Climate Change Bio Exam 3

Same as the previous question, but what kinds of issues would you want to consider in monitoring?

-"At-risk" species (from climate change evidence, threatened species, management targets) -Structured, taxon-stratified sample of all species -Enhanced collection of climate/weather data -Biotic survey -Iterative feedback to management planning and action

What advice about management would you give a reserve manager who is trying to minimize the loss of biodiversity?

-Be aware of climate change effects on current management objectives, such as threatened species or fire control -Be alert for nonthreatening or nonobjective species or processes whose status may change significantly because of climate change - Plan on longer time frames (10-20 years rather than 3-5 years) - Consider interactions between management objectives that may be sensitive to climate change

If you are trying to manage protected areas for better performance under climate-change conditions, what kinds of issues would you want to consider in site planning?

-Climate evidence explicitly incorporated through scenario-building -Multiple time horizons to represent uncertainty and possible long-term future conditions -Refinement of regional scenarios

Same as the previous question, but what kinds of issues would you want to consider in management actions?

-Coordinated with other reserves in region -Planned using scenarios of climate change and range shifts -Based on iterative monitoring feedback

What kinds of factors do you think would increase the vulnerability of a species or population to impacts of climate change? Explain how each would increase vulnerability.

-Temperate range shifts: a temperate occurrence on the low latitude or lowland periphery of a species' historic range -Tropical range shifts: a tropical montane occurrence -Ecosystem resilience: an exposed or management-dependent occurrence -Ecosystem connectivity: an isolated occurrence -Genetic richness: a genetically impoverished occurrence -Topography: a topoedaphically homogenous occurrence -Extinction risk: an occurrence without restricted-range or extinction-prone species -Sea level change: an occurrence on coastal wetlands unable to migrate inland -Montane geography: an occurrence on steep upper mountain slopes where upward dispersal is limited -Disturbance regime: an occurrence smaller than the minimum area necessary to accommodate natural disturbance cycles -Landscape ecology: an occurrence in a highly fragmented landscape

If you wanted to improve the chance to conserve biodiversity in the face of climate change, what components of management of natural systems would you use?

1. Multiple representations of conservation targets, in case one is compromised by climate change 2. Working outside of reserves to encompass areas in which range shifts might occur 3. Managing landscapes for connectivity

How are oxygen isotopes used to determine past temperatures and past climate shifts?

16O is the most abundant form, whereas 18O is a rare form. The ratio of 16O to 18O indicates past sea surface temperature. Because 18O is heavier than 16O, it evaporates less readily. Water vapor in the atmosphere and precipitation are therefore enriched in 16O. As ice sheets form from precipitation, they lock up more 16O than 18O, and oceans become relatively enriched in 18O. Ocean waters high in 18O therefore represent cooler climates, whereas lower 18O/16O ratio to determine past temperatures and past climate shifts.

If we wanted to study the interaction effects of human CO2 pollution of the atmosphere on the distributions of plant functional types, which kind of model would we use?

A DGVM is run with elevated levels of atmospheric CO2, a simulation of climate change, or both. Each DGVM yields slightly different answers, so intercomparison projects have been formed to run several DGVMs with identical inputs and compare the results.

What was the cause of the extinctions in the end-Pleistocene?

A likely scenario is that the climate warming facilitated human arrival, human hunting greatly reduced populations, and loss of habitat due to climate change finished off any survivors.

Give a general example of a resilient species and a resilient area.

A resilient site might be one in an area of high seed rain, so plants are able to reestablish easily. A resilient species might be one with high reproductive potential or good long-distance dispersal.

Why is dispersal an issue for extinction that is caused by climate change?

A species that cannot move, such as a plant species, will inevitably find its suitable climate shrinking: its suitable climate in the future will simply be the overlap of its suitable present climate with its suitable future climate. On the other hand, a species that is well dispersed will be able to move with changing climatic conditions, fully occupying its suitable future climatic space.

Give a general example of a resistant species and a resistant area.

A species with broad physiological tolerances might be resistant, whereas a resistant site may be sheltered in a unique microclimate.

What kinds of events does a gap model show or describe?

A typical gap model shows new species appearing, existing species dropping out, and major changes in dominance among species that persist at any given location.

What do we mean by area of occupancy (AO)? Give an example that is not in the book.

AO, or area of occupancy, is the area within the EO that species actually occupies. For instance, the EO for red-winged blackbird is most of the western United States, but within that EO, red-winged blackbirds actually occur only in wetlands, which are thus the AO for the species. AO is always smaller than EO.

When we talk about adaptation in the context of climate change, what do we mean? What is biodiversity?

Adaptation is a response to climate change that reduced impacts. Biodiversity hot spots are defined both by their high numbers of their endemic species and by high levels of human threat.

In the protection of marine areas, and in particular coral reefs, what kinds of sites get preference for protection?

