Week 3: Demarcation of Species Flashcards
What is the BSC?
Species = groups of interbreeding natural populations which are reproductively isolated from other such groups
What are 2 exceptions to the BSC?
- hybridization
- self-fertilization/asexuality
What are 2 practical limitations to the BSC?
- hard to tell which species can interbreed
- can be difficult to determine interbreeding/reproductive isolation in some spp
Why is it important to know what a species is in conservation?
need to know what we’re conserving
What is the phylogenetic species concept?
Species = a group of species with at least one uniquely derived characteristic (the smallest monophyletic group)
What are 2 limitations of the phylogenetic species concept?
- makes too many species
- doesn’t account well for phenotypic variation across a species (ex. red billed quelea - wide range of interbreeding individuals with different characteristics)
What is the genetic species concept?
species = a group of interbreeding populations that are genetically distinct from other such groups
What are 2 limitations of the genetic species concept?
- highly dependent on data type and analysis
- biases from low number of samples
What is an example of the genetic species concept in practice?
orangutans - given multiple species designations based on non-interbreeding populations with genetic distinction
When is the genetic species concept most useful?
when validating a known relationship
What is a DNA barcode?
a DNA sequence used to identify a sequence
What type of primers are usually used for barcoding?
universal primers
What universal genes are used to barcode microbes, vertebrates, and plants/fungi?
microbes: 16S rRNA
Vertebrates: COI I
Plants/fungi: ITS (internal transcribed spaced)
How do we know if a DNA sequence will work as a barcode?
If there is a barcoding gap
(more interspecific variation than intraspecific variation)
What intraspecific variation is allowed in a species’ barcoding region?
~5%
What is a sequence alignment
lining up sequences from several species to find differences
What are three uses of DNA barcoding as a form of species identification?
- Cryptic species
- life stages
- wildlife forensics
How was DNA barcoding used to study pumpkin toadlets?
- barcoding showed multiple distinct groups
- later evidence supported multiple species distinctions (bone fluorescence)
How was DNA barcoding used to study an invasive calcareous tubeworm?
- species with wide range
- low barcoding diversity means it’s probably one species with high plasticity
What are 3 limitations of DNA barcoding?
- missing barcode gap may be because species diverged recently
- many overlaps between intra- and inter-specific variation
- level of variation can differ by region or species
What are two basic steps for barcoding to detect invasive species?
- describe local variation for where you sample
- develop species specific primers for the invasive
What causes introgression?
Hybridization
What type of DNA is the worst for identifying hybrids?
unipaternally inherited DNA
(only tells us about one parental lineage, no information about hybridization)
How can we barcode for hybrids?
Use species-specific primers for BOTH species A and species B –
