Quiz
Sexual Selection
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1In 1871 [blank_start]Darwin[blank_end] proposed the theory of [blank_start]sexual[blank_end] selection
- that certain members of species have special/extravagant traits? Normally only in one sex.
- Why are these traits only present in one sex and not both?
If it was health/[blank_start]fitness[blank_end] benefitting, then both would show > idea of selection was acting on individuals particularly the males
2 types of sexual selection
1. [blank_start]intrasexual[blank_end] selection = one sex competes for access to reproductive opportunities with the opposite sex
2. [blank_start]intersexual[blank_end] selection = when one gender makes mate choices based on specific characteristics in the other/opposite gender, e.g. peacock
both types of selection relate to the [blank_start]male[blank_end], but why?- ADarwin
- Bsexual
- Cfitness
- Dintrasexual
- Eintersexual
- Fmale
2Fundamental differences between the sexes
females = [blank_start]eggs[blank_end] are costly, scarce and immobile > making them very valuable
males = [blank_start]sperm[blank_end] is less valuable, produce billions of sperm
why do we have such different gametes?
Why do we have such different gametes?
- [blank_start]Selection[blank_end] acts against medium size gametes for they are not [blank_start]mobile[blank_end] enough (if too big) and do not provide enough resources (if too small)
- Selection acts against the [blank_start]medium[blank_end] sized and either produces a small, [blank_start]not[blank_end] very costly gamete or a big (immobile) gamete with [blank_start]lots[blank_end] of resources which is very costly
- Aeggs
- Bsperm
- CSelection
- Dmobile
- Emedium
- Fnot
- Glots
3How does this affect male behaviour?
- A lot of fighting between [blank_start]males[blank_end] to access reproductive opportunities
Competition means:
- Restricted reproductive potential
- Promotes a skew in male [blank_start]reproductive[blank_end] success
o Only the [blank_start]dominant[blank_end] males get to mate, leaving the subordinate males without the same reproductive opportunity
Winning is not everything though
- Reproductive [blank_start]success[blank_end] is limited by the scarcity of egg
- If something is scarce it leads to [blank_start]choosy[blank_end] behaviour
- E.g. choosy female bird of [blank_start]paradise[blank_end]
Male success is also due in part to female’s choosiness
[blank_start]Bateman[blank_end]'s principle =
- [blank_start]Females[blank_end] are high selective because their reproductive success is limited
- Traits that are favoured by females will [blank_start]increase[blank_end] in frequency
- Variance in reproductive success promotes [blank_start]promiscuity[blank_end]
o A lot of females will choose the same male- Amales
- Breproductive
- Cdominant
- Dsuccess
- Echoosy
- Fparadise
- GBateman
- HFemales
- Iincrease
- Jpromiscuity
4intra and intersexual selection can sometimes be [blank_start]hard[blank_end] to distinguish
study looking at 2 population of [blank_start]sand[blank_end] gobies (Forsgren et al.)
