Topic 8b - The species concept & classification of organisms Flashcards
What is the biological species concept? key aspect?
Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.
Key aspect is reproductive isolation
Two broad classifications of repro. isolating mechanisms?
- Pre-mating isolating mechanisms
2. Post-mating isolating mechanisms
Pre-mating isolating mechanisms are/do?
Prevent mating
- geographic isolation (lack of contact)
- ecological “ (occupy different habitats)
- temporal “ (breed at different times)
- behavioural “ (don’t respond to each other)
- mechanical incompatibility (things don’t line up)
Post-mating isolating mechanisms are/do?
Mating occurs, but no viable/fertile offspring
- gametic incompatibility (sperm can’t fertilise egg)
- hybrid inviability (embryos don’t survive)
- hybrid infertility (hybrids are sterile)
What is speciation? Its basic requirements? and two main mechanisms?
The separation of populations into distinct species.
Req.: genetic isolation of populations, genetic divergence during isolation
Mech.: allopatric, sympatric
What is allopatric speciation?
Two populations are physically separated e.g. by a body of water
What is sympatric speciation?
Speciation occurring in the same geographic location
Various factors can isolate pop. e.g. different host plants (insects), use of different habitats
What is adaptive radiation?
Rapid speciation typically occurring when a species colonises a new region
Requires that there be a diversity of ecological niches
e.g. darwin’s finches
What is extinction?
Death of the last remaining members of a species
Major cause is environmental change
Name the 3 main domains of life
bacteria, archaea, eukarya
List the taxonomic hierarchy (in order!)
Kingdom, Phylum, Class, Order, Family, Genus, Species
“Kids Playing Catch On Freeways Go Splat”
What is a clade?
a group that includes all organisms descended from a common ancestor, but no other organisms
What is phylogeny?
The evolutionary history of a group of species
Define biodiversity
The diversity of living organisms; measured as the variety of different species, the variety of different alleles in a species’ gene pools, or the variety of different communities & nonliving environments in an ecosystem or the entire biosphere
