Week 3 Flashcards
How do we know that species are biologically real?
(when comparing DNA) clusters of species are distinct from one another
Define: reproductive isolation
The inability of a member from one species to successfully breed (produce fertile offspring) with a member of another species.
What is the most useful way to define a species (according to the textbook)?
Biological Species Concept
What are the cons of the biological species concept?
- difficult/time-consuming/unrealistic to breed species/test fertility of their offspring
- overlooks organisms (asexual/extinct)
Define: morphospecies concept
- “rule of thumb” species concept used by biologists
- holds that members of the same species usually look alike and have similar DNA sequences
What are the cons of the morphospecies concept?
- members of same species can look different (polymorphisms)
- members of different species can look alike
- ring species/hybridization an issue
Define: ring species
Species that are reproductively isolated but not genetically isolated.
Define: ecological niche
A complete description of the role the species plays in the environment.
Define: ecological species concept
Idea that there is a correspondence between a species and its niche.
Define: phylogenetic species concept
Members of all species share a common ancestor/common trait.
- useful when considering asexual species
What are the cons of the phylogenetic species concept?
- hard to determine a scale - do we consider everyone on earth as one large species (since we had a single common ancestor @ one point)
Define: pre-zygotic isolating factors
Factors that act before the fertilization of the egg.
Define: post-zygotic isolating factors
Factors that act after the fertilization of the egg.
Define: behavioural isolated
Individuals that mate only with other individuals based on specific courtship rituals, songs, and other behaviors.
Define: gametic isolation
Incompatibilities between the gametes of two different species.
Define: mechanical incompatibility
Genitalia is incompatible with that of another species.
Define: temporal isolation
Lack of reproduction due to timing (i.e. one plant flowers at opposite time of the year than another plant - will never have the opportunity to share pollen.)
Define: ecological isolation
Isolation of species based on location/environment.
What is a very common post-zygotic isolating factor?
Genetic Incompatibility (i.e. the horse-donkey hybrid)
Define: allopatric speciation
Reproductive/genetic isolation resulting from geographic isolation.
What are two methods in which populations can become geographically isolated from one another?
1) dispersal
2) vicariance
Define: dispersal
When members of a population separate and colonize in a distant area away from the mainland (i.e. an island).
Define: vicariance
The development of a geographic barrier within a single population.
Define: peripatric speciation
A specific type of allopatric speciation in which a few individuals from a mainland population disperse to a new location remote from the original population and evolve separately.