Although biological value and irreplaceability are primary criteria, unless a site harbors completely irreplaceable attributes, there is little point in protecting a reef that will be destroyed by bleaching. Hence, resistant and resilient sites get preference.

As noted above, climate change is believed to have been involved directly or indirectly in all five major mass extinctions. Does climate change always lead to extinction?

Although the largest extinctions are linked to climate change, not all climate change produces extinction.

What key result has emerged from running Earth system models?

Among the most important findings of early Earth system model runs has been the verification of important feedbacks between vegetation and climate, usually through CO2 or carbon pools. These processes may have important global effects, such as CO2 uptake by boreal forests, or effects at a regional scale, such as drying of the Amazon.

What are the important criticisms of the SDM/SAR approach?

An important criticism of the SDM/SAR approach is that these methods cannot be tested: whereas the SAR is derived from many careful measurements in the real world, reassembling SDM range losses into a SAR extinction risk estimate cannot be confirmed by real-world measurements, at least not until the range shifts and extinctions have taken plane, at which point it will be too late.

How can CO2 affect the distributions of plant functional types directly and indirectly?

Directly: plant growth and competition Indirectly: effects of warming caused by CO2

What would a look at past climate effects suggest about extinctions due to human-induced climate change?

Association between extinction spasms and past climate change would increase the prospects for heavy extinctions associated with human induced climate change.

Let's consider setting up a marine protection area for coral reefs again and expand a bit on the points we made earlier. What are the factors that can be taken into consideration that relate to resistance to coral bleaching?

At site-management level, resilience and resistance may be applied in zoning and management decisions. Local upwelling or currents may make some parts of an MPA more resilient than others. Physical shading is important at this scale as well. For instance, reefs in the shadow of a large mountain will be more resistant than reefs in continual exposure to the sun. Sedimentation, which negatively affects reefs in heavy doses, may actually increase resistance to bleaching by shading and cooling reefs.

What evidence indicates that some species may lose much or all of their range due to temperature changes on the order of only 0.5 C?

Australia was the point of origin for some of the earliest SDMs and thus has had a relatively large number of SDM studies as well. These studies have shown simulated range losses in mountains and across a range of species. In a study of 92 endemic Australian plant species, most were found to lose range and 28% lost all range with only 0.5˚C warming. Large amounts of range loss have been demonstrated in numerous montane species in Queensland.

Why is climate change different from other threats to protected areas?

Because our knowledge of future climate change will never be perfect, prioritization based on resilience to climate change is a risk-management exercise. We want to reduce (but not eliminate) conservation investments in sites at high risk of losing species to climate change and balance these with investment (though not exclusive) in sites with lower probabilities of losing their target species.

If you had one site that was resistant to climate change, one site that was resilient to climate change, and one site that supported endemics, which of these areas would you choose to protect first? Why?

Because protected areas cannot reduce the amount of climate change, resistant and resilient areas should be prioritized for adaptation. By prioritizing protection in areas that are resilient to climate change, conservation strategies ensure that protected area will persist. One important exception to these general principles applies to species that are found in only one location. The sites in which species are found have priority for protection regardless of their resistance or resilience to climate change.

What is one key disadvantage of using lakes to assess past climate?

Because the freshwater realm is tiny compared to overall land surface area, the insights from lake records may also seem tantalizingly incomplete.

What is the typical output of a gap model?

Because the mathematical models needed to simulate these growth and competition characteristics are fairly complex, gap models are generally run for a single forest gap. Their output is therefore a chart of species composition at that particular point rather than a map.

We cannot test the DGVMs against known future conditions; so, how can we gain confidence in how well the models predict?

Because there is no way to test against future, unknown vegetation types, the test of ability to reproduce current vegetation is very important. Semi-independent tests have also been developed, such as the use of evapotranspiration values from the models to predict river flows and comparing the DGVM-derived estimates to actual flow volumes. However, validation of DGVMs, and all biological models, into the future remains a challenge.

How are these models able to account for the effect of CO2 on plant growth?

Because they run from photosynthetic equations, DGVMs are able to simulate the direct effects of elevated CO2 on plant growth and competition, in addition to the indirect effect of the warming caused by CO2 DGVMs are now being integrated into Earth System Models.

Give an example of how biological models are being used to make predictions about marine-organism responses to climate change.

Biological models for individual marine species are less common than terrestrial realm. The models that do exist are generally more complex than SDMs. They typically represent food web interactions and ecophysiological changes in productivity.

Why is the answer to the previous question important to understand?

Changes in climate have affected these food chains with consequences for local extinction, genetic modifications, and diversity. Some of the complexity of these changes is captured in microfossil assemblages, whereas other parts are lost forever due to incomplete macro-fossil preservation.

How will changes in stream flow come about as a result of climate change?

Changes in streamflow result when precipitation and evapotranspiration vary. Streamflow will increase with increased precipitation and decrease or cease with droughts. Timing of streamflow will also vary with changes in snowmelt and storm intensity.

Generally, what kinds of changes do freshwater systems show in response to climate change?

