PDF-(READ)-The Origin of Species

Darwins theory of natural selection issued a profound challenge to orthodox thought and belief no being or species has been specifically created all are locked into a pitiless struggle for existence with extinction looming for those not fitted for the task Yet The Origin of Species 1859 is also a humane and inspirational vision of ecological interrelatedness revealing the complex mutual interdependencies between animal and plant life climate and physical environment andby implicationwithin the human world Written for the general reader in a style which combines the rigour of science with the subtlety of literature The Origin of Species remains one of the founding documents of the modern age. What is a Species?. Speciation. – the origin of new species. The . biological species concept. defines a species as a population or group of populations whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring, but who cannot produce viable, fertile offspring with members of other species. Macroevolution is essentially the formation of new species (speciation) and accompanying events. . Reproductive isolation can occur in a variety of ways. Reproductive isolation is the key to cladogenic speciation. Cynotilapia. . afra. , introduced at West . Thumbi. Island in Lake Malawi in the 1960s, has split into two genetically distinct populations, located at the north and south ends of the island. How can scientists determine whether these populations are now different species, according to the biological species concept?. Part C. Allopatric. and Sympatric Speciation: . A Review. In . allopatric. speciation, geographic isolation restricts gene flow between populations. Reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations. Part C. Allopatric. and Sympatric Speciation: . A Review. In . allopatric. speciation, geographic isolation restricts gene flow between populations. Reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations. KEY CONCEPTS. • Although many species persist for long periods of time both genotypic and phenotypic changes occur over time.. • Even if change is occurring, individuals that interbreed within a population(s) maintain the status of the population(s) as a species.. Question?. What is a species?. Evolution . theory must also explain how species originate.. Darwin’s “Mystery of mysteries. ”. In the Galápagos Islands Darwin discovered plants and animals found nowhere else on Earth. “Both in space and time, we seem to be brought somewhat near to that great fact—that mystery of mysteries—the first appearance of new beings on this Earth.”. — Darwin. What is a species?. Biological species concept. Cartoon – gentleman and ape. 2. Key Concepts:. Species concepts. Development of reproductive isolation. Patterns of speciation. Macroevolution. Human evolution. Evolution continues…... 3. specie. Macroevolution. describes the origination of new taxonomic groups (vs . microevolution. , which deals with change in allele frequency, and frequencies of genotype and phenotype). What is a species?. Reduction in . gene . flow, genetic and phenotypic change in populations. The study of speciation requires that species be real. Speciation. Speciation is the antidote to sex. Keeps together adaptive groups of traits. Do all humans originate from Africa? How did we spread across the globe? Are we separate from Neanderthals, or do some of us actually have their genes? When did humans become \'modern\' - are traits such as art, technology, language, ritual and belief unique to us? Has human evolution stopped, or are we still evolving?Chris Stringer has been involved in much of the crucial research into the origins of humanity, and here he draws on a wealth of evidence - from fossils and archaeology to the mysteries of ancient DNA - to reveal the definitive story of where we came from, how we lived, how we got here and who we are. The publication of Darwin’s The Origin of Species in 1859 marked a dramatic turning point in scientific thought. The volume had taken Darwin more than twenty years to publish, in part because he envisioned the storm of controversy it was certain to unleash. Indeed, selling out its first edition on its first day, The Origin of Species revolutionized science, philosophy, and theology. Darwin’s reasoned, documented arguments carefully advance his theory of natural selection and his assertion that species were not created all at once by a divine hand but started with a few simple forms that mutated and adapted over time. Whether commenting on his own poor health, discussing his experiments to test instinct in bees, or relating a conversation about a South American burrowing rodent, Darwin’s monumental achievement is surprisingly personal and delightfully readable. Its profound ideas remain controversial even today, making it the most influential book in the natural sciences ever written—an important work not just to its time but to the history of humankind. Campbell . and Reece. Speciation. process by which one species splits into 2 or more species. Speciation explains both the diversity of life and the unity of living things.. Speciation : forms bridge between:.