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Rooting the Tree of Life. Natural Selection has been going on since the beginning of life. It is not unique to just any species but it is an evolutionary aspect of adaptation.
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Natural Selection has been going on since the beginning of life. It is not unique to just any species but it is an evolutionary aspect of adaptation. After several scientific investigations, it is believed that all forms of organisms now evolved from earlier forms of organisms dated back to approximately 3.85 billions years ago. “evidence…in the form of gene sequences, fossils, and ancient traces of Earth’s chemistry” enables scientist to rewrite the timeline of history. Rooting the Tree of Life
Tree of Life • Three Main Branches • Eukaryotes • Plants • Fungi • Animals • Single-celled protozoa • Amoebae • Parasites • Dysentery • giardia • Prokaryotes • Microbes Archaea
1970- Carl Woese University of Illinois Biologist found that these simple organisms may look like bacteria, but they have cellular machinery that is radically different. Woese named these microbes archaea, meaning “first” for the branch on which they appear. (103) Most of the diversity of life, not to mention the sheer physical mass, is microbial
In Search of Life’s Origin Chemical Evolution • Many of life’s origin could have came from space. Astronomers discovered a number of basic ingredients of life on meteorites, comets, and interplanetary dusts. • Ingredients from these foreign objects could have seeded the planet w/components for crucial parts of the cell • Phosphate backbone of DNA • Information-bearing bases • Amino acids for making proteins
cont… • Concentrated in raindrops or the spray of ocean waves • Life could have began at the mid ocean ridges where hot magma emerges from the mantle • Bacteria and archaea that live in extreme conditions such as boiling water or acid • Pre biological molecules became organized into cycles of chemicalreactions that could sustain themselves independently
Cont… Biological Evolution • DNA • Capable of carrying information from one generation to another • RNA • Carries information • Produces proteins and amino • Thomas Cech (1982) discovered that RNA can also edit their own code • ENZYMES • Edit useless sequences after DNA is copied into RNA
The Mangrove of Life • Evolution continues to be a story of and about microbes • Possible reasons for evolution of our genetic sequencing and changes • Examination of early bacteria show that bacteria sometimes scoop up its genes and integrate then into their own genomes • Parasites can sometimes inject genetic materials from one hosts to another • Malaria
Evolution on Double Time • Gene Duplication • Create genes that are essential to the functioning of the organism. Those are good for the organism will be duplicated to do new jobs but those that are superfluous will be eradicated because they are not necessary. • Mutations to useless genes that are already in the organism systems are “pseudogenes” • Duplicate Genes can be grouped into families and they reflect a common descendant. • Genes do not simply mutate, they multiply because of duplication and a change in life could have caused a transformation by coming in contact with another organism or it was essential for their function in life due to change.
Fusion Evolution • Bacteria living inside cells and they both benefit each other “symbiosis” • Mitochondria • Respiration: sausage-shaped blobs in our body system that manages the use of oxygen and other chemicals to create fuel for fuel • All eukaryotes has mitochondria • Chloroplast • Captures sunlight in plant to create food for plants in the process of photosynthesis
Cont… • Both Mitochondria and Chloroplast has DNA of their own and duplicate itself within the cells of the organism. • Dalhousie Univ. Novia Scotia (mid 1970) • Carl Woese and W. Ford Doolittle • Found that the DNA in chloroplasts does not resemble the algae’s nucleus. Instead, it is cyanobacteria DNA • (1998-Siv Andersson) Mitochondria is also a relative of Rickettsia prowazekii, a bacteria that causes typhus.
Mitochondria cont… • It is believed that a long-lost oxygen-breathing bacterium , gave rise to the ancestors of both Rickettsia and mitochondria. Both were free-living microbes, feeding on the nutrients that surrounded them. Eventually each lineage began to live inside other organisms. Rickettsia became a ruthless parasite while mitochondria became a helping component in eukaryote organisms.
During the age of the microbes, there were countless number of changes that occurred that create our world today. • It is only after microbes had gone through all of this evolution that our own multi cellular ancestors-the first animal could appear.
