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Animal Behavior > Sex and Reproduction > Flashcards

Sex and Reproduction Flashcards

1
Q

Costs of sexual reproduction

A
  • loss of 50% genes
  • energetic cost of producing gametes
  • time & energy invested in courtship & mating
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2
Q

Asexual reproduction species

A
  • New Mexico whiptail
  • some invertebrate animal species
  • some fish, amphibians, reptiles
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3
Q

Benefits of sexual reproduction

A
  • offspring more varied
  • mutations reduced
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4
Q

Isogamy

A

identical gametes

microorganisms

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5
Q

Anisogamy

A

different gametes

most plants & animals

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6
Q

Why two sexes?

A
  • Sexual reproduction X require (only needs gametes)
  • Small gametes (sperm): increased probability of encountering & fertilizing large gametes
  • Large gametes (eggs): can carry more nutrients & resources
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7
Q

Why is the sex ratio typically 1:1? (Fisher)

A
  • Frequency-Dependent selection acting upon the individual
  • female dominated –> advantage to produce males
  • male dominated –> advantage to produce females
  • a female-biased sex ratio X evolutionarily stable
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8
Q

Alligator sex determination (Ferguson & Joanen)

A
  • temp of egg determines sex of offspring during 2nd & 3rd week of incubation
  • 30 C below –> all females
  • 34 C above –> all males
  • ~32 –> lean females
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9
Q

Red deer (Clutton-Brock)

A
  • maternally-sub sons less reproductive success than maternally-dom
  • daughters equal reproductive success regardless of maternal dominance
  • hypothesis: natual selection might favor ability to adjust progeny sex ratio in relation to parents’ ability to invest in offspring (dominance = more resources for offspring)
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10
Q

Cameron (2004) (more on the red deer shit)

A
  • mothers in good condition have more sons
  • higher uterine glucose levels favor the development of males
  • reveals a potential mechanism for sex-ratio variation in relation to maternal condition around conception
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11
Q

Viviparous mite

A
  • mom produces brood of 1 son & ~20 daughters
  • son mates w/ sisters inside & dies before born
  • no selfish mutants for rare sex to take advantage (limited by environment)
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12
Q

“Ideal” (optimal) mating systems

A
  • male acquires as many mates as possible & invests little in parental care
  • females select “fit” male & leaves parental duties to him while acquiring resources required to produce more offspring (female is more “selective” sex)
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13
Q

Bateman Effect

A
  • as mates increase, mean # of offspring increases for males increases; stays the same for females –> no advantage to increasing mates EXCEPT genetic diversity
  • mean # offspring range much wider for males than females
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14
Q

Moulay Ismail

A
  • Emperor of Morocco
  • 548 sons & 340 daughters in his harem of 500 women during his life (~1.2 copulations/day for 62 years)
  • unlikely due to following factors:
  • ovulation frequency combined w. sperm survival (women fertile only 12.5% of time)
  • female infertility
  • conception likelihood
  • prenatal mortality
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15
Q

Mating systems

A
  • Polygyny (male w. multiple females) –> baboon, safe grouse, elk
  • Promiscuity (both sexes have multiple partners) –> Japanese macaques, bonobos
  • Polyandry (female w/ multiple males)–> seahorses
  • Monogamy (1 male, 1 female) –> only ~5% of species
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16
Q

Ecological factors influence how animals are distributed in space

A
  • Polygyny –> small groups of females
  • Promiscuity –> large groups of females or lack of male dominance
  • Polyandry –> male reproductive output limited by time/energy constraints or female behavior
  • Monogamy –> environmental demands require both male and female input for offspring survival
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17
Q

Polygyny types

A
  • Female defense polygyny: males directly defend several females from other males (greater spear-nosed bat, elk, lions)
  • Resource defense polygyny: males w/ multiple females that are attracted to resources under his control (polygyny threshold model) (red-winged birds)
  • Lek polygyny: multiple females attracted to male display territory (topi bulls, hammer-headed bat, leaf-cutting ant)
  • Scramble competition: male acquires multiple widely scattered mates by being the first to encounter them (horseshoe crab, 13-lined ground squirrel)
18
Q

Polygyny threshold model (lark buntings)

A
  • shade important to keeping nestlings cool
  • females may choose a “polygynous territory” of a male” w/ good shade cover of a “monogamous territory” w/ less shade, even if the polygynous male restricts aid in rearing nestlings to first female
19
Q

Cock-of-the-rock

A
  • Lek Polygyny
  • males assemble in dozens & squabble amongst themselves
  • female spotted –> males spread out & claim plot of land –> try to persuade female to land next to him by competitively bouncing
  • peck neck –> chosen –> immediate fornication
  • female will lay eggs alone
  • another female may choose same male
  • increases chance of displaying to females even in few actually mate
20
Q

