6. Mating Behavior Flashcards
Female Mating System
Can fertilize most or all of her eggs at once
Reproductive success is tied to availability of resources
Concerned with: parental effort & resources
Male Mating Systems
Can fertilize many females
Reproductive success is tied to access to females
Concerned with: Distribution of females & need for parental care
Types of Mating Systems
Monogamy, Polygyny, Polyandry, & Polygynandry
When is monogamy adaptive?
Male inability to monopolize more than one female and/or there is a necessity of bi-parental care
Monogamy in mammals is…
…rare.
Monogamy occurs most often in mammals when…
…females live well apart from one another in small territories.
Bi-Parental care occurs when…
…resources are scarce, male’s fitness may be highest when he’s part of a monogamous pair and provides some sort of care for the offspring.
Hypotheses for Male Monogamy
- Female enforced monogamy
- Male assistance hypothesis
- Mate guarding
Female-Enforced Monogamy
Females attack promiscuous males and nearby females
Mate Assistance Monogamy
In birds, males can incubate (brood) & feed nestlings which can make significant differences in offspring survival.
In mammals, only females can gestate & lactate to feed young which makes effects of male care restricted.
This may explains why Monogamy is so much more common in birds (90%) than mammals (3%).
Monogamy & Mate Guarding
Benefit is it guarantees paternity, keeps females busy, and can lures new suitors away
Cost: lose opportunity to breed with other females
Dual Mate-Enforced Monogamy
Males aggressive towards males & females aggressive towards females.
Social Monogamy
When a male and a female have a long term sequential living arrangement. There are occasionally EPCs (extra-pair copulations) when one mate is off doing something.
Genetic Monogamy
When a male and a female exclusively reproduce with one another.
Costs of EPCs: Males
Time/energy searching for another female
While he’s away primary male may mate with another female
Sexually transmitted diseases
Benefits of EPCs: Females
Fertility insurance hypothesis
Good genes hypothesis
Genetic compatibility hypothesis - maximize genetic diversity in their offspring
Material benefits hypothesis
Polygyny Male Costs
Increased chance of cuckoldry
Costs of achieving dominance or defending a territory
Polygyny Female Costs
Males don’t help with young
Females must share resources
Types of Polgyny
- Resource defense
2. Female defense
Polygyny
Males have several mates
Polyandry
Females have several mates
Resource Defense Polygyny
Males control resources that females need (food/shelter)
Female home ranges are larger than male home ranges
Female ranges overlap but male ranges do not without fierce competition
Female Defense Polygyny
Males compete for sexual access to a group of females (harems) and defend females from mating attempts with other males
Hypothesis for Female Acceptance of Polygyny
- Polygyny Threshold Hypothesis
- “Sexy Son” Hypothesis - Access to good genes for her offspring compensated for the costs of polygyny
- Best Alternative Hypothesis - Best of available options
Polygyny Threshold Hypothesis
Females must choose between male territories, often choosing between being the only, or one of few females in a poor territory or a second female on a rich territory
Jacanas: Resource Defense Polyandry
Females defend breeding territories on floating mats of vegetation which have several males per territory.
Exclusive male care of eggs.
Polygynandry
Mating if multiple males with multiple females within a societal structure.
How is polygynandry different from promiscuity?
Promiscuity is mating of multiple males with multiple females outside of a society structure.
Promiscuity develops when…
…there is little benefit of social living, Defense of mate/resource, when lekking is costly.
Lekking
When males amass into a group to entice females & allow females, who are surveying prospective partners for copulation, to peruse them.
Leks typically contain no resources.
Hotspot Hypothesis
Males form leks because females frequently gather at a given location.
Hotshot Hypothesis
Males form leks because subordinate males congregate around highly attractive males to increase their chance of being noticed by receptive females.
Less successful males may benefit
Females are comparison shopping
Multiple Mating Systems
Some species exhibit monogamy, polygyny, polyandry, polygynandry.
Sperm Competition
After a female has mates with several males, different sperm sizes and shapes.
Kamimaze Sperm Hypothesis
Natural selection might favor the production of some sperm types that are designed to kill other males’ sperm rather than fertilize eggs
Cryptic Choice
Female chooses which sperm is successful, length of mating, etc.
