Principles of Ecology Chapter Summarys
Summarize how the inquires of ecologist and environmental scientist differ
-Ecology is a scientific discipline that is related to, but differs from, disciplines such as environmental science. -Public and professional ideas about ecology often differ
Outline how ecologist use spatial and temporal scales when testing their hypotheses
-Ecology is broad in scope and encompasses studies at many levels of biological organization -all ecological studies address events on some spatial and temporal scales while ignoring events at other scales
Describe the importance of hypotheses, controls, replication and data anaylysis to the scientific process
-Experiments are designed and analyzed in consistent ways: typically, each treatment, including the control, is replicated, treatments are assigned at random, and statistical methods are used in analyzing the results
compare the advantages and disadvantages of using field observations, field experiments, and lab experiments to test ecological hypotheses
-In an ecological experiment, an investigator alters one or more features of the environment and observes the effect of that change on natural processes. -Some features of the natural world are best investigated with a combination of field observations, experiments, and quantitative models
Explain how interactions between organisms and their environment can affect other organisms and potentially lead to unexpected consequences
-Laboratory and field experiments on the effects of parasites on amphibian deformities illustrate how events in nature can be connected with one another -Because events in the natural world are interconnected, any action can have unanticipated side effects -People both depend on and affect the natural environment
evaluate the beenfits of being choosy with mate selection and the conditions that favor selectivity by females vs males
-a. female may recieve indirect genetic benefits when she choosrs to mate with a male that has certain features, such as costly and unwieldy ornament. if she chooses a male that can support such an ornmanet, he will pass those good genes to her sons or daughters. according to the sexy sons hypothesis, the female recieves indiect genetic benefits through her sons, who will themselves be attractive and produce many grandchildren -in most species, females invest more in their gametes and provide more parental care than males do. in this situation, males and females have different interests, it is to a males advantage to mate with as many females as possible, whereas a female should "protect" her investment by mating with those males that provide the most resources or appear to be of high genetic quality
illustrate how the environment can interact with genetics to influence behavior
-animal behaviors are influenced by genes as well as by environmental conditions -by assuming that genes affect behaviors and that natural selection has shaped behaviors over time, we can predict how animals will behave in particular situaitions
explain how ns can lead to the evolution of adaptive behaviors
-animal behaviors can be explained in terms of there immediate, or proximate, causes or in terms of their evolutionary or ultime causes. most research in behavioral ecology addresses ultimate causes -an individuals ability to survive and reproduce depends in part on its behavior. this observation suggests that natural selection will favor individuals whose behaviors make them efficient at activities such as foragaing, obtaining mates, and avoiding predators
describe how salt and water balances can become challeneges for organisms exposed to hypersmotic and hypoosmotic environments
-aquatic animals that are hypoosmotic to the surrounding water must expend energy to excrete salts against an osmotic gradient. on the other hand, aquatic animals that are hyperosmotic to their environment must take up solutes from the environment to compensate for solute losses to the surrounding water
describe how temperature influences photosynthetic rates through its effect on enzymes and chloroplasts membranes
-autotrophs acclimatize and adapt to temperature variation by changing properites of the calvin cycle enzymes and/or the photosynthetic membranes. different photosynthetic organisms have different forms of the same photosynthetic enzymes that operate best under the environmental temperatures where the organisms occur.
