Strategies for Preventing Climate Change Induced Extinction

by Alexander Birk

Climate change is an increasingly problematic obstacle in slowing the rate of species extinction and has been widely accepted as the major threat to biodiversity. With this threat rising, there needs to be a better strategy to protect species. Identifying a species as in danger of extinction is the key to saving them, the current system to detect potential extinctions does not give enough time to effectively save some species once they have been deemed endangered. According to Stanton et al. (2014) it would be much more effective to put species into more specific categories leading up to extinction. This would allow for a more visible pattern of endangerment over the years leading to a trajectory of where the species is headed. Stanton et al. (2014) Continue reading

Analyzing the Vulnerability of Rainforest Birds to Deforestation

by Maithili Joshi

In South East Queensland, Australia Pavlacky et al.(2014) conducted a study on the vulnerability of birds, rainforest ecosystems, and the biological impacts in response to deforestation in local and regional areas. The central idea is the to investigate the life history and forest structure to rank the vulnerability of avian species, while also looking at species loss along different kinds of forest structure and landscape change. The objectives are evaluating the effects of life history traits on the patch occupancy and vulnerability of rainforest birds, determining the relative effects of stand, landscape, and patch structure on species richness, and evaluating the relative contributions of deforestation and fragmentation to species richness. Continue reading

Effects of Alternative sets of Climate Predictors on Species Distribution Models and Estimates of Extinction Risk

by Kyle Jensen

As arid ecosystems have been recognized as being especially sensitive to climate change, they thus provide an appropriate system to assess the use of SDMs in estimating the threat of climate change to various species. Species distribution models (SDMs) can quantify relationships between species and environmental factors, and use this data to predict spatial distributions. SDMs are thus widely used to derive projections of species distribution under conditions of climate change. These models are correlative however, and as such are unable to identify causal species-environment relationships. They can only be used as supporting evidence for an existing hypothesis on factors affecting species distribution; as such the factors must be chosen as inputs for the SDM to function. Identifying the important climatic factors involved in determining the range of a given species is a key factor in assessing the potential effects of climate change on species distribution and extinction risk. Little research however has been done investigating the effects using alternative sets of climate predictor variables may have on the projections of SDMs. Pliscoff et al (2014) seek to examine this area of potential uncertainty, addressing the potential variability of SDM spatial projections and determination of extinction risks through the creation and analysis of several sets of environmental predictors. They found that by adjusting climate predictor variables they were able to significantly affect predictions of spatial distribution as well as, for the first time, extinction risk estimates. This implies greater variability in such studies than previously thought. Continue reading

The Endangered Species Act: Conservation-Reliant Species

by Alexander Birk

The United States Endangered Species Act (ESA) is responsible for the protection of species and their habitats. The ESA maintains a list of the species at risk; the ultimate goal is to get these species off of the list. In order to get an endangered species removed (delisted) the ESA must regard that species as self-sustaining. The definition of a self-sustaining species becomes difficult as the ESA looks at conservation-reliant species. A conservation-reliant species is defined as a species that has been delisted; however it requires management in order to prevent it from once again being at risk. Continue reading

Comets, Climate Change, and Extinctions—2


by Emil Morhardt

When a large meteorite struck the earth 65 million years ago, it killed off the dinosaurs by abrupt climate change; the energy of the strike sharply raised global temperatures, ignited massive wildfires, and filled the atmosphere both with smoke from the fires and dust ejected from the crater which presumably prevented plants from thriving for a long enough time to starve all but the smallest animals (allowing, as it happened, the evolution of humans.) That’s a different cause of climate change than now, and most of us, if we worry about climate change at all, don’t much worry about it being caused by another meteorite strike. But, on August 16, I wrote about a paper published in 2007 that proposed a similar, though not so severe, extraterrestrial impact and abrupt climate change about 12,800 years ago—the initiation of the Younger Dryas (YD) cooling episode that stopped the Continue reading

Disequilibrium between Tree Species Distributions and Regional Temperatures

by Cortland Henderson

Correlations between geographic distributions of plant species and the current climate have been identified, suggesting that species ranges will shift upwards if global temperatures rise. These links, however, are based on models that do not establish whether or not plant species are at equilibrium with the current climate, and are incapable of differentiating between naturally occurring shifts and climate-induced shifts. García-Valdés et al. (2013) examine the ten most common tree distributions throughout the Iberian Peninsula by creating a new species distribution model that relaxes built-in assumptions that tree species and climate are currently at equilibrium. Their model successfully removed previous biases and found that tree species are not at equilibrium Continue reading

Mass-flowering Crops Positively Affect Wild Bee Brood Numbers


by Lia Metzger

The expansion of mass-flowering crops has been linked to the loss of biodiversity of farmlands because they escape into natural and semi-natural habitats. However, these mass-flowering crops have a higher density of flowers than non-crop species, and thus produce more food resources with more access to nectar and pollen, so they may enhance the abundance of wild foraging bees. Holzschuh et al. (2013) investigated how oilseed rape, a mass-flowering crop, affects the abundance of the solitary and polylectic Red Mason Bee Osmia bicornis, a generalist bee species that nests in both natural and semi-natural habitats. Using data from 67 sites in Germany, they compared the abundance of Osmia bicornic in grasslands adjacent to oilseed rape fields and isolated from oilseed rape fields and vice versa. Artificial nests were assessed for Continue reading

