How Climate change impacts organisms on different timescales (lecture 16 17)
Lecture 16: unit 8
Why be concerned:
1. Biological Impacts: biodiversity changes, disease, migration
2. Political and economical impacts : Arctic sovereignty, natural resources, environmental policy
3. Aesthetics: landscapes, tourism
4. Cultural changes: traditional hunting practices
Time domains for temperature change: (time scales)
1. acute :
● duration minutes to hours, daily
● biological response/outcome:
○ behavioural adjustment (sit in water),
○ physiological response (sweating),
● duration: days to weeks, seasonal
● biological response/outcome
○ range change
○ acclimatization to new thermal regime
● duration: multiple generations, climate changes
● biological response/outcome
○ extirpation/ or extinction
● The Arctic has a rich diversity of mosses and lichens, as well as flowering plants, sedges, grasses, shrubs,
and (below certain latitudes) some trees.
● Plants face both a short growing season and challenges related to extreme cold.
● Vascular plants in the Arctic tend to be small and freeze tolerant.
● Lichens are suited to these harsh conditions because they lack roots, do not require soil, and are tolerant of
desiccation and very low temperatures
○ Lichens are composite organisms. There are 2 parts: an algal component and a fungal component.
○ The alga is able to convert solar energy and CO into carbohydrates and O .
○ Fungi require a food source and use the carbohydrates generated by the alga for fuel. Fungi also require 2 to metabolize carbohydrates.
Despite very cold winter temperatures some Arctic birds and mammals remain active, whereas others enter
hibernation and lower body temperature
Endotherms: (meaning “inside heat”) are animals that can generate their own internal heat
Ectotherms: (meaning “outside heat”) are animals such as fishes (and amphibians, reptiles, and
invertebrates) that rely on environmental sources of heat to maintain body temperature.
Evolution: the study of both adaptive and nonadaptive change over time in populations, the
origin and extinction of species and the relationships among living things.
Ecology: the study of interrelationships between organisms and both living (biotic) and non
living (abiotic) components of their environment.
Physiology: the study of organisms structure and function including homeostasis and
encompassing cells, tissues, organs, and body systems.
subArctic regions : of Canada (e.g., Churchill, Manitoba) contain a wide variety of both aquatic
and terrestrial ecosystems, each characterized by different abiotic and biotic factors.
high Arctic : near the communities of Resolute and Devon Island, the terrestrial environment is
dominated by tundra. However, even at very high latitudes, there are both freshwater (rivers,
ponds, lakes) and marine (Arctic ocean) habitats.
Impacts on different levels:
● Molecule: Temperature impacts the motion of molecules. Higher temperatures increase motion, lower
temperatures decrease motion. The increase or decrease in kinetic energy of molecules is a molecular
● Macromolecules: (e.g. lipids, proteins, nucleic acids) are sensitive to temperature change.
○ For example, enzymes act as catalysts to speed up reactions within cells. Enzymes typically
function best within the normal range of temperatures that the cell experiences
● Cell: Temperature changes may cause cells to undergo a stress response. For example, most plant or animal
cells can tolerate a brief increase in temperature, but if longer the cell may die mostly because enzymes are
not functioning properly.
● Organ systems: Arctic Char (Salvelinus alpinus)As ectotherms, their body temperature is matched to the
temperature of the surrounding water. An increase in water temperature will increase the amount of blood
the heart pumps per minute. This increased output from the heart, plus other temperature effects on the
properties of the blood and blood vessels, will induce multiple changes within the cardiovascular system
● Organism: Endotherms regulate body temperature (thermoregulation) ~37°C by sensing changes in internal temperature and altering physiological processes and behavior to bring internal temperatures back to
● Homeostasis: is the maintenance of a constant internal environment. Endotherms maintain body
temperature within narrow limits. Ectotherms don’t maintain a constant body temperature, but other factors
(e.g. ions, oxygen) are under homeostatic control.
Lecture 17: unit 8
Function flows from structure:
whole organism → organ system level → organ and tissue level → cellular level →
macromolecular level → molecular level
How climate change impacts plants and lichens (lecture 18)
Lecture 18 : unit 9
Exchange of substances occurs directly between the interstitial fluid and the cells. Body systems are dependent on
the circulatory system for gases, nutrients and waste removal.
● Gases – most animals requi2e O for metabolism and rel2ase CO as the respiratory waste product.
● Nutrients – animals utilize many different types of food, obtaining carbohydrates, fats, and proteins in their
● Wastes –fluid and solid wastes from digestion and metabolism are released. Organisms must also balance
the ion composition of their internal fluids. Ions are obtained from food or directly from the environment
(especially in aquatic animals).
What is a lichen? → Alga and fungus
Impacts on polar bears:
Declining body condition of Polar Bears
● decline in body condition for all age and sex classes
● magnitude of decline greatest for pregnant females and subadults
Impacts of sea ice reduction
● decrease feeding period
○ reduce stored fat
● increase fasting period
○ increase need for stored fat
● reduce number of successful pregnant females to rear young
● reduce survival rates of dependant young
○ decline in population
Negative feedback: is a regulatory mechanism that counteracts a change in a variable away from a set point or
normal state. Homeostasis is maintained by negative feedback control.
Thermoregulation: is controlled by the hypothalamus in mammals where signals are coordinated to bring about the
necessary response to a change in temperature. Positive feedback: brings a system farther from the set point, is necessary in cases where a maximal response is
beneficial (e.g. during child birth). Oxytocin is a hormone that stimulates contraction of the smooth muscle in the
Acclimatization: Adjustment by individual organisms to chronic stresses
Adaptation: the evolution of populations across generations under natural selection