Anth 101 Ch. 2

Alfred Russel Wallace (1858)

colleagues warned Darwin that if he didn't publish his ideas soon, someone else might take the credit mailed Darwin a 20 pg report outlining his theory of evolution by natural selection (same conclusion as Darwin) b/c Wallace had not amassed the extensive body of evidence needed to support the theory, Darwin is generally recognized as the discoverer

evolutionary synthesis

combo of Darwin's theory of evolution and Mendel's theory of heredity resulted in an evolutionary synthesis A unified theory of evolution that combines genetics with natural selection.

fossils

Physical remains of part or all of once-living organisms, mostly bones and teeth, that have become mineralized by the replacement of organic with inorganic materials

gene

physical unit of inheritance has two subunits of one from the father and one from the mother (each called an allele) each allele is either dominant or recessive In garden peas, the allele for tallness is dominant and the allele for shortness is recessive

gene pool

provided the basis for a newly emerging field in evolutionary biology called population genetics natural selection only operates on variation

Few paid much attention to Hutton's important contribution to our understanding of Earth's history until...

the rediscovery of the idea by the Scottish geologist Charles Lyell (1797-1875;)

systematics

the study of biological relationships over time.

gene flow

third cause of evolution, is the diffusion, or spread, of new genetic material from one population to another of the same species. In other words, via reproduction, genes from one gene pool are transferred to another gene pool.

late 17th century

, scientists generally believed that species were immutable. In their view, life had changed very little, or not at all, since the time of the single Creation. early taxonomists were not motivated by an interest in evolution; they were motivated by their desire to present the fullest and most accurate picture of the Creator's intentions for His newly created world.

deoxyribonucleic acid (DNA)

A double- stranded molecule that provides the genetic code for an organism, consisting of phosphate, deoxyribose sugar, and four types of nitrogen bases. the chemical that makes up chromosomes. In 1953, the American geneticist James Watson (b. 1928) and the British biophysicist Francis Crick (1916-2004) published their discovery that DNA molecules have a ladderlike, double-helix structure. Crucial to their discovery was the work of the British X-ray crystallographer Rosalind Franklin (1920-1958), who used a special technique, X-ray diffraction, to produce high- quality images of DNA. The combined efforts of Franklin, Watson, and Crick opened up a whole new vista for biology by helping explain how chromosomes are replicated.

species

A group of related organisms that can interbreed and produce fertile, viable offspring.

genus

A group of related species

population genetics

A specialty within the field of genetics; it focuses on the changes in gene frequencies and the effects of those changes on adaptation and evolution.

gemmules

As proposed by Darwin, the units of inheritance, supposedly accumulated in the gametes so they could be passed on to offspring.

catastrophism

Cuvier surmised that following each catastrophe, the region was vacant of all life and was subsequently repopulated by a different group of animals moving into it from elsewhere catastrophes rather than evolutionary processes, are responsible for geologic changes throughout Earth's history.

How do the traits that are being selected for (or against) pass from parent to offspring?

Darwin believed that each body part contained invisible particles called "gemmules" Darwin hypothesized that representative gemmules for all body parts resided in the reproductive organs. During fertilization, each parent contributed his or her gemmules to the potential offspring.

After returning from England

Darwin was influenced by a work called An Essay on the Principle of Population by English political economist Thomas Malthus (1st published in 1798)

Bible

Earth is a few thousand years old and its surface is static.

1900 3 scientists working independently

German botanist Carl Erich Correns (1864-1933), the Austrian botanist Erich Tschermak von Seysenegg (1871-1962), and the Dutch botanist Hugo de Vries (1848-1935)—discovered Mendel's research and replicated his findings.

Darwin

Hutton's and Lyell's uniformitarianism led him to recognize that the accumulation of such catastrophes over a long period of time explains, at least in part, the appearance of the present-day landscape. laid the groundwork for Darwin's view of evolution as a long, gradual process. That process, he saw, could be reconstructed through the fossil record. He had read carefully Cuvier's studies of fossils, and in South America he saw fossils first- hand. evidence strongly suggested that an earlier species had transformed into the modern species, most likely through a succession of species over time. wrote: *On the Origin of Species* (1856) (evolution by means of natural selection)

