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Extinctions

Submitted by robynfarrell on Sun, 04/30/2017 - 20:59

All extinctions are generally due to a change in atmosphere, that leads to a closing niches, which in turn leads to species dying. Volcanoes dump large amounts of carbon dioxide into the air, and that gets incorporated into oceans as carbonic acid. This changes the acidity and pH of the ocean messing with the thermal regime and amount of oxygen in the ocean. Rising acidity levels in the ocean precipitates a lot of marine invertebrates to slowly dying out. When a meteorite strikes it causes for an increase amount of iridium, which at an instant cause a radical change of a decrease in the number of species in that location.

Journal #36 - The Five Extinctions

Submitted by robynfarrell on Sun, 04/30/2017 - 18:30

Since the Earth has come to be there have been five mass extinction: Ordovician, Devonian, Permian, Triassic, and Cretaceous. The Ordovician extinction was an omega event, and occurred due to interglacial episodes and changing in marine heights. The Devonian extinction is technically not an extinction rate, it was more of a case where there were not enough new species being produced, and that was due to global cooling followed by global warming. The Permian extinction was an omega event that was caused due to volcanism. The Triassic extinction was another omega event, that was also due to volcanism and increased levels of carbon dioxide. The Cretaceous extinction was due an impact of a meteorite, and global warming followed by global cooling.

All extinctions are basically due to a change in atmosphere, that leads to a closing niches, which in turn leads to species dying. Volcanoes dump large amounts of carbon dioxide into the air, and that gets incorporated into oceans as carbonic acid. This changes the acidity and pH of the ocean which changes the thermal regime and amount of oxygen. Rising acidity levels in the ocean caused a lot of marine invertebrates to slowly die out. When a meteorite strikes it causes for an increase amount of iridium which at an instant decreases the number of species, such a radical change. 

Journal #35 - Environment Changes and Animals

Submitted by robynfarrell on Sun, 04/30/2017 - 17:02

When the environment changes it leads to rapid diversification of animals. Things such as the warming and retreating of glaciers, oxygenating of the ocean, changes of the acidity in water, and decreasing levels of carbon dioxide in the atmosphere can all have major effects on species. For example, the Cambrian radiation of animals was brought about due to an increase in oxygen availability. Species started developing genetic toolkits, body segments, and even skeletal structures. The Devonian radiation of plants happened due to the colonization of terrestrial environment. Plants started developing seeds, and vascular tissue during this time period. These are all examples of adaptive radiation, which means that a group or organisms diversify in order to fill out different ecological niches. 

Journal #34 - Bastian Mimicry

Submitted by robynfarrell on Sun, 04/30/2017 - 15:33

In one of my classes we had talked how some organisms use mimicry to help them escape predation. One form of mimicry that was discussed was Bastian mimicry. This is when one species tries to mimic a species that is distasteful and toxic. There are different results that can happen with this occurs. If a population consists of many toxic species, the species that is going to be mimicked, and few non toxic species, the species that will do the mimicking, the predator is more apt to run into a toxic organism. This is due to the chance of probability. When the predator goes to attack the toxic organism it learns that it is something that they should try to avoid and lessens the predation. So now both the toxic species and the species that is not toxic but looks like the toxic species get ignored, a stable strategy. This would go into fixation, and evolution would allow it to continue down this path.  If there is a population that consists of many mimics, an only a few toxic species the predator is more apt to run into the mimic first, eat it, and not learn that this species is something to avoid. This is an unstable strategy which is going to make the toxic species evolve into something different and get a new morphology. If a different morphology evolves in the toxic species it will be selected for. 

Bottlenecking Events

Submitted by robynfarrell on Mon, 04/24/2017 - 12:20

Bottleneck events reduce the genetic variation in a population. For example, take the species of elephant seals. Elephant seals used to be really common. They bred on islands, but have now shifted their breeding area to be shore lines. When examining their allelic composition, you would think to find a great diversity in alleles, but you find out there is a lot of homozygous diversity, which in the scientific community is not great. This is actually due to human hunting, due to them being hunted for their oils. At one point this species was down to only a few hundred, so rather than stopping hunting on them museums decided to step in. They thought that by taking dozens of these elephant seals that they would help maintain their safety. That actually drastically dropped their population in the wild to only 35. Throughout the last few decades their population has risen in the wild to around 100,000 but due to the incredible bottleneck their gene pool has dramatically shrunk. They have such a small gene pool that there are barely any mutations occurring, so their genetic diversity is slim.

Journal #33 - Bottleneck

Submitted by robynfarrell on Sun, 04/23/2017 - 19:35

I had always heard about the term bottleneck, but was always confused as to what it was and what it meant for a population. Bottleneck events actually reduce the genetic variation in a population. For example, take the animal, elephant seals. Elephant seals used to be really common. They bred on islands, but it has now shifted to shores. When examining their allelic composition, you would think to find a great diversity in alleles, but you find out there is a lot of homozygous diversity, which in the scientific community is not great diversity. This is actually due to human hunting, since we hunt these beautiful animals for their oil. At one point this species was down to only a few hundred, so rather than stopping hunting on them museums decided to step in. They thought that by taken dozens of these elephant seals that they would help them maintain safety, dropping the population in the wild to only 35. Throughout the last few decades their population has risen in the wild to around 100,000 but due to the incredible bottleneck their gene pool has dramatically shrunk. They have such a small gene pool that there are barely any mutations, so their genetic diversity is slim.

