by Paige Brown Jarreau
We’ve all seen the scenario in our high school biology textbooks. A single population of fish shares a large Pond. But then something drastic happens in the landscape. Perhaps a drought occurs, and the large Pond partially dries up to leave two smaller ponds separated from each other by a hill or expanse of higher, dry land. If this separation lasts long enough, combining the fish from pond A and pond B produces an interesting effect – the fish can no longer interbreed.
But why? Perhaps the conditions in pond A during the length of the separation were different than the conditions in pond B, and, in a feat of evolution before our very eyes, the fish in pond A and pond B differentiate into distinct species. And if these species can’t interbreed, then even if the waters rise and the pond becomes the single Pond it used to be, our two different species of fish remain. Hello Darwin.
This type of landscape-change-driven speciation (the formation of distinct species of a once common population, or ancestor, due to landscape change) has been previously credited for the formation of a vast number of different bird species in the Neotropics, the most species-rich region of the world. As violent uplifting, faulting and folding processes in underlying tectonic plates produced the highly various landscapes of the Andes mountain range in South America, ancestral populations were theoretically forced and shaped into different habitats, separated by isolated forests, rivers and elevation. According to the landscape-change-driven speciation hypothesis, also referred to as the vicariance model, drastic changes in the landscape fragmented the distributions of Neotropical birds previously living in overlapping areas, creating new and divergent species. Evidence supporting this mode of species formation includes the finding that many “[n]eotropical lineages originated during time periods associated with major reconfigurations of the landscape, presumably signifying a shared response to landscape history.”
But what if a different model of diversification in the Neotropics altogether was responsible for the formation of a vast number of different bird species? According to this model, it’s not that the landscape changes don’t have an effect, but it’s that these changes have an indirect effect. The primary driver of speciation in this alternative model is movement.
Movement? That’s right. Different bird lineages have different abilities to disperse in a varied landscape, perhaps because the climate or habitat they prefer. Brian Tilston Smith and Robb T. Brumfield at the LSU Museum of Natural Science in Baton Rouge, Louisiana, along with colleagues, analyzed 27 different lineages of Neotropical birds for a study published online at Nature.com on September 10, 2014. They found that speciation of Neotropical birds is linked more directly to the age of a bird lineage and its ability to disperse through a landscape than to landscape changes themselves. They also found that most Neotropical bird speciation occurred during the Pleistocene, long after the landscape changes that produced the Andes Mountains and the Amazonian river system.
“Speciation biologists have long been trying to link speciation with historical landscape changes like glaciers, mountain uplift and formation of rivers,” said Brumfield. “It’s nearly impossible to do with many organisms if there is no fossil data that tells us when and where a species occurred in the past. Distributions can change on the scale of a human lifetime, yet much of the biogeography literature assumes distributions have been more or less as they are today for millions of years. It’s hard for me to make that assumption. Instead of trying to link speciation with these historical landscape changes, our research focuses on things we can understand about the process: the tempo of the formation of new species, their relative timing, and how natural history influences these rates.”
Smith, Brumfield and colleagues found that species diversity usually increases with the age of the bird lineage. Older bird lineages have had more time to disperse and potentially move across geographical barriers like gaps between forests, mountains or rivers – leading to formation of new species in different locations. Species diversity also increases for lineages of birds living in the forest understorey as opposed to tree canopy lineages, where canopy birds can disperse farther and wider in the landscape. Understorey bird lineages, which often don’t travel as far and wide, often end up isolated and thus quickly diverge into distinct species.
According to Brumfield, there were three big signals in their data that pointed away from a vicariance or landscape-change-based model of species formation. First, the number of species within a lineage increased simply with the amount of time the lineage had existed in the landscape. Second, lineages that were not as mobile tended to accrue more species. And third, most speciation occurred in a static landscape, as movements of birds across geographic barriers like rivers produced geographical isolation and the formation of new species.
