Evolutionary Biology Midterm 1

Front 1

Describe two schools of thought (creationism, evolutionary biology) related to the nature of life

Back 1

The evolutionary school of thought believes that living organisms change over time based on natural selection, while the creationists believe that God put unique organisms, including humans, on earth which have gone unchanged.

Front 2

Describe the concept of biological evolution

Back 2

change through time in living organisms

Front 3

Outline the history of pre-Darwin evolutionary thought

Back 3

Anaximander Humans were 1st formed as fishes (notion of progression from fish to human) Xenophanes
Fossils embedded in rocks were remains of living animals (& therefore exposed underwater fossils tell us that water used to cover that portion of the planet)
Empedocles Abiogenesis (spontaneous generation), body parts sprang from the earth & join sporadically: only by chance were organisms formed & survived (others were freaks & didn’t survive to populate the earth) 1st instance of survival of the fittest Plato Essentialism: organisms are immutable and therefore didn’t change over time But knew that individuals were different in looks and that there was a perfect individuals (and therefore there are accidental variations) 1st instance of variation Aristotle Scala naturae (ladder of nature): made a gradation of nature from simple things (primitive/ancestral/basal & inorganic) to more complex things (derived & organic) 3 steps in organic matter Plants: arose from inorganics Plant-Animals: like jellyfish, sea sponges, & anemones Animals: movement, feeling, & sensitivity Branching/ladder of lowest forms to humans at the top John Ray Biological definition of “species” = one species springs from the seed of another (therefore species are distinct form one another) BUT seeds could degenerate from parent type which leads to variation and give rise to new species Recognized the immutability of species Carolus Linnaeus (Carl von Linne) Systema naturae (binomial nomenclature) Noted for taxonomy for plants, system used to classify the organism Genus followed by 2 specifics in 2 words Recognized variation, but thought species were from a grand design (creator) Dennis Diderot Believed in prototype individuals where all living things descended, results of changes in life as a result of organisms needing a different change
Individuals acquired differences because of needs which could be transmitted to offspring
Erasmus Darwin (C. Darwins’s grandfather) Modification to satisfy “wants” (something they lusted for or wanted to eat), so then they could aquire differences and pass the modification on to offspring Jean-Baptiste Lamarck Philosophie Zoologique (1809)
He said there was no difference between species and variety but species could grade into another (notion of evolution) which is called transformism (species over a long period of time from other species) Developed branching lines for animal kingdom (1st branching family tree) Genealogy of family and called it a scale of being, the last branch was humans 2 modes of action in evolution Transformism: tendency for perfection & complexity (simple critters to perfect humans) Evolution resulted because of needs of animals (like giraffe) Inheritance of acquired characteristics: giraffes reach for leaves and pass on their stretching necks to future generations Organs persist only as long as they are used Chain of Being: more complex beings originated spontaneously farther back in time than the ess complex beings Georges Cuvier Catastophism believer Had public debates with Lamarck He suggested dramatic Earthly events were responsible for new life forms periodically (volcanoes, hurricanes, earthquakes) Thomas Malthus Essay on Population (1789): “struggle for existence” When resources deplete, the population will not be able to sustain itlsef (population will outstrip food supply): Therefore they must struggle to exist! William Paley Natural Theology (1802) Catalogued adaptations

Front 4

Describe the geological philosophies of de Maillet, Leclerc (Buffon), Werner, Cuvier, Hutton, Smith, and Lyell as they relate to evolution

