(1) Intro to Ecology & (2) Evolution - BIO 305

Ecology

Scientific study of the interactions that determine the abundance (how many) and distribution (where) of living things

Biotic factors

Interactions living things (predation, competition, mutualism)

Abiotic factors

Physical environment (temperature, salinity, disturbance)

Human interactions with other species and the biosphere are critical for the quality of life on Earth for ourselves and all living things

Why study ecology?

Paradigm

Set of fundamental principles in a particular field that governs how scientists view the world; represents the consensus among scientists on the known truths about the physical world

Evolution

Genetic change in population over time

4 Different Mechanisms of Evolution

- Mutation

- Gene Flow

- Genetic drift

- Natural Selection

Fitness

Survival & Reproduction; Genetic contribution of an organisim’s descendants to future generations

Katmai Bear Take away:

• traits & survive and reproduce

• fitness

• genes

• biotic and abiotic

Katmai Bear Take away:

• There are many ____ that affect the ability of bears to _____ & _____ in a harsh physical environment

• Survival and reproduction determine _____

• These traits are coded by ______

• These traits are also affected by the ____ and ______ environment

• Different traits would be favored (“selected for”) in a different environment

Adaptation as a trait

Genetically based characteristic of an organism that improves its ability to survive or reproduce within its environment

Adaptation as a process

the process of evolution that leads to an adaptive trait becoming more common in a population

Natural Selection

Evolutionary process in which individuals that possess particular characteristics survive or reproduce at a higher rate than other individuals because of those characteristics

Conditions Require for Evolution by Natural Selection

• Individuals in a population vary in their traits

  • different phenotypes

• Variation in traits is heritable

  • Differences in phenotypes among individuals are due to differences in genotype

• Trait variation results in differences in fitness among individuals

Acts on Individuals; Outcome of that selection affects the genetic makeup of a population over generations

What does natural selection operate on?

Adaptively Evolve

Populations _____ ____

Survive & Reproduce (do not adapt or evolve)

Individuals ____ & ______

Artifical Selection

People imposing a direction; Only the tame and extremely friendly populations were allowed to breed which resulted in generations overtime to increase amounts of elite percentage populations; Eventually almost all elite

Nature vs Artifical Selection

Nature, there is no conscious, directional choice

Indiviual

What’s happening in it’s one lifespan

Population

The interacting organisms

Generation

Those line of offspring

Mouse example for evolution by natural selection

1. Individuals vary in phenotype

• mice differ in color

2. individuals with different phenotypes have different fitness

• mice that match their habitat better have higher survival

3. phenotypic variation is heritable

• Agouti gene affects coat color

Local Adaptation (Mice ex.)

If individuals in different areas experience different selection pressures, then populations can become adapted to local conditions

Climate

most important fact determining the geographic distribution and physiological functioning of organisms

Earth’s Shape and Tilt

What determines the amount of incoming radiation in different areas of the Earth?

Equator

Where gets the most solar energy?

• Variation in incoming solar radiation across the Earth’s surface

• A few basic physical principles

What drives global patterns of precipitation and temperature?

decreases (gets lighter)

Physical principle 1: gases expand when heated

Air density ______ as temperature increases

rises

Warm air is less dense than cool air, therefore warm air ______

decreases (as you go up less particles more spread out)

Physical principle 2: Atmospheric pressure ______ as you go higher above the surface of the Earth

less oxygen

As you go up in elevation there is ____ oxygen available

Rising air expands

Atmospheric pressure decreases with altitude → ______

Rain

Expanding air cools → condensation → ______

Why do we see different habitats around the globe?

Differential heating of Earth’s surface combined with physical principals lead to patterns of atmospheric circulation

Hadley Cell

Cycle of air movement caused by incoming solar radiation striking the equator

3 Steps

1. Warm air is less dense than cool air → warm air rises

2. Atmospheric pressure decreases with altitude → rising air expands

3. Expanding air cools → condensation → rain

Why is the equator a low pressure zone?

Air is traveling up

high pressure to low pressure

Wind flows from__________________ , which are created between the cells

Differential heating is responsible for:

patterns of global temperature, precipitation, wind

warmer

Global pattern: _____ at the equator compared to the rpoles

How do mountains modify climate on a local scale, including rainfall in Hawai’i?

The mountains drive it’s own small-scale Hadley cell, Hawai’i’s East tradewinds make the windward side the wet side

Biomes

Large geographic areas affected by similar climatic and physical factors, leading to distinctive forms of plants and animals

Covergent evolution (convergence)

Evolution of similar traits among distantly related species in response to similar selection pressures

1. Temp below 0º C (water freezes)

2. Temp line is above precip line (too dry to grow)

Climate Diagram: When can’t plants grow?

