Evolution: Darwin And Darwin's Theory Of Evolution

chapter 23 name:mathews.t.varghese class:ap bio;period:01 concept 23.1

Today, we can define evolutionary change on its smallest scale, or microevolution, as change in the genetic makeup of a populations from generation to generations.

Darwin found a mechanism for change in species over time. gregor mendel proposed that parents pass on discrete heritable units. that retain their identities in offspring.

When Mendel’s research was rediscovered in the early 20th century, many geneticists believed that his laws of inheritance conflicted with Darwin’s theory of natural selection.

Darwin emphasized quantitative characters, those that vary along a continuum.

These characters are influenced by multiple loci.

Mendel and later geneticists investigated discrete “either-or” traits.

It was not obvious that there was a genetic basis to quantitative characters.

Within a few decades, geneticists determined that quantitative characters are influenced by multiple genetic loci and that the alleles at each locus follow Mendelian laws of inheritance.

These discoveries helped reconcile Darwin’s and Mendel’s ideas and led to the birth of population genetics, the study of how populations change genetically over time.

A comprehensive theory of evolution, the modern synthesis, took form in the early 1940s.

It integrated discoveries and ideas from paleontology, taxonomy, biogeography, and population genetics.

The first architects of the modern synthesis included statistician R. A. Fisher, who demonstrated the rules by which Mendelian characters are inherited, and biologist J. B. S. Haldane, who explored the rules of natural selection. Later contributors included geneticists Theodosius Dobzhansky and Sewall Wright, biogeogra...

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...deportment, she perpetuates the alleles that caused her to make that cull.

As a mechanism of rapid population magnification, sex is far inferior to asexual reproduction.

The traditional explication for the maintenance of sex was that the process of meiosis and fertilization engender genetic variation on which natural cull can act.

However, the postulation that sex is maintained in spite of its disadvantages because it engenders future adaptation in a variable world is arduous to forfend.

Natural cull acts in the present, favoring individuals here and now that best fit the current, local environment.

Evolution does not scrap ancestral features and build incipient intricate structures or deportment from scratch.

Evolution co-opts subsisting features and acclimates them to incipient situations.

The many imperfections of living organisms are evidence for evolution.