Midterm Exam 1

Aldo Leopold

* Hired as chair of game management at UW-Madison in 1933
* Created first academic program in wildlife management
* First professor of our 318 course (then 118) starting in 1939

Leopold’s Contributions

* Author of Game Management and A Sand County Almanac
* Wilderness advocate
* “The Shack”
* Habitat Conservation
* First to apply science of ecology to practice of conservation

Ecology

The relationships between organisms and their environment

Wildlife Ecology

* Applied ecology of wild terrestrial vertebrates and their plant and animal associates
* The science behind the practice of wildlife management

Basic Science

Increase knowledge and understanding without immediate benefit or practical application

Applied Science

Motivated by a specific need for information

Applied Ecology

* Natural resource management (wildlife, fisheries, forestry, range, etc.)
* Conservation biology
* Restoration ecology
* Landscape ecology
* Agroecology
* Urban ecology

Wildlife Management

The art and science of manipulating populations, habitats, and people to achieve some desired outcome

Goals of wildlife management

* Increase rare or threatened species
* Decrease overabundant, invasive, or nuisance species
* Stabilize sustainable harvest of game species
* Monitor - do nothing, but keep track of species

Ecology at the individual level

Focus: Interactions between individual organisms and their biological and physical environment

Properties of Individual Organisms

* Genotype
* Phenotype
* Anatomy
* Morphology
* Physiology
* Behavior
* Fitness

Fitness

* Genetic contribution of an individual to future generations
* Natural selection acts on individual organisms by favoring those with greater fitness

Ecology at the population level

* Population = group of individuals of the same species in the same area at the same time
* Basic unit of evolution
* Population dynamics = changes in population size over time

Properties of populations

* Population size
* Population density
* Geographic range
* Sex ratio
* Age structure
* Birth and death rates
* Immigration and emigration

Ecology at the community level

* Community = group of interacting species in the same area at the same time
* Interactions between species: Interspecific competition, predation, mutualism, etc.
* Food chains and food webs
* Variation over time: Succession

Properties of communities

* Composition
* Structure
* Species richness
* Relative abundance pattern
* Diversity
* Stability

Ecology at the ecosystem level

* Ecosystem = all organisms in an area and their physical environment

Properties of ecosystems

* Biotic environment = living organisms
* Abiotic environment = soil, water, climate, geology, etc.
* Energy production
* Nutrient cycling
* Carbon sequestration
* “Ecosystem services”

Scientific Method

• Make an observation

• Ask a question

• Form a hypothesis

• Conduct an experiment

• Accept / reject hypothesis

Hypothesis formation

• Start out with an observation of a natural pattern

• Pose a research question to explain the observed pattern

• Propose hypothesis as possible answer to research question

What makes a good hypothesis

• Simple

• Well-defined

• Testable

• Falsifiable (possible to disprove)

Why can’t hypotheses be “proved”

We collect data and conduct experiments to either support or refute our hypothesis

Descriptive research (observational study)

• Observe events occuring in nature and describe patterns

• Much of wildlife research before 1980s was descriptive

Experimental research

• Look at the response of one variable to changes in some other variable(s)

• Compare manipulated “treatment” froups with “control” groups to measure the magnitude of change resulting from experimental treatments

Advantage of experimentation

Only way to determine cause-effect relationship

Manipulative experiments

• Vary conditions in treatment groups and compare to control groups with no variation

• Usually conducted in the laboratory, but can also be conducted in the field

• Limited scope of inference

Natural Experiments

• Take advantage of natural variation in the environment, rather than manipulating conditions

• Not “true” experiments

• Example: Compare burned to unburned areas following burn

• Most wildlife research involves natural experiments

What makes a good experiment?

• Clearly articulated hypothesis

• Systematic variation

• Replication

Systematic variation

Experiments involve varying one factor to determine its effect on another factor, while holding all other factors constant

Types of variables

• Independent (treatment) variables = those that you manipulate

• Dependent (outcome) variable(s) = what you measure to determine the effect of manipulating an independent variable

• Potentially confounding variables = those that are held constant in an experiment

Groups to compare in an experiment

• Experimental group = independent variable manipulated

• Control group = baseline condition of the independent variable

Replication

• Experimental unit = entity to which an experimental treatment is applied

• Experimental and control treatments should be applied to multiple experimental units

Forms of replication

• Multiple experimental units in each group

• Multiple measurements of the dependent variable(s)

• Multiple runs of the entire experiment

Why is replication important?