differentiate autotrophy and heterotrophy in the context of building energy compounds using external sources of energy versus consuming them from organic matter
-autotrophs convert energy from sunlight (by photosynthesis) or inorganic chemicals (by chemosynthesis) into energy storesd in carbon-carbon bonds of carbohydrates -hetertrophs acquire energy by consuming organic compounds from other organisms, living or dead
describe the potential benefits and costs of organisms living in groups
-benefits of groups living include access to mates, protection from predators, and improved foraging success -costs of group living include greater expenditures of energy, increased competition for food, and higher risks of disease
explain how mass extinctions and rapid adaptations have influnced long term patterns in diversity
-biological communites can lose much of their diversity in mass extinctions, global events in which large proportions of earths species are driven to extinction in a relatively short time -an adaptive radiation occurs when a group of organisms gives rise to many new species over a short period of time that expand into new habitat or fill new ecological roles -adapative radiations can be promoted by factors such as the removal of competitor groups by a mass extinction or the evolution of a major new adaptation
explain how natural selection can lead to adaptations in populations
-by favoring individuals that have advantageous alleles over individuals that have other alleles, ns can cause adapative evolution, in which the frequency of an advantageous trait in a population increases over time -ns can increase the frequency of advantageous traits rapidym in days to years depending on the organism and the selection pressure
contrast ectothermy and endothermy, and explain how each influences the geographic distributions of organisms, along with organisms sensitivites to changes in body temp
-ectothermy is the regulation of body temp through energy exchange with the external environment, while endothermy is the regulation of body temperature through internal heat generation -generally ectotherms have a greater tolerance of variation in their body temp than endotherms
describe how substrate stability at the bottom of nearshore and shallow ocean zones determines which type of organisms are present, particulary emergent and non emergent vascular plants and large algae
-estuaries, salt marshes, and mangrove forests occur in shallow zones at the margins between terrestrial and marine ecosystems. they are influnced by inputs of fresh water and sediments from nearby rivers. -biological communites at the shoreline reflect the influence of tides and the stability of the substrate -coral reefs and kelp and seagrass beds are productive communities with high diversity associated with the habitat complexity provided by their photosynthesize
explain how evolution can be considered the accumulation of trait differences between populations
-evolution can also be viewed as descent with modification, a process in which populations accumulate differences over time and hence differ from their ancestors -natural selection modifies populations by favoring individuals with some heritable traits over other individuals -although ns acts on indivudals, an indivudal does not evolve, either it has a favored trait or it does not. only populations evolve
evaluate the condiitons in which gene flow can promote or deter adaptions
-gene eflow can promote the extent to which a population is adapted to its local environment by introducing new alleles into a population -gene flow can also limit the extent to which a population is adapted to its local environment by preventing fixation of the favored alleles
Outline the determinants of global temperature and precipitation patterns.
-global temperature patterns are determined by latitudinal variation in solar radiiation, but they are also influenced by oceanic circulation patterns and by the distribution of continents. -global patterns of terrestrial precipaiton are determined by atmospheric circulation cells, but they are also influnced by semipermanent pressue cells
describe conditions under which different mating systems would be favored
-in the rare cases in which males typically provide more parental care than females do, it is the male who is the choosy partner -the rich one is when they choose to maximize their reproductive success
differentiate between adaptation and acclimization by explaining how both individual organisms and populations respond differently to changes in the environment
-individual organisms can respond to environmental change through acclimatization, a short-term adjustment of the organisms physiology, morphology, or behavior that lessens the effect of the change and minimizes the associated stress -a population may respond to unqiue environmental conditions through natural selection for physiological, morphological, and behavioral traits known as adaptations, that enhance indivduals survival, growth, and reproduction under those conditons
describe how the presence of predators can impact foraging behavior
-individuals often alter their foraging decisions when predators are present. a percieved risk of predation can also alter foraging patterns, even in the absnece of actual predation -prey exhibit a wide range of behaviors that can help them avoid being seen by predators, detect predators, prevent attack, or escape once attacked
draw connections between differential heat gain across earths surface and the development of atmopsheric circulation cells
-latitudinal differences in the intensity of solar radiation at earths surface establish atmopsheric circulation cells -the coriolis effect and the different in heat capacity between the oceans and the continents act on atmospheric circulation cells to determine the pattern of prevailing winds at earths surface.
