Ecology- Adaptations to Variability

Principle of Allocation

• Levins 1968

• Basically a budget

• Organisms have limited energy

• Amount used for one function reduces amount of energy available for others

• Trade-offs vary with space and time (environment)

• As population adapts to environment, fitness in other environment is reduced

Phenotypic trade-off

Situation in which a given phenotype experiences higher fitness in one environment, whereas other phenotypes experience higher fitness in other environments

• Phenotype fitness depends on environment

  • Brown fur good for inland (forests, fields)

  • White fur good for sandy coast

Phenotypic plasticity

Ability of a single genotype to produce multiple phenotypes

• One individual that can change phenotype in response to the environment

• Ex. bigger muscles on people = response to going to the gym

• Downside of plasticity is phenotype will never be the best but also won’t be the worst

  • Great for stochastic environments (lots of change) but not great for relatively stable environments

Acclimation

An environmentally induced change in an individual’s physiology

• Form of plasticity

• Ex. training at a high altitude

Biotic variation

Evolved adaptations to variation in enemies, competitors, and mates

Abiotic variation

Evolved adaptations to variable abiotic conditions

Hermaphrodites

An individual that produces both male and female gametes; capable of both sexual and asexual reproduction

• Prefer sexual reproduction

Inbreeding depression

Decrease in fitness caused by mating between close relatives due to offspring inheriting deleterious alleles from both the egg and the sperm

• Fitness decreases as homozygosity increases

• Homozygosity increases as inbreeding/cloning increases

• Results in phenotypes being lost

Microhabitat

Specific location within a habitat that typically differs in environmental conditions from other parts of the habitat 

• Ex. Sun vs shade

Migration

Seasonal movement of animals from one region to another

• Various triggers- temp, length of day, food scarcity

Storing resources

Store energy; alternative when migration is not possible (ex. sessile organisms, squirrels)

Dormancy

Condition in which organisms dramatically reduce their metabolic processes; different types

Diapause

Dormancy associated with a period of unfavorable environmental conditions

• Enter a state of desication- removal of moisuture/drying

• Insects

Hibernation

Dormancy in which individuals reduce the energetic costs of being active by lowering their heart rate and decreasing their body temperature

• Over a long period of time

• Mammals

Torpor

Brief period of dormancy in which individuals reduce their activity and their body temperature

• Over a short period of time

• Birds and mammals (bears)

Aestivation

The shutting down of metabolic processes during the summer in response to hot or dry conditions

• Snails, tortoises, crocodiles