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30.4:

์ข…๋ถ„ํ™”์˜ ์œ ์ „ํ•™

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Genetics of Speciation

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์ข… ๋ถ„ํ™”๋Š” ์ง„ํ™”์ ์œผ๋กœ ์ƒˆ๋กœ์šด ์ข…์ด ํ˜•์„ฑ๋˜๋Š” ๊ฒƒ์ธ๋ฐํ•˜๋‚˜ ์ด์ƒ์˜ ๋ชจ์ง‘๋‹จ์˜ ์œ ์ „์  ๋ณ€ํ™”์™€ ๊ด€๋ จ์ด ์žˆ๋‹ค์œ ์ „์  ๋ณ€ํ™”๋Š” ์œ ๊ธฐ์ฒด์˜ ๋ถ„์ž ๊ตฌ์„ฑํ–‰๋™ ๋ฐ ์œก์ฒด์  ๊ตฌ์กฐ๋ฅผ ๋ฐ”๊พธ์–ด์„œ์œ ์ „ ์žฅ๋ฒฝ์„ ๋งŒ๋“ค์–ด์ข…์˜ ๋ถ„๋ฆฌ๊ฐ€ ์ผ์–ด๋‚  ์ˆ˜ ์žˆ๋‹ค์ด๋ฅผํ…Œ๋ฉด ๊ฝƒ์‹๋ฌผ ์† ํŽ˜ํŠœ๋‹ˆ์•„ ์ข…์—์„œ๋Š”๋‹จ์ผ ์œ ์ „์ž๊ฐ€ ๊ฝƒ ์ƒ‰๊น”์„ ์ •ํ•œ๋‹ค๊ทธ ์œ ์ „์ž์˜ ๋ณ€ํ˜•์ด ๊ทธ๋Ÿฌํ•œ ์œ ์ „ ์žฅ๋ฒฝ์„ ๊ฐ•์š”ํ•  ์ˆ˜ ์žˆ๋‹ค๊ทธ ๊ฝƒ ์ƒ‰๊น”์€ ์–ด๋Š ๊ฝƒ๊ฐ€๋ฃจ ๋งค๊ฐœ์ž๊ฐ€ ๊ฝƒ์„๋ฐฉ๋ฌธํ•˜๋Š”์ง€ ๊ฒฐ์ •์„ ํ•˜๊ณ , ํšจ๊ณผ์ ์œผ๋กœ์—ฌ๋Ÿฌ ๊ฝƒ ์ƒ‰๊น”์„ ๊ฐ€์ง„ ๋ชจ์ง‘๋‹จ์˜ ์ƒ์‹ ๊ณ ๋ฆฝ์„์•ผ๊ธฐํ•œ๋‹ค๊ณ ๋ฆฝ ๊ฟ€๋ฒŒ์€ ์ž์ฃผ์ƒ‰ ๊ฝƒ ์ข…๊ณผ ์ˆ˜๋ถ„ํ•˜๊ณ ๋ฒŒ์ƒˆ๋Š” ์—ฐํ•œ ๋นจ๊ฐ„์ƒ‰ ๊ฝƒ ์ข…๊ณผ ์ˆ˜๋ถ„ํ•˜๊ณ ๋ฐ•๊ฐ์‹œ ๋‚˜๋ฐฉ์€ ํ•˜์–€ ๊ฝƒ ์ข…๊ณผ ์ˆ˜๋ถ„ํ•œ๋‹ค๊ฒฐ๊ตญ ๋‹ค๋ฅธ ํŽ˜ํŠœ๋‹ˆ์•„ ์ข…์ด ์ง„ํ™”ํ•˜๊ฒŒ ๋œ๋‹ค๋˜ ๋‹ค๋ฅธ ์ง„ํ™”์ ์ธ ์žฅ๋ฒฝ์€์œ ๊ธฐ์ฒด์˜ ์ „์ฒด ์—ผ์ƒ‰์ฒด ๋‚ด์šฉ์ด ๋ฐ”๋€Œ๋Š” ๊ฒƒ์ด๋‹ค์ด๋ฅผํ…Œ๋ฉด ํŠธ๋ผ๊ณ ํฌ๊ณค ์‹๋ฌผ์˜์—ฌ๋Ÿฌ ์ข…์ด ์ด์ข… ๊ต๋ฐฐ๋‚˜ ์žก์ข…ํ™”๋Š”์ƒˆ๋กœ์šด ํŠธ๋ผ๊ณ ํฌ๊ณค ์ข…์˜ ํƒ„์ƒ์œผ๋กœ ์ด์–ด์ง„๋‹ค์žก์ข… ์ž์†์€ ๋‘ ๊ฐœ์˜ ์ด์ƒ์˜๋™์ข… ์—ผ์ƒ‰์ฒด๋ฅผ ๊ฐ–๊ธฐ ๋•Œ๋ฌธ์—์ƒ์‹ ๋Šฅ๋ ฅ์ด ์žˆ์–ด๋„ ๊ฐ ๋ถ€๋ชจ์˜ ์ข…๊ณผ์ƒ์‹์„ ํ•  ์ˆ˜๊ฐ€ ์—†๋‹ค์ˆ™์ฃผ ์œ ๊ธฐ์ฒด ์œ ์ „์ฒด์™€ ๊ทธ์™€ ๊ด€๋ จ๋œ๋ชจ๋“  ๊ณต์ƒ ๋ฏธ์ƒ๋ฌผ ์œ ์ „์ฒด์˜ ๊ตฌ์ฒด์ ์ธ ์กฐํ•ฉ ์กฐ์ฐจ๋„์œ ์ „์ ์ธ ์žฅ์• ๋ฌผ์„ ๊ฐ•์š”ํ•  ์ˆ˜ ์žˆ๊ณ ๊ฒฐ๊ตญ ์ข… ๋ถ„ํ™”๋กœ ์ด์–ด์ง„๋‹ค์ด๋ฅผํ…Œ๋ฉด, ๋‚˜์†Œ๋‹ˆ์•„ ๋ง๋ฒŒ ์ข… ์‚ฌ์ด์˜ ๊ต๋ฐฐ๋Š”์ž์†์˜ 90%๊นŒ์ง€ ์œ ์ถฉ ๋ฐœ๋‹ฌ ๋‹จ๊ณ„์—์„œ ์‚ฌ๋ผ์ง„๋‹ค์‹คํ—˜์— ๋”ฐ๋ฅด๋ฉด ์ด ์žก์ข…์˜ ์น˜์‚ฌ์œจ์€๋ง๋ฒŒ ์œ ์ „์ฒด์™€ ์ธ๊ทผ ๋ฐ•ํ…Œ๋ฆฌ์•„ ๊ณต๋™์ฒด์‚ฌ์ด์˜ ์ƒํ˜ธ ์ž‘์šฉ ๋•Œ๋ฌธ์ธ ๊ฒƒ ๊ฐ™์€๋ฐ์ด๋Š” ์œ ์ „-๋ฏธ์ƒ๋ฌผ ์ƒํ˜ธ ์ž‘์šฉ์ด ์–ด๋–ป๊ฒŒ ์ƒ์‹๋ ฅ์„๋ฐฉํ•ดํ•˜์—ฌ ์ข… ๋ถ„๋ฆฌ๋ฅผ ์œ ์ง€ํ•˜๋Š”์ง€๋ฅผ ๋ณด์—ฌ์ค€๋‹ค์ข… ๋ถ„ํ™”์—์„œ์˜ ์œ ์ „์ž์˜ ์—ญํ• ์€ํ™œ๋ฐœํ•œ ์—ฐ๊ตฌ ๋ถ„์•ผ์ด์ง€๋งŒ ์œ ์ „์  ๋ณ€ํ™”๊ฐ€๋‹จ์ผ ์œ ์ „์ž ์œ ์ „์ฒด ๊ตฌ์„ฑ ๋ฐ์—ฌ๋Ÿฌ ์œ ์ „์ฒด์˜ ์ƒํ˜ธ ์ž‘์šฉ์— ๊ฑธ์ณ ์ผ์–ด๋‚˜๋ฉด์ƒ์‹ ๊ณ ๋ฆฝ๊ณผ ์ข… ๋ถ„ํ™”์— ๊ธฐ์—ฌํ•  ์ˆ˜ ์žˆ๋‹ค

30.4:

