drive evolution?
Artificial Selection Natural Selection Sexual Selection Mutation Genetic drift Gene flow, Epigenetics Genetic Drift: random variation in who survives and reproduces (nothing to do with selection) most important in small populations Epigenetics: Methylating DNA, changing histones (change folding in proteins to further effect DNA) to affect an expression of a gene Not evolution because it can happen to an individual Epigenetics changes expression of an allele but not the frequency of an allele Sometimes what you experience can affect default setting of offspring - it can have more of a drastic effect on your kids
What is chilling injury?
At body temperatures a few degrees above zero Celsius, organisms may be forced into extended periods of inactivity, and the cell membranes of sensitive species may begin to break down
What is a homeotherm?
Body temperature is relatively constant -not all homeotherms are endotherms. some are ectothermic but live in one type of environment
What is a poikilotherm?
Body temperature varies with its environment -not all poikilotherms (temp varies with environment) are ectoterms (get heat source from outside)
What is mutualism?
Both organisms benefit from the relationship
What is crypsis?
Camouflage green grasshopper and green grass
What is evolution?
Change in allele frequency over time Results in change of characteristics of populations over time The change, over time, in the heritable characteristics of a population or species Darwin and Wallace are the first two that developed evolution in the form that we know today Malthus focused on human beings - we are capable of producing far more offspring than what actually happens generation to generation If the human population is left unchecked, we could easily overrun the planet Darwin and Wallace used this to their advantage with animals Evolution happens because some individuals have survived the death and destruction of the past, and have reproduced more successfully in the past: not because they were somehow chosen or selected as improvements for the future
Why do ecology and evolution seem so intertwined?
Characteristics today that we see are reflections of what happened in the past The environment on earth is very dynamic, and we have to understand history really well to see how animals have changed according to the environment When we study ecology, we're also studying history to some extent, and a part of that history is how things have evolutionary changed in the past
In what ways do ectotherms and endotherms differ, and in what ways are they similar?
Ectotherms (such as plants, algae, reptiles, and amphibians) rely on outside sources of heat to determine the rate of their metabolism. On the other hand, endotherms (birds and mammals) regulate their body temperature by producing heat within their own body. The distinction between ectotherms and endotherms are not absolute though. For example, hedgehogs (a typical endotherm) allow their body temperature to fall and become very close to the temperature of their surroundings when they are hibernating. Another great example of the trouble of distinguishing between ectotherms and endotherms is that some insects can control their body temperature via muscle activities such as shivering. Although some animals have both attributes of endothermy and ectothermy, these two responses to differing environmental temperatures have very different strategies from one another. For example, over a narrow temperature range, an endotherm consumes energy at a basal rate, but at environmental temperatures further above or below their basal rate, endotherms expend a lot more energy to maintain a constant body temperature. This, in turn, allows endotherms to be more effective in both searching for food and escaping from predators and allows them to stay longer at their peak performance. However, the cost of this strategy is a high requirement for food to fuel them. (There are, however, morphological modifications to reduce their energetic costs depending on the environment they're (the organism) is in) Ectotherms usually require less energy (food) than endotherms, and are able to inhabit places that would normally be inhabitable to endotherms, but the drawback of these conditions are that their activity level is limited by their surrounding environment. (i.e. if the weather gets too cold, they can't move)
Why does body temperature matter?
Enzymes are designed to work at a particular temperature - when you get outside of that temperature the enzymes will have trouble carrying out reactions they need to in the time they need to do it Loss in neural speed and muscle speed and strength when enzymes are out of their optimal temperature range Different organisms have different optimal temperatures - thermophiles vs fish in the arctic Although there are some consistencies with endotherms - 100-degree range give or take Ectotherms are different - enzymes function at a wide range of temperatures
Where do you expect wetter conditions?
Equator 60 degrees north and south The equator has more rainfall because the temperature of the equator is warmer and can hold lots of moisture
Explain, with examples, what exploitation and interference competition have in common and how they differ.
Exploitation competition is when competitors interact indirectly. An example of this type of competition is the interaction between a single-celled algal species, a diatom, and one of the resources it requires, silicate. As the diatom density increases, silicate concentration decreases and there is then less available for the many than there had been for the few. Interference competition means exactly what it says. There are direct interferences of competition between species/organisms for resources. For example, vultures may fight one another over access to a carcass or individuals of other species may fight for ownership of a territory and access to the resources that the territory brings with it. Both of these examples of competition have the same effect on the vital rates of the competitors. Vital rates include survival, growth, and reproduction, compared with what they would have been if resources had been more abundant. Competition usually leads to decreased rates of resource intake per individual, leading to decreased rates of individual growth or development, and thus increased rates of mortality. Both of these intraspecific competitions are also density-dependent, meaning that competition on any individual is typically greater the more crowded the individual is by its neighbors - the more the resource depletion zones of other individuals overlap its own.