Changes that are important on both these short- and long-term scales include alterations in streamflow and temperature, water-shed fragmentation and capture, lake drying and filling, and changes in lake thermal zonation and mixing.

How can climate change lead to extinction?

Climate change can lead to extinctions by decreasing suitable habitat and lowering overall population size, by increasing population fluctuations, or both.

How can local or regional events like asteroid impacts or volcanic eruptions end up causing major mass extinctions around the world?

Climate change is the factor that turns regional events into global killers. It is the effect these events have on global climate that transmits their impacts more broadly. Both asteroid impacts and volcanic eruptions spew massive amounts of particulate matter into the atmosphere. These particulates intercept incoming sunlight, blocking the solar warming of the Earth.

How have coastal freshwater habitats been affected by glacial cycles?

Coastal freshwater habitats have been successively fragmented and reunited during the glacial cycles, Sea level has risen repeatedly as ice sheets have melted during the past 2 million years of the Pleistocene. It has fallen when ice sheets have formed. Low-lying areas are flooded in the melting cycles and re-exposed as sea level drops. In interglacial high sea level stands, lowland freshwater habitats are separated by barriers of ocean water, promoting allopatric speciation.

Where would we want to apply intensive management or translocation?

Conservation actions such as intensive management and translocation will be high priority where resilience is low. For instance, in a protected-area system in which only half the sites are believed to harbor resilient populations of a species, the other half would be prioritized for management or translocation to maintain the populations in the face of climate change.

How is disturbance management used to conserve species?

Disturbance management includes control of fire and guiding recovery and restoration of areas affected by storms, grazing, and other disturbances.

What do we mean by extent of occurrence (EO)?

EO, or extent of occurrence, refers to the convex hull that encompasses all known occurrences of a species- in essence, a range map.

What are the two assumptions that estimates of extinction risk from SDM/SAR must make?

Either the species cannot disperse at all and is limited to ever-shrinking suitable climate within its present range or the species is perfectly well dispersed and can occupy all areas with suitable climate in the future.

What are endemic species? Why would you want to develop a SDM only for species whose entire range falls within your study area?

Endemic species are those that live in a limited area. One criticism of the SDM/SAR method for estimating extinction risk is that most of the species modeled were endemic to the regions being studied, so the results apply to only a subset of species of the region. It is best practice in SDMs for future climates to model only species whose entire range falls within the study region. This is because a species that has range outside of the region modeled has climatic tolerances that cannot be captured in the statistics of SDMs.

In lakes, what is the difference between the epilimnion and the hypolimnion?

Epilimnion: the mixed zone; well oxygenated and biologically productive Hypolimnion: the non-mixed zone; virtually excluded from interactions with the atmosphere during stratification; primary production is limited, and heterotrophic species dominate.

Do you agree or disagree with the claim by the press release for the 2004 Nature paper that there are 1 million species at risk of extinction due to climate change? Explain.

Estimates of the total number of species in the world vary from less than 4 million to more than 100 million. Most scientists now accept that there are 8-10 million species on the planet. Assuming half of all species are marine yields an estimate of 4-5 million land species. One bias in the regions was overrepresentation of biodiversity hot spots. However, because hot spots represent more than two-thirds of the world's species as endemics, inclusion of hot spots should increase the confidence in the result. The number of species at risk of extinction owing to climate change is therefore almost certainly in the hundreds of thousands and probably more than 1 million.

What is the relationship between extinction and warming in deep time (past 500 million years)?

Examination of long-term extinction trends indicates that extinction risk may be greater in warm climates. During the past 500 million years, high CO2 warm periods have had a significant correlation with higher rates of extinction. In these deeper-time warm periods, extinction was elevated - a discomforting trend for human-induced warming in an already warm climate and with extensive habitat destruction standing in the way of natural adaptation.

What climate-related problems exist in the North Bering Sea, and how could a marine protected area help to reduce some of the problems?

Extensive evidence from cold-water fisheries and past climate change indicates that pelagic fisheries and benthic communities experience major shifts linked to climate. Recent changes due to loss of sea ice in the North Bering Sea provide a compelling example of the need for additional MPAs.

Why do the effects of climate change on freshwater systems have very large consequences for biodiversity and human endeavors?

Extinction rates are very high in freshwater systems as dams, diversions for human use, and pollution take their toll on these habitats. Extinction rates among freshwater taxa may be 3 or 4 times those of their terrestrial counterparts in the near future.

What would the DGVMs predict for future climates about various types of forest?

For future climates, the DGVMs show northward expansion of boreal forest, expansion of some temperate southern forests toward the pole, expansion of several temperate forest types, and contraction of some tropical forest types, most notably in the Amazon.

Describe a scenario that would illustrate the idea of state-dependent forest composition.

