動物行為學通識 03 生殖行為鄭先祐 (ayo) 國立臺南大學環境與生態學院...

動物行為學通識

03 生殖行為鄭先祐 (Ayo)

國立臺南大學環境與生態學院生態科學與技術學系教授

Ayo NUTN Web: http://myweb.nutn.edu.tw/~hycheng/

國立臺南大學通識課程 2011 年春

http://myweb.nutn.edu.tw/~hycheng/



Ayo 2011 動物行為學(通識) 2

03 生殖行為• 3.1 性擇 (Sexual selection)

• 3.2 性內天擇 – 競爭性伴• 3.3 性間天擇 – 選擇性伴• 3.4 性衝突 (Sexual conflict)


3.1 性擇 (Sexual selection)

有些物種奇特的特徵，是來自性擇的結果：• 性內天擇 (Intrasexual selection) ：雄性競爭性

伴• 同性 ( 通常是雄性 ) 個體相互打架 ( 競爭 ) ，

贏者可以獲得性伴 ( 雌性 ) 。• 演化朝向增大競爭用武器。

• 性間天擇 (Intersexual selection) ：雌性選擇性伴 • 通常是雌性個體按其喜愛，選擇接受為性伴• 雄性為吸引雌性，而競爭。


生殖行為的性差異

• 雄性的招潮蟹有大螯。• 雄性間的打鬥和吸引雌性

• 於動物世界• 雄性為獲得雌性，競爭 • 雌性選擇是否接受某個雄性個體 ( 性伴 )

• 雄性與雌性的配對策略差異是來自 • 生殖投資量的差異。• 配子生產，受精卵孕育和親代照顧


生殖行為的性差異

• 雌性產生較少、較大，較耗能的卵子；雄性產生數百萬小的精子。• 雄性競爭為獲得較有限的資源 ( 雌性的卵 )

• 雌性個體提高其生殖成功率，是要找到最佳雄性，讓其有限的卵授精。多個性伴，並不會增加其生殖成功率。• 雄性生殖成功率，因增多性伴，而增加。

• 雄性個體往往是 “ undiscriminating eagerness”

• 雌性個體則是 “ discriminating passivity”


Differences in parental care

• There is differential investment in offspring between the sexes• Also responsible for competition and

mate choice• The sex that provides more parental

investment for offspring (usually the female) becomes a limiting resource • The sex that invests less (the male)

competes for access to females • Females have the luxury of choosing

among available suitors


案例：求偶角色 in katydids ( 螽蟴 )

• 雌性個體產生子代的數量，受到來自雄性個體的禮物 (spermatophore) ( 精蟲包 ) 的提升。

• 來自雄性個體的禮物，其重要性取決於食物的供應量。

• 當食物缺乏情況，禮物就非常重要。• 雌性個體未獲得雄性個體而競爭 (females

compete for males)• 當食物豐盛時，禮物的重要性下降。

• Males compete for females


性別角色互換的物種

• 當雄性個體比雌性個體，投資更大於照顧子代。• Females of these species compete for

males• Males are discriminating in their choice of

mates• 於性別角色互換的物種

• males are choosy • Females actively compete for mates


案例：生殖競爭 in meerkats

• Meerkats 是合作繁殖的非洲哺乳類。• 單一顯要的雌性個體 monopolizes

reproduction• 雌性個體表現標準哺乳類的特質， greater

parental investment (gestation and lactation)

• 雌性個體間的生殖機會競爭，相當激烈。• 雌性繁殖者，有較大的體重，

testosterone, 和 aggression


雌性於求偶和交配過程，未必是被動。

• 雌性個體於生殖活動過程，會主動參與。• 誘發交配 from one or several males• 案例：雌性果蠅 approach and pursue males• 雌性個體以 becoming immobile ，表現出 their

enthusiasm and willingness to mate • 案例：雌性 bonobos ( 倭黑猩猩 ) are

dominant to males and mate promiscuously ( 混雜地 )

• With males from within their community and other communities


• Bonobos ( 倭黑猩猩 )