What is the definition of a heterotroph?
Heterotrophs unpack the organic packages, metabolize and excrete some of the contents (mostly as inorganic nutrients, carbon dioxide, and water), and reassemble the remain- der into their own bodies. The heterotrophs in turn may be consumed, unpacked, and reconstituted in a chain of events in which each consumer becomes, in turn, a resource for some other consumer
Why do ecologists do studies at a variety of spatial and temporal scales?
I believe that ecologists do studies at a variety of spatial scales because there is ecology in almost every arena of life, small or large. From the global ecosystem, where many ecological questions are left to be answered, to an individual cell that is infected with two different populations of pathogens that compete with one another for the cells resources, ecologists are the scientists that concern themselves with these questions / problems. So, to reiterate my point, ecologists do studies at a variety of spatial scales because ecology is a major part of the hierarchical levels of life, from an organismal level to even the biosphere level. Ecologists also work on a range of time scales. Usually temporal scales are dependent on the question to be answered by the ecologist, but most of the time the studies tend to be shorter than appropriate for the question due to human weaknesses. (cost, impatience of the scientific community, etc.) Usually, long term studies are preferred because then ecologists can rule out the random ups and downs of population dynamics. For example, the reduction in population of a particular species could be cause for concern, but if a long term study was imposed ecologists could rule out the random ups and downs of the population of the species, and find out what was actually causing a reduction in population of the particular species. Not all ecological studies need to last for years, but they have proved their value in ecology just by the few number of long-term investigations that have been carried out already.
Why do we never see a tundra or boreal forest ecosystem that has rainfall as high as in tropical forests? Why don't we ever see cold-climate biomes with high rainfall?
I feel like specific regions of the planet have a lot to do with why we never see a tundra or boreal forest ecosystems that has rainfall as high as in tropical forests. In areas where the climate is warm, tropical forests dominate at higher levels of precipitation, and on the other end of the spectrum the tundra dominates in the coldest of the planet's regions with little precipitation. The highest rates of rainfall occur in the warmest tropical regions because that is where the air rising in the atmosphere starts out with the greatest moisture content. So in the tundra or boreal forest there is less rainfall because there is not a lot of moisture content (if any in the Tundra) in the air like there is in the tropical regions. Also, permafrost in boreal forest and tundra creates a permanent drought because the soil remains frozen throughout the year, only ceasing when the sun warms the surface. This could also be a reason why we don't see cold-climate biomes with high rainfall.
Biomes are differentiated by gross differences in the nature of their communities, not by the species that happen to be present. Explain why this is so.
I think biomes are differentiated by gross differences in the nature of their communities, not by the species that happen to be present partly because of parallel evolution. For example, marsupials and placental mammals have strikingly similar forms and behaviors, and one might mistakingly put these two very different taxonomic groups together into the same biome based on their similar forms and behaviors. Mainly, lots of mistakes can happen when defining a biome based off of species that happen to be there or look alike, and not the nature of the plants with distinct shapes, forms, and physiological processes. Another problem I see when differentiating biomes is that animals have the potential to migrate and move between biomes when needed. How will one categorize biomes when some animals are present in many different biomes, but there is obviously a vegetation difference between the biomes? It seems more consistent to differentiate a biome by gross differences in the nature of its communities, not by the species present.
Describe how the logging of a forest may influence the community of organisms inhabiting a stream running through the affected area.
I think that the logging of a forest will greatly influence the community of organisms inhabiting a stream running through the affected area. Trees are vital to an ecosystem because they are primary producers, which consumers feed on to survive. The ecological community of the stream is fueled by large inputs of organic matter from the forest, through falling leaves and dissolved organic matter. Insects will shred and eat the leaves, while bacteria grow on the dissolved organic matter, and will then be consumed by the insects. The shading and inputs of relatively cold groundwater in the summer helps to keep the stream cool. This allows for lots of dissolved oxygen in the water that is necessary for several species of fish because oxygen is more soluble in cold water than in warm water. When logging happens, less shading will lead to warmer stream temperatures and less dissolved oxygen, affecting the fish life and other organisms in the stream. The supply of organic matter from leaves is cut off and from dissolved organic matter is lessened, and algal and plant growth in the stream increases, changing the whole community. Erosion from the surrounding land increases, making the streamed have a higher amount of fine mineral particles. Nutrient inputs also increase which have a bad effect on downstream lake and coastal marine ecosystems.