Back 4

Early Uniformitarians De Maillet Telliamed (1748) Linked cosmic evolution and geologic events to biological evolution (thought it occurred very long ago) Notion of fossils and extinction Layers and sheets of rock, proposed water had covered the Earth at one point, but when the sun got closer it evaporated Believed in transformation from life at sea to life on land Thought birds came from flying fishes and connected other seemingly logical conclusions George Louis Leclerc, Comte de Buffon (Buffon) Histoire Naturelle (1749) Thought it took a long time for modern earth to form Thought in 70,000 the life on earth would be extinct because the Earth’s surface was cooling Recognized variation and extinction of species Book was disorganized, but mentioned struggle for species to exist Catastrophists Abraham Werner Neptunist hypothesis Neptune (god of sea), thought sea had once covered Earth, then rocks precipitated out and trapped fossils BUT fossils were created by “creator” or “divine” Georges Cuvier Finalism Assumed series of creation of species from geologic processes & catastrophes (earthquakes & floods etc), so creation was completed with humans Ultimately aimed at human creation Uniforitarianism James Hutton Proposed dynamic geological forces created tensions which uplifted the land from the sea Exposed rock/land continued to erode over time (no universal/biblical flood) Uniformitarians = Earth is very old and processes from long ago are the same ones as today William “Strata” Smith Stratigraphy Proposed strata could be identified by the fossils it contained Lower strata was older than higher layers See that life had change over time, through fossils Charles Lyell Principles of Geology (1830) Notion that current geologic events have been going on for a long time Produced a time scale because of the time it took to form geology “Struggle for Existence” among organisms Healthier plants beating out unhealthy plants Suggested fossil record had gaps and was imperfect Said Earth was old, but humans were recent

Front 5

Describe the significance of de Maillet's Telliamed

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de Maillet’s Telliamed is significant because it argued that the Biblical chronology could not possibly be correct, and thus influenced scientists for hundreds of years. He linked cosmic evolution and geologic events to biological evolution. He introduced the notion of fossils & extinction. He observed layers and sheets of rock and proposed water had covered the Earth at one point but when the sun got closer, it started to evaporate. He believed in transformation from life at sea to life on land. He thought birds come from flying fishes and other seemingly logical conclusions.

Front 6

Explain the significance of catastrophism and uniformitarianism to the notion of evolution

Back 6

Catastrophism The idea that Earth has been affected by sudden, short-lived, violent events (such as earthquakes, volcanic eruptions, or floods) that were sometimes worldwide in scope Believed that God was directly involved in determining the history of Earth. Catastrophism of the nineteenth and early twentieth centuries was closely tied to religion and catastrophic origins were considered miraculous rather than natural events George Cuvier Uniformitarianism The assumption that the natural processes operating in the past are the same as those that can be observed operating in the present The same geologic process in the past continue to operate today Didn’t parallel the prevailing religious beliefs of the time James Hutton & Charles Lyell

Front 7

Describe the principle of stratigraphy as first postulated by Smith

Back 7

Stratigraphy is a geological method of relative dating of rock layers, and hence the fossils they contain, by placing rock layers in chronological sequence from oldest to youngest, bottom to top.

Front 8

Indicate the special importance of Lyell to Charles Darwin

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Darwin was reading Lynell on the Beagle In geology Darwin was very much Lyell's disciple, and brought back observations and his own original theorising, including ideas about the formation of atolls, which supported Lyell's uniformitarianism Sailed to Australia and made observations on attols (coral that incorporates a body of fresh water & and island) Tested other theories of geological formations Studied fossils in the strata Volcanic activity, earthquakes contributed to the elevation of land & land formation Notion of length of time for mineral s to deposit on earther (thicker strata = longer time for minerals to deposit) Developed theory on formation of coral reefs (The Structure and Distribution of Corals, 1842)

Front 9

Summarize Charles Darwin's early academic experiences

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Darwin was born on FEBRUARY 12, 1809, into relative economic security. He tried medicine at Edinburgh, but there were no anesthetics and he was squeamish about the main that accompanied operations. His father sent him to Cambridge for a career in the church but Darwin was not interested. He was a mediocre student but a Reverend, and professor of botany, encouraged Darwin’s long-standing interest in natural history. He took geology excursions, collected biological specimens, and upon graduation joined as a de facto naturalist upon the government ship HMS Beagle at the chagrin of his father, who wanted him to join the ministry. He spent 5 years on the ship, collecting several tortoises, birds and plant species. He arrived back in England in October 1836 and sorted his collection, impressed especially with the ones from Galapagos.

