Bio 1B: Ecology Unit

Air circulation

Circular patterns of air circulation of moist air rising and drying (releasing rain), dry air rises to 30 degree latitude and absorbs moisture

Name the three Climatic Zones and describe their temperature and precipitation levels

1. Tropics: 0-25 deg range. warm, wet, weekly seasonal (wet/dry seasons). Highest precipitation

2. Temperate Zone: 25-60 deg, highly seasonal (cold winter hot summer)

3. Polar: 60-90 deg, year round low temperatures, 24h light/dark at solstices

Compare and contrast past and current rates of change in global temperature regimes

Global Temp and CO2 positively correlated in the 20th Century

Higher CO2 concentration now than in the last 1 million years

Mid 1900s rapid uptick in CO2 flux

Paleocene Eocene thermal maximum: volcanism caused massive release of CO2 > great extinctions

wet bulb temperature

In measuring temperature, the value that would be measured if the bulb of a thermometer was surrounded by a small swatch of wet cloth.

Wet Bulb temperatures of about 31 degC prevent heat dissipation and are lethal in 30 min

People can alternatively survive 100 degC for 30 min if dry air (demonstrating significance of rising humidity from climate change)

Jet Stream

narrow band of strong winds near the polar

weak jet stream destabilizes the polar vortex and allows cool air to move south

Polar Vortex

large area of low pressure surrounding the poles. the vortex refers to the counter-clockwise flow of air that keeps the cold air near the poles

wavy polar vortex - cold air moves south, warm air moves north

Phenology

Seasonal timing

critical to reproduction, migration, and growth

climate change -> spring phenology is getting earlier ->

mismatches in interacting species

Tropicalization

in regions where freezing no longer occurs, cold-sensitive tropical organisms (mosquitoes) are moving polewards

"tropicalization of temperate ecosystems"

Main Biological Responses to Climate Change

Species generally moving towards the poles, and upwards in elevation

Growing seasons are getting longer (trees leaf out earlier in spring and drop later in the fall)

Shifts in time/space lead to mismatches in interacting species

Changes in population abundance, increased extinction rates

Adapt "in situ" (less common)

What is Traditional Ecological Knowledge (TEK) and why is it important to recognize?

Western term to describe understandings of indigenous people, increased interest in learning of TEK as it has been largely excluded from western science

How do temperature and precipitation vary with latitude and altitude?

Hotter annual temperature leads to more overall precipitation.

Rainfaill increases going upward the windward side of a mountain range, as air cools, water vapor condenses and rains. Descending air with reduced moisture results in rain shadow and leward side.

Precipitation is highest at equator and lowest at 30 deg latitude (north and south) due to Hadley cell air circulation

A lot more land in Northern Hemisphere, so more cold land up North than South

How do seasons differ in areas that are farther from the oceans?

Water warms/cools slowly, causing milder seasons in "maritime" areas by the ocean in contrast to stronger seasonal effects in "continental" areas that are farther from the ocean.

Compare and contrast latitudinal temperature gradients over the past 70M years of Earth's history.

Around 50 MYA, latitudinal temperature gradients were shallow and the tropics extended to 30 degrees

Describe how environmental conditions change along elevational gradients, and how mountains create rain shadows.

Cool air flow goes up mountain and gets cooler, holds less water, precipitates out towards the windward side of the mountain, rain shadow is the region of the mountain with little rainfall because its sheltered from prevailing rain bearing wind by mountain range

Chaparral Biome

Identify area of the globe, environmental conditions, and examples of characteristic biota.

West coast of the United States, the West coast of South America, the Cape Town area of South Africa, the Western tip of Australia, and the coastal areas of the Mediterranean

Precipitation 30-50 cm/year, highly seasonal (winter rain)

Cool Fall, Winter and Spring (10-12 deg C) and hot summer (30-40 degC)

Shrubs, trees, grasses, high diversity and endemism

Browsers (deer, goats), small mammals, amphibians, birds, insects

Fire prone, organisms are fire and drought adapted

Desert Biome

Identify area of the globe, environmental conditions, and examples of characteristic biota.

While most deserts, such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia.

Precipitation

Tropical Forest Biome

Identify area of the globe, environmental conditions, and examples of characteristic biota.

Around equator

High precipitation

Wet and Dry seasons

Temeperature = high and aseasonal (25-29 degC)

Highest animal and plant diversity

Tundra Biome

Identify area of the globe, environmental conditions, and examples of characteristic biota.

