Why did outcrossing rates initially rise and then fall in the evolution (static parasite) treatment?

Question

BlackTom AI · Accepted Answer

Question recap: Why did outcrossing rates initially rise and then fall in the evolution (static parasite) treatment?

Option a: 'Early outcrossing allowed recombination to produce resistant genotypes, which spread and eliminated the need for further genetic variation.' This is the most coherent explanation. Outcrossing increases genetic recombination, which can generate novel resistant genotypes. If those resistant genotypes spread through the population, the advantage of maintaining high outcrossing diminishes once resistance is widespread, leading to a reduction in outcrossing rates. The sequence described—rise due to beneficial recombinant resistance, followed by fall as variation becomes unnecessary—fits the expected evolutionary dynamics in a static parasite environment where host resistance is countered by recombination.

Option b: 'The parasite population became less virulent over time, so nematodes no longer needed to outcross.' This claim ties outcrossing to virulence levels, implying a direct causal link between reduced virulence and reduced need for outcrossing. However, the pattern of rising then falling outcrossing is more plausibly tied to the spread of advantageous genotypes via recombination rather than a simple decline in virulence. The statement also asserts no ongoing need for genetic exchange, which is not a well-supported general explanation for this scenario.

Option c: 'Parasite evolution in this treatment kept breaking down host resistance, favouring repeated cycles of outcrossing and selfing.' This option suggests constant host-resistance turnover prompting cycles of outcrossing and selfing. While host resistance dynamics can influence mating systems, the described pattern is a single rise and fall rather than ongoing cycling driven by continuous breakdown of resistance. It does not clearly account for the initial rise due to creation of resistant genotypes followed by a reduction once variation is no longer needed.

Option d: 'Outcrossing initially suppressed nematode reproduction, leading to population collapse and a return to selfing.' This portrays a drastic negative effect of outcrossing on reproduction, which is not typically how outcrossing dynamics work in these contexts. Outcrossing generally facilitates genetic diversity and can enhance adaptation, not cause immediate population collapse and a rebound to selfing. This makes the option biologically implausible for explaining the observed pattern.

In summary, option a provides a logically consistent sequence: outcrossing boosts recombination, produces resistance, resistant lineages spread, reducing the selective advantage of continued outcrossing, which then declines. The other options rely on assumptions about virulence, ongoing cycles, or catastrophic reproductive suppression that do not align with the described evolutionary dynamics of the static parasite treatment.

Why did outcrossing rates initially rise and then fall in the evolution (static parasite) treatment?单项选择题

类似问题

Question at position 24 Lark buntings are polygynous. This means thatone male mates with one female.one female mates with many males.any number of males mates with any number of females.one male mates with many females.Clear my selection

Question at position 13 In many species of tortoises, females will produce clutches of eggs that demonstrate multiple paternity. This reflects what type of mating system? MonogamyPromiscuityPolyandryPolygynyClear my selection

Does the following trait(s) best characterize: humans, chimpanzees, or both (humans and chimpanzees)? Greater female promiscuity

What type of mating structure do gorillas typically have? E2.2124

I am an adult female primate. I live in a territory with two adult males and our offspring. What type of social organization do I participate in?

In a some species of birds, males have only one female mate, while females defend their territories that include multiple male mates. The females' biology is an example of ____.

Based on the evidence provided, what is the most likely mating system of this salamander species?

Which of the following is a mating system associated with infanticide?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单