Front 10

Recount how Darwin acquired the post of "naturalist" on the H.M.S. Beagle

Back 10

Recount how Darwin acquired the post of “naturalist” on the H.M.S. Beagle Invited by Robert Fitzroy in August 1831 to become “naturalist” on the Beagle (its 3rd voyage) and he needed a dinner companion/naturalist Originally rejected him based upon physiognomy (shape of the face)

Front 11

Summarize some of the geological and biological results of the voyage of The Beagle

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Darwin realized that not only birds, but also plant and tortoise varieties, were distinct. Geographically isolated on the Galapagos, these organisms were derivatives of ancestral stocks but now distinct island species of their own. He compared this to the Cape Verde Islands off the coast of Africa, which were also of similar soil and climate. This forced Darwin to consider whether they were uniquely created by God or whether they had somehow evolved and adapted to the different islands. Darwin then realized that if animals, like humans, outstripped food resources, then competition for those scarce resources would result. Those with favorable adaptations would fare best, and new species incorporating these favored adaptations would arise.

Front 12

Describe 3 stages in the development of Darwin's thoughts on evolution after the voyage of the Beagle

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Theory of evolution and natural selection completed by 1838 Wrote full account of theory in Essay on Species (1844) Composed On the Origin of Species by Means of Natural Selection of the Preservation of Favored Races in the Struggle for Life (1859)

Front 13

Outline the principles of natural selection as put forth in Darwin's Essay on Species of 1844

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1. Organisms have potential rate of reproduction higher than rate of increase of their food supply.
2. Number of individuals in a species remains more or less constant.
3. Thus, high rate of mortality occurs—many more young are produced than ever reach maturity.
4. Individuals in a species are not identical but show variation.
5. Therefore, some variants will succeed better than others in competition for survival, and parents of each successive generation will be naturally selected from among those that are most prolific in offspring because they show variation in direction of more effective adaptation to conditions of their environment.
6. Hereditary resemblance between parents and offspring is a fact.
7. Therefore, offspring of each generation will include individuals that maintain and improve on degree of adaptation realizd by their parents, and ultimately depart further from original type until new forms are no longer fertile with old and then constitute a new species.

Front 14

Indicate the significance of Alfred Russel Wallace to evolutionary science

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Naturalist in search of rare plants and animals Recalled the book by Thomas Malthus that only the best fitted to the environment will survive (weeding out the less capable and less adapted to the actual conditions, the fittest alone would continue the race) Came up with “survival of the fittest” and “natural selection” terminology Joint paper with Darwin was read before the Linnaean Society in London in July 1858

Front 15

Discuss the reception of The Origin and Darwin's theory of evolution from 1859 to the 1930s

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The controversy was immediate and still lingers even today in some circles. People resented that humans were compared to apes instead of angels. There was much puffing and posturing in the media. People were ignorant and misinformed, yet there were two serious criticisms within scientific circles. One was the question of variation; the other the question of time. As for time, there seemed not enough. At the time, people thought the Earth was only several thousand years old. As for variation, critics pointed to inheritance of variation as a weak point in Darwin’s theory of evolution. The basis of heredity was unknown in his day. Nobody knew that mutations in genes and chromosomes produce new variations.

Front 16

Describe the significance of de Vries' discovery of spontaneous variation (mutation)

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Hugo de Vries recognized spontaneous variations as mutations, but didn’t recognize natural selection (how they are better suited to the environment)

Front 17

Describe the contributions that led to the Modern Synthetic Theory (Modern Synthesis) and the preocesses involved in and propositions offered by this theory

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Modern Synthesis (Modern Synthetic Theory) was first proposed in Fisher’s The Genetical Theory of Natural Selection (1930). It was actual mathematical documentation in support of natural selection. It stated that the ultimate cause for variation is mutation. The theory involves the following processes: a) variability generated by gene & chromosomal mutations, genetic recombination, migration & hybridization. B) chance & natural selection determine course of evolution (i.e. account for genetic changes in population). The theory proposes two things: 1. Gradual evolution results from small genetic changes acted upon by natural selection. 2. Origin of species & taxa (macroevolution) explained by natural selection acting on individuals (microevolution).