Very north

Precipitation 20-60 cm/y

Cold winters (-30 degC) cool summers (10 degC)

Herbaceous: mosses, grasses, forbs

Dwarf shrubs and trees and lichen, Permafrost restricts plant growth

Migratory birds, large grazers (caribou, musk, oxen, reindeer), predators like foxes, bears, wolves

Significant oil and gas extraction

Predict physiological, morphological, and behavioral adaptations to abiotic conditions characteristics of chaparral biome

Challenges: lack of water, heat, fire

Solutions: avoid water loss, improve water gain, survive and reproduce after fires

Plants: thick waxy leaves, fire-activated seeds, thermal insulation

Animals: low metabolism, highly concentrated urine, heat loss through extremities

Location of Chaparral Biome

Small sections of most continents.

Coastal areas.

West coast California, West coast of South America, Cape Town of south Africa, coastal areas of the mediterranean

Location of Desert Biome

Sahara of North Africa, deserts of the southwestern US, Mexico, Australia,

Location of Coniferous Forest Biome

Northern Hemisphere, North America, Europe, and Asia (50-60 degN latitudes)

Location of Tropical Forest Biome

Around equator (between 10 degrees north and south)

Around Tropic of Cancer and Tropic of Capircorn

Niche

combination of biotic and abiotic factors that a species needs to reproduce

Life History Traits

Suit of traits related to a species' lifespan and the timing and pattern of reproduction:

Size at birth

Growth pattern

Age and size at maturity

Number, size, and sex ratio of offspring

Age- and size-sepcific mortality and repdrodcution

Length of life

Duration and investment of parental care

Life History Strategies

Life History Strategies are defined by investments into maintenance, growth and reproduction, and trade-offs lead to general patterns of variation along a fast - slow (r to K) axis

r vs. K life history variation

r-selection: selects for life history traits that maximize reproduction and the ability for a population to increase rapidly at low density

K-selection (density dependent selection): selects for life history traits that enhance an individual's fitness when a population is fairly stable

Survivorship curve (definition)

A plot of the proportion of numbers in a cohort alive at each age, showing the pattern of survivorship for a population.

Survivorship curve (Type I)

Low death rates during early and middle life, and a sharp increase in death rates later in life.

Found in large animals (humans, elephants, albatross) that produce few offspring but provide them with good care

Life History Trade Offs

1) current reproduction and survival,

2) current reproduction and future reproduction,

3) number and size of offspring

Y model for allocation trade-offs

Acquisition of resources splits into a Y shape model for 2 branches: 1) investment into survival, 2) Investment into fecundity (producing offspring)

Costs of Reproduction

reproduction in one year limits reproduction another year

less resources allocated towards survival/growth/foraging/etc

Somatic Maintenance

energy spent to maintain body (soma) often equated with allocating resources to survival (in contrast to reproduction)

Describe how species richness changes with latitude, and propose hypotheses for this pattern.

Species abundance and richness is highest at the equator and decreases towards the poles

Hypotheses:

Climatic: primary productivity is higher in tropics, more stable conditions encourages specialization and speciation (narrow niches)

Geographic: greater area supports more species

Historical: longer evolutionary history, no glaciations

Interpret evidence from past climates to illustrate how latitudinal diversity gradients have changed through time.

At high latitudes, there was a diversity decline of inverstebrates upon the transition from hot to cold (cooling earth, Ordovician-Silurian extinction)

Apply principles of demography to understand the impact of the COVID-19 pandemic on human populations in the US and worldwide

Life expectancy in 2020 was decreased compared to 2019 in 31/36 countries

Populations with a higher proportion of older people have a dramatically higher burden of mortality

Social distancing and other policies to slow transmission should consider the age composition of populations as well as intergenerational interactions

In the US, data shows historically low US population growth rates during the pandemic (R = 431,000), after record low R in 2018-2019 (R = 923,000)

demography/demographic science

the study of statistics such as births, deaths, income, or the incidence of disease, which illustrate the changing structure of human populations.

Comeptitive Interactions

Both species have negative effects on eachother. causing reduced growth, survival, or fecundity (produce offspring)

Exploitative Interactions

Positive effect for one species, negative for the other. Predation, Herbivory, Paratism

Positive Interactions

positive/neutral effects for both. Mutualism, commensalism/facilitation.

Intraspecific competition

Competition between individuals of the same species. This is the mechanism behind density-dependent population growth

What are the ecological and evolutionary outcomes of competition?

Competitive exclusion

Character displacement

Competitive exclusion principle

If 2 species are competing for the same limited resource, the species that uses the resource more efficiently will eventually eliminate the other locally

Only valid if the resource does not vary in time/space, and there is only a single resource

Ecological effects of species interactions

species interactions impact ecological processes by determining abundance (carrying capacity), range or distribution, and timing of interacting partners

Positive interactions result in...