Mendel's crucial discovery

Mendelian inheritance (went unnoticed for a while)

allele

One or more alternative forms of a gene

Carolus Linnaeus

Presented the binomial nomenclature taxonomy of plants and animals Wrote Systems of Nature (1735) gave each plant and animal a higher-level genus (plural, genera) name and a lower-level species (plural is also species) name A single genus could include one or more spe- cies. Ex. named human beings Homo sapiens—Homo being the genus, sapiens being the species—he thought there were species and subspecies of living humans Today, we recognize that sapiens is the one living species in the genus Homo. named the order "Primates," the group of mammals that includes humans, apes, monkeys, and prosimians. Like Ray, Linnaeus was committed to the notion that life-forms were static, fixed at the time of the Creation. In later editions of his book, he hinted at the possibility that some species may be related to each other because of common descent, but he never developed these ideas. focus on taxonomic relationships over time is now called systematics.

Mendelian inheritance

The basic principles associated with the transmission of genetic material, forming the basis of genetics, including the law of segregation and the law of independent assortment.

Darwin (adaptive radiation)

The diversification of an ancestral group of organisms into new forms that are adapted to specific environmental positions. out of one species branch multiple closely related species.

blending inheritance

The father's and the mother's gemmules then intermingled to form the characteristics observed in their progeny (offspring)

mutation

The only source of new genetic material, mutation is another cause of evolution. new gene could appear as a result of spontaneous change in an existing gene

chromosomes

The strand of DNA found in the nucleus of eukaryotes that contains hundreds or thousands of genes

*Before Darwin*

Western scientists' understanding of Earth and the organ- isms that inhabit it was strongly influenced by religious doctrine. Judeo- Christian view, the planet was relatively young, and both its surface and the life-forms on it had not changed since their miraculous creation.

early taxonomist John Ray (1660)

advocated personal observation, careful description, and consideration of plants' and animals' many attributes. attention to detail laid the groundwork for later taxonomy especially for binomial nomenclature (two name system developed by Swedish naturalist Carl von Linne aka Carolus Linnaeus)

Thomas Henry Huxley

an English biologist, was known as "Darwin's bulldog" because he so forcefully promoted Darwin's theory of evolution by natural selection. Among Huxley's contributions to evolutionary theory was the concept that humans evolved from an apelike animal

1831 Charles Darwin (Cambridge University)

appointed naturalist for a 5 year voyage around the world on the ship HMS Beagle trained in medicine and theology studied the natural world (planets and animals) articulated the phenomenon best in his notes on finches that live in the Galapagos (small island of Ecuador) finches varied according to habitat finches living on the islands coast differed in beak shape compared to those in the interior (called this descent with modification or the theory of evolution) coined the term natural selection (biological characteristics that enhance survival increase in frequency from generation to generation.) regarded evolution as simply biological change from generation to generation Many evolutionary biologists today limit their definition of evolution to genetic change only

Scottish scientist James Hutton (1788)

became dissatisfied with the biblical interpretation of the planet's history devoted his life to studying natural forces, such as wind and rain, and how they affected the landscape in Scotland inferred from his observations that these forces changed Earth's surface in the past just as they do in the present. Wind and rain created erosion, which provided the raw materials—sand, rock, and soil—for the formation of new land surfaces. Over time, these surfaces became stacked one on top of the other, forming layers, or strata, of geologic deposits From the (very long) time it took for these strata to build up, he calculated Earth's age in the millions of years. developed idea of uniformitarianism.

Thomas Malthus

book: An Essay on the Principle of Population made the case that an abundance of food—enough to feed anyone born—would allow the human population to increase geometrically and indefinitely. in reality, the Essay argued, there simply is not enough food for every- one born, so population is limited by food supply who continues on to reproduce? - Those who can successfully compete for food. Applying Malthus's demographic ideas to human and nonhuman animals, Darwin concluded that some members of any species successfully compete for food because they have some special attribute or attributes.

1908, American geneticist Thomas Hunt Morgan & his associates

bred the common fruit fly in experiments that built on Mendel's pea breeding. All genes, they discovered, are transmitted from parents to offspring in the ratios identified by Mendel. The genes are on chromosomes, and both the hereditary material and its carriers are duplicated during reproductive cell division. Morgan showed that a new gene could appear as a result of spontaneous change in an existing gene (mutation)

Wilhelm Ludvig Johannsen (1857-1927)

called the pair of alleles (e.g., TT, Tt, tt) the genotype and the actual physical appearance (tall, short) the phenotype.