Front 18

Distinguish among classification, taxonomy, and systematics

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Classification: assigning organisms to a group Taxonomy: theory & practice of classifying organisms Systematics: science of diversity of life (look at organisms & characteristics to study how they are different from each other)

Front 19

Summarize the rules of taxonomy as the relate to subspecies, species, genera, and higher levels of classification

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Mathematically, a hierarchical taxonomy is a tree structure of classifications for a given set of objects. It is also named Containment hierarchy. At the top of this structure is a single classification, the root node, that applies to all objects. Nodes below this root are more specific classifications that apply to subsets of the total set of classified objects. So for instance, in common schemes of scientific classification of organisms, the root is called "Organism" followed by nodes for the taxonomic ranks: Domain, kingdom, phylum, class, etc. The progress of reasoning proceeds from the general to the more specific.
Linnaean taxonomy is the system most familiar to non-taxonomists. It uses the formal taxonomic ranks (in order) Kingdom, Phylum, Class, Order, Family, Genus, Species. The lower ranks (superfamily to subspecies) are strictly regulated, e.g. by the ICZN for animals, whereas taxonomy at higher ranks is a result of consensus in the scientific community. How researchers arrive at their taxa varies; depending on the available data and resources; methods vary from simple qualitative comparisons for little-documented organisms to elaborate cladistic analyses for well-known groups with abundant DNA sequence data.

In phylogenetic taxonomy, cladistic taxonomy or cladism, organisms are classified into "clades", which are discovered by grouping taxa using derived traits. By using clades as the criteria for separation, cladistic taxonomy, using cladograms, can categorize taxa into unranked groups. The taxonomy is exclusively based on cladistic analysis.

In numerical taxonomy, phenetics or taximetrics, the taxonomy is exclusively based on cluster analysis and neighbor joining to best-fit numerical equations that characterize all measurable quantities of a number of organisms. This method has been largely superseded by the superior cladistic analyses today, except in cases when these are too computationally intensive (a single large-scale cladistic analysis can take months to compute).

Front 20

Define taxon (pl., taxa), phylogeny, homology, monophyly, and classification terms that relate to taxonomic categories

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Taxon: a named group of related organisms Phylogeny: a historical lineage of related organisms Homology: similarity between two or more parts as a consequence of common ancestry (relationships between similarities and differences among organisms that imply evolutionary relationships) Monophyly: species with a common ancestor Taxonomic Characteristics: external and internal morphology (shape) and anatomy, physiology, behavior, cell structure, biochemistry, karyotype (number, size & shapes of chromosomes), haplotype (sequence of nucleotides in DNA) Plesiomorphic: ancestral (hasn’t changed much from ancestors): like 5 fingers per hand Apomorphic: derived (looks different from ancestors) Symplesiomorphic: shared ancestral (share ancestral characteristics with chimps & gorillas in terms of 5 fingers per hand) Synapomorphic: shared derived (between different groups, they all differ from ancestors) Homoplasy: character state (like dorsal fin of fish & blue whales) arising independent of ancestors. Independent species through adaptation, have similar characteristics (because both species must adapt to the same environmental pressures)

Front 21

Describe the process of selecting a particular phylogeny from among alternative hypothetical phylogenies

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The best way to select a phylogeny is the one with the shortest length, fewest base changes, and fewest homoplasies.

Front 22

Discuss the problems in assessment of monophyly posed by homoplasy (convergent evolution [convergence] and evolutionary reversal) of character states

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Evolutionary reversal: change of character states back to ancestral character states Convergent Evolution (Convergence): the pattern of resemblance wherein distantly related species take on similar appearance (possibly due to similar environmental pressures) Parallelism: same as convergence, but between closely related taxa Compare as many characteristics in differing species so that you can understand homoplasy better: to determine plesiomorphic or apomorphic

Front 23

Describe the use of the Law of Parsimony (including the principle of maximum parsimony) in inferring a phylogeny)

Back 23

. In science, parsimony is preference for the least complex explanation for an observation. This is generally regarded as good when judging hypotheses. Occam's razor also states the "principle of parsimony".

In systematics, maximum parsimony is a cladistic "optimality criterion" based on the principle of parsimony. Under maximum parsimony, the preferred phylogenetic tree is the tree that requires the smallest number of evolutionary changes.

In biogeography, parsimony is used to infer ancient migrations of species or populations by observing the geographic distribution and relationships of existing organisms. Given the phylogenetic tree, ancestral migrations are inferred to be those that require the minimum amount of total movement.

