BIOL1030 U4

Environmental Change

A significant change to (or disturbance of) the environment

Biologists must inform society about…

The potential hazards and consequences that will arise from environmental change

Environmental change can be:

I. Human Impacts - habitat destruction, land-use change, fisheries, climate change

II. Natural Disturbances - cyclones, drought, fires, earthquakes, floods

III. Animal Interactions - trophic cascades, disease, invasive species, novel assemblages

All three types of environmental change typically have _________, which…

positive reinforcement, in turn strengthens the environmental change and its effects

Which aspects of the environment are susceptible depends on…

The scale we use to assess susceptibility

Environmental change addresses…

Chemical, biological, geological, and/or physical perturbations

Consequences of changes in biodiversity include the biodiversity crisis, which is…

The rapid loss of species and degradation of ecosystems, reduced genetic diversity, and the collapse of trophic systems

Environmental Change Caused by Greenhouse Gasses

Today’s concentration of CO₂ is 30% higher and rising 250x faster than at any point in the last 800,000 years - this leads to atmospheric global warming and ocean acidification

Environmental change affects Earth’s cycles with attention to:

I. Nutrient and hydrological cycles

II. Time scales from hours to centuries

III. Spatial scales from local to global

IV. Human-caused (anthropogenic) disturbances

V. Impacts on biodiversity and society

Livestock biomass is greater than…

All of the wild mammal and human biomass combined

Global Threats

• Species invasion

• Greenhouse gasses

• Changing temperature

Climate change has happened before, but…

It is the rate of current change that is of concern due to the unprecedented rate

Temperature Anomaly

A departure from a reference value or long-term average - can be warmer or colder, but in recent years (since the 1980s), it has only been warmer

TIme is necessary for species to change, adapt, and/or evolve -

Those with shorter generation times can change quickly. but others with longer times will change slowly

The ability for a species of accommodate or adapt to changes in their environment depends on…

• The rate of change - gradual vs abrupt events

• How fast a species can adapt

Can communities adapt to environmental change?

• Diverse communities are more stable and resilient

• What happens to an individual or population can scale to the ecosystem

• Water and temperature shape our biomes - if the water cycles change, ecosystems will too

“Runaway” Effects

Self-reinforcing feedback(s) could push the Earth system toward a planetary threshold that, if crossed, could prevent stabilization of the climate even as emissions are reduced

Ecosystems: Energy and Nutrients

• Ecosystem size varies from large-scale (forests) to small-scale (micro)

• Can be defined by having energy flow and chemical cycling: an interlinked “bubble” or community of life

• Biotic and abiotic components are part of an ecosystem, which are linked through energy flow and nutrient cycles

• Finite and cycling

Know how energy flows in an ecosystem!

Both heat and chemical energy

Production “Efficiency”:

The percent of energy assimilated by an organism that is converted into biomass - insects are more efficient at this than birds and mammals due to the lack of energy needed for endothermic reactions

Trophic “Efficiency”:

The percent of energy transferred and used by the next trophic level - usually ~10%

Increased temperature (climate) means…

More energy put into cellular respiration and less energy available for growth

Biodiversity loss and changing conditions will…

Impact efficiency pathways

Organisms have complex systems that integrate internal and external information, incorporate feedback control, and respond to changes in the environment- a change in one component can…

Affect many other components, which in turn can change species interactions and community structure and compositions

Physiology

The functions and activities of all living organisms and their parts, including chemical and physical parts

Ecophysiology

The study of the environment (both physical and biological) interacts with the physiology of an organism

Behaviour

The observable action or activity of an organism

Phenology

The influence of climate on annual phenomena (timing) of animal and plant life such as reproduction and migration

Ecophysiology attempts to understand…

• The limits placed on organisms by their physiology

• How organisms respond to environmental changes

• How organisms have adapted to their ecological niches

Changes in the abiotic environment…

Affect physiological processes in organisms (e.g., plants on the rainforest floor, starfish water circulation)

Ectotherms: “cold-blooded” and rely on environmental heat sources

• Most abundant in environments with constant temperatures

• Economical and metabolic rates relative to the environment

• Low metabolic rate = reduced need to feed

• Behavioural changes (basking in the sun, etc)

• Overall lower energy requirement

Endotherms: “warm-blooded” and create their own heat through metabolic processes

• Wider thermal and geographic distribution

• Constant body temperatures

• Active over a wide range of temperatures

• High metabolic rate = increased need to feed

Physiological Limitations: Resources

Liebig’s Law of the Minimum: growth (in plants?) is determined by the scarcest resource (limiting factor): nutrients, water, light, oxygen

Physiological Limitations: Development

Regulated by temperature, moisture, population density, etc. - an importance of understanding the full life history of organisms

Physiological Limitations: Phenology

The timing of important life history events such as reproduction, migration, and diapause are determined by environmental cues (temperature, rainfall, season)

Diapause

The delay in development in response to regular and recurring periods of adverse environmental conditions

