Lecture 3 Flashcards
Taxonomic Categories
Domain, Kingdom, Phylum, Class, order, family genus, species (dear king Phillip came over for good soup)
Taxonomy is
The naming and classification of organisms
Taxonomy is better than common names because
Common names vary from place to place, scientific names are more accurate
Speciation is
the origin of two species from a common ancestor species, when you split off on the tree to form a new line/group of species
Speciation bridges
evolution of populations and the evolution of taxonomic diversity (links micro and macro evolution)
Speciation is responsible for
branching patterns of darwins theory of natural selection
Different species
Undergo independent divergence and maintain separate identities, evolutionary tendencies, and fates
Definitions for speices
vary, there are so many
A species concept is useful if it
classify an organism systematically, correspond to a discrete group of similar organisms, help explain how discrete clusters of organisms arise in nature, represents products in evolutionary history, and apply to the largest possible variety of organisms
Early taxonomists had what notion of species
typological or essentail
Morphological Species Concept
individual was a member of a species if it conformed to that type of ideal or fixed morphological propertys
2 common species concepts are
phylogenic species concept and biological species concept
Phylogenic species concept
emphasizes phylogenetic history of a population
Phylogenetic species concept definition
an irreducible basal cluster of organisms diagnosably different from other such clusters and within which there is a parental patter of ancestor and decent
The phylogenetic species concept definition would occur
whenever a population undergoes fixation of genetic differences even a single DNA base pair
The biological species concept is
most frequently used by evolutionary biologists
Biological species concept definition
species are groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups
Reproductive isolation
biological differences between the populations reduce gene flow between them, even if they are not geographically separated
Barriers to gene flow/Isolating mechanisms
gene flow between biological species is partially or entirely prevented by biological differences
2 main types of isolating barriers are
prezygotic and postzygotic
5 prezygotic barriers are
geographic isolation, ecological isolation, behavioral isolation, post-mating prezygotic barriers, and gametic isolation
Geographic isolation
species occur in different areas which are often separated by a physical barrier
Geographic isolation example
salamanders separated by different mountains
Ecological isolation
breeding at different times of the year (seasonal isolation) or different microhabitats
Ecological isolation example
crickets that breed at only spring or fall
Behavioral isolation
sometimes very specific mate recognition systems consist of signals and responses, one sex won’t respond to another unless they give appropriate signals
Behavioral isolation examples
doing duets, chemical signals, ritualized behaviors, birds doing dances
Post mating prezygotic barrers
females can terminate mating if males’ genitalia fail to provide the appropriate stimulus, even with the transfer of sperm there is no guarantee that fertilization will occur
Gametic isolation
gametes of specific species fail to unite, divergence in surface proteins on the gametes prevent sperm from fertilizing egg of different species
2 post zygotic barriers
hybrid inviability and hybrid sterility
Hybrid inviability
hybrids have a lower survival rate than non hybrids
Hybrid sterility
difference between genes from two parents can interact disharmony, hybrids produce inviable gametes
6 types of geographic variation
allopatry, sympatry, parapatry, hybrid zone, cline, ecotype
Allopatry
species or distinct populations with geographic ranges that are separate from each other
Sympatry
species or distinct populations with overlapping geographical ranges
parapatry
species or distinct populations with adjacent but non overlapping geographical ranges
hybrid zone
a region where genetically distinct parapatric forms interbreed, usually form after secondary contact
intergrade zone usually forms
during primary contact
cline
a gradual change in character or allele frequency over geographic distance
ecotype
a phenotype that is associated with a particular habitat
tree of life
shows evolutionary process linearly, web of life more accurate depiction
