Exam 2

Asexual Reproduction

Asexual Reproduction

Offspring inherit DNA from 1 parent; produces "clones"

What are 3 advantages of asexual reproduction?

1. Offspring assured without another organism

2. Adapted to parent's environment

3. Parent passes on more complete set of genes

What are the 6 types of asexual reproduction?

1. Vegetative propagation

2. Spore formation

3. Binary fission

4. Budding

5. Fragmentation

6. Parthenogenesis

Vegetative Propagation

Immature organisms from non-sexual tissue

Spore Formation

Reproductive cells

Binary Fission

Two daughter cells

Budding

1 mother (larger) and 1 daughter (smaller) organism

Fragmentation

Two mature individuals

Parthenogenesis

Parent produces embryo without fertilization

Sexual Reproduction

Reproduction involving the fusion of haploid female gamete (egg cell) and haploid male gamete (sperm cell) to form a diploid zygote

What is produced by meiosis

Haploid gametes (with independent assortment)

What is the purpose of sexual reproduction?

To mix the genetic material from two parents to produce offspring - creates variation

What are the 4 disadvantages of sexual reproduction?

1. Sex organs and mating behavior are costly

2. Mating behavior can be risky

3. Mating not guaranteed

4. Only half the genes are passed on from a parent (cost of meiosis)

Cost of Meiosis

50% reduction in the parent's genes passed on to offspring via sexual reproduction; relatively inefficient

What are the 3 advantages of sexual reproduction?

1. Coping with environmental change

2. Coping with parasites and pathogens

3. Asexual organisms cannot purge mutations

Red Queen Hypothesis

Sex and genetic recombination provide moving targets for pathogen evolution

Muller's Ratchet

A process in which the absence of recombination (especially in an asexual population) there is an accumulation of irreversible deleterious mutations

What are the 2 ways to determine sex?

1. Genetic determination

2. Environmental determination

What are the 2 ways sex is determined in genetic determination?

1. Chromosome combination

2. Presence/absence of sex chromosome

How is sex determined in environmental determination?

Temperature dependent sex determination

What are the 2 terms to differentiate sex organs in plants?

1. Dioecious

2. Hermaphrodism

Dioecious

Separate male and female plants

Hermaphrodism

A plant have both male and female sex organs

Two types of hermaphrodism in plants?

1. Monoecious

2. Plants with perfect flowers

Monoecious

When one plant has separate male and female flowers

What do sex organs in plants with perfect flowers look like?

When one plant has one flower type with both male and female parts

Are more plants dioecious or hermaphroditic?

Hermaphroditic

Do most vertebrate species have separate sexes or are they hermaphroditic?

Separate sexes

What are the 2 types of hermaphrodites in animals?

1. Simultaneous Hermaphrodites

2. Sequential Hermaphrodites

Simultaneous Hermaphrodites

Both male and female functions at the same time

Sequential Hermaphrodites

Starts with one sex's function and then switches to the other through physiological transformation

Advantage of having separate sexes

Avoid costs of performing both roles

Disadvantage of having separate sexes

Reproductive failure

Hermaphrodism occurs when...

cost of reproductive failure > cost of producing both male and female functions

Hermaphrodism favoritism follows what type of curve?

Convex curve

Favoring separate sexes follows what type of curve?

Concave curve

Self-Fertilization (selfing)

An individual's male gametes fertilize its own female gametes

Out-Crossing

Breeding with other individuals

When is out-crossing and selfing used?

If mates are available then out-crossing is used If mates are unavailable then selfing is used

What are the 3 different types of mating systems?

1. Monogamy

2. Promiscuity

3. Polygamy

Monogamy

One male and one female (can be serial or life-long)

What 3 things are favored by monogamy?

1. Equal and important male contribution to raising offspring

2. Even resource distribution

3. Inability to monopolize > 1 female

Percentages of monogamy in mammals and birds

<10% of mammals and ~90% of birds

Promiscuity

Both sexes have multiple partners

What 2 things are favored by promiscuity?

1. Inability to monopolize resources

2. Unpredictable environment

Which mating system is most common among animals?

Promiscuity

Which mating system is universal among out-crossing plants?

Promiscuity

Polygamy

When one sex has multiple partners

What are the two types of polygamy?

1. Polygyny

2. Polyandry

Polygyny

1 male has > 1 female

Polyandry

1 female has > 1 male

What 3 things are favored by polygamy?

