Mechanisms behind natural evolution Flashcards
Observations on Populations
- Individuals in population vary in their habitable characteristics
- overproduction of offspring and competition for resources
_____ causes competition for limited resources
selection pressure
individuals in population vary in their characteristics (phenotype) due ____
varied genetic makeup (genotype)
Environmental factors are called:
selection pressure
individuals with ____ leave more offspring
heritable characteristics that are well suited to their environment
Selective pressures leads to
differences in reproductive success of individuals
differences in reproductive success of individuals
accumulation of favorable traits in the population
Evolution
the accumulation of heritable variation over many generations
The direction of natural selection may change as ____ changes
selection pressures
Natural selection occurs as the result of _____ of individuals in populations
unequal reproductive success
In the next generation after natural selection:
There are more individuals with that variation of the trait than were present in the previous generation
Darwin’s proposed mechanisms by which natural forces (selection pressures) can select for advantageous variations
- environemnt “selects” for beneficial variation
2. natural selection results in adaptive changes in populations over generations called “descent with modification”
Adaptation
an inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.
Natural selection
a process in which individuals that have certain inherited
traits tend to survive and reproduce at higher rates than other individuals
because of those traits
all you need is _____
greater reproductive success
Individuals with advantageous
heritable characteristics survive and
reproduce at a ____ rate than other
individuals
higher
Natural selection increases the
_____ of populations to their
environment over time
adaptation
As populations adapt to different
environments, ____ may arise over time (over many generations)
new species
Selection pressures act on individuals, but only _____ evolve
populations
Natural selection acts on ____
existing variation