In other words, the landscape changes may provide a platform for the formation of distinct species, but whether, how and when this speciation occurs seems to depend on how different birds move and disperse, and what specific habitats and climate conditions they prefer.
“The widely accepted vicariance model is seductively clean and simple,” said Dr. James Van Remsen, John S. McIlhenny Distinguished Professor of biological sciences & Curator of Birds at the LSU Museum of Natural Science. “However, [Smith, Brumfield and colleagues’] data show none of the signal that would support that model. Instead, their data support a leading role for differences in dispersal ability in birds in explaining differences in genetic differentiation. The dispersal abilities of tropical birds have been chronically underestimated.”
It seems that previous researchers have underestimated the movement of tropical birds as a key factor in the development of new species. In other words, to move is to live, and to move is to potentially create new species.
According to Remsen, the vicariance view “was almost doomed from the start” – it assumed that movement through and between landscapes was nearly irrelevant to speciation. “That might work for salamanders and a few other groups with terrible dispersal,” Remsen said, “but not at all for birds, bats, insects, and plants with vagile [free to move about] seeds.” Where might the vicariance model explain the formation of new species, then? “Islands in water, where the water itself, especially salt water, really imposes a hard barrier for many groups,” said Remsen. So the original Galapagos islands finches might still owe their divergent beaks to a landscape-change-based model of speciation.
What does this all mean, though? For one, the process of new species formation itself depends on dispersal or movement paths that can lead to geographic isolation. For example, if there is no rainforest left on either side of a large river, then the opportunity for movement across the river is gone, and thus the speciation process in that location is ‘extinct’. The river’s physical barrier no longer provides a platform for the potential formation of new bird species. Deforestation, climate change, or any other factor that removes movement opportunities threatens the formation of new species.
“This may all be moot though, because speciation itself can take a long time, perhaps a million years or so,” Brumfield said. “This is much slower than the rate of habitat change due to climate change and other forces.”
by Kaci Jones
We all know multiple fairytales from when we were youngsters, and many of us wish one day that something magical like that might happen to us. For example, us finding our prince while we were asleep, like in Snow White and the Seven Dwarfs, or even in a frog after that gross, slimy kiss, like in The Princess and The Frog. But did you ever wonder about all the biological factors that went into these stories? For instance, did you ever wonder how the wicked stepmother changed the characteristic of the apple’s physical structure to become poisonous or how the frog can live successfully in the area that just so happens to be where the princess was at? YOU DIDN’T?! Well as child that’s all I thought about.
Lets take The Princess and The Frog fairytale. Most frogs and toads, also called anurans, live in swamp-like flooded habitats. These habitats are full of vegetation that is suspended in water. One example of this type of vegetation is nymphaeaceae commonly known as water lilies. The anurans’ initial habitats are natural buffers that are positioned in between the uplands and another contiguous body of water, and are a natural filter of pollutants, which makes these areas a risk to all the species that live there. According the Environmental Protection Agency, it is “important to preserve and restore damage to the wetlands because these areas can play a significant role in managing adverse water quality impacts.” This is like a stranger coming into your home and them leaving trash all throughout the property. If the house doesn’t get cleaned then your home becomes polluted, and then is considered an unsafe environment to live in. You then would probably want to clean up your house. That is what the EPA is taking about when they say you “preserve and restore”. You need to bring their environment back to where it was and if you can’t, like red stains that won’t come out of white carpet, then you try your best to not let it get any worse.
When animals’ surroundings get tampered with they are forced to adapt. This can cause animals to change everything, like: eating habits, death rate and birth rate of particular animals affected. Michele A. Gaston, primary author of a 2010 study on wetland management in the conservation of endangered Anurans in PLOS One, states that, “draining of existing wetlands or replacement of ephemeral wetlands by more permanent impoundments may have negative impacts on amphibian populations.” This shows that when trying to bring a habitat back to its original state that you have to be careful and fully grasp the animals’ environment to see if the actions you’re about to take are the right decisions for that species. Gaston also says that when planning an artificial habitat it is important to use observed evidence to guaranty full benefits after construction.
