Week 6 Flashcards

Question

What is an overview of the good genes model?

Answer 1

TRAITS ARE COSTLY TO DEVELOP / CARRY – THEY ARE A HANDICAP (ZAHAVI 1975) CARRYING THE HANDICAP IS AN HONEST SIGNAL OF INDIVIDUAL MALE ‘QUALITY’ HANDICAP IS EITHER ‘STANDARD’ AND ACTS AS A ‘SURVIVAL FILTER’…. ….OR HANDICAP IS CONDITION-DEPENDENT AND BETTER MALES CARRY BIGGER HANDICAPS BEING FATHERED BY MALES THAT CAN CARRY THE HANDICAP WILL CAPTURE BETTER GENES

Answer 2

HAMILTON & ZUK (1985) PARASITE LOAD IS A MAJOR & GENERAL PROBLEM SIGNAL IS LINKED TO PARASITE RESISTANCE BEING FATHERED BY MALES WITH EVIDENT SIGNALS WILL CAPTURE BETTER RESISTANCE GENES

Answer 3

MATE CHOICE BENEFITS IN CHOOSING GENOTYPES THAT COMPLEMENT SELF GENERAL BENEFIT TO AVOID OUTBREEDING (e.g. similar to self to avoid hybridisation) GENERAL BENEFIT TO AVOID INBREEDING (e.g. different to self to avoid inbreeding) SPECIFIC BENEFIT AT PARTICULAR LOCI / COMPLEXES (e.g. the Major Histocompatibility Complex (MHC) for immunorecognition)

Answer 4

CO-EVOLUTION OF LINKED FEMALE PREFERENCE IMPORTANT IN RUNAWAY MODELS COST OF SIGNAL MORE IMPORTANT IN HANDICAP MODELS SPECIFICITY OF SIGNAL TO IMMUNITY IMPORTANT IN PARASITE RESISTANCE MODELS COMPATIBILITY FOCUSED ON MALE-FEMALE RELATEDNESS

Answer 5

Sexy sons General quality Parasite resistance Compatibility

Answer 6

Male ornamentation varies across different populations of Trinidadian guppy (affected by predation) Observational comparison of male trait and ‘naïve’ female preference across 7 different populations Naïve females prefer their own population’s male ornamentation characteristics = Evidence that female preference genes co-evolved with male trait

Answer 7

Naïve females = separated from males before maturity (and before colour patterns develop), reared in female-only group

Answer 8

Stalk eye flies Male dimorphism in eye stalk lengths Males with bigger eye stalks win in competition for resources and mates

Answer 9

Artificial selection to increase or decrease male eyespan in different lines, Test female preference in those lines for that ‘short’ or ‘long’ eye span males = Evidence that female preference genes experimentally co-evolved with male trait expression

Answer 10

Peacock tails are extravagant and composed of eyespots which vary in size Females prefer bigger males carrying bigger eyespots Peafowl experimentally single-paired to males with different tail eyespot traits Peacocks provide nothing to females except sperm / gene Sons and daughters grew bigger when fathered by males carrying bigger eyespots Chick groups sired by big-eyed fathers had better % survival in Whipsnade Park

Answer 11

Swallows & mites Males with longer and more symmetrical tails find mates quicker Offspring from males with (naturally) longer tails have fewer mites – even when translocated to other nests. More mites one year -> shorter tail the next year.

Answer 12

Mate choice for the major histocompatibility complex

Answer 13

A large chromosomal region crossing over 200 genes that play a role in immune recognition - differntiation between self and non self High polymorphic, probably due to heteroygote advantage and/or selection for rare types

Answer 14

Influences odour through either microbial flora or concerntrations of volatile acids Experimental observations that when mice are allowed to mate, there are more heterozygous offspring than you would expect from random mating – suggesting mate choice for heterozygous offspring.

Answer 15

Heterozygosity at the MHC confers an immune advantage in mice Higher survival of heterozygotes under pathogen challenge Higher growth of heterozygotes under pathogen challenge

Answer 16

Sexual selection could help to purge mutation load (bad genes) from lineages if…. Mutations influence male mating success in the face of competition and choice OR Mutations are more deleterious in males than females because of sexual selection If either applies, then the average successful father should carry less mutations than the average male

Answer 17

High sexual selection population of Tribolium castaneum vs Low sexual selection in a population of Tribolium castaneum They were allowed to breed 10+ years and 95 generations they were forced through multiple extinction events (population bottle neck, heat or low food ie no yeast) for 5 generations and had there population tracked)

Answer 18

High sexual selection backgrounds resist extinction By generation 15 low sexual selection had gone extinct compared to high sexual selection line which had a population fitness of ~25