• 倭黑猩猩，又名矮黑猩猩或侏儒黑猩猩，英文名：Bonobo 或 Pygmy

Chimpanzee ，• 學名是「 Pan paniscus 」。


確保交配： dominance behavior

• 雄性個體確保交配， by dominating other males and excluding competitors from females

• 這需要投資於更強壯和更有效的「武器」。但雌性個體就不需要。• 案例：如鳥類和哺乳類，雄性個體通

常比雌性個體，體型較大，而擁有較大的打鬥能力和生殖成功率。

• Sexual dimorphism


Sexual dimorphism

• Results from • 雄性個體間的競爭• 雌性個體對詞性生殖成功率的影響• 掠食壓力，對雄性和雌性的差異• 食物的差異

• 案例：• 蚊子的口器，雌雄有差異。

• 雄性是吸食花蜜，磁性是吸食血液。• purple-throated carib hummingbirds (蜂

鳥 )• 雌雄各吸食不同類花的花蜜，其雌雄的鳥嘴長度與彎度各不同。


• Purple-Throated Carib (Eulampis jugularis ) hummingbirds


Male dominance relationships

• 於有形成雄性顯要地位關係的物種，高位階的雄性有較高的生殖活動力和有較高的生殖成功率。• 顯要的雄性個體可干擾次位階雄性

個體的交配行為。• 次位階雄性個體，只能偷偷進行交

配。

The Stump-tailed Macaque (Macaca arctoides), also called the Bear Macaque, is a species of macaque found in Southern Asia.


確保交配：另類生殖策略

• 藍鰓魚 (bluegill sunfish) ，雄性表現出多型態(polymorphism)• parentals or cuckholders

1. Parental 雄性個體，七歲才性成熟。• Compete for sites, guard females, and care

for the young

2. Cuckholders 雄性，兩歲就性成熟。 • Do not build and defend nests, or provide

parental care


另類生殖策略1. Parental 雄性個體，七歲才性成熟。 2. Cuckholders 雄性，兩歲就性成熟。

• Sneakers: 小型雄性個體，偷偷溜入巢內排精。

• Satellites: 較大型雄性個體，長相類似雌性個體 (female mimics) with the coloration and behavior of mature females. Female mimics enter a nest and release sperm 。


• bluegill sunfish (藍鰓太陽魚 ) • 分布於北美洲聖勞倫斯河五大湖區

與密西西比河流域至墨西哥北部間的溪流及湖泊中。


兩生類雄性交配策略 (mating tactics)

• Male natterjack toads employ loud, energetically expensive calls to attract females. All males are capable of calling

1. Large males are callers

2. Small males are satellites that remain silent and intercept females attracted to the calls of the other male

3. Intermediate males alternate opportunistically

http://upload.wikimedia.org/wikipedia/commons/c/c0/BufoCalamita_Sand.jpg


Male Dall’s porpoises guard their mates

• Male-female pairs of Dall’s porpoises• Maintain shorter distances

between one another• Remain close for longer durations• Surface in synchrony and • Are less likely to join other

individuals or groups• Males respond more aggressively to

approaches by adult males


Mate guarding reduces extra-pair fertilization

• Male mate guarding reduces the risk of cuckoldry

• A male Seychelles warbler closely follows his mate prior to egg laying• The time when she is most

receptive• Guarding make sense: a pair

produces a single clutch with a single egg • To ensure that the nestling is

his own


Sperm competition: removing rival sperm

• A male removes rival sperm• Damselfly males use their penis to

transfer their sperm and remove sperm previously deposited by competitors

• Male spider crabs push the ejaculates of earlier males to the top of the female’s sperm storage receptacle and seal them off with a gel


Sperm competition: sperm heteromorphism

• The simultaneous production by a single male of at least two types of sperm in the same ejaculate• One sperm morph can fertilize

eggs (eusperm) • And one cannot (parasperm)

• Occurs in mollusks( 軟體動物 ), insects, fishes


Hypotheses for the evolution of parasperm

• 扮演於精蟲競爭時的功能• Killing or displacing sperm • Inhibiting remating by the female or

blocking sperm• Facilitating the survival, transport or

readiness of eusperm• Providing nutrients to the female, eggs or

the eusperm• Diluting the effects of spermicides

produced by females


Avoiding sperm displacement: retaliatory (回敬的 ) copulations

• Males try to prevent sperm displacement by rival males

• 案例： Rocky Mountain bighorn sheep females mate with several males• Subordinate males (coursing rams公