Increased abundance, extended range, synchronized activity of partners

Negative interactions result in...

decreased abundance, reduce range, select for altered timing

Coevolution

Reciproval evolutionary changes in two interacting species

What are the ecological and evolutionaryoutcomes of exploitative interactions?

Boom and bust population cycles

Reducing abundance and range of prey/host, excluding fromotherwise suitable habitat

Defensive and offensive adaptations of morphology, physiologyand behavior

What are the ecological and evolutionaryoutcomes of mutualistic interactions?

Increasing abundance or range of interacting partners•

Adaptations of morphology, physiology and behavior to promoteinteractions•

Increase susceptibility to global change

Name the processes that result in energy flow from the sun to organisms, and carbon cycling through ecosystems.

primary producers capture energy from the sun via photosynthesis

respiration to release stored energy for use in metabolism (releasing carbon to the environment)

energy is transferred up food chains from primary producers to higher trophic levels

Energy flow key concepts

a) Energy for ecosystems ultimately originates from thesun, and energy flows through food webs via trophicinteractions. The degree of connectivity and redundancyof food webs determines their resilience. Both bottom-upand top-down controls regulate ecosystem composition.

b) Biological and geochemical processes cycle nutrientsbetween organic and inorganic parts of ecosystems.

3 types of biodiversity

1) genetic (genetic diversity within a vole population)

2) species diversity (species diversity within a specific ecosystem/biome)

3) community and ecosystem diversity (across an entire landscape of a region)

alpha diversity

mean species diversity at a site/local scale

describes the species diversity within a small community at a small or local scale (one ecosystem)

often measured through # of species in a plot

Describe process of succession

establishment: early colonizers must be weedy, grow and reproduce fast, stress tolerant

facilitation: early species alter environment (fix nitrogen, build up soil)

inhibition: later species may inhibit growth of early colonizers

SIR model

susceptible, infected, recovered

assumes a single population, single host species only

How does vaccination help to reduce disease?

Reduces disease spread by reducing the number of sesceptible hosts in a population

COVID-19 vaccination rates

70.5% have received at least one dose of the vaccine

... but only 23.3% of people in low income countries

Global changes that amplify disease spread

- habitat destruction (more vector species encounter humans)

- urbanization (more people contact, increasing spread rates)

- air travel (increase spread rates)

-climate change (previously tropical-only diseases can affect areas that are becoming warmer)

Anthropocene

the modern geological era during which humans have dramatically affected the environment

about 10,000 years ago to present

Albedo

Ability of a surface to reflect light

results in positive feedback loop for snow/ice metling

Scientific consensus surrounding Climate Change

Scientific consensus:

climate is undergoing an extreme warming trend beyond natural variability

Major cause of warming is rising levels of CO2 from burning fossil fuels and land-use changes

Warming will continue if CO2 continues to rise

Climate change of projected magnitude poses significant danger to humans and the ecosystems we depend on

Scientific Uncertainty surrounding Climate Change

Areas of uncertainty

Magnitude of emissions and resulting magnitude of warming

Magnitude of impacts on biota

Mitigation strategies

Human behavior

Effects of feedback loops (clouds, ice, vegetation)

Humidity under context of climate change

warmer air holds more moisture (7% for every 1 degC)

rising temperatures cause increasing humidity as water evaporates from the ocean

humidity threatens human survival and amplifies the impact of climate change

Whiplash Weather

- Abrupt shifts in weather patterns — droughts followed by severe floods, or sudden and unseasonable fluctuations in temperature — are intensifying.

- Rapid swings in winter weather lead to crossing

freezing point multiple times, warm spells in winter

followed by hard freezes in spring.

- Instability of the jet stream and polar vortex lead to extremes

Environmental gradient

gradual change in an environmental variable (like temperature) through space (elevational/latitudinal). Caused by the tilt and roation of the earth which leads to seasons.

Abiotic Factors

Nonliving components of ecosystems (temperature, light, water, soil, pollutants, etc.)

Biotic Factors

Biotic: living things within an ecosystem (plants, microbes, animals)

Species range limits

Disperal, biotic, or abiotic factors can limit species distributions.

Precipitation

the falling to earth of any form of water (rain or snow or hail or sleet or mist)

Decreases at mid latitudes (around 30 degrees) due to air circulation patterns, highest at equator

More precipitation where annual temperature is hotter

Equinox

Where day and night are at equal length from one another. Sun will be directly overhead at 0 degree equator line.