In the case of having two populations of mice, explain speciation
If the mice can interbreed and produce viable, fertile, offspring, they are one species. This is called the biospecies concept and isn't used as often anymore because we look at morphological differences now
Compare and contrast the role of nutrients in structuring the diversity and food webs of subtropical gyres and coastal upwelling ecosystems.
In subtropical gyres, nutrients are short in supply. In the surface waters the concentrations of inorganic nitrogen and phosphorus are as low as in distilled water. Nutrients are available in the water of the deep ocean but are typically trapped here, with very little exchange of nutrients happening across the thermocline. Most of the phytoplankton species are very small due to an adaptation to the low nutrient availability. (A high surface area to volume ratio allows for a bigger area for nutrient uptake relative to the volume of chlorophyll and other photosynthetic apparatus within the cell) These phytoplankton are consumed by small zooplankton which are then consumed by larger animals, leading to a long food chain. The flow of energy to predators has a rather low efficiency compared to other aquatic and terrestrial biomes, and the production of fish is low even relative to the low rate of net primary productivity. Biodiversity is very high here, which is still in question today as to why. In coastal upwelling systems, nutrient rich deep ocean waters move steadily upward into the photic zone. Also, primary productivity and phytoplankton biomass are low here due to the isolation for the input of particles form erosion on land carried to the oceans in rivers. The water is also very clear here so light can penetrate as deeply as 200 meters. In Coastal upwelling ecosystems, primary productivity and phytoplankton biomass are high, which limits penetration of light into the water column. Phytoplankton in this biome tend to be relatively large with a low surface area to volume ratio, and are eaten by large species of zooplankton which are then eaten by plankton-eating fish and whales. This leads to a relatively short food chain and a more efficient transfer of energy to predators. While productivity here is high, biodiversity is low in this particular biome.
Describe the process of speciation?
In the case of orthodox speciation, two subpopulations become geographically isolated and natural selection gives way to genetic adaptation to their native environment. Next, a degree of reproductive isolation builds up between the two subpopulations. This could be a number of different things such as a difference in courtship rituals, which leads to prevention of offspring production, or the hybrid offspring themselves display reduced fitness. (prezygotic and postzygotic isolation) In a phase of secondary contact, the two subpopulations re-meet, and natural selection will then favor any feature in either subpopulation that enables reproductive isolation, especially prezygotic isolation, preventing the production of low fitness offspring. The breeding barriers have now cemented the distinction between what have now become two separate species. This orthodox form of speciation does not always happen. There is also allopatric speciation, which is occurs when the subpopulations are in different places geographically, and sympatric speciation occurs when populations diverge in the absence of physical separation. In the case of allopatric speciation, it is especially likely for island species, such as the finches Darwin studied in the Galapagos archipelago. There are actually 14 different species of finches found there, and all seem to have evolved and radiated from a single ancestral species that came from Central America. Populations of the ancestor species became reproductively isolated, and evolved separately for a time, and subsequent movements between islands gave rise to non-hybridizing biospecies that evolved to fill different niches. Sympatric speciation occurs without any initial geographic separation of populations, although convincing examples of this process of speciation remain scarce. One example though, is the two species of cichlid fish in Nicaragua. These two species coexist in the isolated volcanic crater lake, Lake Apoyo, which is relatively small and homogeneous in terms of habitat and recent origin. Genetic evidence from mitochondrial DNA indicated that the cichlids of Lake Apoyo had a single common ancestor, and through a variety of genetic evidence, there is indication that the two species are reproductively isolated from one another. The reproductive isolation is supported by mate choice experiments with the two species. Finally, the two cichlid fish species are also morphologically distinct from one another and have very different diets. This evidence shows that the cichlids are two separate species, which have arisen recently from a common ancestor in a small isolated patch of homogenous habitat.
Compare and contrast the role of fires in tropical forests, savannas, deserts, boreal forests, and tundra.
