Chapter 27-28 - Speciation and Phylogenetics (Test 3) Flashcards
Define phylogeny of all organisms
Genealogical relationships between species
How many domains are they, and what are they?
3: Bacteria, Archaea, Eukarya
Characterize the three domains in terms of their nuclei and their # of cells
Most bacteria and archaea are prokaryotic; eukaryotes are the others.
Most bacteria and archaea are single-celled; some eukaryotes are multicellular
Who is responsible for the three-domain classification system?
Woese – thanks to his experiements tracing ribosomal RNA (rRNA) to construct the tree.
Describe the evolutionary relatoinships of the three domaiB
Eukaryotes and Archaea share a common ancestor, which shares a common ancestor with Bacteria.
Are prokaryotic organisms monophyletic?
No; prokaryotes can be bacteria or archaea. But archaea have a common ancestor with eukaroytes before they have one with bacteria.
What is taxonomy?
The effort to name and classify organisms.
what is anamed group of organisms called re: taxonomy?)
a taxon. (plural: taxa)
What is a phylum?
a major grouping within each domain
Describe the system for scientific (latin) names and who came up with it.
Linnaeus.
Two-part name: Genus (closely related group of species)
Species
Capitalize genus but not species. Italicize or underline separately if handwritten.
What causes speciation?
genetic isolation and genetic divergence
What is speciation?
A splitting event that creates two or more distinct species from a single acnestral species.
Define species.
An evolutionarily independent population or group of populations.
What are three common criteria used to develop species?
Biological species concept
Morphospecies concept
phylogenetic species concept
Define the biological species concept
The main criterion for identifying species is reproductive isolation.
What are the two types of reproductive isolation
prezygotic isolation - prevents individuals of different species from mating.
postzygotic isolation, in which the offspring of different species do not survive or reproduce.
Disadvantages of the biological species concept?
- Can’t be evaluated in fossils or asexual species
- Difficult to apply when populations do not overlap geographically
Define the morphospecies concept
Identify evolutionarily independent lineages by size, shape, or other morphological species. Logic: distinguishing features likely to arise if populations are independent and isolated from gene flow.
What are the pros and cons of the morphospecies concept?
- good: Useful when there is little other data
- bad: can lead to the naming of 2+ species when there is only one polymorphic species with differing phenotypes (jaguars with different spots)
- bad: Cannot ID cryptic species, which differ in traits other than morphology, like meadowlarks
- morphological features used to distinguish species are subjective
What are the five mechanisms of prezygotic isolation?
- Temporal – lived at different time
- habitat – lived in different habitats
- behavioral – courtship displays differ
- gametic – eggs and sperm are incompatible
- mechanical – male and female reproductiv structures are incompatible
What are the three mechanisms of postzygotic reproductive isolation?
- hybrid viability – hybrid offspring do not develop normally and die as embryos
- hybrid sterility – hybrid offspring mature but are sterile as adults
- hybrid breakdown
Define the phylogenetic species concept
Species are the smallest monophyletic groups on the tree of life
define monophyletic group
a clade or lineage. an ancestral population, all of its descendants, and only those descendants.
How do we identify monophyletic groups?
synapmorphies
What is a synapmorphy?
a trait found in certain groups of organisms and their common ancestors but is missing in more distanct ancestors
What are the advantages and disadvantages of the phylogenetic species concept?
Pro:
- can be applied to any population.
- logical because different species have different synapmorphies only if they are isolated from gene flow and have evolved independently
con:
- carefully estimated phylogenies are available only for a small subset of populations.
2.