單親幼兒最出色
單親母親在撫養(yǎng)孩子方面比雙親要好——至少在鳥的世界是這樣的。母斑胸草雀必須在努力工作并且親自撫養(yǎng)較少的鳥，但是她們撫養(yǎng)的雄性后代更有吸引力，更容易得到配偶。
這個(gè)發(fā)現(xiàn)顯示家庭沖突是與捕食和食物提供方式這樣的生態(tài)因素同樣重要的進(jìn)化推動(dòng)力。身邊有雙親就總有利益沖突，這會(huì)對(duì)后代的質(zhì)量產(chǎn)生的害的影響。
從進(jìn)化的角度講，在動(dòng)物界，任何一個(gè)父親或母親的策略是讓他人來照顧后代，這樣，他們就可以集中精力再次繁殖后代了。所以父母之間很自然就出現(xiàn)了相互推卸的責(zé)任的現(xiàn)象。但是蘭卡斯特大學(xué)的IanHartley及他的工作組想知道家庭是如何解決這個(gè)沖突的，以及沖突本身是如何影響后代的。
為了找到答案他們衡量斑胸草雀撫養(yǎng)它們的子女花了多少力氣。他們監(jiān)控每個(gè)母親或父親采集的食物量，以及移動(dòng)或增加小鳥，因此每對(duì)草雀養(yǎng)4只小鳥，每只單身母雀養(yǎng)兩只——假定這是相同的工作量。通過這些方法他們對(duì)單身母雀和成對(duì)草雀做了比較。
但是他們發(fā)現(xiàn)單身母雀比與配偶共同撫養(yǎng)后代的母雀多付出25%。如果公雀太懶的話，為了避免筋疲力盡，有配偶的母雀并不十分努力工作。這樣做的后果就是后代付出代價(jià)。Hartley說：“后代要為這種沖突付出某些代價(jià)。”
這種代價(jià)不是表現(xiàn)在身材和體重的銳減，而是表現(xiàn)在他們對(duì)異性有多大吸引力上。當(dāng)小鳥長(zhǎng)大后，研究者通過提供給雌性她們所選擇的伴侶的方法檢驗(yàn)雄性后代的健康情況。那些由單身母親扶養(yǎng)大的雄性比由父母撫養(yǎng)大的雄性更多地被選中。
研究鳥類父母沖突的劍橋大學(xué)動(dòng)詞學(xué)家rebeccaKilner說，很久以來人們就認(rèn)為兩性之間的沖突會(huì)影響對(duì)后代的照顧。"但是試驗(yàn)證據(jù)并不充分，這個(gè)突破主要是以經(jīng)驗(yàn)來顯示這種影響的。"
Kilner說更為令人驚訝的是Hartley說這種沖突可能會(huì)嚴(yán)重影響行為的進(jìn)化、窩卵數(shù)目甚至外表。Hartley說：“人們并沒真正確定這種聯(lián)系?！比藗兺ǔＵJ(rèn)為雌性的繁殖策略受捕食和食物提供方式的影響。Kilner說父母之間的沖突現(xiàn)在也應(yīng)該被考慮在內(nèi)了。
Single-parent Kids Do Best
Single mums are better at raising their kids than two parents—at least in the bird world. Mother zebra finches have to work harder and raise fewer chicks on their own, but they also produce more attractive sons who are more likely to get a mate.
The finding shows that family conflict is as important an evolutionary driving force as ecological factors such as hunting and food supply. With two parents around, there’s always a conflict of interests, which can have a detrimental effect on the quality of the offspring.
In evolutionary terms, the best strategy for any parent in the animal world is to find someone else to care for their offspring, so they can concentrate on breeding again. so it’s normal for parents to try to pass the buck to each other. But Ian Hartley from the University of Lancaster and his team wondered how families solve this conflict, and how the conflict itself affects the offspring.
To find out, they measured how much effort zebra finch parents put into raising their babies. They compared ingle females with pairs, by monitoring the amount of food each parent collected, and removing or adding chicks so that each pair of birds was raising four chicks, and each single mum had two—supposedly the same amount of work.
But single mums, they found, put in about 25 per cent more effort than females rearing with their mate. To avoid being exploited, mothers with a partner hold back from working too hard if the father is being lazy, and it’s the chicks that pay the price. “The offspring suffer some of the cost of this conflict,” says Hartley.
The cost does not show in any obvious decrease in size or weight, but in how attractive they are to the opposite sex. When the chicks were mature, the researchers tested the “fitness” of the male offspring by offering females their choice of partner. Those males reared by single mums were chosen more often than those from two-parent families.
Sexual conflict has long been tough to affect the quality of care given to offspring, says zoologist Rebecca Kilner at Cambridge University, who works on conflict of parents in birds. “But the experimental evidence is not great. The breakthrough here is showing it empirically.”
More surprising, says Kilner, is Hartley’s statement that conflict may be a strong influence on the evolution of behaviour, clutch size and even appearance. “People have not really made that link,” says Hartley. A female’s reproductive strategy is usually thought to be affected by hunting and food supply. Kilner says conflict of parents should now be taken into account as well.
