Animal behavior exam 3

SMSU Dr. Anderson

What are the types of mating systems?

monogamy, polygynous, polyandrous, polygynandry

Monogamous

one male and one female

What is the difference between sexual monogamy and social monogamy?

sexual monogamy is exclusive whereas social monogamy may have cheating

Polygynous

one male with many females

Polyandrous

one female with many males

Polygynandry

many males and females mate with many males and females

Which mating system is the most common? Why would it be a good system?

polygamy, because females have to invest more in offspring, gives certain parentage.

Why would a male ever be voluntarily monogamous? Or commit sexual suicide?

sexual suicide may increase fertilization success in the female, mate limitation hypothesis, mate guarding hypothesis, mate assistance hypothesis, female enforced monogamy

The gain of sexual suicide exceeds cost if:

mate remains receptive after one mating, male’s probability of 2nd female is low

Sexual suicide can be a form of...

mate guarding

Mate limitation hypothesis

individuals roam widely, often difficult to locate a mate

Mate guarding hypothesis

male mate restricts mating behavior of partner, he may also protect her from predators during this time

Mate assistance hypothesis

paternal care and protection is advantageous, creates a long lasting partnership where they mate for more than one season

Female enforced monogamy

female thwarts polygynous intentions

Which hypothesis does sexual suicide fall under?

Mate guarding (genitalia retained), mate assistance (sustenance provided), female enforced (female required sacrifice for mating)

Is monogamy common in mammals?

no, less than 5% of mammals are monogamous

Why is monogamy rare in mammals?

males can’t become pregnant or produce milk so polygyny is mostly the norm

When/why would monogamy become more advantageous in mammals?

when males help with parental/ partner care

Why would a male be monogamous?

mate assistance and mate guarding

Would you expect the occurrence of monogamy in songbirds to be more, less, or approximately the same as mammals? Why?

more, males have to take care of offspring, 90% are socially monogamous

Socially monogamous

partners stay together but there is cheating

What is the assumption of monogamy that is rarely true?

offspring are genetically yours

Extra pair copulations

female has multiple partners but one social father, young are step siblings

Why are extra pair copulations beneficial?

increase offspring quality, more likely to become pregnant, genetic variability, genetic compatibility

If female birds are so promiscuous, why might the guys stick around?

he could inseminate other females, if he’s unwilling to be paternal the female may not mate with him at all, might be his only shot to spread his genes

What is the male role in polyandry in birds?

incubate eggs, care for young, don’t tolerate female near clutch

What is the female role in polyandry in birds?

mate with males then lay eggs and leave, fight for male attention, defend territories

What would make a female confident enough to leave her clutch?

male biased sex ratio, habitat with lots of food, precocial young

Altricial

eggs are small in relation to parental body weight and hatchling are initially completely dependent on food supplied to them by parents 

Precocial

eggs are relatively large and young can move about and feed themselves shortly after hatching 

What are the costs of polyandry?

expensive to look for mates, STDs

What do females gain from polyandry?

indirect genetic benefits: insurance against infertility, good genes, genetic compatibility Direct material benefits: more resources like food, protection, care assistance, infanticide reduction

Why is heterozygosity desirable?

genetic compatibility hypothesis

Genetic compatibility hypothesis

genes from extra males complement those present in eggs leading to higher likelihood of superior offspring

What are the types of polygyny?

female defense polygyny

resource defense polygyny

lek polygyny

scramble competition polygyny

Female defense polygyny

find potential mates and fights with other males to monopolize females

Resource defense polygyny

find and defend preferred territories for female to lay eggs

Lek polygyny

males (sometimes many) attract several females to display territory

Lek

an area where males show off their traits for females

Scramble competition polygyny

males “race” to acquire widely scattered females

Dominance heirarchies

determine who will sire most offspring

What is an example of a species that uses leks and have a dominance hierarchies?

sage grouse, 54-85% of matings happen from the same male in a lek 

What 3 models make leks useful?

hot spot

hot shot

female preference

Hot spot model

males gather where most likely to encounter females

Hot shot model

males gather around experienced , attractive, or dominant males to increase likelihood of being noticed

Female preference model

females prefer to visit large groups of males over individual inspection, allows for quick and safe comparisons