Forests exhibit considerable compositional inertia. Once established, mature trees may persist in climates that would be inhospitable for their establishment. Replacement of these forests happens only with disturbance such as fire or death of the trees owing to old age. These "living dead" forests may prevent the establishment of replacement vegetation and then suddenly burn or die centuries later, opening up the landscape for a completely different vegetation type. Ex., mixed conifer forest might be replaced by oak woodland as montane habitats warm, not in a gradual transition but, rather, in sudden state switches when the coniferous forest dies or burns.

Can freshwater species adapt metabolically to climate change? Explain.

Freshwater species are almost all cold-blooded, leaving them with little metabolic adaptability to climate change

What are dynamic global vegetation models (DGVMs)? How are they used to assess changes in plant functional types due to climate change? Do they make projections about species or ecosystems?

GDVMs use first-principle equations describing photosynthesis, carbon cycling in soils, and plant physiology to simulate growth and competition between vegetation types. DGVMs literally 'grow' vegetation mathematically, fixing carbon from the atmosphere, distributing it to plant parts, and evolving a vegetation that it describes in terms as a number of "plant functional types". If enough carbon is fixed and maintained to build a forest in a particular location, the DGVM registers the plant functional type (PFT) at that point as forest. If enough carbon persists for only a grassland, the PFT is recorded as grassland. The output of a DGVM is a global map of PFTs, although similar models can be run at higher spatial resolution for individual regions, such as countries or continents

What are gap models?

Gap models fall between SDMs and DGVMs on the scale from species to ecosystems. The term "gap model" derives from the attempt to stimulate what happens in a forest gap after a tree falls- the growth of individual trees to fill the gap and competition between these individuals or different species

Is there evidence that gap models do a good job of modeling changes in forest composition in relation to climate?

Gap models have been tested for their ability to simulate known forest compositions and spatial variation of forest composition, such as altitudinal zonation of vegetation in mountains. Gap models have reliably reproduced the general altitudinal zonation features on several mountain ranges in different continents.

What have gap models revealed?

Gap models have been used extensively to model past climates and climate change. These studies have revealed state-dependent, or hysteretic, responses. These arise when a forest may have multiple stable states under a given set of climatic conditions. Which stable state actually emerges depends on the history of the forest- both the history of climate change and the biological history of the site.

For providing information about past climates, compare the advantage of using lakes over glacial ice.

Global changes in mean temperature are often inferred from ice cores from Greenland or Antarctica. Regional temperature and especially precipitation changes are discernable from lake records and follow more complex patterns. Also, geographic coverage of lakes is more extensive.

Why are SDMs also known as "niche models"?

SDMs are sometimes known as "niche models" because they simulate species climate niche in the current climate or the change in the niche as the climate changes

Why are range shifts in response to climate change complicated? What are metapopulations?

In actuality, range boundaries are not monolithic entities but, rather, a collection of metapopulations that vary in time, increasing or decreasing more or less rapidly in response to climate change. A more sophisticated view of range shifts therefore includes metapopulation dynamics, species with both large and small ranges, and a variety of range movements across the landscape.

In north temperate zones, what have SDMs predicted?

In northern temperate settings, they have projected northward movement in a wide range of species and upslope movement in the Alps, Rocky Mountains, Sierra Nevada, and other mountain regions. Studies in the Alps have demonstrated significant loss of range in alpine plants due to the effect of decreasing area as species move upslope, just as there is more area at the base of a cone than at the tip.

Based on previous research, if we ran this kind of model, what would we be likely to find out about the interaction effects?

In some areas, the direct and indirect changes reinforce one another; in many other areas, they oppose one another. Combined CO2 and climate change runs with DGVMs show that the climate change signal is stronger: it is difficult to distinguish between climate change only and climate change plus CO2 runs.

What other names have been given to SDMs?

SDMs may be referred to in the older literature as envelope models, bioclimatic models, or range-shift models.

If we want to get the most bang for our conservation buck, how should we select components for reserve systems?

Irreplaceability is a key driver for selection of cost-effective reserve systems because choosing sites with high irreplaceability minimizes the area needed in a system.

Summarize the value of lakes for providing information about past climates.

Lakes provide information about climate change as well as its past biological effects. Lake preserve abundant fossil microorganisms, which may be used to infer past climates. Lake sediments, especially in long-lived basins, provide information about past climate. One of the most noteworthy findings of these lake records is the occurrence of what have been called "mega-droughts." Mega-droughts are droughts lasting from decades to centuries that bring prolonged harsh conditions to large areas On longer timescales, lakes provide insights into regional climate changes, teleconnections, rapid climate change, and drivers of climate change.

If both lowland and montane species lost the same absolute amount and proportion of their original range to climate change, for which group would you be most concerned in terms of long-term survival? Explain.

Lowland species suffer range loss over large areas because of a very shallow climate gradient in lowlands. Many lowland species are widespread: they begin with very large ranges and can suffer large areal range loss and still maintain relatively large range areas. Montane areas have a steeper temperature gradient, resulting in range shifts that are smaller in spatial extent. Montane species are often arrayed in narrow elevational bands up the slope of a mountain. These species have small absolute range sizes so that relatively small absolute area of range loss translate into large proportional losses. Even where widespread lowland species suffer large proportional range losses, they may retain range sizes that are large relative to those of montane species. Thus, large absolute and relative effects in lowlands may still leave lowland species with larger ranges than those of montane species.

