Study Notes on Flower Thermoregulation by Matt Koski

Introduction to Flower Thermoregulation

• Presenter: Matt Koski, Assistant Professor at Clemson University

• Overview of Presentation:

  • Introduce the concept of flower thermoregulation and its importance.

  • Address specific questions regarding thermoregulation in flowers.

  • Introduce the study system used in research.

  • Discuss two primary research questions and the data approaches used to answer them.

  • Share personal background as a researcher.

Importance of Thermoregulation

• Thermoregulation in Animals:

  • Animals behaviorally thermoregulate when temperatures are not optimal; e.g., lizards seeking shade under warmth.

  • Humans also behaviorally thermoregulate by seeking cooler areas.

• Thermoregulation in Plants:

  • Unlike animals, plants cannot move; they are rooted in their substrate but experience drastic temperature fluctuations.

  • The role of thermoregulation in plants often goes unnoticed, though significant, especially in warming climates.

Plants and Climate Change

• Response to Warming Climatic Conditions:

  • Shifts in flowering times to align with earlier springs.

  • Alterations in photosynthetic rates.

  • Insufficient understanding of how temperature changes influence plant reproduction.

• Reproduction via Flowers:

  • Flowers contain pollen and ovules and are critical for plant reproduction.

  • Thermal stress can adversely affect pollen and ovules.

  • Example: Apple blossoms and frost after blooming lead to reduced harvests.

Thermal Performance Curve

• Definition:

  • Thermal Performance Curve: A graphical representation of how performance, e.g., pollen germination, varies with temperature.

• Example of Temperature Effects on Pollen Germination:

  • Temperatures tested: 3°C, 9°C, up to 40°C.

  • Optimal temperature for pollen germination identified around 23-24°C with diminished performance seen at temperature extremes.

• Objective: To understand optimal temperatures and tolerance breadth for pollen and ovules under varying temperature regimes.

Local Adaptation Hypotheses

• Assumptions Based on Temperature Regimes:

  • Expectations include lower optimal performance temperature in cooler populations and higher in warmer populations.

• Diagram Explanation:

  • A graph could illustrate cold populations (blue) versus warm populations (red) with expected optimal performance temperatures accordingly.

• Distinction between Local Adaptation and Maladaptation:

  • Local adaptation implies an optimum temperature aligns with environmental conditions.

  • Maladaptation implies a disconnection, where an organism cannot optimally function under local environmental conditions.

Research Questions and Predictions

1. Is pollen thermal performance locally adapted?

   • Prediction: Higher thermal optimum in warmer populations.

2. How do flowers thermoregulate?

   • Research will focus on mobile petals that alter the floral temperature in response to solar radiation.

Introduction of Study System

• Geographic Focus:

  • Research is conducted in the San Juan Mountains, Southwestern Colorado, specifically Lake City, Colorado.

• Species of Interest:

  • Argentina ancirrhina:

  • Family: Rose family.

  • Characteristics: Co-sexual (contain both pollen and ovules) and mostly self-incompatible.

  • Modes of reproduction: Sexual and vegetatively clonal.

  • Habitat: Populations span various latitudinal and elevational gradients.

Study Design

• Research Locations:

  • High elevation populations at over 4000 meters versus low elevation populations around 2300-2500 meters.

• Experimental Method:

  • Conducted floral performance experiments using a temperature gradient from 3°C to 40°C.

  • Samples brought to the greenhouse for controlled growing conditions.

  • Pollen collected after exposure to temperatures for germination assessments.

Results and Interpretations

Thermal Performance Curves

• Results for Low Elevation Populations: Optimal germination temperatures observed between 19.5°C and 23°C.

• Results for High Elevation Populations: Unexpectedly, optimal germination temperatures ranged from 24°C to 27°C, higher than low elevation populations.

• Conclusion:

  • Findings contradict the hypothesis of local adaptation: No evidence found of local adaptation for pollen performance among populations studied.

Evidence of Flower Thermoregulation

• Experimental Setup:

  • Thermocouples placed inside flowers to measure temperature differentials compared to air temperature nearby.

  • Measurement of Delta T: difference between flower temperature and ambient air temperature.

• **Findings: **

  • Flowers generally warmed above ambient air temperatures, particularly during peak sunlight hours.

  • High elevation flowers warmed significantly more than low elevation flowers.

Investigation of Physiological Mechanisms

• Petal Removal Experiment:

  • Showed increased flower warming capabilities with intact petals, indicating the contributions of petal morphology to thermal regulation.

• Comparative Measurements:

  • At high elevations, petal morphology was associated with effective solar radiation focusing, leading to increased floral temperatures.

  • Correlation observed between cupping of petals and increased floral temperature at mid-day hours.

Connection to Pollinator Visitation

• Experiment Tracking PollinatorVisits versus Floral Temperature:

  • Pollinators showed a preference for warmer flowers, particularly at cooler temperatures where viability is critical for reproduction.

• Implications of Findings:

  • Floral thermoregulation may enhance reproductive success through increased pollinator visitation, emphasizing the ecological importance of thermal strategies in flower morphology.

Conclusion of Research Findings

• Summary of Key Insights:

  • Lack of locational adaptation in pollen thermal performance.

  • Evidence supporting the hypothesis that flowers thermoregulate through morphological adaptations.

  • Potential implications on future flowering behaviors as climates continue to warm globally.

Personal Journey to Research

• Early Life Influences:

  • Grew up in a polluted area with a focus on environmental issues spurred interest in environmental science and law.

• Academic Journey:

  • Transitioned from environmental policy interests to hard science through various academic experiences and teaching assignments, culminating in a research focus on plant evolutionary ecology.

• Professional Development:

  • Combination of fieldwork and research utilizing the study of floral thermoregulation in natural systems.