4/10 - Functional Diversity: Body Size & Life History Strategies

Graphing Large range of Sizes: Logarithmic(Log) Scale

- way of plotting #’s where each step represents a multiplication instead of addition(linear scale)

EX: 1 → 10 → 100 → 1000 (multiplying by 10)

• graph across large range of sizes,

• exponential growth

• compare rates of change

Scaling Relationships

Surface Area (S) = L²

• length x width

Volume (V) = L³

• length x width x height

Mass (M) = L³

• proportional to V (assuming constant Density)

Key Concepts

- as an organism get bigger…

V or M increases faster than SA

• L³ grows faster than L²

• smaller SA:V

• greater V:SA

Small organisms

• greater SA:V

• lose heat/water quickly

Large organisms

• smaller SA:V

• retain heat better

Counter Availing Forces (Air Resistance): Gravity & Friction

- because M increases faster than SA, larger animals experience less air resistance relative to their weight, fall faster, & suffer greater impact, while small animals are slowed by drag & survive falls

Mouse to Elephant Curve

- describes how biological traits scale w/ body size

smaller animals

• high metabolism

• fast heart rate

• short lifespan

larger animals

• slower metabolism

• slow heart rate

• long lifespan

Life History

- an organism’s growth, reproduction, & survival strategies

Life History: How often to Breed?: Semelparity

- reproducing once in a lifetime & then dying

• many offspring at once

• little to no parental care

• shorter lifespan

tradeoff: use all resources to reproduce NOW; leave nothing for survival (favored when survival after reproduction is unlikely, unpredictable environment)

Life History: How often to Breed?: Iteroparity

- reproducing multiple times in a lifetime

• fewer offspring at a time

• more parental care

• longer life span

EX: humans, elephants, birds

tradeoff: save resources to survive & reproduce again (environment is stable)