Natural Selection and Speciation (Chapter 19 and 20)

1. Natural Selection and Speciation(Chapter 19 and 20)

2. Small Steps or Great Leaps? • Gradualism is the slow change from one form to another

4. punctuated equilibrium- instead of a slow, continuous movement, evolution tends to be characterized by long periods of virtual standstill (equilibrium or stasis), "punctuated" by episodes of very fast development of new forms punctuated equilibrium site

6. Random Changes in Frequencies • a change in a population due simply to chance is called genetic drift • results in a population losing genetic variation

7. Processes leading to genetic drift: 1. population bottleneck – a population becomes reduced quickly producing a random change in gene frequencies • the allele frequency of the “new population” would depend the surviving organisms’ alleles • Tule elk of California in text • Northern elephant seals • 20 seals in 1890, now 30,000

10. 2. founder effect – few individuals stray and establish a new colony, in a new habitat, and therefore a new population with diff. freq. than the original pop. (Fig. 19.8 in text) • Afrikaners of South Africa in text • In the 1680s Ariaantje and Gerrit Jansz emigrated from Holland to South Africa, one of them bringing along an allele for the mild metabolic disease porphyria. Today more than 30000 South Africans carry this allele and, in every case examined, can trace it back to this couple — a remarkable example of the founder effect. • Amish in Pennsylvania • Eastern Pennsylvania is home to beautiful farmlands and countryside, but it's also a gold mine of information for geneticists, who have studied the region's Amish culture for decades. Because of their closed population stemming from a small number of German immigrants -- about 200 individuals -- the Amish carry unusual concentrations of gene mutations that cause a number of otherwise rare inherited disorders, including forms of dwarfism and plolydactyly.

12. Species (Latin for “appearance”) Experimental results: The first steps of speciation have been produced in several laboratory experiments involving "geographic" isolation. For example, Diane Dodd took fruit flies from a single population and divided them into separate populations living in different cages to simulate geographic isolation. Half of the populations lived on maltose-based food, and the other populations lived on starch-based foods. After many generations, the flies were tested to see which flies they preferred to mate with. Dodd found that some reproductive isolation had occurred as a result of the geographic isolation and selection in the different environments: "maltose flies" preferred other "maltose flies," and "starch flies" preferred other "starch flies." Although, we can't be sure, these preference differences probably existed because selection for using different food sources also affected certain genes involved in reproductive behavior. This is the sort of result we'd expect, if allopatric speciation were a typical mode of speciation.

13. morphological definition - type of living organism with fixed characteristics that distinguish it from other species • useful but doesn’t recognize that species evolve and may not be able to interbreed • biological definition – a reproductively isolated group of actually or potentially interbreeding populations having a common gene pool that produce fertile offspring

14. Problems with defining a species • many different species can interbreed • ex. dogs/dingos/wolves/coyotes/PLANTS • fossils can’t be classified according to the biological definition • some species reproduce asexually • species that are geographically close to each other can breed but those far apart can’t

16. Classifying/Naming Species Systematics – the science of determining evolutionary relationships among organisms Taxonomy – the science of identifying, naming, and classifying organisms Both deal with determining how to classify an organism • Use the binomial system consisting of genus and species to name the organism • started by Carolus Linnaeus • normally use Latin names, names of people, or regions organism found

17. Carl Linnaeus, also known as Carl von Linné or Carolus Linnaeus, is often called the Father of Taxonomy. His system for naming, ranking, and classifying organisms is still in wide use today (with many changes). His ideas on classification have influenced generations of biologists during and after his own lifetime, even those opposed to the philosophical and theological roots of his work.

18. Hierarchy of the taxa (also can have prefix super or sub in most taxa) • Kingdom (Monera, Protista, Fungi, Plantae, Animalia) • Phylum • Class • Order • Family • Genus (capitalize & underline or italics) • Species (underline or italics) • the hierarchy of names also defines the phylogeny (evolutionary history of an organism) • for example, two species in the same class should share more ancestry (more closely related) than two species in different classes

19. Kids Playing Chicken On Freeways Get Smashed. • King Phillip called out for good soup. • King Philip came over from Germany swimming. • King Philip came over for good spaghetti. • King Philip came over for good sex. • Kings play chess on fat green stools. • Kings play chess on fine gold steps. • Kings play cards on fairly good soft velvet. (with "v" standing for "variety") • Kings possess crowns of fine gem stones. • Kenneth, please close our front gate soon. • Keep plates clean or family gets sick. • Killing people causes outbursts from general society. • Klingon phasers charge on fast gray ships. • Keep putting condoms on for good sex. • King pine cones often form great saplings