Reproductive Behaviour lecture 8 part 2 Flashcards
What is Sexual reproduction a mechanism for?
mixing genes
What is most important in relation to mixing genes?
propagation of alleles (genetic material), not any particular individual!
What is the driving force behind the organism’s entire design?
Surviving long enough to reproduce and ensuring viable reproductive offspring is the driving force behind the organism’s entire design
In Meiosis how much of % do females lose of her genetic make-up in her progeny?
50%
In an evolutionary sense….
no matter as it is the probability that an individual allele finds its way into the next generation that is important
Alleles that are beneficial are likely to?
find their way therefore the female has then done her job.
What is the evolutionary rate advantage of sexual reproduction?
New genetic combinations increase the oppurtunity to respond adequately to selection pressures
Increased genetic diversity=?
increased chance to respond to novel pressures
How does it overcome deleterious mutations?
by providing genes that correct this > DNA Repair Hypothesis.
What is the difference with genetic diversity between Asexual reproduction and Sexual reproduction?
Asexual reproduction: Deleterious mutations propagate
Sexual reproduction: New gene combinations and increasing the chance of overcoming unwelcome mutations
What does the new combination of genes mean?
more opportunity to respond to selection pressures that result from environmental changes (Physical or biological)
What does focusing the sexual selection on fitness characteristics of partners increase?
The efficiency of the process
What physical differences allow for easy discrimination of the sexes in high animals?
(e.g. penis) or secondary sexual characteristics (e.g. antlers, horns, greater size - male - to - male combat and ornaments - mate choice)
What is the true cost of sexual reproduction?
True cost is decreasing the capacity of the female to produce offspring by producing both male and female offspring
-By producing males and females, which cannot reproduce independently, a sexual female halves her fertility
What species does the true cost of sexual reproduction mostly effect?
-Especially in anisogamous species (i.e. males and females with different-sized gametes) where males invest vastly less at the gamete stage (sperm smaller than eggs) and often during parental care (rarely bi-parental care of paternal care)
Give the evolutionary explanation for why there is 2 sexes?
Advantage to those organisms that had larger ancestral isogametic (single-sized gamete) cells in terms of resource provisioning
Individuals with smaller gametes can exploit this by encountering larger gametes faster than they can encounter each other.
Evolutionary pressures then favour both smaller and smaller (more motile) gametes and large gametes (whose size equates to the optimum for the development of offspring).
What is the net result in relation to Evolutionary explanation?
Net result is development of two types of gametes and anisogamous (different-sized gamete) sexes
What evolved to account for different physiologies?
(Delivery and receptor mechanisms) and behaviours (to improve chances of reproduction success) evolved to account for this
Mating often involves?
some form of mate selection (mate choice = usually female choice of male mates)
Mate quality (individuals in a breeding population vary in quality) is defined in terms of?
- Fertility
- Dominance and/or aggressiveness
- Experience
- Health and/or parasite load
- Immune system
List the 3 parts involved with choice of partner
1) Make sure you have the correct species
2) Make sure you have the right sex
3) Make sure you have the fittest mate
What are the short term benefits of mating with a high quality partner?
Short term material benefits (e.g. resources of a large territory) which will also give an advantage to her offspring.
What are the long term benefits of mating with a high quality partner?
Long-term genetic advantage (i.e. male-derived genes) which confers a fitness advantage to the offspring.
-Remember that fitness refers to the lifetime reproductive success of an individual
What are the costs and benefits of promiscuous mating for males?
Males benefit in maximising spread of genes but there are costs associated with promiscuous mating
- Ejaculatory costs (E.g. quantity and quality of sperm)
- Time and energy costs
- Commitment to one partner where offspring need the input of both parents
- Need to paternity assurance (e.g. by mate gaurding)
How doe females benefit from promiscuous mating?
Mating with more than one male = advantages in mixing genetic material
What kinds of criteria do females use to choose males?
Directly related to quality (e.g. size or brightness of colour, related to disease and parasite load))
Symbolic (e.g. using courtship rituals and ornamentation)
How is male reproductive success measured?
the number of matings achieved
What should males do to be more successful?
Males should attempt to mate with as many females as possible - a non-selective undiscriminating eagerness
How is female reproduction success measured?
measured by the quality of whoever fertilizes her eggs
What should females do to be more successful?
Females (where there is a choice of mate) should be highly selective
In mating systems what do males put a lot more reproductive investment into?
the mating effort
In mating systems what do females put a lot more reproductive investment into?
the parental effort
List the different types of mating systems?
Monogamy
Polygamy
Promiscuity
What do the different mating systems lead to?
-This leads to different parental roles, behavioural responses, groupings and territorial activities
Explain Monogamy
One male defends one females territory - partners may be seasonally or lifetime monogamous. Seems counterintuitive for males.
What does extra-pair copulation often lead to?
Extra-pair copulations often lead to genetic polygamy even if there is a social monogamy. Genetic monogamy is now considered the exception
Explain Polygamy
One female forms pair bonds with several males simultaneously
What is classical polyandry?
One female mates with more than 1 male
What is Resource defence (cooperative polyandry)?
Males defend smaller inclusive territories and often care for young.
What is Uni-male polygyny (Often defence of resouces)?
One male defends several females range
What is Harem polygyny?
One male defends the females group(Non long-term defence of resources)
What is Multi-male polygyny?
Several males defend the females groups (No long-term defence of resources).
Define Lekking
Males perform in distinct, stable display area; females visit solely to choose mate. Can be concentrated (males close together) or exploded (Male some distance apart and interact through calls).
Explain Promiscuity
No pair bond - in one breeding season females and males meet briefly to copulate.
No rule as to which sex provides care for young.
Explain Resource defence
males defend food territory and mate with females who visit to feed (not breeding territory or elaborate rituals
Explain display site defence
Males defend display site with no resources; females visits solely to copulate.