What biological processes are represented mathematically in DGVMs?

Mathematical representation of plant growth, photosynthesis, and respiration, sometimes coupled with empirically driven corrections. For instance, carbon estimates from satellite images may be used to correct the model.

Give an example of how physical models are being used to predict marine-organism distributions.

Modeling physical change with depth is particularly relevant - a challenge that has been addressed in lake models as well.

Was this info sufficient to estimate how many species would go extinct or how many species would be vulnerable to extinction? Explain.

Most showed some decline but not enough to definitively state that a species was headed for extinction. However, some of these declining-range species might become extinct. What was needed was a method for assessing extinction risk in multiple species over the long term. This method used for this was the SAR.

Where are new and disappearing climates expected to be concentrated in the future? Why?

Novel climates and disappearing climates are both projected to be concentrated in the tropics.

What is one way to assess risk of extinction from climate change?

One way to assess extinction risk associated with climate swings is to examine biological responses in past times of rapid climate change.

What kinds of information from lakes can be used to understand past climates?

Our understanding of past change in freshwater systems is limited by a fossil record dominated by lakes and microorganisms. We then must use present conditions and responses to climate, coupled with this fragmentary fossil record, to reconstruct some understanding of past freshwater responses to climate change.

What has been the effect of the major extinction events on biodiversity since deep time (> 100 million years ago)?

Over time, and interrupted by minor and major extinction events, biodiversity returns to previous levels and slowly increases. The long-term trend is a marked increase in the number of species on Earth.

What do we mean by planning for pattern and process? Give examples of important processes.

Pattern targets are generally species or habitat types: planning for pattern means conserving a representative sample of species or habitat types, hence preserving some notion of their "pattern" in the landscape. Planning for process means capturing temporal phenomena in the conservation plan. For instance, wildebeest migrations in the Serengeti are an important process. Any conservation plan for that region should conserve the migration, and it is clear that this is impossible to conserve the pattern of wildebeest and other wildlife on the landscape without also conserving this process.

What kinds of models are used to make predictions in aquatic systems? What kinds of information do these models use?

Physical models of ocean chemistry and temperature suggest changes in range limits of marine organisms, most notably corals. Biological models examine ecophysiological tolerances and food web interactions, with less emphasis on geographic range shifts than in terrestrial models, perhaps because of the great existing variability in the geographic ranges of marine species.

If we are planning a series of protected areas for the purpose of preserving patterns, what strategy should we use to reduce the effects of habitat destruction?

Planning for persistence refers to conservation that endures over longer time frames. Processes such as species population dynamics mean that the abundance of a species today may not be a constant in the future. For example, it may take years to establish and effectively manage new protected areas, so it is important to start the process of protection in the sites most threatened with habitat loss. This prevents the intent of preserving pattern in the landscape from being undermined by habitat destruction.

During population fluctuations in a species, what tends to happen to the population when mean population size is smaller than the magnitudes of the fluctuations?

Populations and species go extinct stochastically, not deterministically. When mean population size is lower than the size of fluctuations, extinction is highly likely to ensue.

How might we increase species representation for those species that have lost representation due to climate change?

Protection for up to 90% of species was able to be regained by adding new protected area to compensate for the effects of climate change in a study of Mexico, South Africa and Europe.

Suppose we ignore the anticipated effects of climate change when setting up a reserve network. What will be the likely consequences?

Reserve selection that ignores climate change will be based on incomplete information about species' ranges and irreplaceability, causing it to be less effective and more expensive in the long term.

Can managers effectively conserve the species in a reserve by focusing on factors within the borders of reserves?

Reserves that manage threats only from their borders inward may find that climate change results in an increased number of magnitude of threats they confront.

What is meant by resilience to climate change?

Resilient species or sites are better able to recover once damaged

What is meant by resistance to climate change?

Resistant species or sites are less damaged by climate change

Do SDM results support a Clementsian or Gleasonian view of communities? Explain.

SDM results support a Gleasonian view of communities- that communities are ephemeral collections of species brought together by similar climatic affinities- and tend not to support a Clementsian view of communities as tightly coevolved entities that respond to climate as a unit. SDM outputs clearly show that individual species within plant and animal communities move at different paces and in different directions in response to alterations in temperature and rainfall, resulting in the disassembly and reassembly of species combinations as climate changes.

What are species distribution models (SDMs)?

SDM, species distribution models, simulate the distribution of species- their ranges- relative to climate. SDMs create a statistical model of the relationship between current climate and known occurrences of a species

When the authors of the 2004 Nature paper applied the SDMs, what did they find?