• Avoid drawing conclusions from misleading results

• Increase scope of inference of an experiment

• Allow us to determine the degree of variability in the data

Ecology of individual animals - themes

• Adaptions to maximize fitness

• Trade-offs

• Economy - balancing gains and losses

• Effects of body size and shape

• Effects of climate

• Differences among vertebrate groups

Physiological ecology

• Study of physiological functioning of organisms in relation to their environment

• How species adapt to their environments and how environmental conditions restrict where species can live

Factors that affect where species live

• Tempterature

• Precipitation

• Amount of sunlight

• Nutrient availability

• pH

• Other species

• Soil conditions

Potential evapotranspiration (PET)

• Total amount of evapotranspiration that would take place if there were enough water available

• Affected by temperature, isolation, and wind

• PET in mm = 2X avg. temperature in degrees C

Actual evapotranspiration (AET)

• Actual amount of evapotranspiration that takes place given temperature and water availability

• AET = PET when the ground is wet and there is sufficient precipitation

• AET = precipitation when precipitation is scarce

Liebig’s Law of Minimum

Growth and reproduction are limited by the availability of the scarcest resource

Tolerances

• Physiological tolerances = limits on environmental conditions that an organism can tolerate

• Geographic range of a species is largely determined by its tolerances to environmental variables

Shelfold’s Law of Tolerance

Abundance or distribution of an organism depends on its range of tolerance for various environmental factors

Reactions to changing environments

• Geographic range shift

• Extinction

• Acclimation

• Adaptation

Adaption

Any heritable trait that increases and individual’s fitness

Adaptions can be

• Behavioral = action

• Morphological = structure

• Physiological = function

Fitness

• Genetic contribution of an individual to future generations

• Trade-off: maximize number of offspring vs. maximize offspring survival

Homeostasis

Maintaining constant internal conditions independent of the external environment

Surface area-to-volume ratio (SA:V)

• High SA:V means more exposure to the environment, more heat and water loss

• As body size increases, SA:V decreases

Water Budget Formula

W_net= Inputs - Outputs

Inputs: ingestion, W_ing

Water obtained from drinking or from eating food with a high moisture content (“performed” water)

Inputs: metabolic water, Q_met

Water obtained as a byproduct of the breakdown of nutrients

• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

Outputs: secretion, W_sec

Elimination of waste products, including urine and feces

Nitrogenous wastes: uric acid vs. urea

• Birds and most reptiles = uric acid

  • Requires less water to excrete

• Mammals and most amphibians = urea

  • Requires less energy to produce

Outputs: evaporation, W_evap

• Water lost directly from skin or from respiratory tract as animal exhales

• Includes water loss through panting or sweating

Input or Output: Osmotic exchange, W_osm

• Direct absorption (freshwater) or loss (saltwater) of water through osmosis in aquatic animals

• Important in fish, but insignificant in terrestrial mammals

Complete water budget

• W_net = Inputs - Outputs

• W_net = W_ing +W_met +- W_osm - W_sec - W_evap

Behavioral adaptations to desert life

• Active at night

• Live in burrows

• Seek food with high preformed or metabolic water content

• Aestivation = summer or dry season dormancy

Morphological adaptations to desert life

• Body parts adapted for fat storage

• Long extremities for dissipating heat

Physiological adaptations to desert life

• Dry feces

• Concentrated urine (long loops or Henle - where water reabsorption occurs back into the bloodstream)

Physiological adaptations to desert life

Cooling and condensation in nasal passages reduce water loss during exhalation

Gloger’s Rule

Endotherms of a given species tend to be darker in humid environments and lighter in arid environments

Adaptations to marine environment

• Salt glands of reptiles and birds

• Marine mammals produce concentrated urine and avoid drinking sea water

• Milk of lactating marine mammals is very concentrated

Heat source: endo vs. ectotherms

• Endotherms use an internal heat source to thermoregulate

• Ecotherms use an external heat source to thermoregulate

Constancy: Homeo- vs. poikilotherms

• Homeotherms maintain a constant body temperature

• Poikilotherms have a body temperature that varies with environmental temperature

• Heterotherm - under certain conditions can allow their body temperature to flucuate

Advantages of endothermy

• Tolerate wider range of conditions

• Can be active day or night, year round

• Aerobic metabolism - sustain longer activity

Advantages of ectothermy

• Greater efficiency

• Lower energy demands

• Able to survive long periods of low food availability

Metabolic rate and BMR

• Metabolic rate = rate of heat production or energy expenditure

• Basal (standard) metabolic rate (BMR) = lowest rate of energy expenditure of resting, fasting animal in its comfortable temperature range

