ANTH 2-3 Flashcards
Macroevolution…
occurs over long timescales that span many, many generations
Microevolution…
Occurs at short timescales, usually from one generation to the next.
Adaptive Radiation
The rapid evolution of multiple species from a common ancestor, each adapting to different ecological niches.
Species
A set of organisms that are similar to each other and distinguished from other species by their behavior, morphology, and ability to create viable offspring
The Biological Species Concept
a group of interbreeding organisms, connected through gene flow
Speciation occurs through reproductive isolation
The Ecological Species Concept
Reproductive isolation is not needed.
Natural selection keeps species distinct from one another.
Relies upon the concept that hybrids have less fitness
Why is defining a species a tricky thing to do?
Because different species concepts apply in varying contexts, factors like hybridization, asexual reproduction, and genetic variation can blur the boundaries.
Allopatric Speciation
Occurs when a population is geographically separated, leading to genetic divergence and the formation of new species over time.
ex: galapagos finches
Parapatric Speciation
When populations live in neighboring areas with some differences in their environment, this leads to the gradual formation of new species.
ex: sweet vernal grass
Sympatric Speciation
happens when a new species evolves from a single population without geographic separation.
ex: apple fly maggots
Barriers to hybridization
geographic
temporal incompatibility
behavioral incompatibility
functional incompatibility
gametic incompatibility
mate recognition
hybrid sterility or inviability
reduced hybrid fitness
hybridization
the process where individuals from two different species interbreed, producing offspring that may have traits from both parent species.
Phylogenetics
The study of evolutionary relationships among species uses genetic, morphological, and molecular data to build evolutionary trees.
Homology
Traits shared due to common ancestry
homoplasy
Traits shared due to convergent evolution
Outgroup:
A distantly related organism that serves as a reference group to determine the evolutionary relationships between a set of species
cladistics
How we choose which traits to use to create evolutionary trees
phylogenetic trees
are hypotheses
They are as accurate as the data used to construct them
Trees can be updated as more data becomes available