SDMs allow estimates for future species' range size. SDMs were constructed for hundreds of species in each of the six regions of the study. Some showed species' ranges disappearing altogether by 2050, whereas others showed species' ranges declining by 2050 and probably headed for extinction.

What are the advantages and disadvantages of SDMs, DGVMs, and gap models?

SMDs deliver species-denominated results appropriate for biodiversity at relatively fine scales because the statistical models involved are not mathematically complex. However, it may require modeling of hundreds or thousands of species to arrive at conclusions about changes in vegetation or ecosystems, and competition between species for novel climatic space is not explicitly addressed. Gap models simulate competition between species and provide species-dominated results. However, they address individual points rather than producing a map relevant to a study region (unless many are joined together), and the data required may be available for only a limited number of (tree) species. DGVMs address competition and produce geographically explicit results (maps) for the globe or individual regions, but they do not give information about individual species

What kinds of marine sites are resistant to coral bleaching?

Sites may be more or less resistant and resilient to coral bleaching based on factors such as currents, upwelling, and previous exposure of reefs to bleaching. Cool currents or upwellings tend to make sites resistant to bleaching because they maintain cooler surface water temperatures. Corals that have been bleached previously and survived may have been naturally selected to ave more resistant zooxanthellae or other natural mechanisms of survival and recovery.

How can a reserve manager manage threats or effects from climate change?

Stopping climate change ultimately requires social and energy consumption changes across the planet- a change process that a reserve manager may participate in but not control. Therefore, the main management option for climate change may lie in trying to modify its effects by changing management of factors (threats, disturbances, species, and tourism) with which it interacts.

What climate influences can alter the stratification regime of a given lake?

Stratification is strongly related to seasonal temperature fluctuations. Reduced temperature difference between the warm surface layer (epilimnion) and deep water (hypolimnion) reduces the stability of stratification and mixing can occur.

How will climate change affect stream temperature?

Stream temperature follows air temperature, with shallower streams responding more quickly to changes in temperature. Short, shallow streams (first- and second- order streams) dominate stream and river systems, so the proportion of temperature-sensitive waterways is high.

Does species representation increase or decrease as climate changes?

Studies showed some species moving into reserves, which both increased the representation of those individual species in protected areas and slowed the rate at which average representation declined owing to climate change.

How do temperature changes in glacial cycles affect highland freshwater systems?

Temperature change acts in an analogous manner in highland freshwater systems,with interglacial warm periods resulting in habitat fragmentation. In glacial periods, global temperatures are cooler, resulting in expanded, connected highland cold-water habitats. In interglacials, these cold water habitats shrink upslope, becoming isolated in mountaintop fragments. During periods of fragmentation, speciation can occur.

For which of the five mass extinctions do we have evidence that direct climate change was a factor? How did climate cause the extinctions?

The Ordovician-Silurian extinction occurred 440 mya when the Earth's climate suddenly shifted from greenhouse to icehouse conditions.

What is meant by the species-area relationship? From what theory was the species-area curve derived? Explain the theory of island biogeography.

The SAR is derived from the island biography theory. It is an empirically measured relationship between the size of an area and the number of species it contains. The larger the area, the greater the number of species present. This relationship has been found to hold in virtually all terrestrial systems studied, from island archipelagos to large continental areas.

What do scientists think caused the end-Devonian extinction?

The cause of the end-Devonian extinction (365 mya) is still debated by researchers, but it may be linked to the evolution/emergence of land plants. Terrestrial plants first flourished about this time, and one result of their emergence would have been the removal of a large amount of CO2 from the atmosphere. Because CO2 is the primary greenhouse gas, reduction in CO2 would have cooled the planet.

How do SDMs/SAR take into account species' dispersal capabilities?

The combination of SDM and SAR cannot account for species dynamics. SDMs can state only what areas have suitable climate for the species in the future; they state nothing about whether the species can reach those places. Thus, the extinction risk estimates derived by combining SDM and SAR can only make two assumptions.

On what basis is there reason to have confidence in SDMs for predicting the effects of future climates? What does this confidence in predictability imply about ecological niches?

The considerable success SDMs have demonstrated in modeling current species ranges and in modeling the spread of invasives lends confidence to the application of these techniques to simulating species ranges in future climates.

What species went extinct and what patterns were apparent in the end-Pleistocene extinctions?

The species that were lost include giant sloths in South America and camels, horses, the mammoth, and saber-tooth cats in North America.

What was the author's criticism of the 2004 Nature paper and its coverage in the press?

The estimate of a "million" species at risk was in the press release for the paper, not the research itself, which generated controversy. Nature published three articles challenging fundamental points of the paper, and publications refining or debating the underlying science continue to appear in top research journals. This welter of publications makes for a diverse literature not easily synthesized or accessed, despite the critical policy implications of the research. This paper and the resulting critiques focused on only one of several possible methods to assess risk. It is necessary to examine several lines of evidence across several disciplines to get a deeper view of extinction risk from climate change.