- sand gobie males like to build nests using [blank_start]mussel[blank_end] shells (resources) for females to lay their eggs in
1st population = not many mussel shells (fewer resources)
- [blank_start]more[blank_end] competition between males
- decreased the choice of a male for females (reduced [blank_start]female[blank_end] choice)
- selection is acting on male [blank_start]body[blank_end] size > [blank_start]intrasexual[blank_end] selection in occurs
[blank_start]Forsgren[blank_end] et al. also looked at a population with lots of mussel shells (lot of resources)
- [blank_start]decreased[blank_end] (ed) competition between males
- [blank_start]increased[blank_end] (ed) female choice
- the males were similar sizes to females; this shows [blank_start]intersexual[blank_end] selection
Selection is acting on male body size; competition varies depending on the mass of resources.- Ahard
- Bsand
- Cmussel
- Dmore
- Efemale
- Fbody
- Gintrasexual
- HForsgren
- Idecreased
- Jincreased
- Kintersexual
5How is sexual selection acting on females: historical thoughts on (female) mate choice
- Early studies focused on male-[blank_start]male[blank_end] competition
- Focus then switched to how [blank_start]female[blank_end] mate choice was controlled by genes
o [blank_start]Proximate[blank_end] factors: how genes affect choice
o Ultimate factors: which [blank_start]genes[blank_end] are favoured?- Amale
- Bfemale
- CProximate
- Dgenes
6Four broad classes of models of how female mate choice was controlled by genes
1. [blank_start]direct[blank_end] benefits
2. good [blank_start]genes[blank_end] (gg)
3. [blank_start]runaway[blank_end] selection (rs)
4. sensory [blank_start]bias[blank_end] (sb)- Adirect
- Bgenes
- Crunaway
- Dbias
71 model of how female mate choice was controlled
1. [blank_start]direct[blank_end] benefit
> female gets something from the [blank_start]male[blank_end], a direct benefit and as a consequence she mates with them
> a [blank_start]genetic[blank_end] predisposition to mate with an individual that provides good resources beyond good genes
> e.g. male [blank_start]dance[blank_end] flies give the females a prey item (pre-[blank_start]nuptial[blank_end] gift); so she doesn't have to expend her [blank_start]energy[blank_end] feeding but can channel more energy into [blank_start]egg[blank_end] production
> the size of the pre-nuptial gift is critical, the longer she spends eating it the longer the male can mate for
[blank_start]Thornhill[blank_end] 1976 demonstrated experimentally that prey [blank_start]size[blank_end] of the pre-nuptial gift is important
- thornhill showed that as the size of the nuptial prey item [blank_start]increases[blank_end] the time of the copulation increases; so more [blank_start]sperm[blank_end] can be transferred into the female
o
Bringing large nuptial gifts is [blank_start]time[blank_end] consuming and dangerous demonstrates quality of [blank_start]male[blank_end]- Adirect
- Bmale
- Cgenetic
- Ddance
- Enuptial
- Fenergy
- Gegg
- HThornhill
- Isize
- Jincreases
- Ksperm
- Lmale
- Mtime
8direct benefit cont.
- example = male [blank_start]redback[blank_end] spiders ARE the nuptial gift
> deposition of sperm
> blackflips into the females [blank_start]mouth[blank_end] = consumed and dies
- it is worth it for the males, for most male redback [blank_start]spiders[blank_end] will die looking for females (very rare)- Aredback
- Bmouth
- Cspiders
92nd model = good [blank_start]genes[blank_end]/indirect benefit
- [blank_start]no[blank_end] direct/nuptial gifts
- females receive an [blank_start]indirect[blank_end] benefit of passing good genes to their offspring
- [blank_start]pronghorn[blank_end] females expend a lot of energy sampling/looking at male harem size
- bigger [blank_start]harem[blank_end] = more successful male
- Ano
- Bgenes
- Cindirect
- Dpronghorn
- Eharem
10Good genes/[blank_start]indirect[blank_end] benefit model cont.
what are females looking at? [blank_start]handicap[blank_end] principle
- honest indicators of quality are expected to be costs
- as cost increases 'fakeability' should [blank_start]decrease[blank_end]
- e.g. in [blank_start]peacocks[blank_end] the bigger the eye spots the higher percentage of chicks that surface produced with the male- Aindirect
- Bhandicap
- Cdecrease
- Dpeacocks
113rd model = runaway selection
the [blank_start]loci[blank_end] for 2 traits are found in males and females but only expressed in the appropriate [blank_start]sex[blank_end]
- in [blank_start]males[blank_end] its active in the expression of that trait