One thing essential for rebuilding a population is to make sure that the species are mating efficiently. If efficiency is met then the growth population rate will increase causing positive relations, which is called the allee effect. Gaston notes that, “frog and toad species that employ aggregated breeding strategies may be particularly vulnerable to component allee effect as their populations decline.” In this case, if the breeding were to not increase after measures were taken to increase the population and the wetlands were too polluted to survive, then in reality the prince would never have been in the water where the princess found him.
All pictures are areas that are apart of the USDA Natural Resources Conservation Service.: http://www.nwrc.usgs.gov/topics/amphibian/wrp.htm
New Orleans Aquarium
by Michelle Watson
Last weekend I attended the Society of Environmental Journalists annual conference in New Orleans. After listening to what the speakers had to say, we went to the aquarium with the passes they provided us. Coming from Atlanta’s aquarium that houses whale sharks, the aquarium in New Orleans was much smaller!
They had all of your typical aquarium attractions like sharks, eels, jellyfish, and catfish. There was even a frog exhibit with lots of exotic tree frogs! However, one exhibit seemed to hit a nerve: the penguin exhibit.
It was nice to see them swimming around and jumping in and out of the water, but to me it seemed as though the exhibit should have had more space. There were at least 20+ penguins in a really small exhibit. I’m usually not someone who gets upset about animals in captivity, but the lack of space that these precious animals had to move around in, made me very upset.
The two species housed in this exhibit are the Rockhopper penguin from South America and African penguins. These are both species that live in warmer climates with sufficient space to move around and migrate in.
Again, I’ve never be upset about animals in captivity…usually because I’m the one who likes to come and see the animals in captivity! The lack of space and water for these penguins to move around needs to be improved.
By Sarah Patterson
Louisiana’s most notable yet devastating story is Hurricane Katrina. The hurricane dislocated millions of people and deeply impacted the Louisiana landscape. After the Hurricane, there became an increased awareness of Louisiana’s diminishing coast and wetlands. In the paper Restoring the Sustainability of the Mississippi River Delta, Paul Kemp, John Day and Angelina Freeman say that “after the storms, wetland restoration was increasingly regarded as an integral, but long neglected…” part of storm protection. They discuss the 2012 Master Plan to replenish and rebuild the Louisiana coast and wetlands.
The Mississippi River drains almost 40 percent of the US river basins. The average discharge from the Mississippi is 19000 cubic meters per second or 19 million liters. To put this in perspective this is approximately 9.5 million two liter coke bottles. This discharge carries sediment down through the Mississippi and forms the deltas and the wetlands along the Louisiana cost. Man’s intervention with structural equipment such as dams and levees on the Mississippi has almost completely separated the river with the deltas along the coast. This has caused sediment discharge to drop approximately 50 percent. Combined with the rise in sea level, dredged canals, and other man made structures, the Louisiana wetlands are disappearing into open water. The Master Plan predicts 386 – 772 square miles of wetland loss over the next 50 years with no restoration. That would be like losing wetlands the size of Lake Pontchartrain, which is 629 square miles.
The 2010 Master Plan put out by the Louisiana Coastal Protection and Restoration Authority proposes three ways to restore the land. First, reconnecting the Mississippi River with the delta, next, pumping of dredged sediment to rebuild barrier islands, and finally, replenishing unnecessary canals.
Since the separation of the Mississippi River from its Delta after the 1927 flood, the wetlands have been disappearing. The plan to fix this is to discharge a large amount of water and sediment in specific areas. After 20 years of sediment diversion, it is estimated that the river delta will begin to gain land. The energy used to produce these diversions is “front-loaded”, or using most of the energy in the initial startup of the project. After the start up, the most important energy that will be utilized is gravity. Although the cost of this at first will be expensive, it is necessary that these deltas be reconnected to the river, and the wetlands are replenished.