What evidence is there that even just moderate amounts of climate change could translate into major extinction risk?

The hot-spots study showed that even moderate amounts of climate change could translate into major extinctions risk and that the largest extinction risk in the long term may lie in the tropics.

How have ice ages had a major impact on lake ecology?

The ice ages have had a major impact on lake ecology because retreating glaciers have left a large number of lakes and freshwater connections. Changes associated with the ice ages have affected freshwater systems far from ice sheets, Fragmentation of freshwater habitats, resulting in speciation, has resulted from both sea level and temperature changes associated with glacial-interglacial cycles.

So, why does the author say the tropics may be vulnerable to climate change?

The impact of climate change is the product of magnitude of change and sensitivity. Sensitivity may be high in tropical organisms, whereas magnitude of change will be greatest near the poles.

Why is the interaction of climate change and human land use particularly worrisome for species persistence?

The interaction of climate change and human land use is particularly worrying. If this relationship is synergistic, actual climate-related extinctions may well outnumber the estimates, all of which fail to take into account threat synergies. Present estimates also fail to include human population dynamics, so simple expansion of human land uses and human responses to climate change may be more deleterious than current estimates reflect.

What explanation can be offered for why there have not been mass extinctions with each onset of a glacial period?

The length of the warm periods (interglacials) between the ice ages were relatively short. An average interglacial lasted on the order of only 10,000-20,000 years. This means that for most of the past 2 million years, the Earth had been in an ice age. Species may be able to hold on through unfavorable climate, as long as favorable climate returns within a few thousand years. These cold-tolerant species may then have been able to persist through the relatively brief interglacials.

In what sense is extinction a stochastic event?

The magnitude of fluctuations varies, so extinction is a matter of chance.

What is the main method used to assess future extinction risk from climate change?

The most prominent method for assessing future extinction risk from climate change is that used in the 2004 Nature paper that brought so much attention to the issue. The authors of that study used species distribution models (SDMs) coupled with the species-area relationship (SAR) to estimate extinction risk in six regions representative of different biomes.

What kind of output do you get from SDMs?

The output of an SDM is typically a map of a species' simulated range, either in the present or in both the present and the future

How do gap models account for growth rates of different species of trees under different climate conditions and spacing?

The parameters of the model are derived from known growth rates of various species of trees under different climatic conditions and spacing. This information is generally most readily available for trees of commercial importance, whose growth has been studied in various areas of their range and under various replanting spacings and combinations with other species

In what ways will the future for species not be like their past?

The present climate is warm and stable relative to the previous 2 million years, whereas levels of habitat destruction are the highest in the history of the planet. Hence, the set of conditions that species will have to navigate as climates warm will be unlikely those any have faced for much of their evolutionary history.

How was the species-area relationship used to assess effects of future climate change on species extinction? What was the idea that was applied?

The rate at which species accumulate with area seems to follow one of two paths - one curve for islands and another, different, curve for continental areas. The main difference between the curves, when the data are log-formed, is the slope of the curve.

What is the significance of the trailing edge of range shifts for a species?

The rear edge of current range shifts is the edge that has been the most stable in glacial-interglacial cycles. Collapse back into glacial conditions has repeatedly wiped out leading-edge populations, whereas trailing-edge populations in warmer climes closer to the equator have endured. The genetic richness of the rear edge may be greater than that of other areas of the range. It also may make rear-edge populations important in resisting extinctions.

How can SDMs be used to estimate how species' ranges may shift with climate?

The same type of model can be run using future climatic conditions, and results can be compared to current distribution to obtain an estimate of how species ranges may shift with climate change.

In what sense is a SDM an "envelope" model?

The simplest SDM uses values for climatic variables at points at which a species has been observed, compares these values to values of the same variable across a study area, and models the species as present where current climate is within the range and as absent where current climate is above or below the range- this is an "envelope" model

Considering this information, what approach is recommended to avoid these problems when developing SDMs and making predictions about extinction risk for endemic species?

The solution to the problem of endemics lies in changing the type of SAR applied. Because it is not wise to expand the SDM to non-endemics, a different kind of SAR is needed - one that applies particularly to endemics. Fortunately, at approximately the same time that the first climate change extinction risks were being calculated a new type of SAR was being derived - one that applied especially to endemics. The endemics-area relationship (EAR) is similar in principle to a SAR, but it is derived especially for endemics.

What are biodiversity hot spots? What evidence is there to support species-based estimates of extinction risk?

The species-based estimates of extinction risk have been confirmed by two independent methods. The second approach used dynamic global vegetation models (DGVMs) and EAR to estimate extinction risk for biodiversity hot spots. The global biodiversity hot spots have been defined based on areas of high species endemism. Projection of future extent of vegetation types of r a hot spot from a DGVM can be used to estimate extinction risk for hot-spot endemics. If a habitat type decreases within a hot spot, it is as if a small habitat island for the endemics occupying that habitat has just gotten smaller.