Similar adaptations to similar physical environments; similar traits, different species

Why do we see similar life forms in different places?

Similar adaptations to similar physical environments

Why do we see similar habitats in different places?

Because they experience similar abiotic conditions, mainly climate; Imposes selection pressures on organisms, causing similar traits to evolve in species

Why do difference places on the plant have the same biome?

• Tradewinds

• Mountains

• Rain shadows

What results in Hawai’i having a huge diversity of biomes?

Explain how changes in elevation on a mountain are similar to global patterns in biomes?

Habitats change as you go up in elevation because abiotic factors are changing; As elevation increases, temperature and oxygen change, creating biome-like patterns similar to moving toward the poles

Differential heating creates global climate patterns, and climate determines biome distribution. Natural selection then favors traits suited to each climate, producing similar biomes and adaptations in places with similar abiotic conditions.

Explain the distribution of biomes on Earth

Physiology

Study of bodily functions and cellular mechanisms at work within living organisms

Physiological ecology

Study of the interactions between organisms and the physical environment that influence their survival and persistence

Range

Environments the organisms can tolerate

Optimum

The environmental value the rate is the highest

Niche

All of the environmental conditions and resources necessary for persistence; What a population needs; includes as many axes as needed to capture all necessary environmental resources and conditions

Connect performance curves to distribution and abundance across the landscape.

Species occur where environmental conditions fall within their performance curves, and they are most abundant near their optimum

Physical Environment

Major determinant of species distribution and abundance

Ectotherms

Organism’s temperature determined by the external environment; most plants and animals (like snake example)

Endotherms

Rely mostly on internal heat generation through metabolism; birds, mammals (me)

Endothermy cost and benefits

• Energetically expensive

  • Must eat alot

  • Must invest in insultation (feathers, fur, fat)

  • Must spend a lot of time being active

    • opportunity cost

    • risk

• But, body temperature stays near optimum

  • wide geographic changes and activity periods

Ectothermy cost and benefits

• Body temperature will often be suboptimal

• Distribution more limited by environmental temperature

Acclimation

Short term, reversible, physiological changes that occur during an individual’s lifetime; changes occur within a lifetime; changes are reversible

Wood frog example

Most northern ranges, can tolerate freezing through acclimation; water flows out of the cells and turn 65% of body water to ice; occurs within a lifetime & changes are reversible; the ability to acclimate itself is an adaptation; some species have evolved over generations to tolerate freezing temperatures

Human Acclimation example

Swimming in cold water

Individuals; Populations

• _______ can acclimate (short term reversible change)

• ____________ can adapt (change in trait frequency over generations due to

natural selection

tolerate

species can only occur in places where they can ______ the physical environment or avoid unsuitable extremes

Why is water important for living things?

Organisms must balance uptake and loss of water, and solute concentrations; Water is the medium in which all biochemical reactions necessary for life to occur; temperature control & structural support

high to low

Water moves from ____ to _____ energy

Water potential gradient

Determines Water loss rates

Why does water move from soil → plants → atmosphere?

water potential gradient — water moves from areas of higher water potential (soil) to lower water potential (atmosphere) ; from positive, to negative, to more negative

Transpiration

Process of the movement of water from soil through plants to the atmosphere as water vapor; how clouds form, how air travels

Photosynthesis

movement of water from the soil through the leaves is important for photosynthesis; Vast majority of biological available energy on Earth — including fossil fuels — is derived from the conversion of sunlight into energy-rich carbon compounds

Stomates

Where water exits plants through pores in leaves; plants can open and close

Cooling effect

Transpiration has a ________ _____ (just like sweating!)

C3 Photosynthesis

Energy efficient, but high water loss; 90% of plants; Calvin cycle takes place in the mesophyll; mostly temperate biomes

C4 photosynthesis: spatial segregation

intermediate energy efficiency and water loss; 3% of plants grasses, corn, sugarcane; C.C. takes place in bundle sheath cells; tropical or semitropical biomes, mostly grasslands

CAM photosynthesis: temporal segregation

low energy efficiency, but highest water retention; 7% of plants cati, succulents; open stomata at night, capture carbon when water loss is lower because its cooler

Connect the need for different photosynthesis strategies

Physiological trade-offs cause different photosynthesis strategies to be distributed in different biomes, shaping global patterns of plant abundance

Integrate and explain the concepts of performance curve and the niche and how this translates into the distribution and abundance of organisms

Performance curves define physiological limits and optima, the niche represents where those conditions occur in nature, and organisms are most abundant near their optima and absent outside their niche

Why are there different photosynthetic pathways?