Scramble competition polygyny

A
  • female usually mates once
  • males X need to display or compete
21
Q

Jacana

A
  • 1 female, male harem
  • female guards territory, need male to watch over nests
  • ~4-5 nesting males
  • predation stresses female in protecting eggs –> recruit males to help + increase in female size to produce more eggs
22
Q

Sexual selection (first proposed by Darwin)

A

selection for traits that are attractive to mates/ traits that concern competition for mates

subdivision of Darwinian selection that concerns mating

23
Q

Long-tailed widow bird (Andersson)

A
  • females preder longer tails even if diff performance areas are weaker
  • dangerously low flights & jumping competitions (in other widow bird species)
23
Q

Intersexual selection

A
  • involves exaggerated traits that one prefers in the other
  • ex. sage grouse, magnificent frigate bird: puffed chests
  • ex. bats: male perfumes scent onto female, female chirp to determine male fitness
24
Q

Bower birds

A

males w/ more decorations @ nest get more females (tend to match colors)

25
Q

Sexual selection hypotheses

A
  • “Runaway” selection (Fisher)
  • Disease/parasite avoidance (Hamilton & Zuk)
  • Handicap principle (Zahavi)
26
Q

“Runaway” selection (Fisher)

A
  • tail length increases due to combination of both survival advantage & female choice
  • optimal tail length for survival heightened largely due to female choice
  • what else promotes a certain trait to “run away” & succeed? –> female choice
27
Q

Female sticklebacks

A
  • use male coloration to identify healthy mates and avoid parasite-infected males
  • brighter red males chosen
  • effect disappears under green light
28
Q

European blackbirds (Biard)

A
  • eating foods w/ carotenoids results in darker beaks –> more sexually attractive to females
  • plant pigments: involved in antioxidant activity & conversion to vitamin A –> increased perceived immune system health
29
Q

House finches (Oh & Badyaev)

A
  • duller-colored males more appealing by being more social prior to mating season
  • by mating season, less attractive male have = success as brightly colored males
30
Q

Disease/parasite avoidance hypothesis (Hamilton & Zuk)

A

some traits signal good health

sticklebacks, house finches, European blackbirds

31
Q

Handicap principle (Zahavi)

A

cost of the trait assumed is cannot be faked by lower-quality males –> effective mechanism for secual selection

32
Q

Results of intrasexual selection on males

A
  • guarding behavior
  • sperm plugs
  • biochemical substances that reduce female receptivity
  • low threshold for mating attempts
  • monopolization of females
  • postponement of mating attempts
  • “sneak” copulations
  • forced copulations
  • sexual interference
  • female mimicry by males
  • assaults on male competitors
  • assaults on offspring of competitors
  • size of testes
33
Q

Guarding behavior

A
  • damselfly: similar to dungflu copulation guarding; use appendage to hold onto female
  • lovebugs: 56 hour copulation tie
34
Q

Sperm plugs

A
  • green anaconda
  • dragonfly: barbs & flagella allow for 2nd male to remove sperm of first
  • primates: penile morphologies - adaptations for sperm removal?
  • orb-weaving spider: male self-destructs during mating –> corpse remains wedged in female
35
Q

Biochemical warfare that reduce female receptivity

A
  • Postman butterfly: during copulation, male deposits scent into female that makes her unattractive to other males
36
Q

Low threshold for mating attempts

A
  • Cock-of-the-rock: presented w/ opportunity –> male proceeds quickly
37
Q

Postponement of mating attempts & “sneak” copulations

A
  • Baboons: sub males may wait for mating opportunity when alpha male unaware
38
Q

Forced copulations

A
  • Scorpionflies: courtship –> female reject –> male use appendage to grasp onto female & mate –> female may try to escape
  • Orangutans
  • Ducks: some female ducks’ vaginas spiral in opposite direction of male phallus & longer (species w/ fewer forced copulations tend to have shorter & simpler genitalia)
39
Q

Female mimicry

A
  • Garter snakes: late male may represent self as female via pheromones
  • Sticklebacks: non-territorial male behaves like female –> allowed into territorial male’s nest –> may deposit sperm into female instead of actual male
  • Western marsh harrier hawk: female-like males may access breeding resources while avoiding costly fights w/ typical territorial males (fem hawks attacked & attack less, may be adaptive)
40
Q

Size of testes

A
  • Primates: tend to be relative to body weight
  • Yellow-toothed cavy
  • Bushcrickets: largest testes to body-ratio –> deposit only small amounts of sperm/mating –> likely for mating w/ many females vs. competitively intrasexually
41
Q

The Evolution of Animal Weapons (Emlen)

A
  • tendency for weapons to begin small –> more ornate
  • smaller = more damaging (only role to attack other males)
  • more elaborate = less injury/death (use as signal to females/ritualized combat)

Animal Behavior (9 decks)

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