Unit 3 Week 3 Flashcards
contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
relative fitness
selection that favors phenotypes at one end of the spectrum of existing variation
directional selection
selection that favors two or more distinct phenotypes
diversifying (disruptive) selection
selection that favors average phenotypes
stabilizing selection
fitness of a phenotype depends on how common it is in the population
frequency dependent selection
selection pressure on males and females to obtain matings
sexual selection
phenotypic differences between males and females
sexual dimorphisms
selection that leads to evolution of traits in males for aggressive interactions with other males over access to females
intrasexual selection
selection that occurs when individuals of one sex are choosy when selecting a mate
intersexual selection
the general reason why natural selection cannot make perfect organisms
evolution is opportunistic
science of naming and classifying organisms into hierarchical classification systems with each organism placed into increasingly more inclusive groupings
taxonomy
any group used in classifying organisms
taxon
order these in decreasing size: phylum, order, species, kingdom, genus, class, family
kingdom, phylum, class, order, family, genus, species
science of resolving evolutionary relationships among organisms
systematics
evolutionary history and relationships of an organism or groups of organisms
phylogeny
ancestral lineage that gave rise to all organisms on the tree
root
where two lineages diverged
branch point or node
a lineage that evolved early and remains unbranched
basal taxon
when two lineages stem from the same branch point
sister taxa
a branch with more than two lineages representing unresolved relationships
polytomy
trait in two or more species that is derived from a common ancestor
homology
a characteristic that is similar between organisms that evolved through convergent evolution, not due to the same evolutionary path
analogy or homoplasy
process by which groups of organisms evolve in diverse directions from a common point
divergent evolution
process by which groups of organisms in distant taxa independently evolve to take on similar forms
convergent evolution
system used to organize homologous traits to describe phylogenies
cladistics
group that includes ancestral species and all its descendants
clad or monophyletic group
group that does not contain all descendants from a most recent common ancestor
paraphyletic group
the simplest explanation and most likely for a phylogenetic tree
maximum parsimony
