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How do we categorize species?
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Phylogeny
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Phylogeny
Biology II
| Term | Definition |
|---|---|
| How do we categorize species? | By comparing traits with potential close relatives |
| Phylogeny | The evolutionary history of a species or group of species |
| Taxonomy | How scientists name and classify species |
| How do scientists name species in order to not get them mixed up? | Binomial nomenclature |
| What is the format binomial nomenclature? | Genus, scientific epithet |
| What is the order for linnaean classifcations? | Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species |
| Taxon | The taxonomic name at any given level |
| What does a branch point on a phylogenetic tree represent? | A divergence of two evolutionary lineages |
| Sister taxa | Organisms that share an immediate common ancestor |
| Polytomy | A branch point that more than 2 descendant groups emerged |
| Rooted | The branch point within the tree that represents the most recent common ancestor of all taxa on the tree |
| Basal taxon | A group that diverged early |
| Three things we can't learn from phylogenetic trees: | 1. Shows patterns of descent, NOT phenotypic similarity 2. The sequence of branching does NOT necessarily indicate the actual ages of a particular species 3. We should NOT assume that a taxon on a phylogenetic tree evolved from the taxon next to it |
| What can phylogenies be used for in real life? | Genetic modification, investigate poaching |
| What do systematics use when creating phylogenies? | genetic information, biochemistry, and morphology |
| Homologies | Similarities in phenotype and genetics due to common ancestry (ex. mammals often have homologous bone structure due to shared ancestry) |
| Convergent evolution | When similar environmental pressures occur in two separate ecosystems |
| Analogous structure | Structures that are similar but evolved separately |
| Example of analogous structure | Bird wings and bat wings - similar function, but they evolved separately and for different reasons |
| Homologous | similar structures from similar descent (ex. human hands and cat paw) |
| Analogous | similar structures from dissimilar descent (ex. flippers on penguins, dolphins, and sharks) |
| Cladistics | common ancestry is the primary criterion used to classify organisms (used to infer phylogeny from homologous structures) |
| Clades | Group of species that includes ancestral species and all of its descendants - clades can be broken down into smaller clades |
| Monophyletic group | Group consists of an ancestral species and all of its descendants |
| Paraphyletic group | Group that consists of an ancestral species and some (but not all) of its descendants |
| Polyphyletic group | Group includes distantly related species but does not include their most recent ancestor |
| For mammals, backbone is a shared ________ character because it originated in an ancestral taxon prior to mammals | ancestral |
| For mammals, hair is a shared ________ character because it is an evolutionary novelty unique to a clade | derived |
| Outgroup | Species/group of species that is known to have diverged before the lineage of a selected ingroup |
| Ingroup | The group you are studying |
| What can outgroups be determined by? | Morphology, paleontology, embryonic development, and genetic sequences |
| What can be determined by comparing members of the ingroup and outgroup? | We can determine which characters were derived at the various branch points |
| True or false: Some diagrams have branch lengths that attempt to indicate a proportional amount of evolutionary change or times for particular events | True |
| What are two things branch lines could possibly indicate on a phylogenetic tree? | Genetic changes, evolutionary change |
| How do systematics narrow down the possibilities for possible phylogenetic trees? | Maximum parsimony and maximum likelihood |
| Maximum parsimony | The simplest explanation that is consistent with the facts (For trees based on morphology, fewest evolutionary events. For trees based on DNA, fewest base changes) |
| Maximum likelihood | Tree most likely to have produced a given set of DNA data based on certain probability rules about how DNA sequences change |
| Phylogenetic bracketing | Features shared by two groups of closely related organisms are present in their common ancestor and all of its descendants |
| What do molecular clocks do | Help track evolutionary time |
| Molecular clocks | An approach to measure evolutionary change based on the fact that some genes/genomes evolve at constant rates |
| Orthologous genes | The homology of species is a result from a speciation event |
| Paralogous genes | The homology of species results from gene duplication |
| Assumptions about molecular clocks | 1. The number of nucleotide substitution in orthologous genes is proportional to the time that has elapsed since the genes branched from ancestry |
| What can cause "differences in clock speed" | Some genes may evolve in irregular bursts, some genes have random deviations from an otherwise "smooth" average, the same gene may evolve at different rates in different groups of organisms, the rate of the clock may vary from one gene to another |
| What are some problems with molecular clocks | 1. Most sequence changes are not truly neutral and some will be favored over others 2. Problems arise when expanding beyond the fossil record, the further back we go the more unclear things get |
| What are the three domains | Bacteria, arachaea, eukarya |
| What does domain bacteria consist of | most known prokaryotes |
| what does domain archaea consist of | a diverse group of prokaryotes that inhabit a wide variety of environments |
| what does domain eukarya consist of | organisms that have true nuclei |
| horizontal gene transfer | genes that are transferred from one genome to another |
| causes of horizontal gene transfer | 1. fusion of organisms (enosymbiotic theory) 2. viral infections 3. mobile genetic elements |
Created by:
carltgra