Intro to evolution • All animals descended form a common single-celled ancestor, but scientists are still learning how it was that they diversified into so many different bodies • All animals use a standard tool kit of body-building genes • The tool kit must have evolved in the millions of years that preceded the Cambrian explosion
Evolution’s monsters • To learn how animals evolve, biologists make monsters • Flies with legs sprouting from their heads • Spinal cord in a frogs belly • All they have to do is alter a single gene • These genes control the development of animal bodies
The process of creating these “monsters” is called homeosis • This process was first discovered in 1915, when mutant fruit flies were discovered growing extra wings • 1980 biologists figured out how to isolate the gene that is responsible for mutations • These genes are called HOX genes
By altering hox genes, biologists could create mutated flies By doing so, biologists were able to figure out how normal Hox genes work It is the Hox genes job to tell the cells of an embryo (baby) what they are going to become Abdomen or leg Hox genes exert their power by acting like master control switches for other genes A single Hox gene can trigger a chain reaction of many other genes, and together they form a particular part of the body Hox genes are lined up on their chromosome in the same order as they are expressed in the body Head genes in front Tail genes in back Hox genes
When Hox genes were first discovered, biologists thought that they were only in flies Biologists soon began to find that Hox genes are in many other types of animals, from worms to humans The Hox gene does the same job in all of these animals It specifies different sections of the head-to-tail axis The genes are so similar in these animals that they could replace a defective gene from a fly with a mouse gene and it would still grow properly
In the 1980’s and 90’s scientists discovered many other master-control genes at work, just as powerful as Hox genes While hox genes work from head to tail, other genes mark the left and right sides, and others establish top and bottom These genes help build organs Each of these master control genes also exists in our own DNA these genes are able to use the same body-building instructions to build very different kinds of animal bodies This common genetic tool kit is so intricate that it couldn’t have evolved independently… Master Control Genes
Once biologists discovered the genetic tool kit, they realized that it might have made the Cambrian explosion possible The genetic tool kit emerged in the common ancestors of all animals about 535 million years ago Evolution did not build a new network of body building genes from scratch, it simply tinkered with the original genetic tool kit to build different body parts An example of this is our own nervous system: all vertebrae have a nerve cord running down their backs, while heart is on the front; insects have the opposite arrangement The genes behind Cambrian explosion
Vertebrae acquired eyes, complex brains, and skeletons during the Cambrian explosion To figure out how this happened biologists studied our closest living relative, the lancelet Looks like a headless sardine Shares key traits with vertebrae Has slits near the front of its body corresponding to gills Has a nerve cord running along its back It also has precursors to eyes and a brain The dawn of Vertebrates
Hox genes and other genes that map out the vertebrate brain do the same job in the lancelet embryo Once the ancestor of vertebrates and lancelets divided, our ancestors went through an extraordinary evolutionary experience Hox and master-control genes duplicated themselves, forming new body parts and organs Thanks to this, vertebrates could start hunting and growing bigger Big mobile predators appeared on earth for the first time Cont
It has been argued that fish evolved legs and toes to move underwater, not on land One biologists has even found fossils of a separate lineage of fish that evolved fingers independently of our own ancestors Flaws and Fingers • Although were are very well developed were are fundamentally flawed • Eyes: human and squid • Biologists looked back at lancelets to figure out how come vertebrates had this flaw
Evolution borrows things adapted for one function to perform a new one Whales are thought to be descended from mammals that lived on land A paleontologist found the first fossil of a land whale in 1979 Cows and hippos are their closest ancestors Although whales went through lots of evolution, they had limits They didn’t change until after the dinosaurs were gone Ever since then, all types of mammals have dominated the land and sea This domination only happened because millions of other species disappeared Cont…and whales
Extinctions • Suspects behind extinctions include volcanoes, asteroids, and sudden changes to the oceans and the atmosphere • Extinctions divide Earth’s history into three great eras: the Paleozoic, “ancient life”, the Mesozoic, “middle life”, and the Cenozoic, “early life”. • Extinctions have destroyed as much as 90 percent of all species at one time.
Permian-Triassic Extinction • Evidence of the Permian-Triassic extinction can be found in the mountains of the Karroo Desert in South Africa. • This extinction destroyed 90 percent of all species living on Earth around 250 million years ago. • The Permian-Triassic extinction was the biggest mass extinction that was ever recorded.
Permian-Triassic Extinction cont’d • Before the extinction hulky reptilian creatures, called synapsids, were the dominant inhabitants of the Karroo Desert. • The mass extinction destroyed almost all species of trees on Earth, along with most of the smaller plants. • Insects, which had not succumbed to any other mass extinction in their history, disappeared in great numbers.
Krakatau • Krakatau was an island in the Sunda Strait whose volcano erupted in 1883. • During the eruption: a column of ash rose 20 miles, mud rained down, clouds of vaporized rocks flew at 300 mph away from the island and incinerated thousands of people. • The eruption caused tsunamis around the world. • The ash from the eruption turned sunsets bloodred, making everything look like it was on fire.
Krakatau cont’d • The eruption killed every living plant and animal on Krakatau. • After a few years life began to return to the island, starting with ferns, mosses, a few beach plants, and spiders. • By the 1890s fig and coconut trees were scattered across the island and beetles, butterflies, and a monitor lizard joined them.