- in females its expressed as a [blank_start]preference[blank_end] for that trait
one of the best examples of it
e.g. the stalk eyed [blank_start]fly[blank_end]
- females prefer males with [blank_start]longer[blank_end] stalks
- male is expressing the trait for long stalks
- and females are selecting [blank_start]males[blank_end] based on the length of their stalks
- need to run an experiment to test for runaway selection
> mate males and females together and examine the preference
> after 13 generations, [blank_start]selectively[blank_end] bred for either long stalks or short stalks in the 2 separate population
> if [blank_start]runaway[blank_end] selection is occuring females from short stalked population should have preferred to mate with the males with [blank_start]shorter[blank_end] stalks - this was seen
- Aloci
- Bsex
- Cpreference
- Dmales
- Efly
- Flonger
- Gmales
- Hselectively
- Irunaway
- Jshorter
124th model = [blank_start]sensory[blank_end] bias/pre-existing bias
- preferences emerge for a trait as a consequence of a [blank_start]neurobiological[blank_end] (neurobiological) response
e.g. if a female bird likes a [blank_start]red[blank_end] food item we might get a selection for red feathered [blank_start]males[blank_end] = development of red feathered males as a consequence of the females [blank_start]preference[blank_end] for a red food item
if we look at phylogenetic history of [blank_start]primates[blank_end]
- some primates possess [blank_start]trichromatic[blank_end] vision (they can see in the red/orange spectrum, 3)
- phylogenetic analysis suggested that early in evolutionary history of primates > that colour vision for the colour [blank_start]red[blank_end]
- colour vision developed, females preference for red and orange items > somewhat later, males started to develop [blank_start]red[blank_end] colouration
pre-[blank_start]existing[blank_end] bias, the preference starts to show in males
- Asensory
- Bneurobiological
- Cred
- Dmales
- Epreference
- Fprimates
- Gtrichromatic
- Hred
- Ired
- Jexisting
13individual learning and mate choice
- experiment involved male [blank_start]quails[blank_end]
- 1 experimental group and 1 [blank_start]control[blank_end]
- both exposed to a certain context
- the experimental group were allowed to [blank_start]mate[blank_end] (females present)
- the control group were [blank_start]not[blank_end] allowed to mate (females not present)
in the test the two groups were exposed to the same [blank_start]context[blank_end] as before, it was found that the experimental group produced [blank_start]more[blank_end] sperm, had learnt about the context and associated in with mating so 'readied' themselves and began to produce more sperm- Aquails
- Bcontrol
- Cmate
- Dnot
- Econtext
- Fmore
14Sexual imprinting in [blank_start]mannikins[blank_end] (clothes)
- males imprinted on their mother who was either adorned with a [blank_start]feather[blank_end] or not adorned with a feather
- when matured, the males were allowed to mate with either [blank_start]adorned[blank_end] or not adorned females
- found that they chose the mate based on whether their [blank_start]mother[blank_end] was adorned or not
- learned their mating preferences from their parents
- highlighted that learning very early can impact [blank_start]later[blank_end] choices
- Amannikins
- Bfeather
- Cadorned
- Dmother
- Elater
15Learning and mate choice in adult [blank_start]Japanese[blank_end] quail
- japanese [blank_start]quail[blank_end] males were allowed to mate with blonde females but not [blank_start]brown[blank_end] females
- all the sexual experience with [blank_start]blonde[blank_end] females
-
over trials, males with experience with breeding with blonde showed preference to interacting with [blank_start]blonde[blank_end] females
- phase two: only exposed to brown female; showed less interest/time associating with brown female
- so shows mate choice can be [blank_start]conditioned[blank_end]
- AJapanese
- Bquail
- Cbrown
- Dblonde
- Eblonde
- Fconditioned
16[blank_start]cultural[blank_end] transmission/social learning and mate chocie
- mate choice is affected by the preference of other, mate choice copying
- black [blank_start]grouse[blank_end] males were used
- [blank_start]black[blank_end] grouse male territories were [blank_start]randomly[blank_end] selected
- dummy [blank_start]females[blank_end] placed on the territories
- then real females brought it > did this effect their mating choices [blank_start]yes[blank_end]!