羊 ) force copulations on ewes(母羊 ) guarded by tending rams

• Tending and coursing rams copulate with ewes(母羊 ) to increase the proportion of their own sperm in the female

• Dominant males mate right after copulation by a coursing ram


Avoiding sperm displacement: retaliatory copulations

• Dominant males mate right after copulation by a coursing ram• Displaces rival sperm• Sperm from the last mating fertilizes

the eggs


Avoiding sperm displacement: prolonged ( 拖延的 ) mating

• Two hypotheses to explain the function of prolonged mating

1. Extended mate guarding: reduces the chances that the female will be inseminated by another male

2. Ejaculate transfer hypothesis: prolonged mating results in more of the male’s sperm being transferred to the female


Avoiding sperm displacement: prolonged ( 拖延的 ) mating

• 案例： A large orb-weaving spider copulates several hundred times with a female• Smaller, peripheral males hang

around but don’t copulate• Supports the mate-guarding

hypothesis• Mating duration did not influence the

number of sperm • The ejaculate transfer hypothesis

is not supported• orb-weaving spider


Avoiding sperm displacement: repellents and copulatory plugs

• Males may apply a repellent (驅除的 ) odor to their mates• 案例： Male neotropical butterflies

( 橘釉蛺蝶 ) transfer an “antiaphrodisiac” pheromone to a female, making her repulsive to other males

• A male may deposit a copulatory plug in the female’s reproductive tract • 案例： In many snakes, lizards,

marsupials, rodents, bats and primates

• neotropical butterflies ( 橘釉蛺蝶 )


Male spiders use copulatory plugs

• In Argiope aurantia, the male dies within seconds of mating • Becoming a whole-body mating plug

• Copulating male golden orb web spiders protect their paternity by leaving parts of their pedipalps in the genital openings of females


• Some male spiders leave parts of their copulatory organs in the genital tracts of females with which they have mated. Such parts appear to obstruct matings by subsequent males. Male’s pedipalps (E, embolus 栓子 ), C for conductor 導體 .


Females may benefit by mating with more than one male

• Mating with several males may • Increase the probability of fertilization • Increase the genetic diversity of

offspring • Result in the accumulation of material

benefits if males provide nutritional gifts at copulation

• Ensure that a female’s sons are good at the game of sperm competition, if the trait is heritable


Sexual interference: infanticide

• Infanticide: killing a competitor’s offspring• In both invertebrates and

vertebrates• Infanticidal males kill unrelated

infants• Increasing a male’s chance of

siring the next infants

• Here, a lion has killed the cub of a rival male.


Intersexual selection

• One sex chooses individuals of the other sex as mates

• Females often do the choosing • Males compete among themselves to

be chosen• Sometimes males choose and female

compete • Characteristics used by females to select

a mate should affect female fitness• Be assessable ( 可評估的 )• Vary among males


Criteria by which females choose mates

• Females choose mates on the basis of their ability to provide • Sufficient sperm• Useful resources• Parental care• Genes that are good or compatible

• Direct material benefits obtained by the female: sufficient sperm, useful resources food or nest and parental care

• Indirect benefits: good or compatible genes benefit the female’s offspring


Ability to provide sufficient sperm

• Female stone crabs prefer unmated males and use chemical cues to assess male ability to transfer sufficient sperm• Males experience sperm depletion

with successive matings • Females spend more time near

unmated males


Males provide useful resources

• Females choose a mate on the quality of resources he provides• Females receive immediate gains from

gifts • Or long-term benefits from access to

valuable resources (food or nest sites) • Females that exchange mating for

material goods are advantaged• Resources improve offspring

survivorship and competitive ability• Females evaluate potential mates

through their material goods


Males present a gift of prey

• nuptial gifts in scorpionflies• Female choose male that bring

relatively large prey items during the courtship process

• These nuptial gifts, which are consumed during courtship, provide females with a direct tangible benefit, food.