Mammals • Only a few synapsids came through the Triassic period, but one that did continued to evolve the equipment for becoming a mammal. • These synapsids, known as cynodonts, evolved rib cages to house diaphragms, which allowed them to develop more stamina. • The cynodonts developed hair and began to nurse their young. • They had a high metabolism that made it easier for them to grow smaller, until eventually none of the early mammals weighed more than 5 pounds. • Their high metabolism also helped them fill a niche left empty by their cold-blooded counterparts, they became able to hunt at night.
Monotremes Oldest lineage of mammals still alive today. They have less control over their body temperatures. Female monotremes lay eggs instead of having a live birth. Example: the platypus. Mammals cont’d Placental mammals • Placental mammals keep their babies in the uterus until they are very developed. • They have a placenta that surrounds the embryo and gives the baby nutrients. • They branched off from the other mammals somewhere between 100 and 65 million years ago. • Example: the rabbit.
K-T Extinction • The K-T Extinction occurred at the end of the Cretaceous period, around 65 million years ago. • This was when the dinosaurs disappeared along with 70 percent of all species. • In the Bottaccione Gorge, in Italy, there are rocks that are from the Cretaceous period and the Paleocene period, but between these two rocks there is a half-inch wide strip of clay which marks the K-T extinction. • This strip does not contain any fossils of the plankton that can be found below it or above it.
K-T Extinction cont’d • American geologist Walter Alvarez and his father Luis tried to identify the clay’s time period by measuring the iridium levels but they found that the rate was 30 times that which was found both above and below the strip of clay. • Because iridium usually came from space the Alvarez duo speculated that the huge dose of iridium at the end of the Cretaceous period must have come from a giant asteroid hitting the earth. • This asteroid’s debris combined with the terrestrial rock its crater gouged out flew into the air and created a dark shroud around the planet. The dark cloud blocked out the sun, which killed the plants, starving the herbivores, with the carnivores disappearing afterwards. This was the K-T extinction.
Ice Ages • While mammals have been the dominant land vertebrates for the past 65 million years, they have had to go through their own changes. • The climate was a lot warmer between 65 and 55 million years ago, so warm that palm trees could grow north of the Arctic Circle and Canada resembled Costa Rica today. • After that the world’s average temperature has been dropping, and it is partly the Himalayas fault. When they were first created, the rains that fell on the Himalayas carried dissolved carbon dioxide which the Himalayas removed from the atmosphere. They removes so much that the climate gradually cooled.
Ice Ages cont’d • Antarctica moved further south until it reached the South Pole. Permanent ice began to form on it and the ice reflected the sun back into space and cooled the atmosphere. • While South America and North America joined together, after their 60 million year separation, The Great American Interchange occurred. The Interchange came from the different species of animals that migrated from one continent to another. • At the time of the Interchange, the global climate found a new pattern. The ice at the poles moved outward towards the equator and then pulled back in a series of ice ages. • These ice ages were controlled by the changing orbit of Earth around the sun. The earth moves closer and farther away from the sun in its 100,000 year cycle. These changes alter how much sunlight the earth receives and this alters the climate and results in ice ages.
The First Waves • The latest mass extinctions began around 50,000 years • It was from the latest mass extinction that humans arrived • The oldest evidence of humans comes from Chile dated 14,700 years ago • Humans did their part to wipe out the huge animals that they coexisted with all around the globe • Human caused extinctions served as catalysts for changing the environment of the planet
History in a Hole • Holes in the ground can do wonders as a time machine • Caves preserve bones, and lakes preserve pollen from plants • Hawaii’s isolation, like the Galapagos provides a great place for study • The arrival of Captain Cook in Hawaii caused a mass extinction of native plants and animals
Extinctions Accelerate • Humans seem to be major catalysts for animals extinctions • Civilizations that began to appear 10,000 years ago caused environmental destruction • Deforestation, and land exploitation for crops destroyed many species • Extinctions proceed based on a half-life many times, in which during a period of time 50% of the species will die, and then the remaining 50% will die in the second period
Alien Invasion • Extinctions are sped up by biological invaders, which are new species that are introduced to a new environment • Biological invasions were rare before humans • Biological invaders killed much faster than even the humans did • Some biological invaders benefit more from their introduced environment, because they don’t suffer from normal predators
The Future of Extinctions • We seem to be entering an era of mass extinction on par with the die-offs of 600 million years ago • Species are disappearing 100 to 1,000 times faster today than before the arrival of humans • Global Warming also stands to substantially alter the worlds climate
Humanity Leaves its Mark • The next few centuries could see the largest number of animals lost ever, well over half of all species • Human can alter the course of biodiversity • Over 90% of the world’s agriculture is based on 20 species of plants and 6 species of animals • Humans may not survive if ecosystems that we rely on collapse due to lack of biodiversity
In Conclusion • Darwin is wrong and there is no theory of evolution, there is just a list of animals that Chuck Norris lets live…
