Life - patterns in evolution Flashcards
What does it mean to say that a species is dimorphic?
Females and males of the species have prominent differences in physical characteristics
What are cryptic species?
Species that are morphologically indistinguishable, yet do not inter breed
What is the lineage species concept
The idea that the history of a species can be seen as starting and ending with a speciation event (or extinction)
What happens, in terms of genetics, to populations that are isolated over time
They may acquire new fixed alleles at many different loci
Offspring between isolated groups is likely to be functionally inferior
What is allopatric speciation?
Speciation caused by geographical/physical isolation
What is the dominant mode of speciation in most oranisms?
Allopatric
What is sympatric speciation?
Reproductive isolation of populations inhabiting the same regions
Speciation is usually a gradual process. Give an exception
Polyploidy (chromosome duplication)
In only a couple of generations, complete reproductive isolation may occur
Give four example of prezygotic reproductive barriers
Mechanical isolation, temporal isolation, behavioural isolation and habitat isolation
What is low hybrid zygote viability?
Hybrid zygotes failing to develop/mature normally
What is low hybrid adult viability?
Hybrid offspring has low survivorship rate
What is hybrid infertility?
Hybrid offspring, like mules,
which are sterile
What is reinforcement?
When natural selection favours traits that strengthen prezygotic barriers, driving isolated populations apart further
What is speciation?
The process by which one species splits into two or more daughter species, which thereafter evolve as distinct lineages
How does the biological species concept distinguish species?
On the basis of reproductive isolation
How does the morphological species concept distinguish species?
On the basis of physical characteristics
Give 4 factors that influence rates of speciation
Dispersal ability, type of pollination, sexual selection and specialised diets
birds which are sexually dimorphic have _ rates of speciation than monomorphic species
Higher
For wind-pollinated plants, speciation rates are _ than those for animal-pollinated plants
Lower
Why can a high diversity of host plants lead to higher rates of speciation for herbivorous bugs?
They usually only specialise on a few closely related plants.
There are lots of opportunities for exploitation
Why do animals with complex sexual selection behaviours have higher speciation rates?
Sophisticated discrimination of partners can have a large impact on which individuals are successful
Why do species with lower dispersal ability have higher rates of speciation?
Even a a small physical barrier can have a large impact
What is evolutionary radiation?
When a large number of daughter species descend from a single ancestor
When is evolutionary radiation adpative?
When daughter species have a diverse array of characteristics used to exploit many different environments