Front 24

Indicate the importance of outgroups in assessing monophyly between or among sister groups

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Ingroups: the assortment of taxa we are interested in examining Outgroups: distantly related taxa, use to contrast what classifications we are focusing on (used as a reference to the ingroup) Sister groups: a taxon most closely related to the group we are studying

Front 25

Indicate the importance of DNA sequences in the derivation of molecular clocks and phylogenies (specifically, gene trees)

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Molecular clocks: used to determine when species divereged by looking at nucleotide bases in DNA (A,C,T,G) Assume they change at the same rate over time Gene Trees Haplotypes: variants of DNA sequences of a single gene Closely related species should exhibit similar nucleotide sequences; distantly related species should exhibit more dissimilar sequences (degree of difference between species generally reflects evolutionary divergence) Assumptions: accumulation of mutations through time occurs at a constant rate and that these amassing mutations are neutral, and therefore exempt from the effects of directional selection.

Front 26

Describe the fundamental difference between phenetic and cladistic approaches to classification

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Cladistics is the hierarchical classification of species based on evolutionary ancestry. Cladistics is distinguished from other taxonomic systems because it focuses on evolution rather than similarities between species, and because it places heavy emphasis on objective, quantitative analysis. Cladistics generates diagrams called cladograms that represent the evolutionary tree of life. DNA and RNA sequencing data are used in many important cladistic efforts.

phenetics, also known as numerical taxonomy or taximetrics, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation.

Phenetics has largely been superseded by cladistics for research into evolutionary relationships among species. However, certain phenetic methods, such as neighbor-joining, have found their way into cladistics, as a reasonable approximation of phylogeny when more advanced methods (such as Bayesian inference) are too computationally expensive.

Phenetic techniques include various forms of clustering and ordination. These are sophisticated ways of reducing the variation displayed by organisms to a manageable level. In practice this means measuring dozens of variables, and then presenting them as two or three dimensional graphs. Much of the technical challenge in phenetics revolves around balancing the loss of information in such a reduction against the ease of interpreting the resulting graphs.

Phenetic analyses do not distinguish between plesiomorphies - traits that are inherited from an ancestor (and therefore phylogenetically uninformative) - and apomorphies - traits that evolved anew in one or several lineages. Consequently, phenetic analyses are liable to be misled by convergent evolution and adaptive radiation. A typical error occurring in phenetic analysis is that basal evolutionary grades - which retain many plesiomorphies compared to more advanced lineages - appear to be monophyletic.

Consider for example songbirds. These can be divided into two groups - Corvida, which retains ancient characters in phenotype and genotype, and Passerida, which has more modern traits. But only the latter are a group of closest relatives; the former are numerous independent and ancient lineages which are about as distantly related to each other as each of them is to the more modern songbirds. In a phenetic analysis, the large degree of overall similarity found among the former will make them appear to be monophyletic too, but their shared traits were present in the ancestors of all songbirds. It is the loss of these ancestral traits rather than their presence that signifies which songbirds are more closely related to each other than to other songbirds.

But the two methodologies need not be mutually exclusive. In general, phenetics is today recognized to provide little if any information about the evolutionary relationships among taxa. But there is no reason why e.g. species identified using phenetics cannot subsequently be subjected to cladistic analysis, to determine its evolutionary relationships.

Phenetic methods can be superior to cladistics when only the distinctness of related taxa is important, as the computational requirements are lower. On the other hand, whenever information on the evolutionary history of taxa is needed for a study, cladistic methods are used today.

Front 27

Indicate the importance of distinguishing between monophyletic and paraphyletic groups in developing classifications

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Monophyletic: a tree that includes an ancestor and all its descendents- but only its descendents

Paraphyletic: groups that include a common ancestor and some, but not all, of its descendents

Polyphyletic: groups formed on the basis of nonhomolougous characters

Front 28

Describe patterns of evolution revealed by homologous characters

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Homologous characters are similar traits found in two or more species due to evolution from a common ancestor that had the trait. Homologous traits, therefore, indicate evolutionary relationships among. Homologous characters most likely developed due to divergent evolution. Divergent evolution occurs when a group from a specific population develops into a new species. In order to adapt to various environmental conditions, the two groups develop into distinct species due to differences in the demands driven by the environmental circumstances. Homologous characters show evidence of evolution because it links many animals to a common ancestor. For example the opposable thumbs of humans and apes show evidence that humans and apes evolved from a common ancestor.