1. Patchy resources

2. Polygyny: females prefer few best males

3. Polyandry: female looks for superior sperm or mating "gifts"; unpredictable environment to maximize egg production

Polygyny Threshold Model

Model that shows that polygyny occurs when territory variation is so great that some females are better off in polygyny than monogamy

Sexual Dimorphism

Phenotypic difference between males and females (primary and/or secondary sexual characteristics)

When are females larger?

When there is a need for larger/more offspring or female gametes

When are males larger?

When males compete physically for mates

Sexual Selection

Individuals differentiate among potential mates based on traits

Intrasexual Selection

Within-sex competition for mates

Intersexual Selection

"mate choice"

Sexual selection and parental investment

The sex that makes the larger investment will be more discriminating

Mate Choice

When the best mate makes the highest quality offspring

What are the 2 types of benefits related to mate choice?

1. Material benefits (ex. high-quality territory, nuptial, parental investment)

2. Nonmaterial benefits; more indirect (higher quality offspring)

What are the 3 hypotheses of sexual selection?

1. Good genes hypothesis

2. Good health hypothesis

3. Handicap principle

Good Genes Hypothesis

Choose a mate with superior genotype

Good Health Hypothesis

Choose the healthiest mates

Handicap Principle

Assess mate quality via trait that is detrimental to mate health

Runaway Selection

When selection for preference is linked to selection for a trait causing the trait to be more extreme over time

Groups

Purposeful joining of individuals

What are the 3 benefits of groups?

1. protection

2. food

3. mating

What are the 4 possible ways to have a protection benefit in groups?

1. Shared vigilance

2. Shared defense

3. Numerical dilution effect

4. Confusion effect

Shared Vigilance (group)

More individuals = more eyes = each individual spends less time watching for predators and can spend more time feeding

Shared Defense - 2 aspects (group)

• groups can attack potential predator

• coordinated distraction and evasion

Numerical Dilution Effect

Reduced probability of predation for an individual during a successful attack on a group

Confusion Effect

Difficult for predators to focus on one out of many moving prey

What are the 3 aspects of a food benefit in groups?

1. Many individuals searching for food may be able to find rare food more easily

2. Probability of prey capture may increase in a group

3. Group may be more successful at defending food

What is an aspect of a mating benefit in groups?

Large groups attract the attention of females (Lek)

Lek

Space where animals aggregate, display, and attract the opposite sex

What are the 3 costs of groups?

1. Predation

2. Disease

3. Resource sharing

What are the 2 aspects of a predation cost in groups?

1. Large groups attract predator attention

2. Alarm-calling attracts attention

What is an aspect of a disease cost in groups?

There is an increased spread of parasites and pathogens

What are the 2 possible ways to have a resource sharing cost in groups?

1. Territory and dominance hierarchies

2. Interactions require energy

Why are territory and dominance hierarchies a cost for resource sharing?

Organization of resource access lets dominant individuals get more

Why are interactions that require energy a cost for resource sharing?

Both aggressive and non-aggressive/friendly interactions require energy

Social Behavior

Behavior within a species; intraspecies interactions

Is there a genetic basis to social behavior?

Yes

What are the 4 main types of social behavior?

1. Spitefulness

2. Selfishness

3. Cooperation

4. Altruism

Are social behaviors just found in animals?

No, also found in plants and bacteria

Spitefulness

Reduction of the fitness of both donor and recipient (-,-)

Examples of spitefulness?

Not observed in natural populations

Selfishness

Donor's fitness increases and recipient's fitness decreases (+,-)

Examples of selfishness?

• intra-specific competition for food or space

• avoidance of a predator by pushing to the center of a group

Cooperation

Donor and recipient both experience increased fitness (+,+)

Examples of cooperation?

• hunting

• feeding by 2 parents

• protection

• heat conservation

Altruism

Cost to donor and benefit to recipient (-,+)

How does altruism effect fitness?

Altruism does not lead to direct fitness, the fitness of an individual gains by passing on genes to its offspring

What are the 2 proposed mechanisms of altruism?

1. Reciprocal "Altruism"

2. Kin selection

Reciprocal "Altruism"

Altruist has expectation that the other organism will act in a similar manner at a later time

Kin Selection

Altruistic behavior increases the fitness of a relative and therefore indirectly increases the fitness of the altruist

Indirect Fitness

Fitness an individual gains through the reproduction of their relatives which passes on copies of their genes

Inclusive Fitness

The mathematical sum of direct and indirect fitness