19th century

century of scientific study

taxonomy

classification of past and living life-forms. This discipline laid the foundation for systematics

(1865) 6 years after the publication of On The Origin of Species //Gregor Mendel//

father of modern genetics Augustinian monk living in a monastery in what is now Brno, Czech Republic, published in an obscure local scientific journal the results of his work on inheritance spent the previous eight years crossbreeding different varieties of garden pea plants. These plants enabled him to identify and carefully observe seven characteristics, or traits, that were especially informative about breeding and its outcome over generations inferred that a discrete physical unit was responsible for each characteristic. the discrete unit could be traced through generations, and its passage (the inheritance) was determined by mathematical laws. discovered that the garden peas' traits did not blend (ex. plants and their offspring were either tall or short) Over time, the short plants diminished in frequency and eventually disappeared.

Erasmus Darwin (1731-1802)

grandfather of Charles Darwin hypothesized about the inheritance of char- acteristics acquired thanks to wants and needs; but he, too, was wrong about the mechanism for change

late 1700s

handful of scientists had begun to argue that, contrary to religious doctrine, organisms are not fixed—they change over time, sometimes in dramatic ways life evolved in the past and is ongoing

French naturalist and zoologist Georges Cuvier (1796)

illuminated by the fossils' potential to reveal the past was demonstrated by him devoted considerable effort to learning the anatomy, or structural makeup, of many kinds of animals pioneered paleontology and comparative anatomy (he applied his extensive knowledge of comparative anatomy to fossils) reconstructed the physical characteristics of past animals—their appearance, physiology, and behavior. (not very accurate by today's standards) fossils found in geologic strata in France were the remains of animals that had gone extinct at some point in the remote past. provided the first basic understanding of the history of life, from the earliest forms to recent ones. coined the term "cell" (used a simple microscope) Micrographia (1667) "book" = micrography (cork wood cells) concluded that animal fossils in each strata went extinct due to some powerful catastrophe such as earthquakes or volcanic eruption (*catastrophism*) revealed that the most recent geologic strata contain mostly mammals and earlier geologic strata contain mostly reptiles, including the dinosaurs.

geology

is the study of Earth, especially with regard to its composition, activity, and history. This discipline has demonstrated the great age of our planet and the development of its landscape.

paleontology

is the study of fossils. This discipline has detailed past life-forms, many now extinct.

pre-Darwinian world

most scientists who studied life-forms realized the importance of developing a taxonomy—a classification of life-forms—for identifying biological relationships. common sense approach: Animals were placed within major groups such as dogs, cats, horses, cattle, and people. Plants were placed within major groups such as trees, shrubs, vines, and weeds.

Charles Lyell (1830)

reinforced and rediscovered Hutton's ideas devoted considerable energy to thinking and writing about uniformitarianism and its implications for explaining the history of our planet. his calculations based on geological strata provided that the Earth was millions of years old empirical evidence and personal observation to develop their ideas (Hutton and Lyell)

late 1700s

scientists had realized three key things about the world and its inhabitants: Earth is quite ancient, its surface is very different from what it was in the past, and plants and animals have changed over time. To generate his theory, Darwin drew on information from five scientific disciplines: geology, paleontology, taxonomy and systematics, demography, and what is now called evolutionary biology.

Jean-Baptiste de Monet aka Chevalier de Lamarck (1744-1829)

speculated that plants and animals not only change in form over time but do so for purposes of self-improvement. believed that in response to new demands or needs, life-forms develop new anatomical modifications, such as new organs. central idea: when life-forms reproduce, they pass on to their offspring the modifications they have acquired to that point—is called Lamarckian inheritance of acquired characteristics, or Lamarckism convinced that humans evolved from some apelike animal.

Robert Hooke (1665)

studied the microscopic structure of fossil wood (tissue structure of the fossil wood was identical to the tissue structure of living trees -> concluded that the fossil wood derived from once living trees)

Evolutionary biology

study of organisms and their changes

demography

study of population, especially with regard to birth, survival, and death and the major factors that influence these three key parts of life.

Genetic drift

the fourth cause of evolution, is random change in the frequency of alleles—that is, of the different forms of a gene. Such change affects a small population more powerfully than it affects a large population Over time, it increases the genetic difference between two genetically related but not interbreeding populations.

uniformitarianism

the natural processes operating today are the same as the natural processes that operated in the past