Evidence of Evolution

Evidence of Evolution

1. Embrological

   • definition
     • Embryology is the branch of biology that studies the development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology is the study of congenital disorders that occur before birth
   • evidence
     • Embryos from many different kinds of animals: mammals, birds, reptiles, fish, etc. look very similar but still differ in small ways. This can prove evolution from the earliest embryos in the earliest species to embryos now
       • examples
         • vertebrate embryo and tunicate larvae
           • invertebrates known as tunicates or sea squirts, develop the same kind of stiff rod, known as a notochord, that vertebrates form in their back as embryos. In vertebrates the notochord curls into the disks between the vertebrae.
             • Researchers determined that a sea-squirt-like animals might have been the ancestor of vertebrates.
               • Recent DNA studies show that sea squirts are in fact the closest known invertebrate relatives of vertebrates
         • chick and reptile embryos
           • the chick embryo may resemble the embryos of reptiles and fish at points in its development
         • chicken embryo to human embryo
           • both chick and human embryos both end up in a stage in which they have slits and arches in their necks like the gill slits similar to the embryo of the fish. These structures are not gills and do not develop into gills in chicks and humans, but they are so similar to gill structures in fish that it supports the idea that chicks and humans share a common ancestor with fish.

2. Fossils

   • evidence
     • The fossil record provides snapshots of the past that, when assembled, illustrate a panorama of evolutionary change over the past four billion years. Fossil evidence clearly shows that life has changed over time.
       • examples
         • sea sponges
           • tiny sea sponges were abundant 635 million years ago, before most of the planet's other major animal groups evolved.
             • Sponges have pores that allow nutrient-rich water to pass through them. They feed by filtering out tiny particles of organic matter that consumes oxygen as it rots. By removing rotting, organic matter from the oceans 600 million years ago, sponges allowed oxygen to thrive. A more oxygen-rich ocean environment allowed larger and more mobile animals to evolve including the first predatory animals and marked the emergence of a modern marine biosphere.
         • Onychonycteris finneryi (Bats)
           • said to be a missing link between modern bats and their flightless ancestors
         • Laia
           • Laia shows the first evidence that present-day apes descended from a relatively small, common ancestor Laia’s discovery also shows for the first time that ancient, small-bodied apes moved from Africa to Europe
             • researchers say that Laia might be an ancestor of gibbons and siamangs, which split from greater apes about 14 million years ago
   • definition
     • the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock

3. Anatomy

   • definition
     • The branch of science concerned with the bodily structure of humans, animals, and other living organisms, especially as revealed by dissection and the separation of parts
   • evidence
     • Comparative anatomy is related to evolutionary biology and phylogeny in which it has evidence for evolution as it shows that various organisms share a common ancestor through bone structure
       • examples
         • structure of reptiles and fish
           • Homologies of the jaws and gill arches as seen in the skull of the Paleozoic shark and the lateral view of an alligator skull are very similar. The articular portion of the lower jaw is similar with the quadrate bone of the skull.
         • loss of limbs­
           • Many animals, like pigs, cattle, deer, and dogs have reduced, nonfunctional digits. The foot of the pig has lost digit 1 completely, digits 2 and 5 have been greatly reduced, and only digits 3 and 4 support the body. Evolution best explains such vestigial features. They are the remnants of ancestors with a larger number of functional digits.
         • Vestigial structures
           • Many organisms contain body parts that have no use. These parts are like fossils and can help scientist understand the past forms of species. Vestigial structures are usually parts that were used by past forms, but through adaptations the body part is no longer needed for survival. By looking at these structures scientist are able to link organisms to similar ancestors.
             • here are some vestigial structures from a gorilla to a human

4. Biogeography

   • definition
     • Biogeography is the study of the distribution of species and ecosystems in geographic space and through (geological) time.
   • evidence
     • The pattern of organisms around the globe, the absence of some species from environments that would suit them, and closer relationships between species that are geographically near each other than between species that inhabit similar environments shows evidence of the evolutionary origin of biodiversity.
       • examples
         • polar bears
           • Studies show that polar bears split from a common brown bear ancestor 350,000-6 million years ago. After beginning to branch off from brown bears, the polar bear's ancestors underwent a series of evolutionary changes in order to survive in the Arctic. The bears adapted to a life of hunting seals and surviving extreme cold. Another adaptation was the ability to live on a fat-rich diet without apparent heart damage.
         • armadillos
           • The first nine-banded armadillo was seen in the United States in 1849. Prior to that, the nine-banded armadillo had been recorded to be seen as far back as the 4th and 14th centuries by native hunters in Mexico. Researchers think that the nine-banded armadillos could have evolved or replaced the extinct species Dasypus bellus, because they are similar, but bigger in size.
             • After the Panamanian strip of land submerged from the sea, two and a half million years ago, it is thought to have been the corridor for these prehistoric armadillos to migrate to Florida . The nine- banded armadillos that remain today are thought to be descendents of a pair that escaped from a small zoo about fifty years ago in Cocoa, Florida. But there is an event recorded of a nine-banded armadillo being introduced to Florida prior to the two that had escaped.
         • Bobcats (lynx rufus)
           • The bobcat has a short tail of only one to two inches, the bobcat’s coat is a gray-brown color that evolved in parts of the U.S., and a red-brown color that evolved in the dense forest habitats of the Pacific North West and Western Canada. The bobcat’s northern cousin, Lynx canadensis (Canadian lynx), has bigger feet and longer legs, characteristics that are key to the northern boundary of the distribution of Lynx rufus.

5. Molecular

   • evidence
     • All organisms on Earth are composed of the same building blocks: DNA, RNA, and proteins. DNA and RNA are composed of specific sequences of nucleic acids that are inherited through generations. Protein is composed of specific sequences of amino acids encoded by the sequence of nucleic acids in RNA.
       • examples
         • The genetic code for protein­ coding genes is nearly universal in all prokaryotic and eukaryotic organisms.
           • The genetic codes for all organisms are homologous even though alternative genetic codes exist. All organisms had a common ancestor with a similar genetic code that passed it down, parent to offspring. Over the ages the genetic code slightly varies between different species, but essentially remains the same.
         • Organisms that contain traits capable of surviving changes in the environment at that point of time are most likely to survive and reproduce.
           • Next generation will contain this characteristic along with the similar traits of the parents. Overtime, new varieties and species will have emerged due to this process.
         • Homologies:
           • Pentadactyl limb = 5 digit homologous structure. All four legged organisms(tetrapods) have limbs with 5 digits at some point in development(Humans, Whale, Bat). Some tetrapods lose these digits during development. If a 5 digit limb is not needed why do all tetrapods still have them? This genetic structure is inherited from ancestors.
   • definition
     • Molecular biology concerns the molecular basis of biological activity between biomolecules in the various systems of a cell, including the interactions between DNA, RNA and proteins and their biosynthesis, as well as the regulation of these interactions

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