Evolution, Fossils & Extinction
Norman MacLeod School of Earth Sciences & Engineering, Nanjing University Evolution, Fossils & Extinction
Objectives
Evolution - understand what evolution is, how it comes about, and the process of adaptation What is evolution? Types of evolution The genetic revolution Adaptation
Fossils - understand what fossils are and what they can be used for What is a fossil? Types of fossils Uses of fossils Extinction as a driver of evolution - understand how extinction is linked to evolution Evolution
A Contemporary Phylogeny of Life on Earth Evolution
What is Evolution?
Biston betularia Biston betularia f. carbonaria
Evolution is the change in the inherited characteristics of an organism through successive generations. That evolution has taken place within the histories of all known species is one of the most well-corroborated facts of science. However, the natural processes that cause evolutionary change remain subjects of controversy and active research. Discovery of Evolution
Classical Antiquity
Aristotle’s Great Chain of Being was Man influential in several respects. It Mammals assumed the fixity of species and Birds was compatible with both the Fish Christian religious doctrine and the theory of spontaneous generation. Eels Importantly, the nodes along the Reptiles chain were conceived a perfect Molluscs representations of the Creators sequence of type (= archetypes). Aristotle Worms (384 – 322 BC) Actual species are imperfect copies Corals of these archetypes generated Trees through the action of the Shrubs environment. Thus, actual cats were regarded as degenerate forms of the Mold cat archetype. Minerals Discovery of Evolution
The Enlightenment
French mathematician and philosopher who proposed one of the first theories of genetic evolution: pangenesis. Pangenesis is the theory that particles from both the mother and father are responsible for the characteristics of the child. He also held that modifications to individuals that occur during reproduction can accumulate over many generations and, eventually, lead to the production of new species. Maupertuis did not specify what the “particles” referred to by pangenesis actually are, or what produces the modifications in individuals during reproduction. But Pierre Louis Maupertuis both these statements were adopted as core (1698 – 1759) components Darwin’s theory of evolution via natural selection and later into the Synthetic Theory of Evolution. Discovery of Evolution
The Enlightenment
French naturalist, botanist and zoologist who proposed the first comprehensive theory of how orgamnismal evolution comes about. Lamarck was not the first to propose soft inheritance (= inheritance of acquired characteristics). His theory has two parts. 1. existence of a “complexifying force” that drove species up Aristotle’s Chain of Being; 2. an environmental force that adapted species to local environments through the mechanism of “use-disuse”. Lamarck denied the existence of extinction because he Jean-Baptist Lamarck thought species were driven to increase their (1724 – 1829) complexity (and so change their morphology) by the complexifying force. Currently there is some debate regarding whether transgenerational epigenetics has “proved” Lamarck right, but this is due to a lack of understanding of the history of evolutionary theory. Evolution
Lamarckism
Origin via Spontaneous Generation
5 4 3 Time 2 CoBGrades 1 Discovery of Evolution
The Scientific Revolution
British naturalist, geologist and biologist who laid the foundations for the acceptance of organismal evolution as a fact and the modern theory of how evolution takes place. In his book On the Origin of Species (1859) Darwin reviewed copies evidence demonstrating high organised correspondences and differences among organisms and argues that these were the result of descent from ancestral forms. According to Darwin, this descent occurred via the mechanism of Maupertuis’ pangenesis and variation between generations occurred as a population-level phenomenon via natural Charles Darwin selection, in which individuals whose slight variation (1809 – 1882) from others gave them an advantage in coping with their environment produced more offspring which exhibited those same advantageous traits. Evolution
Darwinism
Unlike Lamarckism, natural selection posits that individ- uals will compete with each other, and with other species, for environmental resources with those individ- uals that lose this competition being reduced in numbers over time, ultimately to the point of their extinction. One prediction of natural selection is that there should be many more extinct, relative to extant, species. Discovery of Evolution
Darwinism
Danaus plexippus Limeitis archippus (Monarch Butterfly) (Viceroy Butterfly)
English naturalist and explorer who provided convincing scientific proof of organismal Henry Walter Bates (1825 – 1892) adaptation with his study of mimicry in butterflies. Batesian mimicry involves convergent evolution of a palatable species on the morphology of an unpalatable species in order to avoid predation and is regarded as a classic example of evolution by natural selection. Discovery of Evolution
Genetics
Czech theologian and naturalist who discovered the principles of genetic inheritance by Gregor Mendel conducting carefully documented and controlled (1822 – 1884) experiments with peal plants. These involved forcing plants that produced different varieties of peas to reproduce and counting the varieties of offspring the reproduction (or cross) produced. Discovery of Evolution
Genetics
Law of Segregation - during gamete formation the alleles of each gene segregate so that each Gregor Mendel gamete carries only one allele. (1822 – 1884) Law of Independent Assortment - Genes of different traits segregate independently during gamete formation. Law of Dominance - Some alleles are dominant in terms of their expression over others. Discovery of Evolution
Genetics
Drosophila individuals that differ terms of eye color and wing form
Thomas Hunt Morgan Sex-linked inheritance of eye (1866 – 1945) color in Drosophila
American geneticist and embryologist who found Mendelian and non-Mendelian patterns of inheritance in the fly Drosophila, demonstrated location of genes on chromosomes, verified the mechanism of independent assortment, discovered sex-linked inheritance and devised a procedure whereby the locations of genes on chromosomes could be discovered. As a result of these advances, Morgan and his students made studying Drosophila it became the preferred experimental organism for genetic studies. Evolution, Fossils & Extinction
Norman MacLeod School of Earth Sciences & Engineering, Nanjing University