BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: species

Giraffes, Giraffes, Giraffes, and More Giraffes

 

On the left is the Southern giraffe, while on the right is the Northern giraffe. They look the same but are genetically different.

Previously there was thought to be only one giraffe species, but recently with the help of genetic testing there are now four confirmed giraffe species. To make this amazing discovery, Scientists from the Senckenberg and the Giraffe Conservation Foundation utilized several nuclear marking genes on over 100 giraffes and analyzed the genetic relationship between all major species in the wild. The Giraffe Conservation Foundation collected more than 100 biopsy samples over the past decades from all areas of Africa, including war torn regions. They then sent the samples to the Senckenberg Biodiversity and Climate Research Centre for analysis. The nuclear genes, which are genes found in the nucleus of Eukaryotes, were different enough in each group that it reveals how different species do not mate with each other. The four distinct species that were discovered are the southern giraffe, masai giraffe, reticulated giraffe, and northern giraffe. Besides demonstrating four groups, the scientists concluded from the data that some sub-species are in fact the same. The discovery highlights the need for greater conservation efforts for the overall giraffe species. While giraffes are already close to extinction, the idea that there are now four species exacerbates the issue as they are even closer to losing each diverse group.  With the giraffe species declining over 40% in the last 30 years to the point of only 68,000 of them left in the wild.

Are Species We See Everyday Going Extinct Before Our Very Eyes?

A theory has recently surfaced declaring the possibility that there are around 700 species around the world that should be considered threatened species, many of whom who were possibly inaccurately declared non-threatened on the Red List of Threatened Species.

Luca Santini, an ecologist at Radboud University, was quite discouraged by this news and took it upon himself to create a more efficient and precise method when it comes to assessing the extinction risk of a particular animal. On January 17th, Conservation Biology did a segment on Santini’s new approach.

This new approach proved that as much as “20% of 600 species that were impossible to assess before by Red List experts, are likely under threat of extinction, such as the brown-banded rail and Williamson’s mouse-deer.”  In addition, it found that around 600 different species that had been officially declared non-threatened species, were actually likely to be extremely threatened. As Santini, himself, said “This indicates that urgent re-assessment is needed of the current statuses of animal species on the Red List.”

The (IUCN) Red List of Threatened Species is the “world’s most comprehensive information source on the global conservation status of animal, fungi, and plant species.” That being said, every few years, researchers evaluate and record the conservation status of different species, which then gets uploaded into the Red List’s database for the general public to have access to. According to Santini, however, “Often these data are of poor quality because they are outdated or inaccurate because certain species that live in very remote areas have not been properly studied. This might lead to species to be misclassified or not assessed at all.”

Santini’s method provides experts with additional independent information in attempt to help them better assess the species. It uses information gathered from land cover maps, showing how the distribution of different species has changed over time. This then allows said researcher to have more information to be able to more accurately classify species.

Santini describes his goal for this new method in saying “Our vision is that our new method will soon be automated so that data is re-updated every year with new land cover information. Thus, our method really can speed up the process and provide an early warning system by pointing specifically to species that should be re-assessed quickly.” We can only hope that this new method provides better and more accurate information in regards to what and who we will continue to share the planet with, and who we won’t.

 

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.

Yawning and Brain Size

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Recently, scientists discovered a correlation between yawning and brains: the longer the average duration of a specie’s yawn, the bigger that specie’s brain size,  as measured by brain weight and total number of cortical neurons.

The study was conducted on 109 individuals from across 19 different species, including cats, humans, mice, camels, and more. The investigators found that the duration of yawns was shortest in mice, who averaged 0.8 seconds, and longest in humans, who averaged 6.5 seconds. The scientists plan on investigating whether this correlation holds true amongst individual members of a species.

The study was created in response to the ideas set forth in Gallup’s 2007 paper on the thermoregulatory theory of yawning, one of the strongest theories about why we yawn (we do not yet definitively know the biological purpose of yawning). The thermoregulatory theory indicates that yawning cools down the brain in homeotherms via three potential mechanisms. But whether or not this brain-cooling is simply a side effect or the primary function of yawning is up for debate.

Based on Gallup’s paper, the investigators of this study hypothesized that longer yawns would produce greater physiological responses, in terms of blood flow and circulation to the brain– which would be evolutionarily necessary for species with larger, more complex brains.

There are other theories about why we yawn, such as a 2014 paper stating that yawning stimulates cerebrospinal fluid circulation, which in turn increases species’ alertness. A common theory that yawning increases blood oxygen levels has largely been disproved. How would such alternate theories have different implications for the discovered correlation between yawning and brain size?

Odd Little Species Survives Without Sex

Of the two million know species on Earth, only about two thousand reproduce entirely asexually. Scientists think this is because organisms that reproduce without sex – which provides healthy genes from one parent that act as a template to repair mutated genes, leading to “theoretically healthier offspring” – are unable to mitigate the deleterious effects of gene mutation, which leads to their extinction. The bdelloid, a tiny, all-female, sea creature with a name that means “leechlike” for the way it moves, however, has survived for tens of millions of years without sex. In fact, they have diversified into more than four hundred species.

Researchers at the Marine Biology Laboratory in Woods Hole, MA wanted to find out why the bdelloid had avoided extinction, so they zapped some of the creatures with gamma radiation, which breaks up DNA. Oddly, the bdelloids did not succumb to the exposure even as the scientists pushed the radiation levels far past what would naturally occur on earth. When the mystified biologists examined the bdelloids’ DNA, they discovered that an early mutation had copied the entire genome, giving each organism four copies as opposed to the common two, which allowed it to repair severely damaged DNA. This mutation turned out to be beneficial for the aquatic creatures because it allows them to survive desiccation, a danger for bdelloids because of their transient underwater habitats.

More recently, scientists at the University of Cambridge published a paper in the journal PLoS Genetics recounting their discovery that about ten percent of the bdelloid’s genome is composed of alien DNA amassed through the consumption of bacteria, fungi, and algae. These foreign genes become active when a bdelloid dries out, and are thought to be partly responsible for the creature’s incredible ability to survive dehydration. Those same genes might also be behind “powerful antioxidants that protect bdelloids from the by-products of drying out”.

Evolutionary biologists are hopeful that a better grasp of the mechanisms that allow bdelloids to survive will lead to much greater discoveries such as how sex evolved. Matthew Meselson, a geneticist at Harvard University, said in an interview with LifeScience that “being able to understand how animal cells can be so resistant to radiation may be of some interest in understanding how [cancer, aging, and inflammation, of which DNA damage and repair are factors] might be inhibited in human cells.” Further experimentation could uncover new treatments that prolong life or fight cancer.

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