The other way to replenish wetlands and barrier islands is through pumping dredged sediment into the wetlands. Through this method land is created almost instantaneously, which is helpful for flood protection and for building up the wetlands. Pumping sediment can also reach places that diversions cannot. This technique is used to build up barrier islands to protect the coast from storm surges from hurricanes. This way estuaries and fishing volume is not affected because the amount of water that is used is minimal. According to John Day and Paul Kemp, who are professors at LSU in the Oceanography and Costal Sciences Department, this restoration technique’s “advantages, in some cases, may outweigh cost considerations”. Although dredging sediment may be more expensive per acre than diversions, the benefits of being able to control and schedule land building outweigh the costs.
When canals where dredged for oil and gas lines, logging boats, and shipping boats, they allowed an influx of saltwater into the fresh water marshes. This destroyed many of the plants and some of the wetlands have disappeared into open water. One of the goals of the master plan is to replenish these canals, especially the ones that are no longer in use or unnecessarily large. This will keep salt water from rising into the fresh water marshes and preserve more land.
“Operating the 80 year old MR&T [Mississippi River & Tributaries] project as originally conceived is becoming increasingly unaffordable, while its negative side effects are becoming ever more apparent” John Day, Paul Kemp, and Angelia Freeman exclaim. If we continue with the old system of levees, dams, dredging canals, and ignore the disappearing coast. Louisiana will no longer be the state that we know it today. Land, homes, and history will be lost, never to be replenished again.
Day, John W., Paul Kemp, and Angelina M. Freeman. “Restoring the Sustainability of the Mississippi River Delta.” Ecological Engineering65 (2014): 131-46. Science Direct. 23 Oct. 2013. Web. 11 Sept. 2014.
By Kathryn Courtney
What are you willing to pay for? A latte, pizza, a cab ride home or what about protection from Mother Nature? It does not matter how technologically advanced mankind has evolved, mankind cannot alter the weather. Natural disasters are deadly and can potentially wipe cities off the map. Hurricanes, tornadoes and tsunamis are damaging forces to cities. However, taking action before, after and during deadly storms is vital to help protect and prepare citizens. Sometimes citizens need to evacuate their homes because the storm is so catastrophic it can be dangerous for their safety. In 2005 Hurricane Katrina, the strongest storm since the last 100 years, hit the United States and is the most costly natural disaster ever to happen.
Hurricane Katrina forced more than 250,000 people to relocate to a safer city. After Hurricane Katrina, the citizens who relocated still went back to their homes, even though they live in an area still prone to disaster. Evacuating millions of people in one city is not always possible, so why do people still risk living in an area with the possibility of their homes getting destroyed? “New Orleans is where I grew up and is where my heart and soul is… I will never just give New Orleans up,” stated Brain Razin, who evacuated when Hurricane Katrina hit New Orleans. People are not willing to leave their hometowns for whatever reason; therefore, storm protection is in order to protect citizens who live near the coast. How would citizens be protected against hurricanes? How would the city fund storm protection? Would coastal citizens pay for protection against Mother Nature?
Tae-Goun Kim, a scientist at Korea Maritime University, did research to see if Louisiana citizens would pay for storm protection. Specifically, he focused on funding for wetland restoration to protect the city from disastrous storms. Kim conducted a survey and found Louisiana citizens are willing to pay for wetland restoration so that they are protected against storms. However, restoring Louisiana wetlands does not mean a storm will never hit the coastline again. Restoring the wetlands might reduce some of the storms’ destruction. Protecting Louisiana’s coastline from hurricanes benefits the prevention of land loss, oil and gas industries and seafood production, which is vital to the nations economy.
