Topic 4C Flashcards
Monogamy
Single male & single female
Polygyny
Single male & multiple females
Polyandry
Multiple male & single female
Polygynandry
Multiple male & multiple females
List the main sexual strategies
- Monogamy
- Polygyny
- Polyandry
- Polygynandry
List the 5 types of monogamy mates
- Genetic
- Social
- Anonymous
- Obligate
- Facultative
Genetic monogamy
Exlusive mating r/s b/w single male & single female
Social monogamy
Paired males & females spending extensive periods of time together
Anonymous monogamy
Incidental pairings occurring through proximity of a single male & female with no active choice/partner recognition
Obligate monogamy
Males & females mate with single partner irrespective of resource abundance
Facultative monogamy
Resource limitation in some locations constrains males into mating with a single female while polygynous mating occurs when resources are abundant
Benefits of monogamy
- ↑ reproductive successes –> males invest to produce more offspring than to invest in mate search (prominent in small populations)
- Presence of parental care –> ↑ survival rate of offspring
- Secure its own lineage –> females may use sperms of other males if let free to mate
List the types of polyandry
- Classical
- Cooperative
- Convenience
Classical polyandry
Reversed sex roles –> individual male raises offspring with little/no help from female
E.g. pipefish: female transfer eggs to tail of males where he fertilises & carries it till hatching
Cooperative polyandry
Subordinate males to share paternity & brood care with a dominant male
E.g. cichlids: females can control paternity of alpha & beta male by cryptic female choice
Convenience polyandry
Females mate with multiple males to avoid aggressive breeding harassment form these males
E.g. sharks: males inflict injuries (bite pectoral fins/tails)/ males may work cooperatively to force mating
List the benefits of polyandry
- Fertility insurance
- Good sperm competition
- Sexy sperm competition
- More resources
- Better protection
- Infanticide reduction
(Beneficial strategy for females)
Fertility insurance (benefit of polyandry)
More than 1 male may be required to fertilise eggs produced by highly fecund females; ↓ loss of investment
Good sperm competition
benefit of polyandry
↑es the genetic variety of sperms available to the female –> chance
Sexy sperm competition (benefit of polyandry)
↑es chance of having offspring w enhanced attractiveness from various males
More resources (benefit of polyandry)
Females receive more parental care & resources from no. of male partners
Infanticide reduction (benefit of polyandry)
Greater confusion of paternity & ↓ likelihood of losing offspring
Better protection (benefit of polyandry)
Females receive protection from no. of protectors away from other harassing males
Cuckholdry
- Alternate strategy to ↑ mating success
- Sneaker: used by smaller males during spawning dominated by larger males (hides & waits for chance to release gametes)
- Satellite male: large males develop coloration & behaviour hat mimics females (hover above spawning pair & slowly descend upon spawning)
List the types of polygyny
- Scramble competition
- Female defense
- Resource defense
- Lek polygyny
Scramble competition (polygyny)
Competition over accessible resources
- Exist when there is high dd but low quantity of female gametes
- Females are spatially dispersed & hard to find
- Males race against time & compete with other males to look for mates
- Males get equal share of resources as density increases
Female defense
One male defends several females (specific territory)
- Males with greatest physical fitness & ability to defend mates = greatest contribution of gametes
Resource defense (polygyny benefity)
One male attracts several females with the resources he defends (e.g. food, nesting sites)
Lek polygyny
Group of males gather at a common site where females visit and select her mate –> may exhibit competitive displays to attract females (e.g. visual/auditory cues)
List the benefits of polygyny
- Increased fitness
- Increased reproductive success
(beneficial strategy for males)
Increased fitness (benefit of polygyny)
↑ed chance of mating with females that has better DNA & ↑ed survival rate of offspring
Increased reproductive success (benefit of polygyny)
Gain access to many fertile females = ↑ paternity
Costs of polygyny
- ↓ in genetic diversity: many offspring share one father –> ↑ chance of inbreeding
- Incompetence to protect females from other males
Benefits of polygynandry
- Greater genetic diversity
2. Greater dispersal into water column
What is polygynandry commonly observed in
- Broadcast spawners
- Forms huge mating shoals
- Milky water due to milt
Hermaphroditism
Individual having both reproductive organs of the male & female & have the ability to switch sexes
Protogyny
Hermaphroditic fishes exist as females & switch to male
- When dominant male from the harem is removed –> largest female will switch to become male
Protoandry
Hermaphroditic fishes exist as male & switch to females
- When larger size female dies, juvenile male switch to become female & form new pair
Parthenogenesis
- Asexual reproduction method using diploid eggs
- Embryo grows & develops w/o fertilization
- Gynogenesis
- Hybridogenesis
Gynogenesis
Egg growth stimulated by presence of sperm
- Sperm cells do not contribute genetic materials to offspring
Hybridogenesis
- Involves half of the genome intact from female & another half of genome recombined from new male
- Takes place in sexual host