์ข…๋ถ„ํ™”์˜ ์œ ์ „ํ•™

์ข…๋ถ„ํ™”(speciation)๋Š” ์ƒˆ๋กญ๊ณ  ๋šœ๋ ท์ด ๊ตฌ๋ณ„๋˜๋Š” ์ข…(์ฆ‰, ์ƒ์‹์ ์œผ๋กœ ๊ฒฉ๋ฆฌ๋œ ๊ฐœ์ฒด๊ตฐ์˜ ์ง‘๋‹จ)์˜ ํ˜•์„ฑ์„ ์ดˆ๋ž˜ํ•˜๋Š” ์ง„ํ™” ๊ณผ์ •์ž…๋‹ˆ๋‹ค.

์ข…๋ถ„ํ™”์˜ ์œ ์ „ํ•™์€ ์œ ์ „์ž์˜ ๊ตํ™˜์„ ๋ง‰๊ณ , ๋‚˜์•„๊ฐ€ ์ƒ์‹์  ๊ฒฉ๋ฆฌ(reproductive isolation)๋ฅผ ์ดˆ๋ž˜ํ•˜๋Š” ๋‹ค์–‘ํ•œ ํ˜•์งˆ(trait) ๋˜๋Š” ๊ฒฉ๋ฆฌ(isolation) ๊ธฐ์ž‘์„ ๋งํ•ฉ๋‹ˆ๋‹ค. ์ƒ์‹์  ๊ฒฉ๋ฆฌ๋Š” ์ ‘ํ•ฉ์ž(zygote)๊ฐ€ ํ˜•์„ฑ๋˜๊ธฐ ์ „์ด๋‚˜ ํ›„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ์ƒ์‹ ์žฅ๋ฒฝ(reproductive barrier)์œผ๋กœ ์ธํ•ด ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ์ ‘ํ•ฉ์ „(pre-zygotic) ๊ธฐ์ž‘์€ ์ˆ˜์ •์ด ์ผ์–ด๋‚˜๋Š” ๊ฒƒ์„ ๋ง‰๊ณ , ์ ‘ํ•ฉํ›„(post-zygotic) ๊ธฐ์ž‘์€ ์žก์ข…(hybrid) ์ž์†์˜ ์ƒ์กด ๋Šฅ๋ ฅ(viability) ๋˜๋Š” ์ƒ์‹ ๋Šฅ๋ ฅ(reproductive capacity)์„ ๊ฐ์†Œ์‹œํ‚ต๋‹ˆ๋‹ค.

์˜ˆ๋ฅผ ๋“ค์–ด ์ ‘ํ•ฉ์ „ ๊ธฐ์ž‘์€ ์œ ๊ธฐ์ฒด์˜ ์ƒํ™œ์‚ฌ ์ดˆ๊ธฐ์— ์ž‘์šฉํ•˜์—ฌ ์œ ์ „์ž ํ๋ฆ„(gene flow)์˜ ๊ฐ€์žฅ ๊ฐ•๋ ฅํ•œ ๋ฐฉํ•ด๋ฅผ ์ดˆ๋ž˜ํ•˜๊ณ  ์„ ํ˜ธ๋˜์ง€ ์•Š๋Š” ์ง์ง“๊ธฐ ์กฐํ•ฉ์„ ๋ฐฉ์ง€ํ•ฉ๋‹ˆ๋‹ค. ์ผ๋ถ€ ์ง์ง“๊ธฐ ์กฐํ•ฉ์€ ์žก์ข… ๊ฐœ์ฒด๋ฅผ ์ƒ์„ฑํ•ฉ๋‹ˆ๋‹ค. ํ•˜์ง€๋งŒ ์ž์—ฐ์„ ํƒ(natural selection)์€ ๋‚ฎ์€ ์ ์‘๋„(fitness)๋ฅผ ๊ฐ€์ง„ ์žก์ข… ์ƒ์‚ฐ์— ๋ฐ˜๋Œ€ํ•˜์—ฌ ๋‘ ์ข… ์‚ฌ์ด์˜ ์ƒ์‹์  ๋ถ„๋ฆฌ๋ฅผ ์ฆ๊ฐ€์‹œํ‚ฌ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.