If you wanted to minimize the extinction of climate-sensitive birds, what geographic locations would you be most concerned about in the world? Why?

The tropical Andes hot spot was especially rich in climate change-sensitive birds, with more than the rest of the hot spots combined.

Isn't the tropics expected to see little change in the magnitude of warming?

The tropics may be vulnerable to climate change even though the magnitude of warming is considerably less in the tropics than at high latitudes.

Hot spots can be important in conservation. Is there any evidence that hotspots have moved due to climate change?

There is no evidence that current hot spots are shifting, but palaeoecological studies show that they have shifted in the past. A richness hot spot that originated in the Mediterranean migrated to the Arabian Sea and then to the coral triangle area of southeast Asia. This shift has not been linked to climate change. Theory suggests that endemism hot sports will not move. Climate change may make diversity hot spots hop, whereas hot spots of endemism only get hotter.

Based on past climate change effects, can we derive quantitative estimates of how many species may be lost or which species may be vulnerable? Explain.

There is some indication that rapid, large climate changes are more likely to lead to extinctions and that climate change in concert with human activity leads to extinctions - evidence that should raise alarm bells about possible future impacts of climate change. However, for quantitative estimates of how many species may be lost or which species may be most vulnerable, we have to turn elsewhere.

Why does the "perfect dispersal" assumption put a lower bound on the estimate of extinction risk of a species? Why does the "no dispersal" assumption put an upper bound on the extinction estimate of a species?

These are not very satisfactory assumptions because almost all species will fall somewhere in between these two extremes. These two assumptions do bracket the range of possibilities, however, so it is possible to state that the perfect-dispersal assumption puts a lower bound on the extinction risk of a species and the no-dispersal assumption puts an upper bound on the estimate.

Why are the existence and physical characteristics of freshwater systems very vulnerable to climate change?

These freshwater features are ephemeral in geologic time: they often last less than 1 million years and seldom more than 10 million years. Their very existence is dependent on the balance of precipitation and evaporation, making climate a fundamental determinant of their longevity.

What are Earth system models? What are their advantages?

These models integrate biological change into models of global climate. In their simplest form, they are the coupling of a DGVM with a general circulation model (GCM).

Explain what is involved in Earth system models.

These models integrate vegetation and climate processes, in their simplest form, by joining a DGVM and representation of ocean primary productivity to a GCM. Changes in vegetation and marine biomass then release or sequester CO2 which feeds back on climate. The application of these models is relatively new because the massive computing power that they require has been available only relatively recently.

How did climate change cause the extinction of the dinosaurs?

This event was caused by the impact of an asteroid in what is now southern Mexico. The huge crater there suggests than an asteroid slammed into Earth just at the time the extinctions began. Debris from the impact shot up into space, some of it generating intense burning radiation as it reentered the atmosphere. Much of the debris remained in the atmosphere for decades or centuries, blocking out sunlight, cooling the planet, and altering living conditions so drastically that no dinosaur survived the change.

What kinds of threats interact with climate change?

Threats that interact with climate change include encroachment of human land uses, illegal hunting, and invasive species.

How does one use a SDM to simulate the future range of a species (after climate change, for example)?

To simulate the future range of species, an SDM substitutes climate data from a future, elevated CO2 run from a GCM into the statistical model developed for the current climate. The model then predicts species presence or absence based on the suitability of the future climate in a cell.

Give me an example of an interaction between climate and humans that can have an indirect effect on biodiversity.

Tropical farmers often rely on forests for supplemental or emergency income. If crops fail, the sale of timber or collection of forest products can provide needed income. As climate change alters agricultural conditions, changes in crop productivity or crop failure may occur, triggering increased use of forests. Because of this human feedback on biodiversity, even where climate change is not damaging to biodiversity directly, its indirect impacts need to be anticipated to avoid threats to species.

If we want species to persist through time, what factors do we have to plan for that will endure through time?

Waiting to add protected areas for climate change costs more. If protected areas were added first for current ranges and then later for climate change, the double-duty efficiency of the additions was lost, resulting in the need to add more protected area. This suggests that waiting to take action (adding protected areas) until the effects of climate change on species' ranges are evident will result in significantly higher protected area addition needs.

If EO expands but AO shrinks, what kind of a problem can develop?

When EO expands but AO within that region shrinks- a situation that can lead to underestimation of the threat to a species unless AO is proportionally recognized.

In conservation, what do we mean by irreplaceability?

When a species is found only in one location, that site is said to be irreplaceable.

In what ways was climate a contributing factor?

Where climate is a contributing cause, these same factors drive extinctions but are set in motion by forces outside the climate system, such as asteroid impacts or volcanic eruptions.

There have been five major mass extinctions on Earth. Climate has been implicated as either a direct or indirect (contributing) driver of these extinctions. In what ways was climate a direct factor?

Where it is a direct cause, rapid temperature change and sea level rise or fall are often cited as driving extinctions.

Varves

annual layers of sediment created by biological or biogeochemical processes