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pass its successful genes down to other generations. Unsuccessful ones mutate, which can be either a disadvantage or advantage. THREE EXAMPLES OF EVOLUTION: DARWIN DISCOVERED THE VARIOUS FINCHES: PEPPERED MOTHS EVOLVED TO SUIT TIMES OF MASS POLLUTION; AND FLIGHTLESS BIRDS ALL DESCENDED FROM FLYING BIRDS TOO! Darwin's Finches Darwin based and formed a lot of his research, from the Galápagos Islands. 13 different finches were brought back from the islands, to England, after one of his expeditions. After observing them, he realised they were all different species, discovering variations in their beaks, intelligence, colours, and diet. Most variations had seemed to depend on habitat and environment. Here are some factors to each variation: - Beaks: Top overhang on beaks to clutch insects, sharper beaks to pierce insects or chop vegetation (or for getting into cacti), large and strong beaks to crack seeds and nuts, smaller beaks for smaller seeds. - Colours: Darker to blend in with the tree bark, lighter for blending in with the ground, etc... - Intelligence: Some finches used sticks to pick up larvae to eat, from small gaps, etc... - Diet: One finch may eat insects because that is what is readily available to them, another may eat vegetation, as that is what is found in their location. PEPPERED MOTHS 0 Peppered moths were extremely pale, and lightly coloured before the Industrial Revolution, so as to blend in and disguise from predators. However, post-revolution, they gained a mutation that allowed them to become darker - this was to blend in with the soot-engulfed environment. Due to this, the dark moths could avoid predators, whereas light moths were in decline after being eaten. Over the course of a few years, the population gradually became dark - noticeably though, their light colour was returned after the pollution decreased. FLIGHTLESS BIRDS Flightless birds (such as penguins, emus, and ostriches) all descended from ancestors that could easily fly. Over generations, ostriches and emus, evolved to have large bodies and feet, that were needed to run on land. This left them inable to fly, as it wasn't necessary. Penguins also adapted to sacrifice their typical wings, for flippers to swim. PEACOCKS AND SEXUAL SELECTION HOW DID PEACOCKS EVOLVE, AND HOW DID DARWIN INCORPORATE THIS INTO HIS THEORIES? CASE STUDY/FACT FILE Peacock Evolution 1) Many male peacocks used to be essentially dull, and colourless. 2) Male peacocks use their vibrant, exotic colours to attract females, but as a result of their prior lack of colour, females remained uninterested. 3) The bland males eventually die of natural causes, but without any offspring or descendant, the population is rapidly decreasing. 4) Females instead mate with the other variant of male peacocks: the colourful ones, as they are better attracted to them. 5) As the females mate with the coloured peacocks, the mutation and genes of the enticing, vibrant feathers is passed down to the offspring. 6) The population is eventually restored and increased, with more males being born with the colourful feathers. DARWIN'S THEORY 0 Darwin was plagued by the peacock and it's feathers - he simply could not understand how it related to his theory of evolution, in April 1860, he even wrote "Just the sight of a feather makes me sick!". He felt it represented a flaw in his theory, as the feathers were not exactly useful in the environment. However, sexual selection was of strategic importance to Darwin, as it could explain what his theory of natural selection could not. Natural selection was a "struggle for survival", whereas sexual selection was "a struggle for mate", as it was attributed to the desire for appearance. This was portrayed in peacocks, as the female was only attracted to the vibrant, and exotic-feathered males. As animals evolved on the basis of natural selection, some also evolved due to sexual selection. EVIDENCE AND PEER REVIEW EVOLUTION AND NATURAL SELECTION ARE TWO OF DARWIN'S FAMOUS THEORIES, THAT HAVE INFLUENCED THE WORLD AND SOCIETY'S CORE BELIEFS, BUT WHAT ARE THEY? Evidence A There is a lot of evidence to support Darwin's theory, but here are some predominant pieces: - Fossils: Fossils are physical records of extinct species, which can prove survival of the fittest. Skeletons also provide insight on old variations of species, and their previous adaptations, before their further evolution. However, few organisms fossilise, they can be damaged, and there are some gaps in fossil records. រ Extinction: Species die out due to natural selection. Anti-biotic Resistance: Over generations, species gradually become immune from disease, as their immune systems evolve. -DNA and Genetic Evidence Gene sequences are similar between many species, due to sharing one common ancestor - Animal Embryos Embryos have developed over time, with evolution. ☐ PEER REVIEW 0 Peer review in science, is when multiple scientists may discover something, or formulate the same theory individually. This can strengthen a theory with shared, uncommon, pieces of information from each scientist, or thoroughly validate it off of various perspectives. E.G. By adding to the theory, and analysing weaknesses and strengths. This applies to Darwin, as another scientist - Wallace - was creating his own document in the theory of evolution as well. Both of them read each other's unpublished work, and since their ideas were so similar, they ended up jointly publishing the theory of evolution in a scientific paper. DARWIN VS LAMARCK Lamarck's Theory Jean Baptiste Lamarck, was one of the other famed evolutionists. However, Lamarck's theories we're significantly different to Darwin's though, as predominant things he believed, were: - Organisms evolved in a continuous upwards direction, from dead matter, to simple, and then complex forms. Essentially, they are adapted into "human perfection". He also believed that species could not go extinct, they just "turned into another species". This contrasts to Darwin, as he has stated that life cannot die out, and mutated genes cannot be a disadvantage (they always have to be beneficial). - According to his theory, since simple organisms exist alongside "advanced" animals today, Lamarck thought they were continually created by spontaneous generation (not random variation and natural selection, like Darwin). - Lamarck had other "odd" beliefs though, as he said, organisms altered their behaviour in response to environmental condition. Their changed behaviour, in consequence, modified their organs, and their offspring inherited those "improved" structures. For example, giraffes developed their elongated necks and front legs, by generations of reaching for high tree leaves. The exercise of stretching up to the leaves altered the neck and legs, and their offspring inherited these adapted characteristics. - In Lamarck's theory, a structure/organ would shrink or "disappear" if used amply or not at all. Motivated by these heritable modifications, all organisms would become adapted to their environments, as its conditions changed. - Lamarck maintained that evolution was a constant process of striving toward a greater complexity and "perfection". Whereas, Darwin believed that it was for survival purposes, and not all of the species would be able to adapt like this, and would die out (become extinct).