AP Biology class blog for discussing current research in Biology

Tag: invasive species

The Silent Extinction: How an invasive species is likely to destroy the Ash Tree

There is a mass extinction occurring right now all across North America that millions of people have never hear of. First discovered in North America in 2002, the Emerald Ash Borer, an invasive species native to Mongolia and northern China, has destroyed tens of millions of Ash Trees across North America; and it is likely to destroy millions more.

The Emerald Ash Borer does its damage as larvae. They burrow into the bark of Ash Trees to protect against the cold and in the process of this, cut off the nutrients and water the Ash Tree needs. Scientist suspect that the Emerald Ash Borer has been in North America at least ten years before it was detected.

The devastating effects of the Ash Borer go far beyond losing a tree on your property or favorite hiking trail. The destruction of Ash trees could have a chain effect that leads to the endangerment of numerous plant and animal species. The removal of the canopy that the Ash Trees create leads to sunlight hitting spots of the forest floor that it previously did not. This could lead to invasive species of thickets and bushes covering the forest floor, preventing native plants from growing. Which, in turn, would lead to animals that inhabit the forest going without some of their primary food sources.

In the past, invasive insects have been fought by a combination of insecticides, awareness, and felling of infected trees. This proved fairly successful with the Asian long-horned Beetle in Chicago, but the Emerald Ash Borer presents a different set of challenges. Firstly, the Emerald Ash Borer is march harder to spot than the more distinctive Asian Asian long-horned Beetle. Secondly, it is much easier to deal with an invasive species when it is still localized. While the long-horned beetle was still mostly confined to Illinois, the Ash Borer has spread all across the Upper Midwest.

All factors considered, it may seem that there is nothing that can be done. However, with increased awareness, improved insecticides, and new containment techniques there is hope. The fate of millions of Ash Trees depend on that hope.

For more information click here




Tree Lobsters Are Back!

Image result for Stick insects Tree lobsters Lord Howe

Lord Howe Tree Lobster

Tree Lobsters are actually not lobsters at all. Nor are they crustaceans.  They are actually just insects with a similarly shaped exoskeleton. But that’s not what makes them interesting. What does, is that Tree Lobsters have seemingly come back from extinction.

The Species, originally from the Lord Howe Island in the Tasman Sea between Australia and New Zealand, went extinct during the 1920’s due to becoming the main food source for an invasive rat species that came onto the island. The Tree Lobsters were only formally declared extinct in 1960 though. Since then scientist had pretty much forgotten about them.

Image result for Stick insects Tree lobsters Lord Howe

Ball’s Pyramid Stick Insect

Thus, when scientists found a small group of stick insects similar to Lord Howe Tree Lobster’s on Ball’s Pyramid, a volcanic stack 12 miles away from Lord Howe Island, in 2001, they were quite surprised. The Ball’s Pyramid stick insects were skinnier and darker but scientists were still hopeful the newly discovered insects were, in fact, the same species as the extinct Lord Howe Tree Lobsters. Scientists tested the genes of the stick bugs from Ball’s Pyramid with genes extracted from preserved Lord Howe Tree Lobsters and found out that despite some morphological variance, they are still the same species. They speculate that diet, age, and environment had caused the Ball’s Pyramid Stick Insects to look a little different. How the species got to the volcanic stack is still a mystery as the insects cannot swim but they infer that they had been carried over by birds.

The newly discovered Tree Lobsters are now being bred at the Melbourne Zoo and elsewhere in an attempt to reintroduce the species to Lord Howe Island. However, the invasive rat species on Lord Howe Island still remains a problem as it threatens the lives of over 70 different native species. In order to successfully reintroduce the Tree Lobsters back to Lord Howe, the rat problem needs to be taken care of first.

Invasive Troubles

In the 2000’s a container ship carrying Asian toads arrived in Madagascar. Invasive species have a reputation have a reputation for causing an imbalance in local ecosystems. However, what has happened with the Asian toads in Madagascar since then?

File:Asian Common Toad (Duttaphrynus melanostictus).jpg

Photograph of Asian Toad taken in Thailand

A new report says that the eradication of the species from Madagascar is “not currently feasible.” Estimates place their current population at around 4 million. Each female toad can lay an average of 20,000 eggs each year. Although most don’t survive, their population is not going down anytime soon. Scientists estimate that keeping the population stable would require 1.5 million toads killed each year while eradicating the population would require 2.5 million toads killed per year. It wouldn’t be very expensive, but no one knows where to look for these toads, let alone kill over 60% of its population.

As a result of being a new introduction into the ecosystem, predators do not have any way of dealing with this toad. Since the Asian toad is also poisonous, predator populations can decline. This can have profound effects on the ecosystem, one of which the further decline of the snake population. Snakes are also predators for rodents. If their population is allowed to skyrocket, diseases can run rampant. Industries and commercial items can be overrun. Toads can also directly affect the human population if humans decide to try and eat them.

If nothing is done, which is probably the most likely case, the toad population will go past the point of recovery similar to the case of the introduction of cane toads to Australia. Madagascar’s only choice is to attempt to adapt to this invasion.

