Relative Fitness - Chapter 21-230911 (PDF)

Relative Fitness (상대적 적응도) • The phrases “struggle for existence” and “survival of the fittest” are misleading, as they imply direct competition among individuals ("생존을 위한 투쟁"과 "적자생존"이라는 표현은 개인 간의 직접적인 경쟁을 암시하므로 오해의 소지가 있다) • Reproductive success is ge...

Relative Fitness (상대적 적응도) • The phrases “struggle for existence” and “survival of the fittest” are misleading, as they imply direct competition among individuals ("생존을 위한 투쟁"과 "적자생존"이라는 표현은 개인 간의 직접적인 경쟁을 암시하므로 오해의 소지가 있다) • Reproductive success is generally more subtle and depends on many factors (생식 성공은 일반적으로 더 미묘하며 여러 요인에 따라 달라진다) – For example, individuals that are able to collect more food than others may be able to invest more energy in producing larger numbers of offspring (예를 들어, 다른 개체보다 더 많은 먹이를 수집할 수 있는 개체는 더 많은 수의 새끼를 낳는 데 더 많은 에너지를 투자할 수 있다) • Relative fitness (상대적 적응도) is the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals (상대적 적응도는 다른 개인의 기여도와 비교하여 한 개인이 다음 세대의 유전자 풀에 기여하는 정도이다) • Selection indirectly favors certain genotypes by acting directly on phenotypes (선택은 표현형에 직접 작용하여 특정 유전자형을 간접적으로 선호한다) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Directional, Disruptive, and Stabilizing Selection (방향성 선택, 분단성 선택, 안정화 선택) • There are three modes of natural selection – Directional selection (방향성 선택) occurs when conditions favor individuals at one end of the phenotypic range (방향성 선택은 표현형 범위의 한쪽 끝에 있는 개체에 유리한 조건이 있을 때 발생한다) – Disruptive selection (분단성 선택) occurs when conditions favor individuals at both extremes of the phenotypic range (분단성 선택은 표현형 범위의 양 극단에 있는 개체에 유리한 조건이 존재할 때 발생한다) – Stabilizing selection (안정화 선택) occurs when conditions favor intermediate variants and act against extreme phenotypes (안정화 선택은 조건이 중간 변형을 선호하고 극단적인 표현형에 대항하여 작용할 때 발생한다) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Frequency of individuals Figure 21.13 Modes of Selection (선택의 방식) Original population Evolved population (a) Directional selection shifts the overall makeup of the population by favoring variants that are at one extreme of the distribution. In this case, lighter mice are selected against because they live among dark rocks, making it harder for them to hide from predators. (방향성 선택) Original population Phenotypes (fur color) (b) Disruptive selection favors variants at both ends of the distribution. These mice have colonized a patchy habitat made up of light and dark rocks, with the result that mice of an intermediate color are selected against. (분단성 선택) (c) Stabilizing selection removes extreme variants from the population and preserves intermediate types. If the environment consists of rocks of an intermediate color, both light and dark mice will be selected against. (안정화 선택) Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Key Role of Natural Selection in Adaptive Evolution (적응진화에서 자연선택의 핵심적인 역할) • Striking adaptations have arisen by natural selection (자연 선택에 의해 놀라운 적응이 일어난다) – For example, certain octopuses can change color rapidly for camouflage (예를 들어, 특정 문어는 위장을 위해 빠르게 색을 바꿀 수 있다) – For example, the jaws of snakes allow them to swallow prey larger than their heads (예를 들어, 뱀의 턱은 머리보다 큰 먹이를 삼킬 수 있다) • Natural selection increases the frequencies of alleles that enhance survival and reproduction (자연 선택은 생존과 번식을 강화하는 대립 유전자의 빈도를 증가시킨다) • Adaptive evolution occurs as the proportion of individuals in a population that have traits favorable for the particular environment increases (적응 진화는 특정 환경에 유리한 형질을 가진 개체군의 비율이 증가함에 따라 발생한다) • Because the environment can change, adaptive evolution is a continuous, dynamic process (환경은 변할 수 있으므로 적응형 진화는 지속적이고 역동적인 프로세스이다) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 21.14 Movable Jaw Bones in Snakes (뱀의 움직이는 턱뼈들) The bones of the upper jaw that are shown in green are movable. Ligament The skull bones of most terrestrial vertebrates are relatively rigidly attached to one another, limiting jaw movement. In contrast, most snakes have movable bones in their upper jaw, allowing them to swallow food much larger than their head. Copyright © 2021 Pearson Education Ltd. All Rights Reserved