In tropical forests, where there is intense biological activity in the soil, the nutrients are released and leached or washed away when a fire occurs. On slopes the whole soil may go too. The full regeneration of soil and nutrients in a new forest could take centuries to rebuild from a fire. In the savannas, fire is a critical thing. It is usually a common hazard in the dry season, and usually tips the balance in the vegetation against trees and shrubs and favors perennial grasses because of their underground rhizomes and protected regenerating surfaces. Fire does not have much effect on deserts because they are too arid to bear any vegetation and there is relatively no animal life due to the low productivity of the vegetation and indigestibility of it. Fires are a major disturbance in boreal forests. When a fire occurs here, some of the organic matter in the soil burns, which contributes to the flux of carbon dioxide in the atmosphere. In this biome, major fires occur every century or so, resetting the stage for ecological succession because most of the mature trees die. The result of this is a forest of low species diversity and an even age distribution of species. In the tundra, fires used to be very rare. Now global warming has led to many more and larger fires due to warmer temperatures leading to higher rates of evapotranspiration and convective thunderstorms. Along with boreal forest fires, the tundra is an increasingly important source of carbon dioxide in the atmosphere.
What is an ecosystem?
Include both the community of organisms and the physical environment in which they exist
What is the definition of interference competition?
Individuals of other species may fight for ownership of a 'territory' and access to the resources that a territory brings with it
Describe how plants' requirements to increase the rate of photosynthesis and to decrease the rate of water loss interacts. Also, describe the strategies used by different types of plants to balance these requirements?
Photosynthesis mainly depends on the plant absorbing carbon dioxide, which can only happen across surfaces that are wet. (usually the walls of the photosynthesizing cells in leaves) If the leaf of the plant allows carbon dioxide to enter, some water vapor also leaves. Also, any mechanism the plant contains that will slow down the rate of water loss, such as the stomata on the leaf surface, will lower the rater of carbon dioxide absorption and will thus diminish the rate of photosynthesis. So, there is a delicate balance between the plants requirements to increase photosynthesis which can only happen if the surfaces of the walls of the photosynthesizing leaves are wet, and the mechanisms that decrease the rate of water loss on a leaf surface. To balance these requirements, different plant species have varying ways in which they survive. One strategy is to avoid the problem. These plants are called "Avoiders" such as desert annuals and most crop plants. These plants focus their photosynthetic activity during concentrated periods when water is relatively available. For the rest of the year, they remain comatose as seeds, which is a stage that requires neither photosynthesis nor transpiration. Other plants, called "tolerators" have evolved differently from the avoiders. These plants produce long-lived leaves that transpire slowly, and although they can tolerate drought and low-water conditions well, their highest rate of photosynthesis is lower. They have forfeited their ability to have rapid photosynthesis when water is abundant (like avoiders) but gained the security of being able to photosynthesize throughout every season. Lastly, there are specialized biochemical processes that may increase the amount of photosynthesis that can be achieved per unit of water lost. Most plants on earth use what is termed the C3 pathway, which means that their first product of photosynthesis is a sugar containing three carbon atoms. These plants are highly productive photo-synthesizers, but are relatively wasteful of water and reach their maximum rates of photosynthesis at low intensities of radiation. Another alternative approach to photosynthesis is the C4 pathway, which produces a four carbon sugar as the initial product. These plants are more efficient in their use of carbon dioxide, thus meaning more efficient in their use of water as well. They do not need to leave their stomata open as much to get carbon dioxide, so less water escapes the plant. Although, C4 photosynthesis is inefficient at low radiation intensities, so they make for poor shade plants. The last approach I want to mention is the CAM approach, which is very efficient in its use of water. These plants open their stomata at night and absorb carbon dioxide and fix it as malic acid, and then close their stomata during the day and release the carbon dioxide internally for photosynthesis. Since the stomata are only open at night, less water is lost from the leaf for the same amount of carbon dioxide taken in. Also the shape of the leaves - smaller leaves with more layers at the top of the trees with lots of sun
What are conditions?
Physicochemical features of the environment such as its temperature, humidity, pH, or, in aquatic environments, salinity. They are not consumed nor used up by the activities of the organisms
Why aren't populations always perfectly adapted to their environment?
Populations aren't always perfectly adapted to their environment for a number of reasons, including lack of genetic variation on which natural selection can act, the forces of hybridization, and delays between alterations to the environment and evolved, along with adaptive changes in the population. It's the best of what's available - if the allele isn't there, they can't be adapted perfectly Other factors like migration, sexual selection, and mutations affect what natural selection can do The environment is constantly changing Other species are changing the environment (coevolutionary arms races - for everything the predator does, the prey does better aterm-38nd vice versa)
What is ecological speciation?