- some of the male black grouse started [blank_start]mating[blank_end] with the dummies others did not, this effected the females choice
- the real females were [blank_start]more[blank_end] attracted to the males who appeared to be mating with other (but really just the dummies)- Acultural
- Bgrouse
- Cblack
- Drandomly
- Efemales
- Fyes
- Gmating
- Hmore
17song learning and cultural transmission
- [blank_start]cowbirds[blank_end] (moo) were cross-fostered from south dakota and [blank_start]indiana[blank_end] which have [blank_start]different[blank_end] songs
- if If [blank_start]cultural[blank_end] transmission is occurring, then males should learn from their [blank_start]cross[blank_end]-fostered parents and [blank_start]females[blank_end] should choose the songs of their foster parents
showed that males learned the songs of their cross-[blank_start]fostered[blank_end] parents and females showed a [blank_start]preference[blank_end] for the song of their cross-fostered parents
- if there was a [blank_start]genetic[blank_end] basis the birds would not learn the songs/have a preference of their cross-fostered parents
- Acowbirds
- Bindiana
- Cdifferent
- Dcultural
- Ecross
- Ffemales
- Gfostered
- Hpreference
- Igenetic
18[blank_start]intrasexual[blank_end] selection = the best quality male gains priority access to females
- e.g. in red [blank_start]deer[blank_end] initially use vocalisations (roaring), if there is little difference they begin to…
- engage in a [blank_start]parallel[blank_end] walk so they can compare their physical size if there is little difference…
- they engage in a [blank_start]fight[blank_end]
o very costly, so only engage in fight as [blank_start]last[blank_end] resort- Aintrasexual
- Bdeer
- Cparallel
- Dfight
- Elast
19Interference Competition and Selection
- females sometimes incite competition to assess who is dominant
- e.g. [blank_start]elephant[blank_end] (trunk) seals
o females vocalise to call [blank_start]dominant[blank_end] male if they are mounted by subordinate males
- females protest is subordinate try and mate
- very effective at soliciting help from dominant male
- often led to [blank_start]mating[blank_end] with dominant
- other strategies that have evolved
o blurring between inter and Intrasexual selection
o competition between males but females are involved in provoking this aggression- Aelephant
- Bdominant
- Cmating
20selection acts on size/sexual size dimorphism
- if individuals hold big harems = the levels of [blank_start]dimorphism[blank_end] are very extreme, very large males compared to [blank_start]females[blank_end]
but size isnt everything; there are other strategies
e.g. the blue [blank_start]gilled[blank_end] sunfish has 3 different morphs
- the [blank_start]parental[blank_end] morph - gets a territory, very aggressive and big and tries to attract females to lay [blank_start]eggs[blank_end]
- [blank_start]sneaker[blank_end] morph hang around on fringes of parental morphs territory, when the female comes in the sneaker morph will try to run in an inseminate the [blank_start]eggs[blank_end] before he is attacked by the parental morph
- [blank_start]satellite[blank_end] morph = look very like [blank_start]females[blank_end], drift in with females hoping not to be spotted, once the female lays eggs they try and inseminate the eggs
the parental morph sperm are [blank_start]not[blank_end] always in competition, the sneaker morph is always in competition
so selection acts on the [blank_start]size[blank_end] of testes, knock on effect to the quality, lots of sperm but poorer quality
- Adimorphism
- Bfemales
- Cgilled
- Dparental
- Eeggs
- Fsneaker
- Geggs
- Hsatellite
- Ifemales
- Jnot
- Ksize
21sperm competition and races
- [blank_start]Drosophila[blank_end] (fly) sperm competes inside the female
- [blank_start]selection[blank_end] does act on sperm!
there are a whole range of strategies adopted by males to ensure their genes/sperm are passed on: (mostly in [blank_start]insects[blank_end])
- sterile [blank_start]filler[blank_end] sperm; aim to pack the female with their sperm
- can remove [blank_start]sperm[blank_end]
- anti-[blank_start]aphrodisiac[blank_end] odours on their sperm, to make her less attractive to other males
- can flush out
- copulatory [blank_start]plugs[blank_end]
- there are also accessory [blank_start]proteins[blank_end] with can incapacitate rival sperm
females are not passive either- range of evidence
- example from [blank_start]fowl[blank_end] (chickens), females can eject sperm after copulation
- [blank_start]flycatcher[blank_end] (flycatcher) birds can store sperm for [blank_start]1[blank_end] month- ADrosophila
- Bselection
- Cinsects
- Dfiller
- Esperm
- Faphrodisiac
- Gplugs
- Hproteins
- Ifowl
- Jflycatcher
- K1
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- Description
- Behaviour Quiz on Sexual Selection, created by sophie waddington on 21/12/2018.
- Author
- sophie waddington
- Language
- English
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