Mating System Evolution: Correlations between Seed Set and Physiological rates By: Anthony Linarez Principal Investigator: Susan J. Mazer Post Doctorate Mentor: Leah Dudley Department of Ecology, Evolution & Marine Biology University of California, Santa Barbara
Ma ting Syste m •Outcrossing •Vector needed •Great genetic diversity •Ability to adapt •Self-fertilization •No vector needed •Low genetic diversity •Inability to adapt •extinction
Hypo the se s Selfing evolved from outcrossing species •Reproductive assurance hypothesis •Drought avoidance hypothesis Why does Selfing persist? •Counterintuitive •Long-term problems Question: Is fitness correlated with drought avoidant traits?
Whe n Se lfe rs E vo lve If trends exist then selfers will have evolved from outcrossers on the high fitness spectrum. fitness fitness Drought Avoidance Trait 1 Drought Avoidance Trait 2
Dro ug ht Avo ida nc e Water Use Photosynthesis Transpiration Efficiency Carbon Gain Carbon Gain Water Loss Water Loss Higher rates Higher Rates ? Positively correlated Positively correlated with fitness with fitness
Se e d Se t Definition: A measure of plant fitness. Corresponds to the actual number of mature seeds compared to seed potential. How you measure: Percentage: Mature seeds Mature seeds + aborted ovules Aborted ovules Mature Seeds
Study Site : Sawmill • Clarkia xantiana ssp xantiana •Seasonal Temperatures •Sympatric with selfing sister •Extreme edge of habitat taxon: xantiana ssp parviflora •Hot and dry region
Pro je c t Go a ls •Correlating physiological rates with fitness •Looking for general patterns in outcrossing species What will be done in lab : •Measure Seed set in plants collected in field •Correct physiological data taken in the field using leaf area •Correlate physiological rates to seed set
E xpe rime nta l Me tho ds: Physio lo g ic a l ra te s An infrared gas exchange analyzer was used to measure: Photosynthesis Transpiration Measures the CO 2 taken in and H 2 O given off Collected measured leaves Measure area of leaves analyzed in IRGA Infrared gas analyzer
E xpe rime nt Me tho ds: Se e d se t In the Field: Glued fruits shut with silicon Collected plants after all fruits matured In the Lab: Separate fruits from stem underdeveloped Open fruits Separate mature seeds from aborted ovules Count mature seed and aborted ovules Aborted ovules Mature seeds
Re sults: Pho to synthe sis y=0.82-.0016x 1 R 2 =0.03 P=0.3 0.8 Seed Set 0.6 0.4 0.2 0 0 10 20 30 40 50 60 Photosynthetic Rate (umol CO 2 m -2 s -1)
Re sults: T ra nspira tio n y=0.67-0.02x R 2 =.018 P=0.42 1 Seed Set 0.8 0.6 0.4 0.2 0 -8 -6 -4 -2 0 Log e Transpiration (umol H 2 O m -2 s -1 )
Re sults: Wate r Use E ffic ie nc y y=0.77+0.0006x R 2 =0.000008 P=0.98 1 0.8 Seed Set 0.6 0.4 0.2 0 -2.5 -2 -1.5 -1 -0.5 0 Log e WUE (umol CO 2 /umol H 2 O)
Ana lysis What patterns are present between outcrossing species? There is no correlation between seed set and physiology Only one population of a data Preflowering vs. Flowering The Next Step: Analyze more data from different populations and species Account for flowering stage Take out other effects, such as biomass.
Ac kno wle dg e me nts •NSF •Susan Mazer •CNSI •Leah Dudley •UCSB •Alisa Hove •UC Leads •Ofelia Aguirre •Eric Pressly
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