Front 29

Discuss rates of evolutionary change

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Conservative characters Mosaic evolution: The pattern of evolution within a lineage wherein characteristics appear at different times and change at different rates [Phyletic] gradualism: Darwin says accumulation /gradual change over time Punctuated equilibrium: long period of time (geologically) where no change occurs, then quantum evolution where a lot happens, then stasis again

Front 30

Discuss the importance of ontogeny in assessing evolutionary relationships and patterns

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Ontogeny is the growth and development of organisms over time. Those organisms with similar growth/development patterns can be assumed to have an evolutionary relationship (i.e. gill slits in land-living and air-breathing vertebrates).

Front 31

Discuss evolutionary change arising from adaptive radiation

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Adaptive radiation: rapid development of new forms or species in reaction to environmental species

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Monophyletic

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a tree that includes an ancestor and all its descendents- but only its descendents

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Paraphyletic

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groups that include a common ancestor and some, but not all, of its descendents

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Polyphyletic

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groups formed on the basis of nonhomologous characters

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Mosaic evolution

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The pattern of evolution within a lineage wherein characteristics appear at different times and change at different rates

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[Phyletic] gradualism

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Darwin says accumulation /gradual change over time

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Punctuated equilibrium

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long period of time (geologically) where no change occurs, then quantum evolution where a lot happens, then stasis again

Front 38

Ontogeny

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the growth and development of organisms over time. Those organisms with similar growth/development patterns can be assumed to have an evolutionary relationship (i.e. gill slits in land-living and air-breathing vertebrates).

Front 39

Adaptive radiation

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rapid development of new forms or species in reaction to environmental species

Front 40

Cladistics

Back 40

is the hierarchical classification of species based on evolutionary ancestry. Cladistics is distinguished from other taxonomic systems because it focuses on evolution rather than similarities between species, and because it places heavy emphasis on objective, quantitative analysis. Cladistics generates diagrams called cladograms that represent the evolutionary tree of life. DNA and RNA sequencing data are used in many important cladistic efforts.

Front 41

Phenetics

Back 41

also known as numerical taxonomy or taximetrics, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation

Front 42

Molecular clocks

Back 42

used to determine when species divereged by looking at nucleotide bases in DNA (A,C,T,G)

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Haplotypes

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variants of DNA sequences of a single gene

Front 44

maximum parsimony

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a cladistic "optimality criterion" based on the principle of parsimony. Under maximum parsimony, the preferred phylogenetic tree is the tree that requires the smallest number of evolutionary changes.

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Evolutionary reversal

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change of character states back to ancestral character states

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Convergent Evolution

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the pattern of resemblance wherein distantly related species take on similar appearance (possibly due to similar environmental pressures)

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Parallelism

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same as convergence, but between closely related taxa

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Taxon

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a named group of related organisms

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Phylogeny

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a historical lineage of related organisms

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Homology

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similarity between two or more parts as a consequence of common ancestry (relationships between similarities and differences among organisms that imply evolutionary relationships)

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Monophyly

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species with a common ancestor

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Taxonomic Characteristics

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external and internal morphology (shape) and anatomy, physiology, behavior, cell structure, biochemistry, karyotype (number, size & shapes of chromosomes), haplotype (sequence of nucleotides in DNA)

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Plesiomorphic

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ancestral (hasn’t changed much from ancestors): like 5 fingers per hand

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Apomorphic

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derived (looks different from ancestors)

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Symplesiomorphic

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shared ancestral (share ancestral characteristics with chimps & gorillas in terms of 5 fingers per hand)

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Synapomorphic

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shared derived (between different groups, they all differ from ancestors)

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Homoplasy

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character state (like dorsal fin of fish & blue whales) arising independent of ancestors. Independent species through adaptation, have similar characteristics (because both species must adapt to the same environmental pressures)

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Classification

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assigning organisms to a group

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Taxonomy

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theory & practice of classifying organisms

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Systematics

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science of diversity of life (look at organisms & characteristics to study how they are different from each other)

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Stratigraphy

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a geological method of relative dating of rock layers, and hence the fossils they contain, by placing rock layers in chronological sequence from oldest to youngest, bottom to top.

