Redwood (Sequoia sempervirens)

Chapter 12 – Life Histories

Lifespan: 2,000 Yrs

Seed Production: Millions

Pacific Salmon (Oncorhynchus spp.)

Salmon: Anadromous

Lifespan: 2-7 Years

Egg Production: Thousands

8 Mayfly Hatch

9

Adult Lifespan: One Day

Egg Production: Hundreds

Mayfly

Lifespan: 2000 YearsSeed Production: Millions Lifespan (Adult): 1 Day

Egg Production: Hundreds

Lifespan: 2-7 YearsEgg Production: Thousands

LIFE HISTORY TRAITS

Life History TraitsStudy of Adaptations that Influence …

• Reproductive Output

• Size of Offspring

• Growth Rate

• Age at Reproductive Maturity

• Competitive Ability

• Life Span

Available Energy is Limited

UNDERSTANDING LIFE HISTORY TRAITS

A) OFFSPRING NUMBER VERSUS SIZELIFE HISTORY CHARACTERISTICS

Sturgeon

Trout

Angel Fish

Fig. 12.4 in Molles 2008

Number of Eggs versus Egg Diameter

Evolutionary Consequences of Life History Traits

RR, Rr

rr

“Hypothetically”

High Gene Flow Among Populations(p = frequency of R allele; q = frequency of r allele)

Population A(p = .80, q = .20)

Population B(p = .78, q = .22)

Population A(p = .82, q = .18)

Low Gene Flow Among Populations(p = frequency of R allele; q = frequency of r allele)

Population A(p = .80, q = .20)

Population B(p = .40, q = .60)

Population A(p = .20, q = .80)

Fig. 12.5 in Molles 2008

Evolutionary Consequences of Life History Traits

Fig. 12.6 in Molles 2008

A) OFFSPRING NUMBER VERSUS SIZELIFE HISTORY CHARACTERISTICS

Fig. 12.7 in Molles 2008

Life History Patterns

Seed Mass versus Plant Growth Form

Graminoid

Forb

Woody

Climbers (Vines)

Fig. 12.8 in Molles 2008

Seed Mass versus Plant Growth Form

Seed Mass versusSeed Dispersal Strategies

Unassisted (Mustard)

Wind(Cottonwood)

Adhesion(Snakeroot)

Elaiosome(Poppy)

Aril(Pomegranite)

Scatterhoard(Walnut)

Fig. 12.8 in Molles 2008

Seed Mass versus Dispersal Mechanism

LIFE HISTORY CHARACTERISTICSB) Adult Survival (Mortality) and Reproductive Allocation

Age at Maturity versus Adult Survivorship

Fig. 12.12 in Molles 2008

Age at Maturity, Reproductive Effort versus Adult Mortality

Age at Maturity, Reproductive Effort versus Adult Mortality

Figs. 12.12, 12.13 in Molles 2008

Evolution of Life History Characteristics: Within Species Variation?

(Are Age at Maturity, Reproductive Output Related to Adult Survivorship?)

Figs. 12.15, 12.16 in Molles 2008

Variation in Survivorship Among Populations of Pumpkinseed

Age at Maturity versus Adult Survivorship(Age at Maturity versus Adult Mortality)

Fig. 12.17, 12.18 in Molles 2008

Available Energy is Limited

UNDERSTANDING LIFE HISTORY TRAITS

Different Ecosystems, Different Challenges and Opportunities

24

Evolutionary Strategies for Coping with Different Ecostystems

R selection K selection

• MacArthur and Wilson 1967 (Birds, Insects)• Pianka 1970, 1972 (Lizards)

Variable, UnpredictableEnvironment

Fairly Constant, PredictableEnvironment

Life History Classification

Table 12.1 in Molles 2008

Fig. 12.20 in Molles 2006

Life History Classification of Plants(Grime 1977, 1979)

25

26

27

Grime’s Variable # 1 (Environmental): DEGREE OF STRESS

2

Grime’s Variable # 2 (Environmental): DEGREE OF DISTURBANCE

28

29

Grime’s Variable #3 (Biotic): INTENSITY OF COMPETITION

7

8

Fig. 12.21 in Molles 2006

Life History Classification of AnimalsWinemiller and Rose (1992)

A) OPPORTUNISTIC

B) PERIODIC

C) EQUILIBRIUM

Equilibrium Life History

Cavefishes, Marine Catfishes

Periodic Life History

Cod, Tuna, Ocean Sunfish

Opportunistic Life History

Anchovy, Silverside, Killifish, Mosquitofish

Fig. 12.22 in Molles 2006

Life History Classification of AnimalsWinemiller and Rose (1992)