Evolution 2 Flashcards
a continuous evolutionary process, progressing through a continuum of forms, as interbreeding populations evolve into two or more distinguishable species
Speciation
refers to reproductive isolation that occurs before zygote formation for sexually reproducing organisms
Prezygotic
occurs when zygotes or offspring produced from hybrid matings are non-viable or sterile
Postzygotic
external environment or ecological conditions
extrinsic
due to internal genomic incompatibilities
intrinsic
Geographic barriers prevent gene flow
Geographic isolation
“Sexual isolation” due to different mate signals prevent individuals from different populations from mating
Behavioral isolation
Adaptation to different habitats and/or different activity or breeding time can inhibit gene flow
Ecological isolation
Different genitalia structures impede succesful transfer or sperm despute attempted matng (copulation)
Mechanical isolation
Transferred gametes cannot affect fertilization
Gametic isolation
Hybrids fall between parental ecological niches
Ecological inviability
Hybrids are less attractive (and successful) in obtaining mates
Behavioral sterility
Hybrids suffer developmental problems
Hybrid inviability
Hybrids suffer reproductive problems and produce fewer number or no functional gametes
Hybrid sterility
a population becomes divided into geographically isolated subpopulations, and migration or gene flow is inhibited due to the area between subpopulations being unsuitable for survival and migration
Allopatric speciation
a subpopulation can be geographically isolated from all of the other populations within the species due to the formation of physical barriers
Allopatric speciation
a populations becomes split into two or more relatively large, geographically isolated subpopulations by a physical or environmental barrier to migration, resulting in prezygotic reproductive isolation
Dichopatric (or vicariant)
a small group of individuals migrate and are isolated in a new niche (such as being stranded on a biogeographic island)
Peripatric speciation
it can also be a manifestation of the founder effect wherein a small population establishes a geographically isolated population in a different area
Peripatric speciation
there is no extrinsic barrier to gene flow and the populations partially overlap geographically
Parapatric speciation
True or false: Gene flow is higher in parapatric vs allopatric speciation, but lower than sympatric
True
occurs in the face of continuous gene flow
Sympatric speciation
Fossils are preserved remains or traces of animals, plants and other organisms from the past
Paleontology
Anatomy can also serve as an important evidence for evolution because it can preserve similarities in the structures of phylogenetically related organisms
Comparative anatomy
These are features of different species that are similar in function but not necessarily in structure and do not derive from a common ancestral feature
Analogous structures
these are features that may be very different in function but does share a common ancestral feature
Homologous structures
these are features that were functional in the past but now are non-functional, yet remain present in organisms
Vestigial structures
This field compares and contrasts embryos of different species
Comparative embryology
Similarities between biological molecules can reflect shared evolutionary ancestry
Genetics and molecular biology
Supports evolution by showing that species in different areas evolve unique traits to adapt to their environments
Biogeography