compare the effects of stabilizing selection and disruptive selection on the temporal changes in the genetic structure of population
-natural selection occurs when indivudals with certain heritable phenotypic traits survive and reproduce more sucessfully than individuals with other traits -natural selection may favor the average traits (stabilizing selection or traits near the extremes in a population (disruptive selection)
explain how surface winds and ocean currents move heat between the tropics and the poles
-ocean currents are driven by surface winds and by differences in water temperature and salin ity. -winds and ocean currents transfer energy from the tropics to higher latitides
compare the benefits and costs assosiated with sexual vs asexual repro
-organism may repro sexualy or asexually. in many situations they do both -there advantages and disadvantages to both. high levels of genetic variation in sexual is benefical to challenging environments
explain how organisms can control water water gains and loss by adjusting resistance to water movement, and describe how high resistance may involve trade odds with other functions
-plants and microorganims can influence water potential by adjusting the solute concentration in their cells (osmotic adjustment) -terrestrial organims can control their gains or losses of water by adjusting their resistance to water movement, as by the opening or closing of stomates in plants or adaptations of the skin in animals
explain how an areas seasonal changes in temperature are affected by its location, whether it is near a large body of water or at the center of the continent
-seasonal variation in temperature is greater in the middle of a continent than on the coast because ocean water has a higher heat capacity than land
contrast the benefits and costs assosiated with small size in early life cycle stages
-small sizes of early life cycle stages make them vulnerable to predation and food shortagrs -small life cycle stages are well suited to some important functions such as disperal and formacy
outline how seasonal changes in surface heating in temperate and polar lakes influnce water density and result in the stratification of water
-temperarture induced differences in water density result in nonmixing layers of water in oceans and lakes. In temperature-zone lakes, these layers break down in fall and spring, allowing the movement of oxygen and nutrients
identify the heat exchange mechanisms used by plants and animals to regulate body temps
-terrestrial plants may modify their energy balance by controlling transpiration, increasing or decreasing absopriton of solar radiation or adjusting the effectiveness of convective heat less -animals modify their energy balance mainly through behavior or morphology to adjust heat losses and gains, and in the case of endothermic animals, metabolic heat generation and insulation to lower heat loss
outline what determines the salinity and aciditiy of soils and waters
-the salinity of earths waters, including water in coils, is determined by the balance between inputs of salts and gains (by precipation) and losses (by evaporation) of water - the pH of soils and surface waters is determined by inputs of salts from the breakdown of rock minerals, organic acids from plants, and acidic pollutants
9 major terrestrial biomes
-tropical rain forests, tropical seaonal forest and savannas, and hot deserts in tropical and subtropical zones, grasslands, shrublands and woodlands, deciduous forests and evergreen forests in the temperate zone and boreal forests and tundra in polar regions -biological communities with close ananlogs to global biomes occur in mountains along elevational bands associated with climate gradients
Outline the difference between weather and climate, with specific reference to their temporal scales
-weather refers to the current conditions of temperature, precipitation, humidity, wind, and cloud cover. Climate is the long term average and variation in weather at a given location
outline the steps in the light driven reactions and carbon reactions during photosynthesis, describing their outcomes and how they produce energy rich compounds in autotrophs
2 main steps the absorpiton of sunlight by pigments to produce energy in the form of ATP and NADPH (the light driven rxns) and the use of that energy in the calvin cycle to fix CO2 and synthesize carbohydrates (the carbon rxns)
illustrate how adaptation and acclimization may result in trade offs with other functions
acclimization and adaptation are not free, they require an investmen of energy and resources by the organism. they represent possible trade offs with other functions of the organism that may also affect its survival and reproduction
explain how the physical environment is the ultimate determinant of the geographic distribution of species
affects an organisms ability to obtain energy and resources, therby determining its growth and reproduction and more immediteatley, its ability to surivive the extremes of that environment. the physical enevironment is the ultimate constraint on the geographic distribution of a species
explain how providing care to offspring may compromise other functions in adults
allocation of time and energy into caring for offspring lowers the ability of the adult to forage and may increase risk of disease and predation
understand that allocating energy and resources to reproduction amy affect parental growth, survivial, and future repro
an individuals investment in current rrepro can result in trade off between repro and other life history traits,including survival, growth, and potential for future repro
explain how the depth and amount of light penetration in a pond or lake influence the distribution of photosynthetic and non photosyntheitc organisms
biological communites in lakes vary with depth and light pentration. photosynthetic plankton are limited to the surface layer of water where there is enough light for photo-synthesis. zooplankton -tiny anumals and non photosynthetic prottist occur throughout the pelagic zone, feeding on detritus as it falls through the water.
explain how different sources of energy and food affect the type and number of ocean organisms that exist in the waters surface and the deepest depths
biological communites of the open ocean and deep benthic zones contain sparse populations of organisms, whose distributions are determined by light avaliabiity and proximity to the bottom
summarize how the size of particles on the bottom of streams, as well as water velocity and clarity change from source streams to large rivers and subsequently influence the organisms that inhabit different zones of moving waters
biological communities in streams and rivers vary with stream order and location within the stream channel. coarse terrestrial detritus is most important near the stream source, while the importance of fine organic matter, algae, and rooted and floating aquatic vascular plants increases downstream. the general feeding styles of organisms change accordingly as the river flows downstream.
