Evolution Exam 3

what are the components of natural selection

characteristics that enhance survival or reproduction of organisms compared to alternate character states

What accounts for the evolution of adaptions?

-The schedule and manor in which an organism invests in survivorship and reproduction over lifespan -reveals trade-offs

-the nonrandom survival of randomly varying replicators -any consistent difference in fitness among different classes of biological entities

Is natural selection goal-directed?

biological entities avg per capita rate of increase in numbers

What are key components of fitness?

special kind of natural selection that results from the competition for mates.

Natural selection exists whenever there is _______. Natural selection is not an ________. It is a name for a statistical difference in _________ among genes, organisms, (and populations)

describes trait that creates advantage/higher fitness

any trait correlated with advantageous trait but has no effect on fitness, piggybacks

In the ball example, would red balls be selection for or of?

What are the 2 types of sexual selection?

When some features may be subjected to conflicting selection pressures (e.g. sexual selection and predation), the direction of evolution depends upon which is ________.

In many species, there exist ____________, which are transmitted at a higher rate than the rest of an individual’s genome and are detrimental.

Change 1:1 ratio of being in gamete towards certain trait Ex: allele has 90% frequency in sperm

organisms do things for good of species

Problems with group selection.... -The survival of alternative alleles is much more likely to be determined by differences in the reproductive success of genetically different _________ than by genetically different _________. -Behaviors that appear to be ________ often really aren’t

Who would benefit more: females that produced fewer chicks for the benefit of the species or those females who raised extra offspring?

one individual aids another in a way that improves others fitness but declines their own as consequence

Seemingly altruistic behaviors evolve by ________

An allele for altruistic behavior can increase in frequency if the beneficiaries of the behavior ________.

gene for altruism leads to aid of others with same _____, therefore increasing fitness of that and leading to its ________.

Loss of offspring-> hormonally inclined to care

-features evolved in the past under different conditions and serve new functions -Ie: beaks good for fruits and nuts also break through sheep skin

Are all traits of organisms adaptations?

Not all traits are adaptations... 1.Traits may be consequences of _______ 2. Traits may have evolved by ________. 3. Traits may have evolved because they were _________. 4. Traits may be consequences of ___________.

what can be used to infer adaptation?

what should not be expected of natural selection and adaption

what are some constraints of natural selection?

Is natural selection the same as evolution?

Why is natural selection different than evolution by natural selection?

Does natural selection act at the same rate on all loci in a genome

A feature cannot evolve by natural selection unless in makes ______ contribution to reproduction or survival

Consequences of natural selection depend on… -Relationship between phenotype and _______ -Relationship between phenotype and _________ -So relationship between ___________ determines whether or not evolutionary change occurs

-Selection where average does the best (reduced fitness at extremes) -Reduces varience -In environments stable for long periods of time

-selection seen in environments w/ environmental change -Favors one more extreme value compared to the mean

-Individuals w/ mean trait do worst -Extreme traits do better than mean (not necessarily equally) -Common w/ environmental change or move to new area

As long as no other evolutionary factors intervene, a character state with any advantage will be _______ by natural selection.

average lifetime contribution of individuals of genotype to the population after 1 or more generations

Per capita growth rate

Genotypes value of R relative to some other genotype

Average fitness of individuals in population relative to the fittest genotype

What does R depend upon?

Why do deleterious alleles persist?

The fitness of a genotype is dependent upon its frequency in a population

High fitness bc a gene is rare Fitness declines when fitness increases

Fitness increases as a gene becomes more common

What is the approximate sex ratio?

physical causes can result in any one of several outcomes, we cannot predict what the outcome will be

Most phenomena are affected by both ______ and ______ factors

Adaptations evolve by natural selection which is ________

What are the two most important random causes of changes in allele frequencies in populations

The process of random fluctuation in allele frequencies due to sampling effects in finite populations.

In genetic drift...

1. In a finite population, allele frequencies _______, even in the absence of natural selection.

2. Some alleles are fixed, others are lost, and the fraction of __________ in the population decreases over time.

3. Separate populations _______ in their allele frequencies and in terms of which alleles are present.

Genetic drift as sampling error.... -If an allele is rare, it is _______ to be lost by chance alone. -One or a few copies of the allele may_______. -Genes in one generation are a _______ of the genes in the previous generation. -Any sample is subject to random variation or ________.

There is no _______ so allele frequencies do not stay the same and instead drift to either 0 or 1

allele frequencies ______ among the demes

Evolution by genetic drift...

1. Allele frequencies fluctuate at random in a population and eventually one or another allele becomes ____.

2. As the frequency of one allele approaches 1, the frequency of _______declines.

3. An allele’s probability of fixation equals its _______ at that time.

4. Populations with the same initial allele frequency ________, and a proportion of the populations is expected to become fixed for that allele.

5. Evolution by genetic drift proceeds faster in ________ populations.

The number of individuals that contribute genes to the next generation

Due to effective population size, the rate of genetic drift will be _____ than expected from populations census size

Effects of genetic drift that occur with reduction in population size

-Sudden restrictions in population size -Genetic drift has more pronounced effect on smaller population

The neutral theory of molecular evolution states... -Most of genes organisms carry _________ -Most genetic variation lacks _________ significance

Does the neutral theory hold that the morphology, physiology, and behavior of organisms evolves by random genetic drift?

In the case of an environmental difference does natural selection or evolution occur?

what keeps the sex ratio around 1:1?