์ ‘ํ•ฉํ›„ ๊ธฐ์ž‘์€ ๋‚ด์žฌ์ ์ธ ์š”์ธ์ธ ์žก์ข… ์น˜์‚ฌ(hybrid inviability) ๋•Œ๋ฌธ์ผ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ๋Œ€๋ฆฝ์œ ์ „์ž(allele)๋“ค์ด ์ ์ ˆํ•˜๊ฒŒ ๊ธฐ๋Šฅํ•˜์ง€ ๋ชปํ•˜๊ฒŒ ๋งŒ๋“œ๋Š” ๋ฐฐ์ˆ˜์„ฑ(ploidy) ๋ณ€์ด, ๋‹ค๋ฅธ ์—ผ์ƒ‰์ฒด ๋ฐฐ์—ด, ์œ ์ „์ž์˜ ๋น„ํ˜ธํ™˜์„ฑ ๊ฐ™์€ ์œ ์ „์  ๋ฌธ์ œ๋Š” ์žก์ข…์˜ ๋‹ค๋ฅธ ์œ ์ „์  ๊ตฌ์„ฑ๊ณผ ๋Œ€์ฒด ๋ฐœ๋‹ฌ ๊ฒฝ๋กœ์— ๊ธฐ์—ฌํ•ฉ๋‹ˆ๋‹ค. ์ด๋Ÿฌํ•œ ์œ ์ „์  ๋ณ€ํ™”๋Š” ์‹๋ฌผ๊ณผ ๋™๋ฌผ ๋ชจ๋‘์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋ฉฐ, ์ ‘ํ•ฉํ›„ ๊ฒฉ๋ฆฌ ๋ฐ ์ข…๋ถ„ํ™”๋กœ ์ด์–ด์ง‘๋‹ˆ๋‹ค.

์ƒ์œ„์„ฑ(epistasis), ์ฆ‰ ๋น„๋Œ€๋ฆฝ ์œ ์ „์ž ์ƒํ˜ธ์ž‘์šฉ(non-allelic gene interaction)์€ ์ข…๋ถ„ํ™”์— ๊ธฐ์—ฌํ•˜๋Š” ๋…ํŠนํ•œ ํ˜„์ƒ์ž…๋‹ˆ๋‹ค. ์œ ์ „์ž ๋ณ€์ด(gene variant)์˜ ์˜ํ–ฅ์€ ๋ณ€์ด๊ฐ€ ๋‚˜ํƒ€๋‚˜๋Š” ์œ ์ „์  ๋ฐฐ๊ฒฝ(genetic background)์— ๋”ฐ๋ผ ๋‹ฌ๋ผ์ง‘๋‹ˆ๋‹ค. ์˜ˆ๋ฅผ ๋“ค์–ด ๊ฐ™์€ ์ข…์˜ ๊ตฌ์„ฑ์›์—์„œ ์ •์ƒ์ ์ธ ํ‘œํ˜„ํ˜•(phenotype)์„ ๋‚ณ๋Š” ๋Œ€๋ฆฝ์œ ์ „์ž๋Š” ์žก์ข…์˜ ์œ ์ „์  ํ™˜๊ฒฝ์—์„  ๊ธฐ๋Šฅ์ด ๋–จ์–ด์งˆ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ์ด๋Ÿฌํ•œ ์žก์ข… ์•ฝํ™”(hybrid weakness)๋Š” ์ƒ์‹์  ๊ฒฉ๋ฆฌ์™€ ์ข…๋ถ„ํ™”๋กœ ์ด์–ด์งˆ ์ˆ˜๋„ ์žˆ์Šต๋‹ˆ๋‹ค.

Suggested Reading

Dagilis, Andrius J., Mark Kirkpatrick, and Daniel I. Bolnick. "The Evolution of Hybrid Fitness during Speciation." PLoS Genetics 15, no. 5 (2019): E1008125. [Source]

Magurran, A. E., R. M. May, Jerry A. Coyne, and H. Allen Orr. "The Evolutionary Genetics of Speciation." Philosophical Transactions of the Royal Society B: Biological Sciences 353, no. 1366 (1998): 287-305. [Source]

Wade, M. J. "A Gene's Eye View of Epistasis, Selection and Speciation." Journal of Evolutionary Biology 15, no. 3 (2002): 337-46. [Source]