summarize the genetic basis for the evolution of traits in organisms
biologist often define evolution in a relatively narrow sense as a change over time in the frequencies of alleles in a population
show how differences in species size or age can be accounted for in describing the allocation of energy and resources to reproduction and other life history stages
charnov's dimensionless life history analysis attempts to remove the effects of size and time in order to compare life historries across a broad taxonomic range
explain how adaptions at specficic stages in a complex life may benefit the species
complex life cycles allow life histories the flexibiltiy to respond to differences in selection pressures on different life cycle stages
describe factors that limit the devlopment of adaptations in populations
constraints on adapative evolution result from factors such as lack of genetic variation, evolutionary history, and ecological trade-offs
summarize chemosynthesis, which results in the synthesis of energy rich carbon-carbon bonds
during chemosynthesis, bacteria and archcea oxidize inorganic substrates to obtain energy, which they use to fix carbon and synthesize sugars
evauate how ecological processes can result in evolutionary changes in populations
ecological interactions among organisms and between organisms and their environment can cause evolutionary changes, ranging from allel frequency changes in populations to the formation of new species.
evaluate the environmental consitions that would favor the persistence of r reselected and k selected speices
environments subject to frequent disturbances and low pop size favor species exhibiting r selected traits. where the environment is stable with population sizes near the carrying capacity k selected traits are favorable
describe how an evolutionary change in a population has the potential to impact ecological processes
evolutionary change can alter the outcomes of ecological interactions, thus having a large influence on biological communites
use info about the gains and loses of energy to determine wheter an organisms temp is rising or dropping
gains of energy and losses of energy to the external environment determine an organisms temperature. modifying this exchange of energy with the environment allows an organism to control its environment
describe the role of gene flow among populations in terms of homogeizing genetic structure as well as enhancing evolutionary change
gene flow, the transfer of alleles between populations, makes populations more genetically similar to one another and can introduce new alleles into populations, enhancing evolutionary change
evaluate how random events can affect populations through time via genetic drift
genetic drift, which occurs when random events determine which alleles are passed from one generation to the next, can have negative effects on small populations
describe the tradeoffs in plant allocation described in grimes competitive/stress/redural model
grimes truangular model catergorizes plant life histotires by the degree of competition, stress, and disturbance in the habitat type to which they are adapted
explain how the balance between benefits and costs of living in groups determines the net impact to individual organisms and populations
group size may reflect a balance betweeen the costs and benefits of group living, in some cases this balance appears to have caused groupos to be larger than the optimal size
evaluate the trade offs that result when a plant controls water loss
keeping stomates open while tissues lose water can permently impair physiological processes in the leaf. closing stomates, however not only limits photosynthetic CO2 uptake, but also increases the chances of light damage to the leaf
explain how genetics and the environment act as controls on life history traits
life histories are under genetic control and subject to natural selection. environmental variation can also impact life histories through phenotypic plasticity
describe how additional complexitity in a life cycle, such as larval and adult forms, may benefit a species
most organisms have complex life cycles with multiple stages that differ in size, morphologaly, or habitat
describe the changes in an air mass that moves from a maritime zone across mountains on both the leeward and windward slopes
mountains force air masses passing over them to rise and drop most of their mositure as precipation, resulting in moister environments on winward slopes and drier environments on leeward slopes
summarize how mutuations contribute to the process of evolution
mutation and recombination are the sources of new allels and new combinations of alleles, therby providing the genetic variation on which evolution depends
explain the theory of optimal foraging by outlining the factors that influence the profitability of foraging
optimal foragaing theory predicts that foraging animals will maximize their net energy gain per unit of feeding time and per unit of energy invested in seeking, capturing, and extracting food resources
explain why oxygen concentrations vary depending on elevation, the influence of water on diffusion and biological consumption
oxyegn concentrations are stable in most terrestrial ecosystems, but oxygen avaliability decreases as elevation increases. Concentrations of oxygen in aquatic ecosystems are low where its consumption by organisms exceeds its slow rate of diffusion into water
explain the difference between photosynthesis and photorespiration and evaluate conditons where photorespiration is detrimental to plant growth
photorespiration operates in opposition to photosynthesis, lowering the rate of energy gain, particulary at high temperatures and low atmospheric co2 concentrations
illustrate how photosynthetic organisms acclimatize and adapt to variations in the intensity of light
photosynthetic responses to variations in light levels, water avaliability, and nutrient avaliability include both short term acclimatization and long term adapation.