單親母親在撫養(yǎng)孩子方面比雙親要好——至少在鳥的世界是這樣的。母斑胸草雀必須在努力工作并且親自撫養(yǎng)較少的鳥，但是她們撫養(yǎng)的雄性后代更有吸引力，更容易得到配偶。
這個(gè)發(fā)現(xiàn)顯示家庭沖突是與捕食和食物提供方式這樣的生態(tài)因素同樣重要的進(jìn)化推動(dòng)力。身邊有雙親就總有利益沖突，這會(huì)對(duì)后代的質(zhì)量產(chǎn)生的害的影響。
從進(jìn)化的角度講，在動(dòng)物界，任何一個(gè)父親或母親的策略是讓他人來照顧后代，這樣，他們就可以集中精力再次繁殖后代了。所以父母之間很自然就出現(xiàn)了相互推卸的責(zé)任的現(xiàn)象。但是蘭卡斯特大學(xué)的IanHartley及他的工作組想知道家庭是如何解決這個(gè)沖突的，以及沖突本身是如何影響后代的。
為了找到答案他們衡量斑胸草雀撫養(yǎng)它們的子女花了多少力氣。他們監(jiān)控每個(gè)母親或父親采集的食物量，以及移動(dòng)或增加小鳥，因此每對(duì)草雀養(yǎng)4只小鳥，每只單身母雀養(yǎng)兩只——假定這是相同的工作量。通過這些方法他們對(duì)單身母雀和成對(duì)草雀做了比較。
但是他們發(fā)現(xiàn)單身母雀比與配偶共同撫養(yǎng)后代的母雀多付出25%。如果公雀太懶的話，為了避免筋疲力盡，有配偶的母雀并不十分努力工作。這樣做的后果就是后代付出代價(jià)。Hartley說：“后代要為這種沖突付出某些代價(jià)。”
這種代價(jià)不是表現(xiàn)在身材和體重的銳減，而是表現(xiàn)在他們對(duì)異性有多大吸引力上。當(dāng)小鳥長(zhǎng)大后，研究者通過提供給雌性她們所選擇的伴侶的方法檢驗(yàn)雄性后代的健康情況。那些由單身母親扶養(yǎng)大的雄性比由父母撫養(yǎng)大的雄性更多地被選中。
研究鳥類父母沖突的劍橋大學(xué)動(dòng)詞學(xué)家rebeccaKilner說，很久以來人們就認(rèn)為兩性之間的沖突會(huì)影響對(duì)后代的照顧。"但是試驗(yàn)證據(jù)并不充分，這個(gè)突破主要是以經(jīng)驗(yàn)來顯示這種影響的。"
Kilner說更為令人驚訝的是Hartley說這種沖突可能會(huì)嚴(yán)重影響行為的進(jìn)化、窩卵數(shù)目甚至外表。Hartley說：“人們并沒真正確定這種聯(lián)系?！比藗兺ǔＵJ(rèn)為雌性的繁殖策略受捕食和食物提供方式的影響。Kilner說父母之間的沖突現(xiàn)在也應(yīng)該被考慮在內(nèi)了。
Single-parent Kids Do Best
Single mums are better at raising their kids than two parents—at least in the bird world. Mother zebra finches have to work harder and raise fewer chicks on their own, but they also produce more attractive sons who are more likely to get a mate.
The finding shows that family conflict is as important an evolutionary driving force as ecological factors such as hunting and food supply. With two parents around, there’s always a conflict of interests, which can have a detrimental effect on the quality of the offspring.
In evolutionary terms, the best strategy for any parent in the animal world is to find someone else to care for their offspring, so they can concentrate on breeding again. so it’s normal for parents to try to pass the buck to each other. But Ian Hartley from the University of Lancaster and his team wondered how families solve this conflict, and how the conflict itself affects the offspring.
To find out, they measured how much effort zebra finch parents put into raising their babies. They compared ingle females with pairs, by monitoring the amount of food each parent collected, and removing or adding chicks so that each pair of birds was raising four chicks, and each single mum had two—supposedly the same amount of work.
But single mums, they found, put in about 25 per cent more effort than females rearing with their mate. To avoid being exploited, mothers with a partner hold back from working too hard if the father is being lazy, and it’s the chicks that pay the price. “The offspring suffer some of the cost of this conflict,” says Hartley.
The cost does not show in any obvious decrease in size or weight, but in how attractive they are to the opposite sex. When the chicks were mature, the researchers tested the “fitness” of the male offspring by offering females their choice of partner. Those males reared by single mums were chosen more often than those from two-parent families.
Sexual conflict has long been tough to affect the quality of care given to offspring, says zoologist Rebecca Kilner at Cambridge University, who works on conflict of parents in birds. “But the experimental evidence is not great. The breakthrough here is showing it empirically.”
More surprising, says Kilner, is Hartley’s statement that conflict may be a strong influence on the evolution of behaviour, clutch size and even appearance. “People have not really made that link,” says Hartley. A female’s reproductive strategy is usually thought to be affected by hunting and food supply. Kilner says conflict of parents should now be taken into account as well.