SPECIES CONCEPT AND SPECIATION Flashcards
controversies about how species should be discriminated against
species problem
2 levels of discontinuity that are of special importance to the taxonomists
individuals, reproductively isolated populations
populations that have some of the properties of species but lack other
incipient species
a convenient term for the different forms or phenotypes that may occur within a single population
phenon
phenon is composed of
intrapopulation variants
populations which are the material of classification
taxon
replaced the term variety in 19th century; an aggregate of phenotypically similar populations of species inhabiting a geographic subdivision of the range of that species
subspecies
designates rank or level in a hierarchic classification
category
vehicle of macroevolution or keystone of evolution
species
the observed diversity of the universe reflects the existence of a limited number of underlying universals or types (the eidos of Plato)
typological species concept
typological species concept is also known as
essentialist species concept
deny the existence of real universals; only individuals exist while species are abstraction
nominalistic species concept
points out that the species receives its reality from the historically evolves shared information in its gene pool
biological species concept
biological meaning of species
protected gene pool
species is a set of organisms that can recognize each other as potential mates
recognition species concept
species is a set of organisms that are phenotypically similar and look different from other set of organisms
phenetic species concept
a species is a tip on a phylogeny, that is, the smallest set of organisms that share an ancestor
phylogenetic species concept
lineage-splitting event that produces two or more separate species
speciation
causes of speciation
geographically isolated
reproductively isolated
geographic separation: other island
allopatric
still live in the same area: same island
sympatric
before fertilization
prezygotic barriers
after fertilization
postzygotic barrier
speciation started because populations were prevented from interbreeding by geographic isolation
geographic isolation
species occur in the same region but occupy different habitats so rarely encounter each other
ecological isolation
species breed during different times of the day, different seasons, or different years cannot mix gametes
temporal isolation
unique behavioral patters and rituals associate species
behavioral isolation
morphological differences can prevent successful mating
mechanical isolation
sperm of one species may not be able to fertilize the eggs of another and vice versa
gametic isolation
receptor recognition; lock and key between egg and sperm
biochemical barrier
sperm cannot survive in female reproductive tracts
chemical incompatibility
prevent hybrid offspring from developing into a viable, fertile adult
post-reproduction barriers
genes of different parent species may interact and impari the hybrid’s development
reducedd hybrid viability
even if hybrids are vital, they are sterile
reduced hybrid fertility
hybrids may be fertile and viable in F1 generation, but when they mate, offspring are weak and sterile
hybrid breakdown