compare the benefits of semelparity and iteroparity in the context of total lifetime repro of an organism
semelparous species repro once in a lifetime, iteroparous repro multiple times
describe how the body temperature of an organism influneces its functioning
temperature controls physiological processes through its effects on exymes and membranes
explain why ecologist use plants, and plant growth forms, to categorize global terrestial biomes
terrestrial biomes are characterized by plant growth forms, particulary of dominant plants. plants are immobile, so they must be able to cope with its environmental extremes as well as its biological pressures, such as competition for water, nutrients, and light. Plant growth forms are therefore good indicators of the physical environment, reflecting climate zones as well as rates of disturbance.
describe how global patterns of precipitation and temperature and their variability influence the location of terrestrial biomes
terrestrial biomes reflect global patterns of precipation and temperature. temperature influences the distribution of plant growth forms directly through its effect on the physiological functioning of plants. precipation influnences the avaliability of water, which is important in determining the supply of nutrients in the soil. which is also an important control on plant growth form.
summarize how biochemical and anatomical adaptations assosiated with the c4 photosynthetic pathway minimize photorespiration, thereby enhancing photosynthesis rates
the c4 photosynthetic pathway concentrates co2 at the site of the calvin cycle, minimizing photorepsiration
summarize how temperature is determined by the gains and losses of energy at earths surface
the climate system is driven by the balance between energy gains from solar radiation and reradiation by the atmosphere and energy losses due to infared radiation from earths surface, latent heat flux, and sensible heat flux
describe the process by which isolation of populations can lead to speciation
the genetic divergence of populations over time can lead to speciation, the process by which one spiecies splits into two or more speicies. speciation requires evolution of reproductive barriers between populations
summarize how air density and air exchange cause a decrease in air temperature with increases in elevation on a mountain
the heating of air by the ground surface is less effective in the highlands because of the lower air density, therefore, temperature decreases as the elevation of the land surface increases
summarize what determines optimal foraging in an area with different food densities with reference to the marginal value theorem
the marginal value theroem predicts that animals foraging in an area with patches of food resources of different densities will deplete rich patches first and leave them once the density of food is the same as the average of the entire area
evaluate the roles of speciation and extinction in determing the diversity of species
the number of species in a group of organisms increases when more species are produced by speciation than are lost to extinction, and decreases when the reverse is true. the outcome of this process can be visualized with an evolutionary tree
evalaute how human acitivities differentially impact the potential and actual distributions of biomes
the potential and actual distribtuions of terrestrial biomes differ because of human acgtivies, particulary conversation of land for agriculare, forestry, and grazing
explain how the tilit of earths axis influnces (1) seasonal changes in air temperature in temperate and polar zones and (2) precipation in the tropics
the tilt of earths axis as it orbits the sun causes seasonal temperature changes in temperate and polar regions and precipation changes in tropical regions
illustrate how the number of offspring may affect the size of those offspirnds
theres a trade between offspring size and number, such that organims tend to produce large numbers of relativelty small offspring or small number of large offspring
summarize the seven key stages that makeuo the life history of an organism
theyre diverse, varying between individuals of the same species as well as between species. the source of this variation may be genetic or environmental
explain the importance of weather variability for ecological processes
through their impact on mortality, extreme weather events influence geographic distribution of organisms
describe how cyclic change in the position and strength of high and low pressure cells, which occurs during ENSO for example, influences weather and climate variability
variations in climate over years to decades are caused by cyclic changes in atmospheric pressure cells. the osillation in the position of high and low pressure cells can lead to a weakening of the easterly trade winds or a shift to westerly winds. These changes have widespread effects beyond the regions where the pressure cells are located
illustrate how energy exchange components are influced by vegation anf subsequently affect climate -
vegation influnces regional climates through its effect on energy exchnage assosiated with albedo, evapotranspiration (latent heat transfer), and surface winds (sensible heat transfer).
list 3 factors that influence movement of water from high-energy state, to a low energt state in biological systems
water flows along energy gradients determined by solute concentration (osmotic potential), pressure or tension (pressure potential), and the attractive force of surfaces (matric potential)
describe examples of the behaviors utlizied by animals to increase their access to mates
within a speicies, males are often larger or more brightly colored than femalees, or they may posess unsual weapons or have gaudy ornamnets. such differences between males and females of the same species can result from sexual selection
