An Introduction to Ecology

The Distribution and Adaptations of Organisms

Introduction to Ecology

Ecology is the study of organisms and their interactions with their environment.

The environment includes 2 types of factors: Biotic factors – the living parts of the environment

Plants, animals, bacteria, fungi, protists Abiotic factors – the nonliving parts of the environment

Water, oxygen, light, temperature, etc.

Abiotic or Biotic?

Abiotic or Biotic?

Abiotic or Biotic?

Abiotic or Biotic?

Levels of Organization Ecologists can look at the world in levels of increasing complexity:

Population – A group of organisms of the same species that live together in

a certain area Example: a pride of lions in the Serengeti

Community – A group of organisms of different species that live together in

a certain area Example: all of the organisms living in or around a lake

Ecosystem – All the living and nonliving things in a certain area Example: Lake, trail in Red Rock Canyon

Biome – a group of ecosystems that have similar climates and communities Example: Tundra, Desert, Deciduous Forest

Biosphere – the entire portion of the planet that supports life

Distribution of Species

When considering ecology, the distribution of species are determinant in how an ecosystem evolves Dispersal is the movement of individuals away

from centers of high population density or from an area of origin

Biological imperative is to breed and pass on genetic information (thus they should spread)

Strategies for Dispersal

Many species are not able to migrate to all parts of the world (geographic barriers)

Some organisms can overcome these barriers and allow species to spread One method is known as natural range expansion

(the organism is able to overcome barriers and begin colonies in different locations)

Example: many species of strong flying birds (egret, grackle) have expanded into Africa, Eurasia, Australia and recently (last 150 years) both of the Americas

Strategies for Dispersal

Another method to move species to new areas is Species Transplants Humans love to influence their natural

surroundings We have brought many foreign species into new

habitats Example: Mammals are slowly “taking over” many of

the niches in Australia The Eucalyptus tree in Australia has several footholds

in California

Success of Dispersion: Biotic Factors

Even though an organism is able to spread to a new environment, it does not mean that it will be successful Behavior of the organism may not be suitable to

the environment (mating rituals, reproductive barriers, etc)

Negative interactions with other organisms (parasites, predation, disease, competition for resources)

The Importance of Abiotic Factors

Not every organism can live everywhere on Earth Abiotic factors determine which organisms can

survive where: Temperature – effect on body temperature Water – too much/not enough water Light – availability for photosynthetic organisms Wind – amplifies effects of temperature Rocks/Soil – which organisms can live with/on them, based

on pH and mineral composition Periodic Disturbances – catastrophes, such as tornadoes,

fires, tsunamis, etc.

Climate: Abiotic Factor

Climate combines four abiotic factors (temperature, water, sunlight, and wind)to determine prevailing weather conditions that greatly affect ecosystems Macroclimate: patterns on a global, regional or

local level Microclimate: very fine patterns that are

localized to very specific regions in an ecosystem (example: communities underneath a log)

Determination of Climate

Many factors affect a global or regional climate Solar energy Planet’s movement in space Sun’s warming effect on the atmosphere Land Water Cycles of air movement Evaporation/Precipitation

Oceans/Bodies of water

Ocean currents have a huge influence on climate Heat or cool air masses (affects

weather) In general, large bodies of water (lakes

included) moderate temperaturesRemember properties of water

Mountains

Mountains affect both amount of sunlight and rainfall Depending on which side of a mountain an ecosystem

is on, they may receive more sunlight or less sunlight (if in the shade)

Additionally, mountains force clouds to release their moisture before crossing over the peak One side of a mountain often receives significantly more

precipitation than the other Elevation can cause different climates due to

temperature, O2 content and precipitation

Seasonality

The Earth’s relative position around the sun determines the seasons Facing away from sun (fall and winter) Facing towards the sun (spring and summer) The different levels of solar radiation lead to

variations in wind patterns, temperatures, variations in ocean currents All of these variations change the climate in a region

that an organism must adapt to

Microclimates

As varied as macroclimates can be, microclimates have infinite variations Shading from biotic or abiotic structures affect sun

exposure Clearing vs. forested can have effects on

temperature and wind exposure High ground vs. low ground for water availability Above vs. below ground

Again organisms must adapt to survive in each scenario

Long-term Climate Change

Even with the variety of change in climates, global climates (as a whole) are fairly predictable based on environmental data and historical analysis (otherwise, weathermen wouldn’t have a job)

