Quest 5 Flashcards
Evolutionary Species Concept
defined species when lineage of populations that maintains its identity from other lineages and have its own evolutionary tendencies and history
Biological Species Concept
considered a species when groups can interbreed and are reproductively isolated from other such groups, gene flow determines boundaries
Ecological Species Concept
Different Species when two populations occupy two distinct niches
Phylogenetic Species Concept
Different species when shared derived characters that are unique to one monophyletic group and absent from all other populations in the phylogeny
Phenetic Species Concept
considered a species if they look phenotypically similar and look different from other sets of organisms
Genealogical Species Concept
a distinct species when a group of organisms are all more closely related to each other than they are to any organisms outside the group
Cryptic Species
two or more taxa that have a single name because they are morphologically indistinguishable
Allopatric speciation
speciation occurring in populations that are geographically isolated from one another.
Parapatric speciation
HYBRID ZONE diverging populations have distributions that overlap one another
Sympatric speciation
populations diverge into new species while in the same location
Parapatric models
- hybrids are inferior to non-hybrids
-hybrids are superior
Ring species
species are located at one end and as they travel along each side they evolve so when they meet back up they are so different that there is almost no gene flow
Reproductive character displacement
reproductive trait is less similar when two incipient species overlap than when two species do not overlap
Variance model
allopatric speciation, initially large population subdivided into new populations that are themselves still relatively large
Peripheral Isolate model
allopatric speciation, populations that are geographically isolated from one another differ in size, with one large population and one or several smaller populations
secondary reinforcement
reproductive isolation partly evolves allopatrically and is then reinforced when the two populations come into secondary contact
Prezygotic isolating mechanisms
Never going to mate with each other
postzygote isolating mechanisms
mate but end up dying, are sterile, or inviable
Reproductive isolation
inability of a species to breed successfully due to geographical, behavioral, physiological, or genetic barriers or difference
Chromosomal fusion
joining of chromosomes or parts of chromosomes
Chromosomal fission
splitting of chromosomes
Chromosomal inversion
segment breaks off and reattaches within the same chromosome, but in reverse orientation.
Chromosomal translocation
genome abnormality in which a chromosome breaks and reattaches to a different chromosome
Hybrid Inviability
hybrids carrying derived alleles have less reproductive success than those carrying no derived or only one derived allele.
haldane’s rule
if among hybrid offspring: one sex is absent, sterile and that is the heterogametic one (in human case males)
Pleistocene Megafauna extinction
extinction of large genera of mammals due to either climate change or human killing
extinction
all individuals of a certain species have died out with no living descendants
methods of fossil formations
-compression
-casts and molds
-permineralized
-unaltered remains
compression
material is buried in water or wind borne sediment prior to decomposition and leave an impression due to weight deposited above
casts and molds
when material decays after burial in sediment a mold is left of the organisms shape, preserves internal and external structures
permineralized
structures buried in sediment and minerals infiltrate the material and harden, preserves fine details
unaltered remains
whole organisms trapped in environment that discourages desiccation and weathering
important info we get from the fossil record
provides information on preexisting life but also has geographic, taxonomic, and temporal bias
geographic bias
-tend to be produced in lowland and marine environments
-marine organisms dominate the fossil record and only make up 10% of extant species
taxonomic bias
-species that lack body structures that can be preserved are lacking in fossil record
temporal bias
fossils are lost when the geological structures they exist in disappear
Ediacaran fauna
found in Ediacaran Hills, oldest fossil recorded, beginning of Cambrian explosion
Ediacaran fossils:
-small size
-lacks hard parts
-simple body plans
-asymmetrical or radial symmetry
Burgess Shale
fossil bearing deposit in Canada, many Cambrian fossils
Chenjiang biota from Yunnan Province
vast representation of cambrian fossils
Law of superposition
fossils found lower down in the sediment at a particular locality are older than those found closer to the surface
chemical dating
provides information on the relative age of a fossil due to the fluorine buildup
radiocarbon dating
carbon 14 decays at a constant rate, half of the C14 will decay into N14
paleomagnetic dating
estimates the age of a fossil by measurement in the change of the earths magnetic field
Signor-Lipps effect
backward smearing, time lag between last fossil found and actual extinction date
Background extinction
-extinction caused by predation, climate change, disease, or competition
-usually endemic species
mass extinction
extinction event that cause 50% to 90% of all living species to go extinct
endemic species
species native to a particular area and not really found anywhere else
K-pg
Cretaceous mass extinction, wiped out the dinosaurs likely occurred due to a giant asteroid, iridium deposit
Permian - Triassic Mass extinction
-over 10,000 years 24,000 gigatons of CO2 released
-more destructive percentage-wise compared to K-pg
-Chain reaction of volcanic activity
Dead clade walking
post mass extinction event, 10-20 more species go extinct
factors for predicting extinction
distribution of the group
Pseudo-extinction
species doesn’t die out, rather becomes something else
anagenesis
modification of form over evolutionary time without seperation
cladogenesis
new forms appear in the fossil record that arise through branching speciation
phyletic gradualism
things evolve and change slowly over long periods of time
punctuated equilibrium
changes remain static for a long period of time and then a massive change occurs
copes rule
species in clades tend to increase in body size over evolutionary time, active