Journal #32 – Resistance to Pesticides

Submitted by robynfarrell on Sun, 04/23/2017 - 18:21

In one of my classes we learned about the resistance to pesticides. Insects pests, such as scale insect, were a lot to deal with so people in the scientific community tried to come up with something to deal with it. The scale insect is a tiny insect, around .5mm, and has a tube mouth that drinks plant fluid. It grows scales all over itself so nothing can get into it, sort of as a defense mechanism. They realized that if you sprayed it with lime and sulfur it killed this insect, but as time passed on a resistance built up. After few years they saw that some populations in certain areas didn’t succumb to this resistance mechanism, due to genetics. They then turned to the fact that maybe diesel oil would be another solution. Though scientists did warn farmers that if you use it too much the insect will build up a resistance to it and the same pattern would occur again, but the farmers did not listen. A trend was found that resistance started evolving to their mechanisms 5 years after it was sprayed, and after 10 to 20 years it became ineffective. This process still continues on to this day.

The same trend was found with gypsy worms. In order to make silk it requires a lot of intensive, long labor if you get it from silk worms. So some person decided to come back to his home location and use gypsy moths to do the same thing. Sadly, the population he was breeding escaped and in a few years there was an outbreak of gypsy moths. These gypsy moths started creeping up in bad places such as apple crops and ruining them. Scientists realized that if you sprayed the apple trees with arsenic and lead it was very effective in killing these gypsy moths. But the consequence of this is that now you’re eating apples with lead arsenic in it, which is really unhealthy, as it does not break down into anything and is toxic. This is seen in the soil in Worcester currently. Now farmers have to leave a big chunk of their land free of pesticides, it ranges from 30-50% depending on the crop you’re growing. These big areas that are left untreated will have a good percent of insects that have a decent percentage of insects that are nonresistant

Saturn’s and Jupiter’s Moons

Submitted by robynfarrell on Fri, 04/21/2017 - 12:19

In my physics class the other day my professor had mentioned that Saturn’s and Jupiter’s moons may be habitable. NASA has been watching these moons for quite some time now and shocking new evidence has come into play. They used a mass spectrometer that helped detect an ample amount of hydrogen molecules in the water that sits beneath its icy surface. They think that this hydrogen came from a hydrothermal reaction, which means that methane could be forming in their ocean as well. It reflects a lot like our planet. These moons have a potential of microbes existing and other organisms which can branch of and become a vast amount of species. Most of our species originated from water, so to know that there is capability of species now living in the ocean on their moons, it shows potential for life.

Journal #31 – Toads and Cane Beetles

Submitted by robynfarrell on Fri, 04/21/2017 - 11:34

In my evolution class recently we learned about canes beetle and toads. The plant, Sugar cane was planted in a lot of tropical places around the world and it brought about these beetles that would prey on it. It would be such a heavy infestation that you could see swarms of beetles flying around the sugar cane. For a long time, there wasn’t a good solution to get rid of them, but biologists thought of an organism that would help rid them of this beetle. They used a toad as a biological pesticide that would actually consume these bugs. These toads are originally from South Africa, but they have been established in other places like South Florida, Hawaii, and Australia. They proliferated like crazy in Australia. These toads are capable of eating anything that fits in their mouth, and they were also very hard to be predated on since anything that ate it would die, as they had huge poisonous glands next to their head. What made this toad inefficient for the job they needed for was the fact that they were nocturnal and the cane beetles were diurnal, so they were actually really horrible at reducing the number of beetles infesting on sugar cane. They were great at killing other things, so through that their population started to increase rapidly through the coast of Queensland and there was no way stop them. Now throughout hundreds of years there has been a reduction in their size (of toads), toxicity, and their hind legs have been growing longer in proportion to their shrinkage. This is due to the fact that some of the snakes that feed on the toad. Some of the snakes that feed on this toad have also become increasingly larger, so they can assimilate more of the poison without dying, and their heads have gotten smaller so they can eat smaller toads and get smaller amounts of poison.

Journal #30 - Habitable Moons

Submitted by robynfarrell on Fri, 04/21/2017 - 10:18

In my physics class my professor had mentioned about Saturn’s and Jupiter’s moons maybe being habitable. NASA has been watching these moons for quite some time now and shocking new evidence has come into play. They used a mass spectrometer that helped detect an ample amount of hydrogen molecules in the water that sits beneath its icy surface. They think that this hydrogen came from a hydrothermal reaction, which means that methane could be forming in their ocean as well. It reflects a lot like our planet. These moons have a potential of microbes existing and other organisms which can branch of and become a vast amount of species. Most of our species originated from the water, so to know that there is capability of species now living in the ocean there might be potential for more life.

 

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