Organism Response to Environmental Change

The success of the response is influence by an organism’s fitness (the ability to survive and reproduce)

Fitness Response Curves

Within the lifetime of an individual, if the environment changes, the optimum does not change except in the case of acclimation

Organisms use physiology and behaviour to help them maintain fitness…

An optimal range

Wide physiological tolerance to broad ranges of environmental factors =

Lower risk to susceptibility to environmental change

A species’ response to environmental change depends on its ability to:

1. Stay - modify physiology and behaviour

2. Go - colonise new territory

3. Die - Not able to adapt or leave

   All organisms can tolerate some variability in the environment, but the change may be too great for them to tolerate

Stay - options

• Tolerate - no change, can be energetically costly or result in death

• Evolve - slow, changes in DNA of a population over time, happens over many generations, leads to speciation

• Modify physiology or behaviour - fast, does not require changes to DNA, enables the organism to maintain homeostasis, happens within the lifetime of an individual and within the individual

Modify

• Acclimate

• Behavioural change

• Phenotypic plasticity

  The above modifications are not mutually exclusive

• Occurs by individuals or groups (individuals, species, populations)

Acclimation

The adaptation of an organism to its natural climatic environment

Acclimatisation

The climatic adaptation of an organism that has been moved to a new enviornment

Acclimation (Individual Response)

A gradual process by which an organism adjusts its physiology or morphology

Behavioural Change (Individual or Group Response)

• Altering the use of its habitat

• Altering the interactions with other species

Phenotypic Plasticity

The ability of a genotype to produce more than one phenotype (trait) in response to different environmental conditions

The range of responses to change can be…

• Developmental (reproductive size of fish, rate of development)

• Phenological (flowering, migration, etc.)

• Morphological (size/structure of seeds/feeding structures)

Ecophysiology attempts to understand…

Physiological thresholds in response to environmental change

Weeds and pests are human concepts and are considered to be…

Plants and animals living where we don’t want them to live, even native species

Some species invasions can be natural!

Know island colonisation and how it relates to ecological succession

Populations and communities are _________ in a state of equilibrium

Never

Ecological Succession

The gradual process of species colonisation and species replacing each other - post-disturbance is all about “recoverability”

Natural invasion events are…

Range expansions and speciation opportunities

The 4 Stages of Invasion

1. Arrival - a species is introduced outside of its native range

2. Naturalisation - establishment - population size dependent

3. Invasion - the spread of the invader

4. Impact - the impact of the invader

A species can move outside its native range through…

Human-mediated transport (accidental or deliberate)

Know examples of this!

Naturalisation is all about establishment -

Larger populations are more likely to establish while smaller populations are more vulnerable to environmental change, low genetic diversity, environmental stochasticity, etc.

A population is considered established once it is able to…

Successfully reproduce outside of its native range

Allee Effect

Slow population growth when the population is small - difficulty finding a mate, cooperative feeding and defending vulnerabilities

Naturalisation can have a…

10-15 year “lag” phase before invasion where the species is not yet flagged as a species of concern

Know an example of this!

In invasion, individuals…

Start to spread away from the point of introduction

Invasion’s impacts can be on:

• Agriculture - lost production, damage, water, control costs

• Quality of Human Life - health impacts, control costs

• Environment - impacts on native species and ecosystems, control/management

Managing Invasion

1. Prevent - Introduction

2. Eradicate - Establishment

3. Contain - Invasion

4. Maintain - Impact

The distribution of water across the globe influences…

The diversity and distribution of living forms, including humans

Cohesion

Water molecules stick to each other due to their molecular formation and resulting polarity

Adhesion

The polarity of water molecules attracts them to other polar substances, making them stick to things

Surface Tension

Water’s resistance to penetration (can be by a liquid) - water drops can form due to it, where water takes a shape that minimizes its surface area

High Specific Heat (Heat Capacity)

Water has a high heat capacity due to the hydrogen bonds between molecules

Because of its chemical and physical properties, water both...

Limits and provides opportunities for biological processes

Water can also butter temperature on…

Large and small scales due to its high specific heat

Universal Solvent

Water can dissolve more substances that any other liquid

Solute Particles

Irrespective of chemical nature, water imparts a set of physical properties in a solution including pH, salinity, and oxygen saturation - these properties determine how biological processes function

Out of the 2.5% of water on earth that is fresh, 0.0072% of all of earth’s water is easily accessible freshwater

glug glug as the fishes say

Australia is the 2nd driest continent on earth!

Idk just thought it was cool

Water Cycle

1. Precipitation

2. Infiltration, percolation, and flow

3. Storage

4. Evaporation

5. Transpiration

6. Condensation

Biogeochemical Processes

The use of biotic and abiotic components in nutrient cycles

Know the carbon cycle!

CARBON!!!!

Know the nitrogen cycle!

NITROGEN!!!!!!!!!

Phosphorus is used by plants to synthesize organic compounds - phosphorus enters the system by…

Weathering rocks and leaches into ground and surface water, taken from the soil by producers which may be eaten by consumers