LE 6: Parental Care and Reproductive Strategies

Question 1

How is lifetime fecundity calculated?

Answer 1

Lifetime fecundity = (# of offspring per reproductive event)x(# of reproductive events)

Question 2

What two broad categories can conflict between species be they be separated into?

Answer 2

Intraspecific: within a species
(Parent-offspring; sexual; sibling-sibling)

Interspecific: between two species

Note: optimal strategies to increase an individual’s fitness does not coincide with another individual

Question 3

What is parent-offspring intraspecific conflict?

Answer 3

Different organisms provide different amounts of parental investment into their offspring.

Parents may not want to invest into offspring in order to survive longer while the offspring wants more parental investment to survive.

Question 4

What are the different types of sexual conflicts?

Answer 4

Intersexual (parent-parent): who does the work?

Intrasexual: who gets to mate? who gets the resources?

Question 5

What is intrasexual selection? Give examples and their impacts.

Answer 5

Competition and selection within the same sex by…

Signaling status/dominance:
- sparrows with bigger bids
- larger trains in peacocks

Fighting

Question 6

What is intersexual-mate choice? Give examples and their impacts.

Answer 6

Courtship behaviors to indicate fitness

Showy displays:
- staghorn beetles have pinchers that are for fighting and for caging females while they mate

Question 7

How can mating behaviors and courtship affect future fitness of offspring?

Answer 7

Allows for organisms to choose a more high, quality mate that would increase the fitness in their offspring.

Example:
- widow birds with full and long tails = more high quality mate

Question 8

What is sibling-sibling conflict?

Answer 8

When siblings only care about their own survival and reproduction more than your siblings because your sibling only has half of your genes and you want to maximize your fitness.

Question 9

What can cause sibling-sibling conflict? Give examples.

Answer 9

Sibling-sibling conflict can be caused by large clutch size, resulting in more fit offspring being selected.

Examples:
- Sharks have a divided uterus; sibling can swim to the other half of the uterus and eat their siblings
- piglets may have a runt that does not get enough milk because of the limited amount of nipples = less nourished
- tadpoles can eat each other or they can lay unfertilized eggs in the phytotelmata (where the tadpole eggs are) for the tadpoles to eat when they hatch
- shoebill birds pick on their siblings
- higher quality/healthier chicks will beg more and get ged more because they are more likely to survive

Question 10

How does life history affect nutritional investments?

Answer 10

mammals/placentas: provides almost all nutrition from their body to their offspring before birth

Eggs: mothers have to produce yolks for nutrition of the offspring

Nuptial gifts: male spiders will gift female spiders for nutrition

Question 11

What are the cost and limitations of parental investment? Give examples:

Answer 11

Parental investment can detract from future fecundity:

Examples:
- pythons darken in color in order to absorb the sun more when sunbathing to incubate their eggs. It becomes too warm that it damages their bodies and takes years to recover

• Birds may leave the next more to get food/resources for their offspring, especially if there are more chicks. This shortens the lifespan of the parents. (more chicks = shorter lifespan)

Question 12

Why are nipples important and what is the rule of half size?

Answer 12

Nipples are a derived trait in mammals that facilitate nutritional parental care.

Rule of half size is used to determine how many nipples there are based on the litter size:

Litter size is 1/2 of the # of nipples (simply, the # of nipples is twice the litter size)

Question 13

How are mating systems classified?

Answer 13

The number of biological males and biological females in each breeding group.

Question 14

How do different mating systems affect resource distribution and sexual conflict?

Answer 14

Resources:
- uniform/indefensible
- clumpes/defendable

Sexual:
- female-biased care
- male-biased care

Question 15

What are the characteristics of Monogamy and when is it favored?

Answer 15

Definition: one male, one female per breeding system/for life

monogamy = less genetic diversity

True monogamy is rare, usually extrapair copulations: female mates with other males
- parental investment from one male, genes from another
- more genetic diversity

Conditions that favor:
- predation risk is high and young can be left alone
- young need to be kept warm
- low resource environment
- biparental care is necessary

Question 16

What are the characteristics of Polygyny and when is it favored?

Answer 16

Definition: one male, many females

characteristics:
- females are in a harem (males born leave once they reach sexual maturity)
- infanticide is common (when a male displaces another male) because the new males do not want offspring that do not have their genes

Favored when:
- female biased parental care
- males defend a resource
- females aggregate (safety from other males/ take care of sister’s children/resources)
uniform resources result in female defense polygyny to defend females from other males .
clumped resources result in resource defense polygyny to provide females with access to resource

ecological factors that lead to polygyny:
- protection from predators
- grooming (less fleas = less susceptible to disease)
- avoid harassment from other males
-distribution resources
- shared parental duties

Question 17

What are the characteristics of polyandry and when is it favored?

Answer 17

definition: one female, multiple males

characteristics:
- Usually in shore birds; rare
- sequential polyandry: female mates, lay eggs, + repeat
- simultaneous polyandry: female mates with many males in her territory and they help care for all of the offspring because paternal uncertainty is high

favored when:
- predation rates low
- gestation time low
- parental care is male biased (no nursing needed)

Question 18

What are the characteristics of polygyandry and when is it favored?

Answer 18

definition: multiple males and females mate with each other

characteristics:
- confined to within a social group instead of the whole population
- evolves when benefits to living a social group is high (multiple male lions protect 7-9 females; all mate with each other; facilitates hunting success; infanticide is common when males are displaced)

Example:
Female bonobos have sexual swellings, which indicate fertility but is unreliable (can conceal fertility resulting in paternal uncertainty)
Females mate with more males = more paternal uncertainty allowing for…
- more assistance
- less violence towards infants
- more chances to reproduce (can mate anytime)
- spreads out mating
- more mate choice: mates with best male when most fertile

Question 19

What are the characteristics of promiscuity and when is it favored?

Answer 19

definition: multiple males and females mate with each other

characteristics:
- not confined to a specific group
- evolves when benefits to living in a social group are LOW and parental care is female dominant/low (females have litters with different fathers)

Question 20

How has monogamy evolved and the hypotheses behind the phenomenon?

Answer 20

Monogamy has evolved from biparental care to no parental care.

territorial cooperation hypothesis: two individuals can better defend a resource than one

Mate guarding hypothesis: guarding a mate = exclusive access to them for multiple seasons
- favored if finding a mate is costly

Question 21

How do polygamous mating systems affect genetic diversity of a population relative to random mating (promoscuity)?

Answer 21

random mating increases genetic diversity relative to polygamy