Topic 3-3 Flashcards
define anagenesis
evolutionary change of various characteristics in each descendant
define cladogenesis
branching of a lineage in two or more descendant lines
- evolution that results in the splitting of a lineage
define punctuated equilibrium
- sudden changes and unchanged for a period of time
-results in the splitting of a lineage
species is the only what in nature
real taxonomic category
define the morphological species concept
- unique set of structural features
- nothing to do with evolution
define phylogenetic species concept
- in terms of smallest group of individuals on the phylogenetic tree
- populations that share a recent evolutionary history
- smallest group of individuals based on sharing the most recent common ancestor
- the terminal taxa
What is the main focus of the biological species concept?
REPRODUCTIVE ISOLATION
Define the biological species concept
- focus on reproductive isolation
- weakness- cannot be applied to asexual species
MEMORIZE THIS
“Species are groups of actually or potentially
interbreeding natural populations which are
reproductively isolated from other such groups”
- this is biological species concept - you try memorized now !
biological species concept must follow isolating mechanisms for species to be _______
valid
what are the two reproductive isolating mechanisms?
Prezygotic and postzygotic
What is prezygotic isolating mechanism
- inhibits mating between species
or hinders fertilization of ova should there be mating - prevents them from even having sex in the first place
What is postzygotic isolating mechanism
- prevents hybrid zygote from developing into a viable fertile adult
- fertilization can happen but hybrid can not continue on
regardless of which species definition is used _______ and ________ are required
pre and post zygotic isolating mechanisms
List the Prezygotic isolation types
habitat
behavioral
temporal
mechanical
gametic
what is Habitat isolation?
- prezygotic
- species live in different places - never meet = never mate
what is behavioral isolation?
- prezygotic
- little to no sexual isolation between male and female
what is temporal isolation?
- prezygotic
- mating happens at different seasons or time of day
what is mechanical isolation?
structural isolation
- prezygotic
- difference in genitals (example)
what is gametic isolation?
female and male gametes fail to attract eachother or are invible
What are the postzygotic barriers?
reduced hybrid viability (inviability)
reduced hybrid fertility (sterility)
hybrid breakdowns
what is reduced hybrid viability?
hybrid zygotes fail to develop or fail to reach sexual maturity
what is reduced hybrid fertility?
hybrids fail to produce functional gametes
what is hybrid breakdown?
offspring or hybrids have reduced viability or fertility
