Project Overview Effects of Population Size on the Reproductive - PDF document

Santa Cruz Tarplant Recovery Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve Project Overview Effects of Population Size on the Reproductive Fitness of • Project began for an undergraduate thesis Holocarpha macradenia requirement while attending school in Rhode Island • Met with Grey, applied for a permit, explored the populations with the help of Grey, Sue Bainbridge, Val Haley, CDFG survey team in Wildcat Canyon • Using the GPS data on CNDDB looked for other populations both extant and extirpated Data Collection Populations Summer of 2000: – Seed heads collected from nine populations – Individual seeds counted, weighed, and germinated Project focused on nine populations : – Physical plant data taken (number of heads, number of – Watsonville Airport florets, plant height, ect….) – Porter Ranch – Some environmental data taken (neighboring plant species – Apple Hill composition, ect..) – Graham Hill – Non-dormant seeds were sprouted and grown in a randomized greenhouse trial – ‘5’ Experimental Populations in Wildcat Canyon – Similar seed and plant data taken from greenhouse plants, – Some data also taken from Arana Gulch and Twin some pollination experiments conducted Lakes, but nothing removed Summer of 2001: – Same data set taken with the exception of not removing seeds from certain populations (Graham Hill, some of the experimental populations) Disk Achenes Per Head vs. Pop. Size Population Size Data 18 • Population data taken from the CNDDB, � 2000 Native 16 population managers, other researchers, and � 2000 Re-introduced Non-Dormant Seeds � 2001 Native counting plants myself. 14 � 2001 Re-introduced 12 • Plant data plotted against the geometric 10 average of population size over the last ten 8 years on a logarithmic scale 6 • Better population data would be very 4 welcome!!! 2 R 2 = .540 p = .0003 0 y = 2.041x + .500 1/5 August 20, 2003 1

Santa Cruz Tarplant Recovery Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve Proportion of Ray Achenes Per Head Ray Achenes Per Head vs. Pop. Size vs. Population Size 1.0 16 � 2000 Native Porportion Seeds Dormant � 2000 Re-introduced 0.9 � 2001 Native 14 � 2001 Re-introduced Dormant Seeds 12 0.8 10 0.7 8 0.6 6 R 2 = .368 0.5 � 2000 Native 4 p = .0059 � 2000 Re-introduced R 2 = .167 y = -.0465x + .855 � 2001 Native 2 0.4 p = .0825 � 2001 Re-introduced 0 1 2 3 4 5 6 7 y = .872x + 8.252 0 Population Size ( Logarithmic Geometric Average) Number of Disk Achenes per Head Proportion of Ray Achenes per Head Controlled for Head Size Controlled for Head Size 3.5 seeds / seed head perimeter 2.2e-4 # non-dormant / head area 3.0 2.0e-4 porportion of dormant 2.5 1.8e-4 2.0 1.6e-4 1.5 1.4e-4 1.0 1.2e-4 R 2 = ..432 0.5 1.0e-4 p = .0077 R 2 = .337 y = 1.197x + 1.072 0.0 p = .0091 8.0e-5 y = .316x + .711 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Population Size (Logarithmic Geometric Average) Individual Ray Achene Weight Individual Disk Achene Weight Average Non-Dormant Seed Mass 0.0014 0.0016 Average Dormant Seed Mass 0.0012 0.0014 0.0010 0.0008 0.0012 0.0006 0.0010 0.0004 0.0002 0.0008 R 2 = .719 R 2 = .219 0.0000 p < .0001 p = .0673 y = 1.190e-4x + 6.568e-4 y = 8.418e-5x + 4.904e-4 0.0006 2/5 August 20, 2003 2

