甲、乙、丙是同一物种的三个种群，其年龄组成见表。三个种群年龄结构的类型为 <table style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; BORDER-COLLAPSE: collapse; MARGIN-LEFT: 6.75pt; BORDER-TOP: medium none; MARGIN-RIGHT: 6.75pt; BORDER-RIGHT: medium none; mso-border-alt: solid windowtext .5pt; mso-yfti-tbllook: 480; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-table-lspace: 9.0pt; mso-table-rspace: 9.0pt; mso-table-anchor-vertical: paragraph; mso-table-anchor-horizontal: margin; mso-table-left: center; mso-table-top: .1pt" border="1" cellspacing="0" cellpadding="0" align="left" _dj="MsoNormalTable"><tbody><tr style="HEIGHT: 15pt; mso-yfti-irow: 0; mso-yfti-firstrow: yes"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt" rowspan="2" width="116">年龄期</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 260.85pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" width="348" colspan="3">个体数</td></tr><tr style="HEIGHT: 7pt; mso-yfti-irow: 1"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 7pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">甲</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 7pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">乙</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 87pt; PADDING-RIGHT: 5.4pt; HEIGHT: 7pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">丙</td></tr><tr style="HEIGHT: 15pt; mso-yfti-irow: 2"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">幼年期</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">600</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">400</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 87pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">200</td></tr><tr style="HEIGHT: 15.4pt; mso-yfti-irow: 3"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15.4pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">成年期</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15.4pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">400</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15.4pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">400</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 87pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15.4pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">400</td></tr><tr style="HEIGHT: 15pt; mso-yfti-irow: 4; mso-yfti-lastrow: yes"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">老年期</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.9pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">200</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 86.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">400</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 87pt; PADDING-RIGHT: 5.4pt; HEIGHT: 15pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width="116">600</td></tr></tbody></table>