• There is a positive relationship between prey size and copulation time.


Some animals offer themselves as gifts

• In some spiders, scorpions, and mantids ( 螳螂 )• The male gives his body to the

cannibalistic female• The male redback spider ( 紅背蜘蛛 )

stores his sperm in a tightly coiled structure (a palp) on his head• The coil unsprings and sperm is

transferred while the female eats him


Some animals offer themselves as gifts

• Males gain two advantages from suicidal behavior • A cannibalized male fertilizes

twice as many eggs as a male who survives copulation because he copulates twice as long

• A female is less likely to mate again after she’s eaten

• redback spider ( 紅背蜘蛛 )


Females selecting a mate assesses the quality of his territory

• Female house wrens select a mate based on the number of nest sites in his territory• Males with the most nest boxes

were selected first • Extra nest sites decrease the chances

that the female’s own nest would be found by predators


Females assess a male’s parental abilities

• In other species, females evaluate the amount or quality of food on a male’s territory

• Females use physical or behavioral features of males to predict parental quality

• Some female birds judge male parental ability on the quality of nutritional gifts provided during courtship• Lots of high-quality gifts signal a

male’s superb foraging skill and willingness to feed his mate and offspring


Females assess a male’s parental abilities

• A male European crossbill passes regurgitated(反芻 ) seeds to a female.

• Females may judge the parental ability of a male by the quality and quantity of gifts provided during courtship feeding.


Female gobies judge males

• They use a current’s speed to judge the parental abilities of potential mates

• Male gobies ( 蝦虎魚 ) build nests and provide sole care to the eggs• Female gobies favor males that court in

the fastest water• Only exceptional males can dance in

fast currents • Males unable to court in fast currents

are less well-conditioned and more likely to consume their eggs

• Courting in fast current is an “honest signal” of a male’s ability to offer paternal care


Male gobis court in fast currents

• The water velocity where a male dances is positively correlated with survival of his eggs


Male physical condition and dominance indicate genetic quality

• Male satin bowerbirds build stick structures (bowers) they display to females• Males decorate their bowers (涼亭 )• They prefer blue and purple flowers • Orange, red, and pink are unacceptable • Males also chew leaves and paint the

mixture on the walls • Bowers and their decorations indicate male

quality • Males steal decorations from

competitors


• Bower↑• Satin bowerbirds → male

• female →


Female bowerbirds prefer exotic ( 奇特的 ) bowers

• Females favor males who exhibit exotic decorations • Accumulating and holding these

decorations indicates that a male is in top physical condition

• The number of flowers and rare decorations could be used by females to assess the experience of a male


Mice MHC-dependent mating preferences

• Female house mice use odor cues to select males with a different makeup of the MHC region

• Females prefer males with different MHC regions• To avoid inbreeding • But extreme outbreeding may cause the

breakup of successful parental complexes of genes

• Females strike a balance between extreme inbreeding and outbreeding when choosing a mate

MHC = major histocompatibility complex


Female mice increase offspring resistance

• A female can increase her offspring’s resistance to disease• By choosing a male whose MHC

alleles differ from hers• She increases the variability of the

MHC region in her offspring• Making them resistant to a wider

variety of disease-causing organisms


Origin and maintenance of mate choice

• How do female mate preferences originate when there are no direct benefits?• The female’s preference affects

her offspring’s fitness, not hers• Explanations for the origin of

preferences that do not involve direct material benefits

1. Indicator mechanisms

2. Runaway mechanisms

3. Sensory bias


Indicator mechanisms

• Often called good genes model• Assume that a particular trait in males

indicates viability ( 發育能力 )• And both the trait and viability have

a genetic basis• If a female preference (genetically

based) for the male arises • Females mate with males carrying

genes for the trait and enhanced viability

• Genes for the male trait, high viability, and female preference become associated