Original Article

Invaders or Saviors: The Truth Behind “Invasive” Species


With a name such as “invasive” its hard for an emerging species in a new biome to establish a good reputation.  An “invasive species” can be defined as an organism establishing a presence in a newly introduced area not native to it whether by accidental or intentional means.  For the most part, as stated by the New York Times, it has been the general opinion of conservation organizations to either eradicate or eliminate the invasive species.  However, a large number of scientists including Dov Sax and Ken Thompson, both professors of Ecology at Brown University and the University of Sheffield respectively, are beginning to dispute this idea.  Dr. Thompson claims that species have been moving around for centuries and that humans play a large role in their movement.  In a modern era of globalization, it is getting increasingly harder to stop the spread of “invasive” species and climate change is multiplying the number of species considered “invasive” drastically.  Although Thompson’s theory has a large following, it is not universal.  Some “invasive” species are undeniably harmful such as the fungus that causes chestnut blight which decimated thousands of trees across America in the 1900s or more recently the Zika virus spreading rapidly through mosquitoes drawn north by the warmer climates.  It has been discovered that islands and mountaintops are even more susceptible to these species due to their isolation and indigenous population’s lack of evolutionary defenses.  For example the the accidental transport of the brown tree snake to Guam has nearly eliminated the bird population.  However, this general trend has given many nonnative species a bad representation.  For example, monarch butterflies of California prefer to live in the eucalyptus tree which was brought there 150 years ago.  Or the nonnative crayfish pictured above which feeds the migratory wetland birds of Spain.  In fact the term “invasive species” was coined in Charles Elton’s 1958 book The Ecology of Invasions by Plants and Animals drawing from the heightened tensions caused by World War 2.  This term did not gain its modern weight until the 1990s when the field of Invasive Biology began to grow popular.  Despite findings such as the ones by Thompson and Sax, this is still a much highly debated topic in the field of biology.

original article:




Invasive Rabbitfish

A team of researchers, lead by Dr. Adriana Vergés and Dr. Fiona Tomas, has recently discovered a species of tropical fish that “poses a major threat to the entire Mediterranean basin.” The species, called a rabbitfish has greatly harmed the algal forests in the Mediterranean Sea, primarily the eastern portion. The rabbitfish arrived in the waters of the Mediterranean through the Suez Canal. The rabbitfish are not indigenous to the Mediterranean waters, which makes them so dangerous to the ecosystem. This phenomenon has also been observed in lionfish, snakehead fish, and other organisms that are not indigenous to the location that they are harming. The rabbitfish have been eating seaweed and other ocean plants, which provide shelter and food for other species.


The scientists conducted their study by examining 1000 kilometers of coastline in the eastern Mediterranean specifically Turkey and Greece. Both places two separate species of rabbitfish have come to inhabit. The two areas focused upon were warm and cold regions. In the warmer regions the rabbitfish were present while in the colder regions they were not. The warmer regions filled with rabbitfish had a much lower abundance of seaweeds, and were mostly barren rocky bottoms. On the other hand the colder climates had a thriving ecosystem. There was a 60% reduction in algae and invertebrates and 40% reduction in overall species present in the warm rabbitfish filled environment. After filming rabbitfish as well as indigenous species scientists realized that rabbitfish didn’t actually eat more algae than other fish. However, the distinction was that rabbitfish ate both young and adult algae while indigenous species only ate adults. Eating the young and growing algae before it has a chance for reproduction quickly reduces the overall population.

This topic interested me not only because of my love for marine biology, but also because marine sustainability is extremely important to humans. Without oceans there would be no human life on Earth. The abundance of water is what separates a lush green planet like Earth from the rest of the planets in our solar system. In addition the marine ecosystems are very important, and there have become more and more invasive species due to changes in the environment. Fish such as the rabbitfish threaten whole ecosystems as well as hundreds or even thousands of species that rely on those ecosystems.

Should humans attempt to stop this infestation of rabbitfish? If so, what should be done?



Bacteria to become a new environmentally safe way to control invasive species?



zebra mussels attached to a dock

Zebra mussels have, since 1991, become a huge problem in the hudson river. They devour the phytoplankton and disrupt the ecosystem, and, being an invasive species and having no natural predators in the americas, their population has soared uncontrollably. Until recently, Dr. Daniel Malloy has discovered a species of bacteria that is deadly to the shellfish, and to his knowledge, not to any other organism in the ecosystem. This solution might be just what the Hudson river ecosystem needs, a way to eradicate the aggressive zebra mussel without using chemicals that are harmful to the rest of the river’s inhabitants. This idea sprang from the use of the natural pesticide BTI (Bacillus thuringiensis israelensis) to control blackflies. Malloy has discovered a species of  Pseudomonas fluorescens called “Strain CL145A” that had the desired affect on zebra mussels. When ingested, the dead cells of the bacteria, emit a toxin that destroys the digestive tracts of mussels, the live cells, outside of the digestive system have little to no effect. Malloy and his team are working on finding a fresh water strain of the bacteria to start to eradicate invasive mussels in other bodies of water.


Powered by WordPress & Theme by Anders Norén

Skip to toolbar