Solstice

When day and night are at maximum differences from one another.

December Solstice: North Pole is in 24 hour darkness

June Solstice: North Pole in 24 hour light

Identify the levels of hierarchy under Ecology

Organismal < Population < Community < Ecosystem < Landscape < Global

Main Abiotic Factors in Terrestrial Biomes

Temperature and Precipitation

Main Abiotic Factors in Aquatic Biomes

Light and Nutrients

Coniferous Forest Biome

Identify area of the globe, environmental conditions, and examples of characteristic biota.

High precipitation: 30-50cm/year, cold winters and warm summers, cone-bearing trees (some fire-dependent), migratory birds, mammals, brown bears, large impact of logging

Predict physiological, morphological, and behavioral adaptations to abiotic conditions characteristics of desert biome

Challenges: lack of water, large temperature fluctuations, sand

Solutions: avoid water loss, improve water gain, modulate heat loss and gain through insulation and physiology

Ex: Camels allow body temp to rise during the day and drop at night to save water (avoid sweating to cool body)

Predict physiological, morphological, and behavioral adaptations to abiotic conditions characteristics of tundra biome

Challenges: cold, snow/ice, lack of food

Solutions: avoid heat loss, camouflage, reduce metabolism, cold tolerance

Mammals: thick, white fur, large feet, waterproof coat, small extremities

Invertebrates: cold tolerant, dormancy, active at low temperatures

Location of Tundra

The arctic, just below ice caps. Across North America, Europe, Siberia in Asia.

Much of Alaska and Half of Canada

Demography

the statistical study of populations

(we use life tables, age-specific summaries of survival and reproductive rates within a population, by making a "cohort" to inform demography)

Survivorship curve (Type II)

Constant death rate throughout life. Straight line.

Found in some rodents, invertebrates, lizards, and annual plants

Survivorship curve (Type III)

High death rates for the young, steeply declines for survivors of early period die-off

Found in organisms with a large number of offspring with little to no care (long-lived plants, many fishes, most marine invertebrates)

Principle of Allocation

Principle of Allocation:

Organisms generally don't live a long time AND reproduce a lot

Individual organisms have limited resources and allocate them towards specific functions and not others

Resources in a life cycle are allocated among growth, survival, and reproduction

Animals allocate time and energy to things like foraging, breeding, caring for offspring, etc.

Plants allocate biomass and nutrients to different parts (roots, stems, leaves, etc.) to carry out different function

Semelparous

repoduces only once (short adult lifespan)

Iteroparous

reproduces multiple times throughout life (long adult lifespan)

BIDE model

A model of population growth that takes into account immigration and emigration, in addition to births and deaths.

Nt+1 = Nt + B + I - D - E

Population size in following time interval = Number of individuals at time t + number of births in the next interval + incoming immigrants - deaths in next interval - emigrants in next interval

Simplified version, assume no immigration/emigration, closed population:

Nt+1= Nt + B - D

per capita

per individual in the population, often just females

r (definition)

intrinsic rate of increase, a percentage change in population size per capita

when r is constant over time, populations grow exponentially

r > 0

population increases in size

r = 0

population does not change in size

r < 0

population decreases in size

Geometric Growth vs. Exponential Growth

Geometric: population growth over discrete time periods

Exponential growth: time intervals are infineitely small and continuous, continuous curve

Population Growth on a Log Scale

Exponential growth will look linear

When does exponential growth occur?

- Populations are introduced into a new environment

- Important predator has been removed

(ex: locust swarm)

Logistic growth

(s-shaped) population growth resulting from density-dependent factors

at low density, growth is exponential, but population growth slows until carrying capacity K is reached

dN/dt = rN*( (K-N) / K)

Density-Independent Factors

Unrealted to population density (cold winters, droughts, storms, natural disasters, etc.)

Density-Dependent Factors

limiting factor that depends on population size. Competition, predation, parasitism, and disease

Apply principles of exponential and logistic population growth to interpret trends in human population growth.

The size of the world population was relatively stable for tens of thousands of years

In the last 12,000 years, we have seen exponential growth

Although our population is increasing, our growth rate is declining which does not fit the assumptions of exponential growth

We add about net 82 million people per year

Population expected to peak around 11 billion in 2100

Demographic Transition

1. High mortality rates and high birth rates

2. Mortality falls but birth rates stay high

3. Mortality stays low and birth rates fall

4. Mortality and birth rates are low

Interspecific competition

competition between individuals of different species

Exploitation competition

competition mediated by consumption of shared resource, individuals do not actually physically encounter each other (nocturnal/diurnal rodents/ants competing over the same food)