Species Most Vulnerable to Climate Change

by Elizabeth Medford

While it has been recognized in the past that climate change will have impacts on biodiversity, many approaches ignore the differences between species that will increase or reduce their vulnerability. Foden et al. (2013) chose to address three different aspects of climate change vulnerability to account for species’ biological traits: sensitivity, exposure, and adaptive capacity. In combining these traits with the modeled exposure to projected climate change, the authors assessed the species with the greatest relative vulnerability to climate change. These methods were applied to each of the world’s birds, amphibians, and corals. The authors also identified the geographic areas in which the most vulnerable species are concentrated. These included the Amazon basin for amphibians and birds, and the Indo-west Pacific for corals. The aim of Foden et al. is that Continue reading

Comets, Climate Change, and Extinctions—1

by Emil Morhardt

At the end of the last ice age as the Earth was warming to its present condition there was an unexplained 1000-year pause and partial reversal in the warming (called the Younger-Dryas stadial). The result was a millennium of very cold weather in the Northern Hemisphere. The cause was widely attributed to the abrupt stoppage of the Gulf Stream; warm water was no longer transported from the equator north past the US east coast and Europe toward Greenland. The physical cause of the stoppage was presumably the melting of the Laurentide Ice Sheet covering Canada; enough freshwater flowed out over the North Atlantic near Greenland, that it formed a thick layer on top of the ocean that was not dense enough to sink through the underlying salt water. It is sinking saltwater off Greenland that drives the major global ocean currents—the Meridional Overturning Circulation (MOC)—of which the Gulf Stream is the last leg. Scientists are somewhat worried that under the current warming conditions, enough meltwater could flow off the Greenland Ice sheet to wreak the same sort of havoc…a much colder North America and Europe in the midst of a generally warming globe. In 2007, Firestone et al. presented an unexpected theory that the trigger for the freshwater outflow 12,900 years ago was an extraterrestrial (ET) impact event—a comet or meteorite—that also directly led to the Continue reading

Evolutionary Rescue from Extinction is Contingent on a Lower Rate of Environmental Change

Natural selection is defined as the method that allows species to persist and survive in an ever changing world.  But natural selection is a very long and slow process, so rapidly changing environments will hinder the ability of natural selection to keep species alive.  Lindseyet al. 2013 used the bacteria Escherichia coli to prove that rapid climate change will hinder the process of natural selection and may therefore cause extinction.  Although some experiments have shown that slower rates of environmental change have led to more adapted populations or fewer extinctions.  Lindsey et al. used different concentrations of the antibiotic, rifampicin with E. coli over different time periods to simulate slow, intermediate and rapid environmental change.  They then genetically created all possible combinations of mutations that can result from slow rates of environmental change.  The assessment of the engineered strains show that certain genotypes are evolutionarily inaccessible under rapid environmental change, and that rapid change could eliminate entire sets of mutations as options.  They further speculated that intermediate levels of change might enhance expressions of genes, then there could be more endpoints as a result.  This could have an effect on rates of adaptation that could among other things, increase rate of development of antibiotic resistance. —Cameron Lukos

Lindsey, H.A., Gallie, J., Taylor, S., Kerr, B., 2013. Evolutionary rescue from extinction is contingent on a lower rate of environmental change. Nature 494, 463–467.

                  The experiment was carried out by propagating 1,255 populations of E. coli.  The experimenters also created mutants to add the secondary factor of selective accessibility.  These populations were then placed under increasing amounts of the antibiotic rifampicin.  The treatments had different rates of change, ranging from sudden to gradual.  The populations all started in an antibiotic free environment and ended at a maximum concentration of 190µg/ml.  The populations that were subject to rapid change were exposed to the maximum rifampicin concentration after the first transfer and remained at that level for the rest of the experiment.  Populations exposed to moderate change received the maximum amount of rifampicin halfway through the experiment and the populations exposed to gradual changed experienced the full amount of rifampicin on the last transfer of the experiment.
                  The results indicate that as the rate of environmental change increased the number of populations that survived the whole experiment decreased.  Populations exposed to gradual change were able to become resistant to the antibiotic because there was more time for mutations to occur and spread.  They also found that there were significant differences in growth rates of the populations exposed to gradual and sudden change, indicating that different mutations occurred in different treatments.  For instance, in the case of the sudden populations only one mutation was detected, while in the moderate and gradual populations many different mutations were discovered.  Lindsey et al. found a clear historical contingency for mutations that occurred in the intermediate environments.  It suggests that the mutations allow for the lineage to gain other mutations, a historical contingency.  From this, the results suggest the high rates of climate change will cause problems for species resulting in higher extinction rates.  Not only will it wipe out genetic diversity but it may also result in the loss of potential mutations that could occur under less extreme conditions.
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