BIOL 215 Selection Flashcards
What are the [3] conditions of natural selection ?
- Rise in the number of individuals in a population
- Competition for limited ressources
- Survival of the few that fare better than their competitors
What are negative and positive selection ?
Negative: not able to survive in the environment, so the population decrease
Positive : Conditions favour reproduction, so the population increase
What is the main mechanism of natural selection ?
The individuals able to survive in their environment will be the ones that will pass their advatangeous characteristics to the next generation.
With what kind of factors do individuals struggle with 6
Abiotic and biotic factors.
What is fitness?
The capability to be both able to survive AND reproduce to pass their gene to the next generation.
What is the impact of natural selection on phenotypes? Genotypes ?
N.S. has a direct impact on phenotype but an indirect impact on genotype (the phenotype that are favoured will be kept and their genotype will be preserved and passed to the next generation )
What are the [4] types of selection ?
Artificial
Natural
Sexual
Group
What are the [3] different ways that selection can affect a population distribution of phenotypes ?
Stabilizing (keep the average individuals)
Directional (keep individuals in one extreme)
Disruptive (keep individuals from both extremes)
What is artificial selection ?
A selection driven by humans that favour parents showing specific phenotypes to reproduce together and repress the individuals showing undesirable traits. ex: pigeons breed, dogs breeds, agriculture
What is the experiment that was done to show directional selection in the wild ?
Cain and Shepard observed the color of the snails (Cepaea) shells by looking which one were found broken on anvil rocks by bird (so eaten). Those who were more visible because their colour was too flashy were those who were found broken and were more rare in the habitat.
What is sexual selection ?
It is the fact that the sex with the more parental implications will choose a mate with specific traits, which will generate sexual dismorphism, that is not a survival trait, but a reproductive trait. Most of the times, females are choosy (eggs require more energy than sperm) and show less flashy features than males that needs to compete for the female. The dismorphism can be behavioural or on phenotype.
What are the three kinds of sexual selection ?
Male-Male competition : male combat, sperm competition (remove the sperm of the previous male)
Female choice: male display flashy traits or behaviours (ex: jumping spider, peacock, birds of paradise)
Sexual conflict: males want to reproduce more than females does, so they rape them and show feature that will obligate the female to mate like horns that holds the female from the eyes
What experiment did they do to show sexual dismophism and the effect on reproduction ?
Barn swallow show dismorphism (males have longer tails than female). They used a control group, cut tails of another group and glued a longer tail to a third group. The group with glued tails reproduced more than the control group that reproduced more than the group with shortened tails.
How can sexual and natural and sexual selection can be in conflict ? Explain with the examlpe of guppies.
Guppies in different pools have different intensity of spots and coloration induced by the presence or absence of predators
Experiment # 1: Lab - simulate natural conditions and
add predators: less coloured guppies survived and reproduce
Experiment # 2: Wild - swap populations of guppies: more coloured guppies survive in absence of predators because females prefer to reproduce with them
