教甄◆生物專業題庫

(九)下列短文主要研究當雌果蠅交配兩次時，精子的使用發生偏差的現象。 請以中文摘要此短文，並說明如何引導學生判讀圖 2，以驗證文中的假 設是否正確。(6 分)
       When a female fruit fly mates twice, 80% of the offspring result from the second mating. Scientists had hypothesized that ejaculate from the second mating displaces sperm from the first mating. To test this hypothesis, Rhonda Snook, at the University of Sheffield, and David Hosken, at the University of Zurich, used mutant males with altered reproductive systems. “No-ejaculate” males mate but do not transfer sperm or fluid to females. “No-sperm” males mate and ejaculate but make no sperm. The researchers allowed females to mate first with wildtype males and then with wild-type males, no-sperm males, or no-ejaculate males. As a control, some females were mated only once (to wild-type males). The scientists then dissected each female under a microscope and recorded whether sperm were absent from the spermathecae, the major sperm storage organs.