Ch thirteen evolution test X_X Flashcards
Biogeography
- geographic distribution of species
- migration from one place to another
- new species form but resemble old species in other locations
comparative anatomy
- anatomical similarities between species
homology
similar characteristics that result from common ancestry
homologous sructures
features that have different functions but similar structures
vestigial structures
leftover features that used to serve an important function in the orgnism’s ancestors
analagous structures
same function, different strucures
comparative embryology
comparisons of the early stages of development of two different species
molecular biology
homologous genes with similar sequences
artificial seletion
shaping evolution by human intervention
evolution is apparent when…
seen in a population
population
a group of individual organisms from the same species that live in the same area and interbreed
gene pool
total collection of genes in a population at any one time… alll the alleles
mutations
- a change of the normal nucleotide sequence of DNA
- usually not great for the organism
- very rarely a mutant allele might improve the genome
-differentiation of small pieces of DNA could lead to new genes with novel functions
Sexual reproduction
most genetic variation occurs from the combination of alleles in offspring
Three components of sexual reproduction
- crossing over– prophase one, meiosis
-independent assortment
-random fertilizaton
- Five requirements for Hardy Weinberg to be true
- very large population
-no gene flow between populations - no mutations
-random mating
-no natural selection
Microevolution
- random/ rare events
- three main methods
-bottleneck effect
-founder effect
-gene flow
Bottleneck effect
- drastic population reduction
- natural disasters
- genetic drift may continue for many generations until the population builds back up
founder effect
- genetic drift that occurs when a small set of individuals found a new habitat
Gene flow
immigration/ emigration
polymorphic
a population where there are more than two forms of a characteristic
balancing selection
occurs when natural selection maintains stable frequencies of two or more phenotypes
heterozygote advantage
possible explanation for balanced polymorphism
frequency dpendant selection
the survival and reproduction of any one form declines if phenotype becomes too common
directional selection
graph with arc shifted either to the right or left
shift in the genetic makeup of population by favoring one phenotype to the extreme
stabilizing selection
one arc higher than original
favors an intermediate trait
disruptive selection
MacDonalds M on drugs graph
favors both ends of a phenotypic range
sexual selection
form of natural selection in which animals with certain traits have a higher chance of finding a mate
sexual dimorphism
distinction in appearance
intrasexual selection
individuals of one sex choose their mate
Four reasons why natural selection cannot make a perfect organism
- selection can only go on existing variations
- evolution is limited by historical constraints
- adaptations are often compromises
- change natural selection, environment changes