Action needs to be taken immediately to protect Louisiana citizens from hurricanes by restoring the wetlands. Although mankind cannot alter Mother Nature, human intervention needs to take place. Putting together different methods of planning, protecting and restoring Louisiana’s coast and cities takes multiple teams of people. Many organizations already exist to help restore Louisiana’s coastline to a sustainable and productive state. Without people supporting and rebuilding the coastline, hurricanes will destroy and devastate more families and citizens of Louisiana. The United States will continue to lose an additional 1,000 square miles of land by the year 2050 and no longer can sustain the oil and gas industry, which is vital to the nation’s economy and Americans’ way of life. Take action and join or donate to one of the many organizations to help rebuild, restore and protect Louisiana’s coast.
Along the coast, a storm surge can be the greatest threat to life from a hurricane. This abnormal rise of water generated by a storm can cause extreme flooding. In 2005, at least 1,500 people lost their lives during Hurricane Katrina directly and indirectly because of the storm surge. Another imminent danger of living along the coast is the fact that Louisiana’s coast is deteriorating. It has been estimated that in Louisiana alone, the protection and restoration of coastal areas is projected to cost $50 billion. Coastal wetlands provide storm protection for coastal communities. They act as a buffer, stabilizing shorelines and reducing wave energy.
Storm surges, though infrequent and destructive, result in the deposition of inorganic sediments into the soil profile. However, the frequency, magnitude, spatial distribution, and influence on wetland soil development of this sedimentation is not well understood in Louisiana or other coastal systems. What if coastal restoration strategies could be improved with more knowledge of this deposition?
Scientists Andrew Tweel and Eugene Turner of Louisiana State University’s School of the Coast and Environment investigated the long-term contribution of hurricane events to soil inorganic matter content in Louisiana coastal wetlands in their research article Contribution of tropical cyclones to the sediment budget for coastal wetlands in Louisiana, USA, published in July in Landscape Ecology. To better understand how the mineral sediment in coastal Louisiana wetland soils got there to better inform coastal restoration, scientists studied all wetlands within the coastal zone from the Louisiana/Mississippi border west to Galveston Bay. The sediment budget impact from three hurricanes, Rita, Katrina and Gustav, were studied. A database from the National Oceanic and Atmospheric Administration isolated hurricanes, tropical storms and tropical depressions that entered this area between 1851 and 2008. These three storms were used to estimate the average deposition on the deteriorating Louisiana coast during this 157-year period.
“Basically, we went out to the wetlands after hurricane events and measured the amount of sediment that had been deposited on the marsh surface,” said Tweel. “It was clear what sediment was from the hurricane, and what was the existing sediment because they were so different.”
Surprising similarities between different events were discovered, allowing the scientists to make predictions about other historical events. All the predictions from 1851 to 2014 were layered on top of each other to determine the average rate of sedimentation along the coast for different areas at different times.
The long-term and coast-wide effect of these events on the distribution of inorganic sediment is difficult to quantify because of the irregular and infrequent occurrence of these storms, and the logistical challenges of sampling across such a vast area in a timely manner after each storm.
This data suggests most of the inorganic material in soils along the coast beyond active deltas directly corresponds to hurricane events. This could positively impact Louisiana’s deteriorating coast by improving coastal restoration strategies. Currently, the majority of coastal restoration strategies are based on the assumption that leveeing the river will restore the coast. However, this research shows this is not the case for most of the coast beyond active deltas.
“The general restoration strategy should be revised to address the organic processes that are mostly responsible for maintaining the elevation of wetlands on the Louisiana coast,” said Tweel. “There is always the excitement of making a new discovery that helps us better understand how coastal systems work. One of the coolest aspects of my work is getting to go out in the marsh and to see the coast from small airplanes.” Prior to this model, there was too little data on how hurricane sedimentation varied across the coast.
The research article Contribution of tropical cyclones to the sediment budget for coastal wetlands in Louisiana, USA can be found here. (http://link.springer.com/article/10.1007/s10980-014-0047-6)