Hox Genes Think of them as switches or tool boxes for running other genes. Effect timing and expression of other genes. Vertebrates have 4 sets of HOX genes, so more options exist in the vertebrates “tool box”

Chapter 52 An Introduction to Ecology and the Biosphere

Ecology The study of the interactions between organisms and their environment.

Ecology Integrates all areas of biological research and informs environmental decision making.

Organisms All living things. Studied at many levels.

Ecology - levels 1. Organismal Ecology 2. Population Ecology 3. Community Ecology 4. Ecosystem Ecology 5. Landscape Ecology 6. Global Ecology See page 1145 for definitions and examples

Distribution of Species Limited by interactions between organisms and the environment.

Environment Abiotic Factors: non-living factors. Ex: Temperature, Light, Water Nutrients Biotic Factors: effect of other organisms. Ex: Competition, Predation

Abiotic Factors 1. Temperature 2. Water 3. Salinity 4. Sunlight 5. Rocks and soil 6. Wind 7. Disturbance

Temperature Effects biological processes. Ex: Cold – cells will rupture if they expand while freezing. Hot – many proteins denature above 45 oC. Point – life can only exist over a fairly narrow temperature range.

Water Review the properties of water from Chapter 3. Cells must maintain a correct water potential (keep from exploding or drying out).

Salinity Salt concentration affects osmotic potential and water balance. Most aquatic organisms are limited by their ability to osmoregulate.

Sunlight Provides energy for Ps, which drives most food webs. Plants often compete for light because of shading or absorption of light by deep columns of water.

Rocks and Soil Physical structure, pH, mineral composition of rocks and soil limit where plants can grow. Ex. Se soils. Plants limit what animals can be found in an area.

Wind Effects temperature and water conditions for many organisms. May carry abrasive particles that limit plant growth by killing the growth points.

Disturbance Disturbance is often an important part of an environment. Allows organisms to re-colonize an area. Ex: Fire Humans Wind

Climate Shapes environments and what organisms can live in a particular area. Temperature, precipitation, sunlight and wind.

Global Climate Patterns Determined largely by solar energy and the movement of heat across the planet.

Great Ocean Currents

Wind Patterns

Climatic Factors Solar Radiation and Latitude Axis Tilt/Seasons Air/Water Circulation Patterns

Solar Radiation and Latitude Changes the amount of light and energy delivered per surface area.

Result Poles: less light Equator: more light The unequal heating causes air and water to circulate.

Seasons Caused by the Earth's tilt. Day length changes over time. Many organisms are restricted in range by how well they adapt to changing seasons.

Global Air Patterns Air rises when heated, sinks when cools. Zones of rising/sinking are created. Earth's rotation causes zones to "twist”.

Result Air circulation patterns. Rainfall patterns. rising air: wet areas descending air: dry areas

Biomes Broad geographical regions with characteristic communities of organisms.

Aquatic Biomes

Fresh water Biomes Have <1% salt concentration. Strongly influenced by temperature and light. Classification – based on water flow patterns.

Freshwater Biomes Lakes Wetlands Streams and Rivers Estuaries See Pg 1159-1160 for details

Marine Biomes Cover 3/4 of the Earth's surface. Average 3% salt. Controlled by light and the distance to the shore.

Marine Biomes 1. Intertidal 2. Oceanic Pelagic 3. Coral Reefs 4. Benthos See page 1161-1162

Light Zones Photic - Enough light for Ps. Red light lost rapidly as depth increases. Aphotic - Lacks enough light for Ps and depends on food made in photic zone for energy. Part of the most extensive biome on the planet.

Estuaries Where a freshwater river meets the ocean. Salinity variable. Very productive Biome.

Coral Reef Characterized by coral. Found in shallow warm waters. Very productive. High species diversity.

Benthos Bottom area. Usually fed by nutrients drifting down from upper levels. Fairly rich in life.

Biomes Controlled by: Temperature Water Geography

Terrestrial Biomes Recognize all, but be able to describe features of 2-3 types. See pages 1153-1156.

Tropical Forests Areas covered with dense growth of trees and vines. Climate: Warm temperatures. Constant day length. High water.

Tropical Forests

Tropical Forests Have the greatest diversity of species of any area on Earth. Soil is usually very infertile. Most of the nutrients are in the plant life. One of the most endangered Biomes.

Savanna Grasslands with a few trees. Climate with three growing seasons: Cool and dry Hot and dry Warm and wet

Savanna Rich in herbivores and predator species. Only major biome not found on North America.

Desert Characterized by plants adapted to dry growing conditions. Climate: Dry (<30cm/yr). May be cold or hot. Often found in areas of descending air masses. Low productivity, but still fairly diverse in species.

Chaparral Characterized by spiny evergreen shrubs. Climate: Mild rainy winters Hot summers Ex: Southern California

Chaparral Maintained by fires. Plants adapted to periodic fires by seeds or re-growing from the roots.

Temperate Grasslands Grasses and other herbs are the dominant vegetation. Climate: Intermediate water Relatively cold winters

Grasslands Very productive for agriculture. (wheat, corn) Need disturbance (fires) to keep trees out. Come in several types: Tall grass Short grass

Temperate Forests Deciduous trees dominate. Climate: Relatively high rain Cold winters Very little natural area left. Good diversity of species.

Taiga or Northern Coniferous Forest Coniferous trees dominate. Climate: Long cold winters Short wet summers Long summer daylength

Taiga or Northern Coniferous Forest Relatively low species diversity. Being logged at an alarming rate.

Tundra Grasses and sedges dominate. Climate: Very cold and dry Low light in winter

Tundra Permafrost present. Plants low in height. Poor species diversity.

Assignments Read Chapter 53 or 43 in Hillis Chapter 52 – Fri. 4/25 Chapter 53 – Mon. 4/28 Labs – Transpiration, Aquatic Productivity

Altitude and Latitude Mirror each other. Their Biomes are similar because the environments are similar. Ex: Alpine = Tundra

Summary Know what is involved with the study of “Ecology”. Know the major factors of planet Earth that shape climate. Know the major aquatic and terrestrial biomes and the factors that control them.