Answer 19

The competition within a single female between the sperm from two or more males over the fertilisation of the ova

Answer 20

Selection arises when sperm from two or more males compete for a females ova

Answer 21

Across 203 natural populations, 160 species across all taxa shows that it is quite widely spread, though with varying amounts Some level of polyandry is the norm

Answer 22

How likely sperm overlap and compete

Answer 23

Fish - Seconds Humans - 3-5 days Birds - days to weeks Most insects - weeks to months Bats - weeks to month Solenopsis (Hymenoptera) - >5 years

Answer 24

In a sense all male:male competition is just so much sperm competition

Answer 25

Male:male competition is ultimately: Avoid sperm competition Enhance the sucess of self's sperm

Answer 26

Control female x Male with distictive identifiable trait (marker male) The bred there offspring with organisms with the trait you are investigating Replicate crosses and mating order, then genotype to compare the male success

Answer 27

Control females bred with clubbed antennae (Tribolium) Their offspring where bred with males that were inbred or not The impacts inbreeding has on sperm competition

Answer 28

First males produced fewer offspring than second males In both first and second males the inbred males produced fewer offspring than not inbred

Answer 29

But in a bucket with water make sure conditions are correct Mix and then genotype the offspring to see which were more sucessful

Answer 30

Farmed salmon vs Wild salmon In all group sizes farmed salmon produced more offspring than wild salmon

Answer 31

Behaviour Genitalia Gonads Ejaculates Spermatozoa

Answer 32

Number Size Motility Polymorphism Cooperation Gigantism

Answer 33

Mate guarding - damselfly Male will guard female to prevent female from copulating with other males Pressure finding new to female to mate with vs guarding current female

Answer 34

Plasticity in male mate guarding depending on risk of sperm competition form operational sex ratio More females to males = less mate guarding More males to females = more mate guarding

Answer 35

Anti aphrodisiac - males cover female in antiaphrodiasic to put males off - seen in butterflies Seminal fluid - proteins inserted that makes females less receptive to mating and can cause females to lay eggs earlier - seen in drosophilia Mating plug - seal up females to prevent males from mating which will fall off after a couple days so it doesnt prevent egg laying

Answer 36

Seen in Mnais pruinose (damselfly) which in stage 1 removes sperm and then transfers in its own sperm

Answer 37

Interrupted mating experiments show the different stages of copulation involved in sperm removal More stage 1 inflexions less sperm in total More stage 3 inflexions more sperm from male

Answer 38

Sperm removal allows fertilisation precedence to be almost 100% in some odonates

Answer 39

Bonobo - 168g testes Chimpanzee - 149g testes Human - 34g testes Gorilla - 23g Group living organisms have bigger relative testes compared to both single male or pair living species

Answer 40

Plodia interpunctella (indiameal moth) Polyandry goes up with adult density (OSR) Higher density results in bigger volume of testes meaning males produce and ejaculate more sperm

Answer 41

Copula duration = number of sperm transferred More transferred = more fertilisations = relative sperm number important

Answer 42

Mammalian sperm morphology Harvest mouse, human and African elephant have similar sized sperm Platypus sperm is massive Porcupine sperm is tiny

Answer 43

Bigger sperm are more competitive so more sperm competition means selective pressure on bigger sperm

Answer 44

Anisogamy --> should be more advantgaous to produce more smaller sperm

Answer 45

Not really known. Investment in sperm quality traits evolving within quantity

Answer 46

Tribolium beetles Evolved 4 beetle in lab for 77 generation under either female biased OSRs (low sperm competitive) or male biased OSRs (higher sperm competition) Then compared compteititvely with marker male offspring against both groups each being first of not first

Answer 47

Male-biased OSRs became more competitive and their sperm got bigger

Answer 48

Atlantic salmon Sperm reach peak speed soon after activation Males with faster sperm win ie most likely to be 1st down micropyle

Answer 49

Butterflies and moths produce two distinct sperm types eupyrene (fertile, 10%) and apyrene (nonfertile, 90%)

Answer 50

Female Pieris napi butterflies remate depending on numbers of apyrene sperm not eupyrene sperm in storage Being full of sperm prevented remating not matter sperm type eg sperm dertility

Answer 51

Apyrene sperm as 'cheap filler' in female storage - alternative gametic strategy for sperm competition

Answer 52

Wood mouse Hooks on head to form sperm trains Bigger sperm trains are faster

Answer 53

Drosophila bifurca - 58.3 mm long much bigger than fly Significant associayion between sperm length and female sperm storage size across Drosophila species

Answer 54

Drosophila - evolve females with long and short tracts and males with long and short sperm (these then competited against each other) Long sperm more competitive in female long tracts than short female tracts Short sperm more competitive in female short tracts than long female tracts