New Topics • Coevolution • special case between interdependent species • Study examples in PollinationBiology • best understood examples of coevolution • Focus on Role of NaturalSelection
Coevolution: reciprocal change driven by the interaction of 2 or more species. Arms race = Plant/Herbivore Mutualism = symbiotic specialization Geographic Mosaic Theory Modern synthesis by John N. Thompson and others. COEVOLUTION Gilia tricolor
Pollination: Has 3 Components 1.) Receipt of genes () 2.) Delivery of genes () 3.) Pollination Vector Wind or Animal Pollination Gilia tricolor
Flowers Optimize pollination Minimize costs make it hard to get pollen & Nectar Maximize rewards receive enough of correct pollen Pollinators Optimize feeding Minimize costs feed easily Maximize rewards eat enough pollen or nectar to more than compensate for their effort How do Pollinators and Flowers affect each other?
Pollination Syndromes • Under “right conditions” pollinators can exert selection pressures on floral traits, resulting in floral morphology and structure that may be adaptations to maximize efficiency of pollination. • Flowers that are specialized for specific Pollinators … Have a distinct morphology.
Pollination Syndromes • Bird – Great sight! Poor smell. • Floral traits: • Odorless • Large • Tubular • Often red • Large nectaries
Jewelweed, Impatiens sp Nat. Hist. 5/99.
Pollination Syndromes • Bats – very poor sight, very good smell. • Floral traits: • Strong odors – musky or fruity • large • dull colors – white or green • often only open at night.
Pollination Syndromes • Bees – good sense of sight, smell ok. • Floral traits: • Blue or yellow (yellow = blue in UV specturm) • Distinctive markings = “honey guides” = path to nectaries. • Landing pads.
References • http://elib.cs.berkeley.edu/photos/flora/ • Ethan J. Temeles and Paul W. Ewald. 1999. Fitting the Bill? Natural History. 5(March):52-55. • John N. Thompson. 1994. The Coevolutionary Process. The University of Chicago Press, Chicago. p376. • Peter H.Raven, Ray F. Evert and Susan E. Eichorn. 1999. Biology of Plants. W.H. Freeman and Company, New York.P944. • Scott A. Hodges and Michael L. Arnold. 1994. Floral and ecological isolation between Aquilegia formosa and A. pubuscens. Proc. Natl. Acad. Sci. 91:2493-2496. • Teresa Audesirk and Gerald Audesirk. 1999. Biology: Life on Earth (5th ed). Prentice-Hall; Upper Saddle River, NJ. P890.
Review of Previous Topics • Evolution by Natural Selection. • “Survival of the Fittest” & much more. • Three types of Selection Forces • Stabilizing • Disruptive • Directional