Thermoneutral Zone

Temperature range over which a homeotherm can maintain a constant body temperature without raising its metabolic rate

Heat budger

H_net = Inputs - Outputs

Absorbed solar radiation, H_sr (input)

Heat gained depends on exposed surface area, intensity of solar radiation, and the proportion of radiation that is absorbed

Metabolic heat, H_met (input)

• Heat generated through energy expenditure

• Varies with body size and activity level

Thermal radiation, Htr (input or output)

• Animals constantly both emit and absorb thermal radiation from their surroundings

• Depends on animal’s body temperature, surface area, and emissivity

Conduction, H_cond (input or output)

Animals can either gain heat or lose heat to the ground and the surrounding air, depending on their relative temperatures

Convection, H_conv (inout or output)

• Animals can gain or lose heat depending on relative temperature of animal and fluid

• Heat transfer increases with wind speed

Evaporative cooling, H_evap (output)

• Heat is released when water changes from liquid to gas (latent heat)

• Animals cool off by sweating or panting

Heat Balance equation

H_net = H_sr + H_met +- H_tr +- H_cond +- H_conv - H_evap

Bergmann’s Rule

Individual of a given species are larger in colder climates than in warmer climates

Allen’s rule

Individuals of a given species have shorter extremities in cold climates than in warm climates

Inefficiency of food consumption

• 2^nd law of thermodynamics

• Net energy = gross energy - cost of extraction - feces - urine

Self-maintenance

• Most of net energy consumed is devoted to self-maintenance

• Includes cellular activity required to maintain BMR and physical activities required for survival

Self-maintenance energy demands

• Looking for food

• Processing food

• Predator avoidance

• Growth

• Locomotion

• Themoregulation

Reproduction

• Energy left over after self-maintenance needs are met is devoted to reproduction

• Trade-off: allocating energy to reproduction reduces survival probability

• Animals will forego reproduction when short on energy

Reproduction energy demands

• Courtship

• Territorial defense

• Nest or den construction

• Gamete production

• Egg laying or bearing live young

• Lactation

• Parental care

Time-energy budget

• Recordof how an animal divides its time and energy expenditures among different activities to maximize net energy gain

• Studies show that animals prioritize among activities in predictable ways

Field work

Observe animals in the field and record how much time they spend on different types of activities - time budget

Lab work

Have animal run, fly, or swim in the laboratory and measure its rate of O₂ consumption to estimate energy expenditure

Environmental factors: Temperature

• Energy required for thermoregulation increases as temperature decreases

• Animals must eat more or or expend less energy in cooler weather

Environmental factors: Food availibility

• Influences how much time and energy an animal must spend looking for food

• Varies daily, seasonally, yearly

Intrinsic factors: body size

• Small animals must eat much more relative to their body mass than large animals

• Chickadees in winter must spend >90% of daylight time and energy looking for food

Intrinsic factors: Type of locomotion

Energetic cost: swimming < flying < running

Essential nutrients

• Water

• Carbohydrates

• Fats

• Proteins

• Vitamins

• Minerals

Macro- vs. micro-

• Macronutrients = needed in relatively large quantities

• Micronutrients = nutrients needed in very small quantities

Energy and nutrition for carnivores

• Nutritionally balanced diet

• Little variation in food quality

• More difficult to get enough food, than to get a balanced diet

• Face undernourishment

Energy and nutrition for herbivores

• Food more abundant, but lacking in some nutrients, especially proteins and minerals

• Food quality is highly variable

• Face malnourishment

Nutritional quality for herbivores

seeds > fruit > buds > young leaves > old leaves > stems and branches > bark

Animals with specialized diets: hummingbirds

• Diet: nectar (mostly carbohydrates)

• Nectar very low in protein, vitamins, or minerals

• Also eat insects and spiders to balance diet

Animals with specialized diets: vampire bats

• Diet: blood (mostly protein)

• Blood very low in fat or carbohydrates

• Minimal nutrient storage - most consume and excrete large amounts of liquid

Animals with specialized diets: porcupines in winter

• Diet: mostly tree bark (low in nutrition)

• Low energy demands

• Digestive microbes increase protein intake

• Attracted to anything salty

Daily periodicity

• 24-hour cycle of light and dark periods caused by earths rotation

• Animal activity patterns follow daily fluctuations in environmental conditions

Environmental factors that fluctuate daily

• Daylight

• Temperature

• Relative humidity

• Precipitation

• Food availability