15 - Speciation And Phylogeny Flashcards
Gene flow is a mechanism of _____ but not _____
Gene flow is a mechanism of microevolution but not speciation.
4 ways of defining species
Morphological
Biological
Ecological
Phylogenetic
How does the biological perspective define species?
Species is a group of populations who can interbreed and produce fertile offspring.
What is the disadvantage of the biological perspective, in terms of defining species? (Ie., the type of organism that it doesn’t apply to)
Cannot be applied to extinct organisms, for example, those found in fossils.
Also cannot be applied to asexual organisms.
How does the morphological perspective define species?
Defines species in terms of measurable anatomical criteria.
What is the disadvantage of the morphological species concept?
Based on highly subjective criteria.
- needs elaboration; look at textbook
How does the ecological perspective define species?
In terms of their ecological niche; their roles.
Disadvantage to ecological perspective?
2 different species could inhabit the same niche!
How does the phylogenetic concept define species?
The smallest group of organisms that share a common ancestor…ie., one branch in a lineage.
This includes the comparison of both morphology and DNA sequences.
Disadvantage of phylogenetic species concept?
Life is so vastly varied. hard to decide how many differences are required to define a separate species?
What are reproductive barriers?
Circumstances that isolate gene pools of species, preventing gene flow.
What prevents gene flow?
Reproductive barriers!
What are the two types of reproductive barriers?
Prezygotic and postzygotic barriers
Prezygotic barrier
Prevents mating or fertilization
Postzygotic barrier
Occurs after fertilization; prevents formation of VIABLE AND FERTILE offspring.
Types of prezygotic barriers (5)
Habitat isolation Temporal isolation Behavioural isolation Mechanical isolation Gametic isolation
Types of postzygotic barriers (3)
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
Temporal isolation is a type of ______ barrier
Prezygotic
Mechanical isolation is a type of ____ barrier
Prezygotic
Reduced hybrid fertility is a type of _____ barrier
Postzygotic
Hybrid breakdown is a type of _____ barrier
Postzygotic
Reduced hybrid viability is a type of _____ barrier
Postzygotic
Reduced hybrid fertility
When hybrids fail to produce functional gametes.
Reduced hybrid viability
When the development or survival of hybrids is impaired.
Hybrid breakdown
When offspring of hybrids are feeble or infertile.
A horse and a donkey mate. Their offspring is a mule. Mules are sterile. What reproductive barrier is this? Pre/post? And what kind?
Postzygotic; reduced hybrid fertility
Hybrid breakdown
Infertility that occurs at or after F2 generation.
What are the mechanisms of speciation?
Allopatric speciation and sympatric speciation.
What is sympatric speciation?
Emergence of new species, due to barriers that emerge WITHOUT geographic isolation
What is allopatric speciation?
Emergence of new species that occurs after reproductive barriers emerge due to geographic isolation.
Examples of allopatric speciation
Emerging mountain range Partitioning lake Continental drift (plate tectonics!)
Reminder to look at fly experiment in textbook
Do it!
Sympatric speciation
Speciation that occurs without geographic isolation! So new species is in same geographic area as parent species!
3 mechanisms of sympatric speciation?
Polyploidy
Habitat differentiation
Sexual selection
Polyploidy
An organism having 2+ sets of chromosomes due to accident during cell division
2 types of polyploidy?
Autopolyploidy and allopolyploidy
Habitat differentiation
Organisms mate with others who are on their preferred resource
Sexual selection
Organism mates with others that use the same preferred resource
Phylogeny
Evolutionary history of a species
Marsupials and eutherians evolved from common ancestor. T F?
F; they’re an example of analogies/convergent evolution
Name the structures on your arm
Humerus Radius and ulna Carpals Metacarpals Phalanges
Convergent/divergent: dolphin and puma?
Divergent! Both evolved from mammalian ancestor
Convergent/divergent: shark and dolphin?
Convergent! Shark is a chondrichthye. Dolphin is a mammal.
Systematics
Biology discipline; classifying organisms, determining evolutionary relationships
Taxonomy
System of naming and classifying
Claude
Group of species including the ancestor species and /all/ of that ancestor’s descendants
Shared ancestral character
Character shared by members of a clade, that originated before the ancestor of that clade
Shared derived character
A character that is unique to clade being discussed
