topic 9 - adaptation and natural selection Flashcards
why is natural selection inmportant?
Natural selection - centerpiece to biology and evolution
why is adaptation important?
ne of the basic phenomena of biology
• Ex. 6 mya bipedalism developed -
• A characteristic that enhances survival or reproduction of organisms
adaptation definitions?
Relationship between structure and/or function & an
organism’s environment that makes the structure or
function suitable for life in that environment
process of genetic change in a population
A feature that has become prevalent in a population
because of its selective advantage for certain
function
Evolutionary process whereby a population becomes
better suited to its habitat
Takes place over many generations
*
* Example - egg eating snake adaptation
• Cranial kinesis ○ Movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw snakes have hte most kinesis and 5 other extremely movable joints
bee example
Pseudocopulatory pollination in bee orchids Attract male bees by producing species- specific pheromones t•: Bees pick up the pollens • One petal looks like a female bee • Observations ○ Adaptations possible in both animals & plants
spider adaptation ex
§ Ex adult female black spiders - females larger, during mating, spider tries to fertilize w the female in both orafices - males actively assist the female - female usually fully consume the males
§ More eggs = pass on genes, females which have eaten are more likely to pass up other males
plant vs animal adaptations? are all organisms well adapted?
○ Floral adaptations more for reproduction than for survival ○ Plants achieve goals by exploitation, deception; insect gains nothing! • Not all organsims equally well adapted • Natural selection
natural vs artificial selection
natural - environmental factors -> selection pressure -> change in organisms
artificial- human intervention -> “ -> “
diversity of dogs?
eeds - all from wolves
• Artificial selection has produced numerous breeds
of dogs, which diverged from wolves about 15,000
years ago (some studies suggested —20-40,000 years
ago).
• Ex great dane vs chihuahua
• Ex. Bull dog
○\ ○
○ Some call it “deevolution”
Traits are worse
matheus and darwin observations - why do organisms match their environment?
- Darwin was influenced by Thomas Malthus who noted the potential for human population to increase faster than food supplies and other resources
- If some heritable traits are advantageous, these will accumulate in the population, and this will increase the frequency of individuals with adaptations
- This process explains the match between organisms and their environment
natural selection - look at complex definitions. define it simply
ifferential reproductive SUCCess among individuals due to the interaction with environment
• Mechanism that allows populations to
respond (over generations) to environment by refining adaptive traits (within constraints) to meet challenges of environment
• Mechanism through which evolution occurs
what is fitness
fitness/reproductive success
• Average per capita rate of increase in numbers
fitness components
Probability of survival to various reproductive age
Average number of offspring produced via female
function
Average number of offspring produced via male
function
fitness - guppies example? read it
ok
mportant points on natural selection
• Natural selection can only work on heritable traits
○ Acquired traits are not heritable and are not subject to natural selection
• Environmental factors are variable
• A trait that is beneficial in one place or time may be detrimental in another place or time
• Natural selection is not random
• It occurs in response to environmental
pressures and results in adaptation
• When natural selection is occurring, some individuals are having better reproductive SUCCess than others
Alleles are being passed to the next generation in frequencies that are different from the current generation