Speciation where there is both an ecological source of divergent selection and a means of reproductive isolation
What is the definition of endemics?
Species known only from one island or area
What is population ecology?
Stresses the trends and fluctuations in the number of individual of a particular species at a particular time and place, as determined by the interactions of birth and death rates and the interactions between the populations themselves
What is ecosystem ecology?
Strives to understand the functioning of entire lakes, forests, wetlands, or other portions of the Earth in terms of energy and material inputs and outputs
Account for the fact that the tissues of plants, algae, and animals have such contrasting C:N ratios. What are the consequences of these differences?
The C:N ratio of plant tissues usually exceeds 40:1, and is often much higher. In animals, the ratios rarely exceed 8:1. Thus herbivores who eat plants, who undertake the first stage of making animal bodies out of the plants, are involved in the massive burning off of carbon as the C:N ratio is lowered. This means the main waste product of herbivores are carbon-rich compounds. Carnivores usually get most of their energy from the protein and fats of their prey, so their main excretory products are nitrogenous. Algae have very little structural material since they are supported by the water in which they live. They are mainly composed of chlorophyll, enzymes and other proteins held within a cell wall, which explains why they have a very low C:N ratio. So, herbivores feeding on algae have a much more protein-rich diet than the herbivores feeding on plants. The waste products of herbivores feeding on algae will be more nitrogen rich and lower in carbon than the herbivores feeding on plants. For herbivores and decomposers, the body of a plant is an abundant source of energy and carbon while the nitrogenous components of the diet are more limiting.
What is the Cedar Creek natural field experiment?
The Cedar Creek studies, begun only in the 1980s, take advantage of the abandonment of agricultural land beginning many decades earlier. To understand the successional sequence of plants that occur in fields in the years following abandonment, we could plan an artificial manipulation, under our control, in which a number of fields currently under cultivation were forcibly abandoned and the communities in them sampled repeatedly into the future. (We would need a number of fields because any single field might be atypical, whereas several would allow us to calculate mean values for, say, the number of new species per year, and place confidence intervals around those means.) But the results of this experiment would take decades to accumulate. The natural experiment alternative, there- fore, was to use the fact that records already exist of when many of the old fields were abandoned. This is what David Tilman and his team did. Data from a group of 22 old fields surveyed in 1983, having been abandoned at various times between 1927 and 1982 was accumulated. These can be treated as 22 'snapshots' of the continuous process of succession in old fields at Cedar Creek in general, even though each field was itself only surveyed once. Advantages - Have information from many years ago to conduct an experiment Saves time and money Might find something you weren't looking for Ethics involved because clearcutting a forest just for the sake of research isn't ideal Cons - Fields might not be comparative to each other Can't control for confounding variables
How would you expect the climate to change as you crossed from west to east over the Rocky Mountains? Explain.
The climate on Earth is controlled by differential heating of the planet by sunlight, and the interactions of the atmosphere with the oceans and with mountain ranges. So, when looking from west to east over the Rocky Mountains, the climates between these two regions should be vastly different. The side of the Rocky Mountains that gets hit by prevailing winds, (the eastern side between the Equator and 30 degrees and between 60 degrees, and the western side between 30 degrees and 60 degrees) air masses rise to go over the mountains, cool and drop their moisture as they do so on the other side. On the downward side of the mountain, descending air will be very dry, creating a rain shadow. This causes a dry, desert climate on one side of the mountain range, (the west) and another climate consisting of rain and snowfall on the other side of the mountain range (the east).
Why are we so worried about human caused climate change?
The environment changes faster than it normally would meaning a lot of animal extinctions will happen because they can't adapt quickly enough to the quickly changing environment Some of this concern is out of fear We as Christians are commanded by God to take care of the earth and the organisms that inhabit it We shouldn't think too highly of ourselves though - God is in control
Can environmental conditions affect how species interact with each other?
The salmon fish from the book Temperature changes the competitive dynamic between the two As humans? Winter and pathogens
Why do we never see an ocean biome that has both deep penetration of light into the water column and high nutrient availability?