Santa Cruz Tarplant Recovery Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve Total Seed Weight per Head Germination vs. Pop.Size 1.00 0.040 n2 0.95 Total Seed Weight per Head 0.035 r7 Percent Germination 0.030 n1 0.90 0.025 r5 2000 R 2 = .792 r8 0.020 0.85 r9 p = .0013 y = 5.054e-3x + 5.606e-3 0.015 n3 n4 0.80 2001 0.010 R 2 = .530 p = .0262 0.005 y = 4.499e-3x + 3.758e-4 0.75 R 2 = .173 r6 0.000 t- test p = .266 p = .0352 0.70 -0.005 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Plant Chacteristics: Longest Plant Chacteristics: Total Seed Branch Length Heads per Plant Longest Branch Length (median) 16 16 n1 14 14 n2 12 nB Total seed heads 12 n2 10 10 8 r5 n1 8 6 r6 nB 4 6 r5 r8 r7 2 4 r8 r6 r9 R 2 = .545 n4 0 r7 nA n3 p = .0095 2 R 2 = .467 r9 n4 nA n3 p = .0203 0 1 2 3 4 5 6 7 0 0 1 2 3 4 5 6 7 Greenhouse Plants: Density of Plant Chacteristics: Plant Height Disk Achenes Density of Non-Dormant Seeds 3.5 28 3.0 26 nB n2 n2 r7 n1 24 2.5 r9 Height (median) 22 n3 n1 2.0 20 1.5 18 r6 r5 16 r7 1.0 r5 r8 14 r6 n4 r9 n4 0.5 r9 12 r6 r8 n1 n3 r7 n2 n4 r5 10 0.0 r8 n3 R 2 = .122 nA 8 p = .291 6 0 1 2 3 4 5 6 7 3/5 August 20, 2003 3

Santa Cruz Tarplant Recovery Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve Greenhouse Plants: Porportion of Greenhouse Plants: Total Seed Ray Achenes Heads Per Plant Total Seed Heads Produced per Plant 30 1.0 n4 r8 Porportion of Dormant Seeds r6 25 r5 n3 0.9 n1 r5 20 r9 r8 r9 n1 n4 0.8 r9 n2 n3 15 r6 r7 n2 r8 r5 0.7 r7 10 n1 n4 n2 r6 r5 5 0.6 r7 r8 r6 r7 r9 n4 n3 n3 n2 0 n1 0.5 0 1 2 3 4 5 6 7 0.4 Population Size ( Logarithmic Geometric Average) Data Summary Greenhouse Plants: Pollination • Smaller Populations Tend to Contain: – fewer disk achenes (regardless of seed head size) 18 – a higher proportion of dormant seeds (also Non-Dormant Seeds (Disk Achenes) Dormant Seeds (Ray Achenes) 16 regardless of seed head size) 14 – lighter dormant seeds Number of Achenes 12 – less seed weight per head 10 – plants with fewer seed heads 8 – plants with shorter branches 6 4 • Smaller Populations Do Not Tend to Contain: 2 – Fewer Dormant Seeds 0 – Lighter disk achenes – Less germinable disk achenes non-dormant achenes (crossed) non-dormant achenes (selfed) – Smaller plants by all measures dormant achences (crossed) dormant achenes (selfed) More Data Summary Possible Mechanisms for When grown in a Common Garden Relationships with Population Size Situation: – Plants in smaller populations DO NOT • Less pollination leads to less non-dormant exhibit any traits that distinguish them from seed production. larger populations • Stressed plants allocate more energy to – Cross-pollinated plants produce more disk achenes than selfed plants but not more dormant seeds. ray achenes • Stressed plants in unfavorable environments are producing lighter seeds, fewer seed heads, and fewer branches 4/5 August 20, 2003 4

Santa Cruz Tarplant Recovery Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve Recommendations for What does it mean? Management • Apparently no loss of genetic viability in smaller populations • Increase Quantity and Quality of Seed Output in Small Populations • Tarplant Strategy: • Maintain non-dormant seed production – In hard times, go dormant and wait for a stimulus to bring the population back. – Increase plant size • Bad News: Small tarplant populations – Increase pollination decrease exponentially because they are producing mostly dormant seeds • Stimulating germination of non-dormant • Good News: There should be plenty of seeds is important in rehabilitation but many dormant seeds (albeit small ones) should we seeds might be very small and more sensitive decide to restore ‘extirpated’ populations than larger seeds Native Populations: Santa Cruz Re-Introduced Populations: Berkeley 1e+8 1e+5 1e+7 1e+4 1e+6 1e+3 1e+5 Population Size Population Size Precipitation Precipitation 1e+4 1e+2 1e+3 1e+1 1e+2 1e+1 1e+0 1e+0 1e-1 1e-1 1e-2 1e-2 1980 1985 1990 1995 2000 1980 1985 1990 1995 2000 Thank You’s • Grey Hayes • Sue Bainbridge • Val Haley • Melanie at CDFG • EBMUD Survey Team 2000 • Advisors back in R.I. 5/5 August 20, 2003 5