X hits on this document

50 views

0 shares

0 downloads

0 comments

25 / 25

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

FIGURE 7.12 Barn Swallows

To test the effects of male tail length, four groups of males received four treatments. “Shortened” tailed males were produced by cutting out the middle of the tail and regluing the tip to the base. “Elongated” tailed males were produced by cutting and gluing the removed section (from shortened tailed) to the middle of the tail. “Control I” males had tails cut but then reglued, thereby exposing them to the basic treatment but without changing tail length. “Control II” males received no tail clipping or gluing. The solid boxes represent the average number of young each group of males produced during a summer; the vertical lines express the range of variation of the results (standard deviation). The control groups did not differ significantly from each other, but both differed from shortened males, which produced significantly fewer offspring, and from elongated males, which produced significantly more offspring. (After MØller, 1988)

Document info
Document views50
Page views50
Page last viewedSat Dec 03 14:07:03 UTC 2016
Pages25
Paragraphs98
Words1439

Comments