title: Evolutionary optimization of material properties of a tropical seed.
abstract: Here, we show how the mechanical properties of a thick-shelled tropical seed are adapted to permit them to germinate while preventing their predation. The seed has evolved a complex heterogeneous microstructure resulting in hardness, stiffness and fracture toughness values that place the structure at the intersection of these competing selective constraints. Analyses of different damage mechanisms inflicted by beetles, squirrels and orangutans illustrate that cellular shapes and orientations ensure damage resistance to predation forces imposed across a broad range of length scales. This resistance is shown to be around the upper limit that allows cracking the shell via internal turgor pressure (i.e. germination). Thus, the seed appears to strike an exquisitely delicate adaptive balance between multiple selection pressures.
authors: Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 13110, Kuwait. peterwlucas@gmail.com
authors: Peter W
authors: PW
authors: Lucas
authors: John T
authors: JT
authors: Gaskins
authors: Timothy K
authors: TK
authors: Lowrey
authors: Mark E
authors: ME
authors: Harrison
authors: Helen C
authors: HC
authors: Morrogh-Bernard
authors: Susan M
authors: SM
authors: Cheyne
authors: Matthew R
authors: MR
authors: Begley
references: Naturwissenschaften. 2008 Jan;95(1):17-23
references: 17646951
references: J Hum Evol. 2008 Jul;55(1):60-74
references: 18243275
references: Proc Natl Acad Sci U S A. 1984 Feb;81(3):801-5
references: 6583680
references: Bioessays. 2008 Apr;30(4):374-85
references: 18348196
references: Integr Comp Biol. 2010 Nov;50(5):888-907
references: 21558248
references: Science. 2001 Apr 27;292(5517):686-93
references: 11326091
references: Mol Phylogenet Evol. 2002 May;23(2):171-88
references: 12069549
references: Philos Trans R Soc Lond B Biol Sci. 2004 Oct 29;359(1450):1495-508
references: 15519968
references: Am J Phys Anthropol. 1994 Jul;94(3):365-78
references: 7943191
references: Science. 2003 Mar 7;299(5612):1568-72
references: 12595609
references: Annu Rev Plant Physiol Plant Mol Biol. 1999 Jun;50:447-472
references: 15012216
references: J R Soc Interface. 2007 Aug 22;4(15):637-42
references: 17341452
references: Mol Biol Evol. 2003 Mar;20(3):424-34
references: 12644563