Lecture 1: RH Introduction Flashcards
What are the subgroups of the linnaean classification system?
Kingdom Phylum Class Order Family Genus Species
What is the highest level of classification?
Domain (3 domains of life)
What is a rank/group called?
Taxon (plural: taxa)
What is the latin binomial and how must it be written?
The genus and species put together respectively. This binomial must be always italicized or underlined. Abbreviation can be used for genus (eg C. familiaris)
What is classification based on?
evolutionary relationships
What is the graphic representation of evolutionary relationships?
Cladograms
What are sister taxa?
Taxa within branch points that are more closely related to each other than other species
How accurate are evolutionary trees?
They are hypotheses
What are traits?
Informative characters such as: Gene sequence Comparative body architecture and morphology Development
What are the types of evidence that are used to construct a phylogeny?
Fossil record informative characters
Which characters are used in constructing phylogenies?
Derived characters
What is a share-derived character (synapomorphy)?
character shared by all descendents of the ancestor in which it arose due to common descent (homologous not analogous characters)
What is the difference between homologous and analogous structures?
Homologous characters are similar because they are the same structure inherited from a common ancestor but have been modified for different functions. Analogous structures are similar in function but are not structurally and evolutionary similar.
How are genetic sequences compared?
Computer algorithms
What are some other types of evidence for constructing phylogenies?
Levels of organisation in complexity (unicellular, tissue level, organ level, etc) Body symmetry Number of embryonic tissue layers (have one, others have 2, others have 3) Body cavities of triploblastic animals between gut and outer body wall (coelomate or not)
What is cephalisation and which types of animals have this?
Bilaterally symmetrical animals often have a head with concentrated nerve tissues and sense organs
What are the types of organisation of body cavity?
Pseudocoelomate (body lined by mesodermally derived tissue on outer side only) Acoelomate (no body cavity) Coelomate (body cavity lined by mesodermally derived tissue on outer and inner sides)
What are protostomes?
Blastopore becomes the mouth
What are deutrostomes?
Blastopore becomes anus
What are synapomorphies?
shared derived characters
What is the problem with using several traits to create phylogenies?
Molecular phylogenies often disagree with morphological phylogenies
What is a monophyletic group?
Includes all descendants of the most reent common ancestor (excluding the ancestor) Also known as a clade
What is a paraphyletic group?
A group that does not include all descendants of the most recent common ancestor. A paraphyletic group typically includes the ancestor
What is a polyphyletic group?
A group that is neither monophyletic nor paraphyletic. This kind of grouping typically groups together taxa that resemble each other due to convergent evolution.
Which groupings are most effective at displaying relationships between animals?
Monophyletic grouping
What is an example of paraphyletic grouping being problematic?
The reptile class separates reptiles from birds. Birds and reptiles are derived from the same common ancestor. This paraphyletic grouping is changed to monophyletic grouping by including birds in class reptilia.