A good genes model: exaggerated male traits and offspring viability

• Peacocks(孔雀 ) have a train of long feathers• Each tipped with an iridescent

“eye” • Peahens prefer males with

elaborate trains• Male mating success is

correlated with the number of eye-spots

• A female visits multiple males before copulating


Sexual ornamentation (裝飾 ) is correlated with survivorship

• Peacocks killed by foxes had also been unsuccessful in mating

• Offspring of males with elaborate trains weighed more • And had more attractive to females.• But may lower survival


Runaway mechanisms

• Runaway (Fisher or Fisherian) mechanisms: the male trait is correlated with the female preference for that trait

• It begins when females evolve a preference for a particular male characteristic

• A female that mates with a male with an attractive characteristic has sons with the trait

• If the attractive character of the male is inherited

• Her daughters will show a preference for that trait

• The attractive sons acquire more mates with a preference for that characteristic

• And leave more progeny

• 案例： Stalk-eyed flies and runaway selection


When does runaway selection stop?

• It can produce increasingly exaggerated male traits • And a stronger female preference for them

• Females acquire genes that make their sons attractive• Runaway selection results in mate choice for arbitrary

or disadvantageous traits• The process is stabilized when natural selection

balances sexual selection • The male trait becomes too energetically costly to

produce • Or when males are less likely to escape from

predators


Sensory bias

• Female preferences for male traits evolve because these traits stimulate an existing bias in the female’s sensory system• i.e. females have a sensory bias to help

them find certain colored food• Males exploit this bias by using the same

color to attract females during courtship• Male satin bowerbirds decorate their bowers

with blue grapes • Female regent bowerbirds and satin

bowerbirds prefer to eat blue grapes


Learning and mate choice

• Sexual imprinting• Young individuals quickly learn mating

preferences from their interaction with adults.

• Imprinting is restricted to some small time window during normal development, but the length of this window varied dramatically across species.

• Learning and mate choice in mannikin bird


Experimentally examine sexual imprinting

Using the cross-fostering approach. Employing the “novel trait” approach,

in which offspring are raised by parents that have some novel trait that an experimenter has introduced.

Using the novel trail approach to studying sexual imprinting on the mannikin bird, Lonchura leucogastroides.


Four groups

1. Group 1, served as a control.

2. Group 2, offspring were raised with their mother and father, each of whom had a red head feather attached to their forehead.

3. Group 3, father with a red feather

4. Group 4, mother with a red feather.

• Young mannikins imprinted on the red head feather of their parents, and expressed a preference for such adorned birds when they themselves matured.


Cultural transmission and mate choice

• Mate-choice copying • When a female’s mate-choice

preference is affected by the preference of other females in her population.

• 案例：• Mate-choice copying in grouse


Once some females have chosen mates, mate-choice copying will play a role in the mating decisions of other female black grouse, as they choose to mate with the males chosen by other females.


Black grouse and mate-choice copying

• A single “top male” grouse obtains about 80 percent of all the mating at an arena (lek).

• Older females mated, on average, three days earlier than younger females, suggesting that mate-choice copying, if it occurred, was most common among younger females.

• Using stuffed “dummy” females placed randomly on a male territory within a lek. • Males courted these dummy females and even mounted

them and attempted numerous copulations.• Females were more interested in mating with a male who

had copulated with other females on his territory, even if they were dummy females.


Song learning and mate choice in cowbirds

• Cowbirds• One population from South Dakota (SD)• One from Indiana (IN)

• Cowbirds display different social behaviors and sing different songs across populations.

• A cross-fostering experiment (Fig. 6.28)


Song learning and mate choice in cowbirds

• Birds paired up and mated with others who came from the same rearing regime (IN or SD) in which they were raised.• SD birds raised with SD adults preferred SD

birds as mates, and SD birds raised with IN birds preferred IN birds as mates– the mating preferences of the SD birds were strongly dependent on the social environment in which the birds were raised.

• Males copied the songs of the adults with which they were raised.


問題與討論

[email protected]

• Ayo 台南 NUTN 站 http://myweb.nutn.edu.tw/~hycheng/

動物行為學 通識 03 生殖行為 鄭先祐 (ayo) 國立 臺南大學 環境與生態學院...

Documents

動物行為學通識 03 生殖行為鄭先祐 (ayo) 國立臺南大學環境與生態學院...