Yet even large-scale climates can be altered over time Ice ages (last for about 40,000 – 100,000 years)

Next ice age is predicted in the next 10,000 years Global warming

Long-term Climate Change

Many of these changes will have far-reaching effects on ecosystems and species distribution

Many of the extinctions that have taken place on Earth are due to an organisms inability to adapt to a changing environment

Homeostasis Organisms must maintain homeostasis, a steady-state

internal environment, despite changes in the external environment

Organisms respond to abiotic factors in one of two ways (REVIEW):1. Regulators (endotherms) maintain a nearly constant internal environment, despite external conditions (Warm-blooded)2. Conformers (ectotherms) allow their internal environment to vary (Cold-blooded)

- live in environments which remain relatively stable

The Principle of Allocation

This principle states: Each organism has a limited amount of energy

that can be spent on obtaining food, escaping from predators, coping with environmental fluctuations (maintaining homeostasis), growth, and reproduction

Adapting to Changing Conditions

Organisms can respond to their changing environments using 3 different types of responses:

1. Physiological Responses

- changing the functioning of the body

- acclimation

- athletes in Torino, moving to Denver...

2. Morphological Responses

- changing the anatomy (structure) of the body

- example: dogs growing thicker fur

3. Behavioral Responses

- changing behavior to adapt to the change

- moving to a more favorable location

- cooperative behavior (huddling, etc.)

Adapting to Changing Conditions

Overview of Biomes Not on AP test, but will be on MY test (good

background information) Aquatic Terrestrial (Our focus will be on these!)

Tundra Taiga Tropical Forest Savanna Chaparral Desert Temperate Grassland Temperate Deciduous Forest

Tundra Arctic = 20-60 cm/yr. Alpine (mountains) = may exceed 100 cm Average winter temp. -30 degrees C Summer < 10 degrees C Long winter; short summer Herbaceous (low) plants, a few DWARF shrubs due

to PERMAFROST. Musk oxen, caribou, reindeer, bears, wolves,

various birds High latitudes or highest elevations (even at

equator!)

Taiga (Northern Coniferous Forest) 30-70 cm ; some much more Winters -50 degrees C in winter Summer 20 degrees C Long winter; short summer may be hot Plants: cone-bearing trees, diverse

shrubs,herbs Animals: Birds, moose, bears, Siberian tigers;

insects Northern N. Am. and Eurasia to edge of

tundra

Tropical Forest

T. Rainforest: 200-400 cm/yr T. Dry forest 150 – 200 cm/yr 25-29 degrees year round (Warm!) Summer year round Plants: diverse; 4 or more layers Animals: diverse: 5-30 million species yet to

be discovered! Equatorial regions

Savanna

Seasonal rainfall; 30-50 cm/yr with long drought season

Temperature: 24-29 degrees C (warm!); more variation that Tropical forests

Dry season lasts 8-9 months Plants: Scattered trees; thorny; small leaves

(why?)Grasses; Must be fire & drought tolerant Animals: Herbivorous mammals; insects; grazers Equatorial & subequatorial regions

Chaparral

Seasonal ppt.; Rainy winter; Long dry summer (30-50 cm)

Cool fall, winter, & spring (10-12 degrees C) Summer can reach 30-40 degrees C Plants: shrubs, small trees, grasses; adapted to

drought; some have seeds that germinate after fire. Animals: mammals (browsers) amphibians, reptiles,

insects Mid latitude coasts

Desert

< 30 cm / yr (arid/dry) Hot deserts > 50 degrees C Cold deserts (Antarctica) <-30 degrees C Temps vary seasonally and daily (colder at

night) Plants: Cacti, shrubs w/ deep roots (why?);

small leaf surface area (why?) Animals: lizards, scorpions; birds; insects;

many nocturnal animals (why?)

Temperate Grassland

Dry winters; wet summers;; 30-100 cm/yr.; seasonal drought

Cold winters < -10 degrees C; Hot summers 30 degrees C

Plants: Grasses Animals: Large grazers; burrowing mammals Plains & prairies around the world

Temperate Deciduous Forest

70-100 cm/yr Cold Winters 0 degrees; Hot summers 35

degrees C; 4 distinct seasons Plants: Trees, shrubs, herbaceous layer;

(broadleaved, deciduous plants) Animals: variety of mammals, birds, insects Midlatitudes Our biome!