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when and why poeple started explaining things by evolution
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It changed in 17th century - due to development of knowledge, possibility of traveling to foreign lands
example of structural smiliarities between species
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five digits on each had and foot in primates; why do we walk on two legs etc
geology in evolution
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Bones from older geological strata differ from those in more recent strata -> change in organic structure over time
emryology in evolution
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Similarities in embryological development development across different species, even dissimilar ones
Lamarck
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18-19th century; He noticed that species aren't static, that there are some similarities in species
2 major causes of species change in lamarck's theory
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1. Natural tendency for each species to progress toward a higher form 2. Inheritance of acquired characteristc (black will have black child)
Lamarck's mechanism for change:
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Believed animals must struggle to survive, leading to the secretion of fluid by nerves. This fluid was thought to enlarge the organs involved in the struggle
Darwin
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He developed the theory of evolution, proposing that all living things share a common ancestor and change through natural selection
Darwin figured out that giraffe's neck became longer because those with longer necks survived better. So there were no fluids, just genetics
NATURAL SELECTION
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THE DIFFERENTIAL SURVIAL AND REPRODUCTION OF INDYVIDUALS DUE TO DIFFERENCES IN PHENOTYPE
Favourable variations persist, unfavorable ones decline. Repeated over generations, this process lead to the development of new adaptations
• 3 essential concepts: (so that natural selection could exist, there need to be):
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1. Variation 2. Inheritance 3. Differential reproductive success
Variation
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Diversity of traits within population
Inheritance
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The transmission of certain traits from parents to offspring
Differential reproductive success
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a. The uneven ability of individuals with specific traits to survive and produce offspring, influencing evolutionary change
Sexual dismophism
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sometimes sexes differ significantly in size and structure
Sexual selection
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the preference by one sex for certain characteristics in individuals of the other sex
Two primary means by which sexual selection operates:
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1. Intersexual selection 2. Intersexual competition
Intersexual selection
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one sex displays a certain trait or behaviour with the goal of attracting and mating with the opposite sex (mantis)
Intersexual competition
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occurs between members of the same sex. They compete for the opportunity to mate with the opposite sex (lions)
Genetic drift
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random changes facilitated by processes like mutations, founder effect, genetic bottlenecks
Mutations
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random hereditary changes in DNA
Founder effect
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A small population establishes a new colony, and the genetic makeup of the founders differs from the original population (chitas)
Genetic bottlenecks
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Population shrinkage due to random events like earthquakes, results in survivors carrying only a subset of the original population's genes

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