进化发育生物学的兴起.pptVIP

进化发育生物学的兴起 概念 进化发育生物学的发展历程（合分合三个阶段） 进化发育生物学的发展历程（合分合三个阶段） 进化发育生物学的发展历程（合分合三个阶段） 进化发育生物学的提出 生物机体进化发育的演化发展 (a) Cell-fate specification in the ventral epidermis of C. elegans. The 12 Pn.p cells are distributed equally between the pharynx and the rectum. P(1,2,9–11).p have an epidermal fate and fuse with the hypodermal syncytium hyp7 (white ovals). P(3–8).p form the vulva equivalence group and have the spatial pattern3°-3°-2°-1°-2°-3°. 3° cells (dotted ovals) divide once and fuse with hyp7. 2° cells (grey ovals) generate seven progeny and form the terior and posterior part of the vulva. The 1° cell (black oval) generates eight progeny, some of which connect the vulva to the terus. The anchor cell is shown as a small grey circle. P12.p (hyp12) has a special fate and forms part of the rectum. (b) Modes of vulva induction in species of three different families of nematodes. Oscheius, two-step induction with both steps provided by the AC (small whitecircle). C. elegans, one-step induction. P. pacificus, continuous induction from early gonadal stages until the birth of the AC. Teratorhabditis palmarum and Brevibucca sp. are species with a posterior vulva not requiring a gonadal induction. Panagrolaimus sp. And Halocephalobus sp. with a two-step and threestep induction, respectively. Arrows indicate cell–cell interactions. The gonad is shown as a long white oval. Outer (2°) vulval fates are shown in grey, inner (1°) vulval fates are shown in black. Phylogeny is based on work described in [40??,42]. (See main text for details.) Asymmetric divisions and the evolution of multicellularity in Volvox carteri. (A) A wildtype spheroid. (B) A Mul, multiple gonidia, spheroid. A mulB mutation results in a one-cycle delay in the occurrence of asymmetric divisions. As a result, there are more cells in the spheroid at the time of the asymmetric divisions and more cells undergo asymmetric divisions. This results in an increased number of large cells and a subsequent increase in the n