ch.14 Flashcards
populations that normally interbreed and produce fertile offspring
biological species concept
emergence of a new species from a previously existing species
speciation
Reproductive isolation can be caused by pre-zygotic and post-zygotic barriers
reproductive barriers
The human arm and whale flipper are homologous structures, meaning that
they are modified versions of a common ancestral structure
Homologous structures provide evidence for evolution because
they are best explained by descent from a common ancestral structure
a prediction made by Darwin that was proven.
that all life would depend on DNA and a common genetic code
A hypothetical population of rodents lives on a rocky beach and have a fur colors that range from white to dark gray. A group of these rodents migrates to a forested area and after several generations only rodents with darker fur are present. This is an example of
directional selection
The allele for cystic fibrosis causes a serious disease when present in two copies, but this harmful allele has not been eliminated from populations where it’s present. How do harmful alleles remain in populations?
harmful recessive alleys can “hide” in the diploid genomes of eukaryotes
Natural selection can best be summarized as
differential reproductive success based on inherited characteristics
Humans share features with salamanders. Some genes and proteins are nearly identical between the two species; both species have four limbs and a similar skeletal plan; the early embryos of both species are very similar; and where the salamander has a functional tail, humans have a vestigial tailbone. In evolutionary terms, these are examples of
homolgy
One of the core themes of biology that we study, which explains both the unity and diversity of life, is
evolution
Evolution occurs when
a populations allele frequencies change over a span of generations
All new alleles and all genetic diversity ultimately derive from
mutation
What do we call changes in allele frequency that result from a disaster or other event that drastically reduces population size?
bottleneck effect
Of the several mechanisms that can drive evolution, which can lead to a population that is better adapted to its environment?
natural selection
One of Darwin’s key observations was that geographical proximity, not environment, was the best predictor of relatedness. An example of this was the fact that many of the species on the Galápagos islands
were identical to South American species
Which of the following is an example of intrasexual selection?
large antlers in male elk, which are used for battles between males
Evolution explains the ____ and the _____ of life
unity, diversity
Allopatric speciation
new species arise because of geographic separation
prezygotic barriers & postzygotic barriers
pre: before zygote is formed, behavioral isolation, gametic isolation
post: reduces viability or reproductive capacity of hybrid offspring
hybrid polyploidy
hybridization of two different plant species
Asexual reproduction
mostly happens in plants
