Human Impact on the Evolution of the Cheeta!!

Chapt. 22: “ Constructing and Using Phylogenies ” One Species from Another!! I DON”T BELIEVE IT!! Systematics-- the study of the evolutionary relationships of organisms; relationships of present-day organisms with the past. How can we tell what species came from another? What species are more closely related than others? What species will persist into the future? Taxonomy- the classification of different species Taxon- a unit in a classification system Carolus Linnaeus- the binomial nomenclature system I.e. Genus, species-- Homo sapiens

Binomial Nomanclature: Genus name is capitalized, species name is not, both are italicized. e.g. Escherichia coli, Drosophila melangaster, Agropyron smithii (also E. coli, D. melangaster, Agropyron spp.or sp.) What is the “true” phylogeny of a particular group of organisms? Evidence: fossils (extinct) and living (extant) organisms Systematics: (1) Determine evolutionary relationships and express them in phylogenetic (family) trees (2) Express evolutionary relationships in a classification system Hierarchical Classification (order of taxons in the Linnaean system): Species--Genus--Family--Order-- Class--Phylum--Kingdom (see Fig for the moss rose, Rosa gallica)

Cladistics and cladograms-- evolutionary trees; points at which branches occur, respectively Clade- a complete portion of the phylogeny that comes from a common ancestor Phylogenetic tree- cladogram with dates of branches; common ancestor at bottom (Fig. 22.6) Systematists must determine ancestral (original) versus derived (changed from original) traits Special versus General homologous traits-- shared by a few vs. shared by many To construct a cladogram-- (1) select group of organisms (2) choose traits to compare (3) determine if they are ancestral or derived

Outgroups- a group branches off due to Special homologous traits, but still have General homologous traits in common Most challenging task of a cladogram- recognizing divergence versus convergence in ancestral traits, e.g. homlogous structures (cactus spines and bat/bird wing). PROBLEM: Homoplasy = convergent evolution of same trait more than one time (e.g.modified leaves and analogous wings of insects and birds, Fig. 22.4). Homologies from Analogies, Fig. 22.5) Table 22.1 and Fig Derived traits in vertebrates and a probable cladogram. I.e. jaws, lungs, claws/nails all derived traits; feathers and fur (birds/mammals) derived from claws and nails (reptiles).

Molecular Evolution and Phylogeny-- ancestry and cladograms based on differences in proteins and nucleic acids (RNA and DNA), no longer just gross morphology MICROEVOLUTION-- alleles change = changes in DNA & proteins (Review Chapt. 12) e.g. all land plants have 100 genes for making RNA to control synthesis of photosynthetic enzyme production DNA Hybridization-- mix DNA of two species--denatured --reassociated-- degree of reassociation = closer ancestry (Humans and chimpanzees, 1.6 % difference in DNA sequences; cow/pig = 20%) Table 22.2 and Fig (panda bear ancestry; dogs split with racoons-pandas-bears)

Figure 22.10, Horseshoe crab evolution from over 600 mya !! Figure 22.13, Phylogeny of the Domains and Kingdoms Where are the fungi in terms of being a plant or animal?