Lecture #6 Life History and Phenology

Life History

• The patterns of growth, reproduction, and survival in an organism's lifetime

Phenology

• The timing of biological events (e.g., flowering, migration) in relation to seasonal and environmental changes

Growth vs. Reproduction tradeoff

• Investing energy in growth can delay reproduction, while investing in reproduction can limit future growth

Seed Size vs. Seed No. Tradeoff

• Large seeds provide more resources per seed but fewer are produced; small seeds are numerous but each has fewer resources.

r-selected plants

• earlier age at time of first reproduction; usually greater number of seeds produced; should be found in disturbed habitats

K-selected plants

• later age at time of first reproduction; usually greater investment in individual seeds; should be found in stable habitats

CRS model

C (Competitors)

• Thrive in stable, resource-rich environments

S (Stress-Tolerators)

• Adapt to low-resource, stressful conditions

R (Ruderals)

• Rapid colonizers in disturbed areas

Seed Masting

• the synchronized, large-scale production of seeds (or fruits/nuts) by a population of trees or shrubs at semi-regular intervals, followed by years of low production

Triggers of seed masting

• Climate cues (temperature, rainfall), predator satiation, resource availability.

Phenological Mismatch

• When species’ life cycle events (e.g., flowering, migration) fall out of sync, often due to climate change, disrupting interactions like pollination or food availability.

Phenological mismatch due to global climate change

• Plants & Pollinators – Flowers bloom earlier, but pollinators (like bees) may not emerge in time.