What are the basic costs and benefits of parental care?

benefits: increases offspring survival, increased fitness Cost: attract predators, time, energy

How might annual mortality rate influence parental behavior?

low adult mortality means that they need to protect themselves, high adult mortality means they need to be more careful for offspring

Why do mothers tend to care more than fathers?

cost of care is higher for mothers, fathers have uncertain paternity and may miss out on other matings if taking care of kids

Is male parental care rare?

no

What types of animals is male parental care common?

fish and water bugs

Why might eggs of giant water bugs require brooding?

the eggs are large so more oxygen is needed for the eggs to breathe, they have a low surface to volume ratio. This requires males to keep them moist and protect them from predators

Why do female water bugs not take care of the brood?

having a partial load of eggs makes males more attractive so they want to do it, the female needs to forage in order to produce more eggs

Would you expect a parent to care for young other than their own?

sometimes: to gain experience, to help family/group, unknowingly

Under what circumstances might adoptions raise the caregiver’s reproductive success?

dilution effect, experience

Brood parasites

trick a host family by using deceptive signals triggering parental care

Brood parasitism

addition of eggs to another bird’s nest, can be intraspecific or interspecific

What is the benefit of being a brood parasite?

allows females to increase number of eggs without the cost of care

What strategies do brood parasites use?

size differences (parents are too small to remove the egg or baby is large enough to out compete the other chicks)

mimicking egg patterns

baby can mimic movements/mouth spots/ calls of native species

What are the benefits of being an adult obligate brood parasite?

reduced cost and commitments, allows bird to lay more eggs per season, spreading out the eggs increases their odds of survival

How are hosts affected by brood parasitism?

host species rarely fledges their own young (reducing productivity), expending more time and energy into getting food to feed the demanding parasite

How do hosts respond to parasitism?

some accept parasite, some abandon the whole clutch

Why aren’t more species rejecting the parasite?

risk of damaging own eggs in the process, re nesting may not be successful, the parasite parent might retaliate

Intraspecific brood parasitism

a “floating” female lays her eggs in the nests of parents of the same species

How do nesting moms fight against intraspecific brood parasitism?

they have learned to “count” or recognize the number of eggs that should be there; they will bury the parasite egg or they’ll put it outside the nest

What offsprings are often “favored”?

the 1st born

Why are 1st born often favored?

they are typically bigger and healthier, 2nd born are often an insurance policy

Trivers-Willard hypothesis (1973)

offspring sex ratio is dependent on parental condition 

According to the Trivers-Willard hypothesis, what causes more sons?

when both parents are in good condition 

According to the Trivers-Willard hypothesis, what causes more daughters?

when the female is in poor condition, male could be in good or poor condition, and it’d still cause more female offspring

According to the Trivers-Willard hypothesis, when was having more female offspring favored?

when resources are abundant so that they stay and help take care of siblings 

According to the Trivers-Willard hypothesis, when was having more male offspring favored?

when resources are scarce because males leave to find different groups to reproduce in 

What is the benefits to being big in terms of sibling rivalry?

bullying nest mates means you get food 1^st 

How do some moms compensate for bigger/older siblings bullying younger/smaller siblings?

younger eggs are given more testosterone 

What happens when parents don’t compensate for older/bigger siblings being bullies?

siblicide 

Why is siblicide common in Great Egrets but not the Great Blue Herons even though they are closely related?

great blue herons feed on fish which can be shared between the siblings whereas great egrets feed on crawfish which can only feed one at a time

Why don’t parents step in to stop siblicide?

beneficial if resources are scarce, rivalry helps parents decide which offspring is more fit

What might genetic variation within a species lead to?

differences in development of proximate mechanisms

What is the impact of behavioral variation?

fitness, varying ability to pass on genes

What’s your take on the following statement…”Some traits are genetically determined while others are environmentally determined.”

Yes and no, both genetics and environment work together or against each other to develop traits. They interact

Zenk gene

first responder when hearing song of their species

Interactive theory of development

development of behavioral traits required genetic and environmental inputs, interaction leads to production and evolution of behavior

Ethyl oleate

fatty acid produced and passed on by forager bees