The photic zone is a surface layer in the ocean where light penetrates. At depths below the photic zone, no photosynthesis can occur. This means no plants can grow below this region because they require photosynthesis to survive. The availability of both light and nutrients are determined by the physical mixing characteristics of a region and by the proximity to land. Below the photic zone, food webs are fueled by dead organic matter falling below photic zone. This organic matter is consumed by heterotrophs, and inorganic nutrients and carbon dioxide are released. So, deep ocean waters are therefore enriched by nutrients and carbon dioxide, but little organic matter persists in the deep ocean. Organic content of sediments is very low because of the inputs of organic matter to the deep ocean from the surface photic zone are small. Overall, when no photosynthesis from plants is occurring, there really isn't a chance at all for there to be high nutrient availability because plants produce a lot of the nutrients available via photosynthesis. Nothing really grows without light (from what I've seen)
What is the definition of hybridization?
The production of offspring sharing the characteristics of two parents
Three generalities across all scales of biological hierarchy?
The properties observed at a particular level arise out of the functioning of parts at the level below. For example, how a tissue functions is the result of the functioning of the cells in that tissue, and how an ecosystem functions is the result of the function- ing of the communities within it interacting with the physical environment. In order to understand the mechanistic reasons that a particular property is observed at any level of bio- logical organization, a scientist needs to look at the next lowest level of organization. To understand dysfunction in an individual organism, we must look at the functioning of the organs in that organ- ism; and to understand the controls on birth rate in a population, we must look at reproduction in individual organisms. However, properties observed at a given level of organization may be predicted without fully under- standing the functioning at lower levels. This third generality may seem to contradict the other two, but it does not. Consider an analogy from the physical sciences. As early as 1662, Boyle knew that when the pressure of a gas is doubled, its volume is halved, if temperature remains constant. This behavior of the gas as a whole is the result of the interactions of the gas molecules, yet Boyle's law provided valu- able predictive power for centuries, long before the concept of the molecule was developed. Today, physical chemists can indeed explain gas behavior based on understanding of the behavior of individ- ual molecules, but the explanation is complex, and not even taught to most undergraduate college stu- dents. Similarly, ecologists can predict patterns in ecosystems without understanding all of the details of the dynamics of constituent populations, and can predict patterns in populations without understanding all of the details and responses of individual organisms
What is phenology?
The recording of the changing behavior of organisms through the season, was essential before agricultural activities could be intelligently timed
What is Ecology?
The relationship between organisms and their environment From what I read in the book, there are multiple definitions of ecology. Ernst Haeckel claims that ecology is the relationship between an organism and its environment, but this was when plant and animal ecology were conjoined. Eventually, plant and animal ecology drifted apart and a later definition of ecology emerged and is explained as the relations of plants with themselves and their surroundings that depend on differences in habitats among said plants. The definition for ecology pertaining to animals is the sociology and economics of animals instead of adaptations that they possess. Since this time though, plant and animal ecologists agreed that they belong together, and some of the more recent definitions of ecology include lots of different organisms such as fungi and bacteria. (along with others) From what I gathered, each definition has one main point that it stresses: the relationship between and among organisms. Although, most ecologists agree now that stressing the relationship between and among organisms is too narrow of a scope because ecologists also evaluate the interaction between life and the physical environment. Thus, a new, broader definition of ecology came to life by the mid 20th century. This definition states that ecology is the study of the structure and function of nature, including the living world. This definition though is sometimes seen as too broad, so yet another definition of ecology was made. The final definition of ecology that the book states is: the scientific study of the abundance and distribution of organisms along with the interactions that determine said distribution and abundance, and the relationship between organisms and the flux of energy and matter. I think ecology is hard to define because there are so many aspects of ecology, including various interactions of organisms through many different levels of life.
From your understanding of the global climate system, why are deserts more likely to be found at around 30 degrees latitude than at other latitudes?
The rising and falling of air masses such as Hadley, Ferrel, and Polar Cells along with the Coriolis Effect dramatically affects precipitation patterns on Earth. The pressure of air decreases with increasing height as it rises in the atmosphere. The Universal Gas Laws state that the temperature of a gas is proportional to its pressure when the volume is held constant, meaning that temperature falls as pressure falls in the rising air masses of Hadley and Polar Cells. Colder air cannot hold as much moisture as hotter air, so as warm and moist air rises, the moisture condenses and falls back to the surface as precipitation, which happens particularly at the equator and 60 degrees north and south. The descending air at 30 degrees and the poles becomes even drier as its pressure and temperature increases. This means that there is a lot of rainfall near the equator, dry regions in the areas north and south of 30 degrees in both the southern and northern hemispheres, high precipitation in the areas north and south of 60 degrees, and little precipitation at the poles. This is why most of the major deserts in the world such as the Sahara, Majave and Sonoran are found near 30 degrees north or south.