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Catastrophism

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The idea that Earth has been affected by sudden, short-lived, violent events (such as earthquakes, volcanic eruptions, or floods) that were sometimes worldwide in scope Believed that God was directly involved in determining the history of Earth. Catastrophism of the nineteenth and early twentieth centuries was closely tied to religion and catastrophic origins were considered miraculous rather than natural events

Cuvier

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Uniformitarianism

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The assumption that the natural processes operating in the past are the same as those that can be observed operating in the present The same geologic process in the past continue to operate today Didn’t parallel the prevailing religious beliefs of the time

Hutton & Lyell

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Anaximander

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Humans were 1st formed as fishes (notion of progression from fish to human)

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Xenophanes

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Fossils embedded in rocks were remains of living animals (& therefore exposed underwater fossils tell us that water used to cover that portion of the planet)

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Empedocles

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(spontaneous generation), body parts sprang from the earth & join sporadically: only by chance were organisms formed & survived (others were freaks & didn’t survive to populate the earth) 1st instance of survival of the fittest

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Plato

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Essentialism: organisms are immutable and therefore didn’t change over time But knew that individuals were different in looks and that there was a perfect individuals (and therefore there are accidental variations) 1st instance of variation

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Aristotle

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Scala naturae (ladder of nature): made a gradation of nature from simple things (primitive/ancestral/basal & inorganic) to more complex things (derived & organic) 3 steps in organic matter Plants: arose from inorganics Plant-Animals: like jellyfish, sea sponges, & anemones Animals: movement, feeling, & sensitivity Branching/ladder of lowest forms to humans at the top

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John Ray

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Biological definition of “species” = one species springs from the seed of another (therefore species are distinct form one another) BUT seeds could degenerate from parent type which leads to variation and give rise to new species Recognized the immutability of species

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Carolus Linnaeus (Carl von Linne)

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Systema naturae (binomial nomenclature) Noted for taxonomy for plants, system used to classify the organism Genus followed by 2 specifics in 2 words Recognized variation, but thought species were from a grand design (creator)

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Diderot

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Believed in prototype individuals where all living things descended, results of changes in life as a result of organisms needing a different change
Individuals acquired differences because of needs which could be transmitted to offspring

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Erasmus Darwin (C. Darwins’s grandfather)

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Modification to satisfy “wants” (something they lusted for or wanted to eat), so then they could aquire differences and pass the modification on to offspring

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Jean-Baptiste Lamarck

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Philosophie Zoologique (1809)
He said there was no difference between species and variety but species could grade into another (notion of evolution) which is called transformism (species over a long period of time from other species) Developed branching lines for animal kingdom (1st branching family tree) Genealogy of family and called it a scale of being, the last branch was humans 2 modes of action in evolution Transformism: tendency for perfection & complexity (simple critters to perfect humans) Evolution resulted because of needs of animals (like giraffe) Inheritance of acquired characteristics: giraffes reach for leaves and pass on their stretching necks to future generations Organs persist only as long as they are used Chain of Being: more complex beings originated spontaneously farther back in time than the ess complex beings

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Georges Cuvier

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Catastophism believer Had public debates with Lamarck He suggested dramatic Earthly events were responsible for new life forms periodically (volcanoes, hurricanes, earthquakes)

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Thomas Malthus

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Essay on Population (1789): “struggle for existence” When resources deplete, the population will not be able to sustain itself (population will outstrip food supply): Therefore they must struggle to exist!

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William Paley

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Natural Theology (1802) Catalogued adaptations

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Vestigial structures

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rudimentary structures, the remains from a prominent past

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Atavistic structures

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Throwbacks, the return of structures typical of ancestors (i.e. in horses, sometimes born with additional toes)

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Biogenetic Law (Ernst Haeckel)

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Early events of embryonic development retain current clues to distant evolutionary events. From egg to complete adult body, the individual passes through a series of developmental stages that constitute a brief condensed repetition of stages through which its successive ancestors evolved. The biogenic law states that the sequence of embryonic stages in current species is a rerun of former evolutionary steps. In short, ontogeny (embryology in abbreviated form recapitulates (repeats) phylogeny (evolution)