Evolution Exam 3

variation, inheritance, differential reproductive success

what are the components of natural selection

adaptions

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

natural selection

What accounts for the evolution of adaptions?

life history strategy

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

natural selection

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

no

Is natural selection goal-directed?

fitness

biological entities avg per capita rate of increase in numbers

probability of survival to reproductive age, avg # of offspring produced via female and male functions

What are key components of fitness?

sexual selection

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

variation in fitness, external force, reproductive success

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)

selection for

describes trait that creates advantage/higher fitness

selection of

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

selection of

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

male/male competition and female choice

What are the 2 types of sexual selection?

stronger

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

selfish genetic elements

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

segregation distortion

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

group selection

organisms do things for good of species

individuals, groups, self-sacrificing

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

females who raised extra offspring

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

altruism

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

kin selection

Seemingly altruistic behaviors evolve by ________

are related to individual performing behavior

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

gene, survival in future generations

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

misfirings of kinship

Loss of offspring-> hormonally inclined to care

co-options

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

no

Are all traits of organisms adaptations?

physics or chemistry, genetic drift, correlated with other adaptive traits, phylogenetic history

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 ___________.

complexity, appearance of design, experiments, the comparative method

what can be used to infer adaptation?

1. The necessity of adaptation
2. Perfection
3. Progress
4. Harmony and the balance of nature
5. Morality and ethics

what should not be expected of natural selection and adaption

1. Variation
2. Pleiotropic effects
3. Gene flow
4. No foresight
5. Physics

what are some constraints of natural selection?

no

Is natural selection the same as evolution?

Natural selection is a mechanism that allows individuals best suited to an environment to pass on genes. Evolution by natural selection is the change in acquired traits over generations because of this.

Why is natural selection different than evolution by natural selection?

no

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

positive

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

fitness, genotype, fitness and genotype

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

stabilizing selection

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

directional

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

diversifying selection

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

fixed

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

fitness

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

Absolute Fitness (R )

Per capita growth rate

relative fitness

Genotypes value of R relative to some other genotype

Mean fitness (w)

Average fitness of individuals in population relative to the fittest genotype

1. proportion of individuals surviving to each age class
2. fecundity of each age class
3. age of reproduction

What does R depend upon?

Recurrent mutation and gene flow

Why do deleterious alleles persist?

frequency dependent selection

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

inverse frequency dependent selection

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

Positive frequency dependent selection

Fitness increases as a gene becomes more common

1:1

What is the approximate sex ratio?

chance or randomness

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

chance and nonrandom

Most phenomena are affected by both ______ and ______ factors

nonrandom

Adaptations evolve by natural selection which is ________

genetic drift and natural selection

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

genetic drift

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

fluctuate over time, heterozygotes, diverge

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.

likely, not be included in genes that form zygotes, sample, sampling error

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 ________.

stabilizing force

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

may vary

allele frequencies ______ among the demes

fixed, heterozygotes, frequency, diverge, small

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.

effective population size

The number of individuals that contribute genes to the next generation

greater

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

founder effects

Effects of genetic drift that occur with reduction in population size

bottlenecks

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

selectively neutral, adaptive

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

no

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

natural selection

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

Inverse frequency dependent selection

what keeps the sex ratio around 1:1?