Lecture 2 Evolutionary Approach Flashcards
What are the 5 assumptions of natural selection?
- variation among individuals
- variation is heritable
- organisms produce more offspring than can be supported by available resources
- competition occurs among individuals
- organisms that can reproduce are favored
What are the 4 levels of selection?
- gene 2. individual 3. group (interdemic) 4. species
What is GENE selection?
selection may favor particular gene; natural selection operates upon the phenotypic expression of a gene
What is INDIVIDUAL selection?
selection favors individual; individuals with a combo of well adapted genes are most likely to survive and reproduce
What is GROUP (interdemic) selection?
selection favors group rather than individual “for the good of the species”; to avoid overpopulation, groups which limit their reproduction or commit suicide have a selective advantage over groups whose populations increase then crash ie. honey bees sting an intruder and die to protect the group
What is a major problem with group selection?
individuals may cheat; in nature cheaters always prosper
What is an explanation for self sacrificing or altruistic behavior?
altruistic behavior is performed by individuals for the benefit of the closely related kin; may increase its genetic fitness by performing behavioral act that decreases its own fitness by increases fitness of closely related relatives; altruistic behavior is actually selfish
What is SPECIES selection?
selective distinction of species; removes species within a group of species rather than genes within a species; thought to be a driving force in macroevolution
Which level of selection has strongest evolutionary effect?
selection acting on differences among individuals.
What are the two factors that cause behavior?
- ultimate 2. proximate
The variable that determines the value of the measured variables is the ________?
independent variable
What kind of factors deal with immediate mechanisms of behavior?
Proximate factors
What are ultimate factors?
long term evolutionary causes of behavior; resources-based: food, water, territory, mating, shelter, etc; ultimate factors answer “why” questions about behavior
What are proximate factors?
immediate conditions or mechanisms that cause behavior; environmentally-based photoperiod, rainfall, olfaction, etc., answer “how” questions about behavior
Why do temperate species of birds in North America fly southward during autumn and northward during spring?
Birds migrate in search of resources.
- ultimate factors: food, less competition during breeding season
- proximate factors: increasing photoperiod triggers hormones, which cause birds to migrate north/south
What is an ethogram?
inventory of behaviors performed by a species of animal (time budget); allows for hypotheses to be tested to explain similarities or differences between species
What is the experimental method?
one of more variables are controlled under natural or lab conditions
What is an independent variable?
factor that defines condition or treatment of a group in an experiment
What is a dependent variable?
behavior that is observed or measured
What is the control group?
an unmanipulated set of test subjects
What is an experimental group?
a manipulated set of test subjects; often more than 1 experimental group in a study
What is a null hypothesis?
No difference between groups being tested; either accepted or rejected; best evaluated in terms of probability with inferential statistical tests
How do we test hypotheses?
find a satisfactory explanation for a particular behavior by using scientific method
What is observer behavior?
When a male lion takes over a pride and kills all of its infants… ask a question.. form a hypothesis…test it
