Clonal Growth
Pros and Cons of Clonal Growth Advantages Rapid growth More widespread foraging Lower mortality than seedlings Greater competitive ability Disadvantages No recombination Limited dispersal range Disease accumulation Avoid cost of sexual repro. Resource sharing
Forms of Clonal Growth Phalanx Guerilla
Modes of Foraging Behavior Number of Branches (n) Ramet size (S) Shoot Root q Branch angle (q)
Optimal Foraging? Nutrient Rich Nutrient Poor Nutrient Rich
Optimal Foraging: Rich Habitat X
Optimal Foraging: Poor Habitat X
Optimal Foraging through a Plastic Response
Predictions Nutrient Rich Habitat Nutrient Poor Habitat Short internodes Profuse branching Acute branch angles High shoot:root Long internodes Few branches Obtuse branch angles Low shoot:root
An Experimental Test of Optimal Foraging
The plant: Glechoma hederacea Slade, A. J., and M. J. Hutchings. 1987. The effects of nutrient availability on foraging in the clonal herb Glechoma hederacea. Journal of Ecology 75:95-112.
General Growth Pattern
Experimental Design Nutrient poor Legend Nutrient rich Mixed
Predictions and Results Nutrient Rich Habitat Nutrient Poor Habitat Short internodes Profuse branching Many large ramets High shoot:root Long internodes Few branches Few small ramets Low shoot:root
Predictions and Results Mixed Treatment Nutrient Rich Areas Short internodes Profuse branching Many large ramets High shoot:root Nutrient Poor Areas Long internodes Few branches Few small ramets Low shoot:root
Predictions and Results Mixed Treatment Nutrient Rich Areas Nutrient Poor Areas Short internodes Profuse branching Long internodes Intermediate growth in all locations Few branches Many large ramets Few small ramets High shoot:root Low shoot:root
General Interpretation Glecoma hederacea exhibits a plastic growth response to nutrient conditions This response is not localized, but represents an average to conditions encountered across the clone What role does physiological integration play?
Physiological Integration through Movement of Resources Xylem: Transport of raw materials, e.g., H20 and soil nutrients Phloem: Transport of products of photosynthesis
Experimental Examination of Integration through Xylem Experimental design Cut leaf off Inject fuchsin dye into xylem Price, E. A. C., C. Marshall, and M. Hutchings. 1992. Studies of growth in the clonal herb Glechoma hederacea. I. Patterns of physiological integration. Journal of Ecology 80:35-38.
Experimental Examination of Integration through Xylem Experimental results Complex pattern of nutrient flow, depends on xylem architecture Apparent unidirectional flow of nutrients Leaf with dye Leaf without dye
Experimental Examination of Integration through Phloem Leaf labeled with 14 C
Experimental Examination of Integration through Phloem Resulting radiograph Leaf labeled with 14 C
Experimental Examination of Integration through Phloem Interpretation Photosynthate stays in leaf or is transported to young developing tissues Source-sink relationship
General Interpretation of Experiments Patterns of physiological integration can be shown Resource sharing seems to be in the direction of younger ramets Optimal foraging is an ideal that is only partially met
Forms of Asexual Reproduction in Plants
Clonal Growth (revisited) Rhizome Stolon Bulbils Suckers Plantlets
Fragmentation: jumping cholla
Production of seeds with no fertilization Agamospermy
Key Stages in the Life-History of a Plant Growth Flowering Pollination seed phase Seed Maturation Dispersal Dormancy Germination
Sexual Reproduction in Plants
Typical Angiosperm Lifecycle Alternation of generations Sporophyte (2n) Gametophytes (1n)
Typical Angiosperm Lifecycle Alternation of generations Sporophyte (2n) Gametophytes (1n) Fertilization
Gender Expression in Plants Hermaphrodites
Gender Expression in Plants Hermaphrodites
Gender Expression in Plants Hermaphrodites
Sequential Hermaphrodism Some plants change sex over time! Jack-in-the-pulpet (Arisemea triphyllum)
Distribution of Flower Types
Variability in Flowering Patterns Semelparity Flower once and die Iteroparity Flower many times
Semelparity: A closer look Annuals Biennials