2023-2024 Introduction to Ecology Lecture Notes

Ecology 2023-2024 Lecture 14 Ecology ´the study of how organisms interact with… 1. other organisms ´intra- & interspecific (biotic interactions) 2. their physical environment (abiotic interactions) ´soil, light, temperature, rainfall, pH, water, topography ´Ecology is studied at many levels: ´organi...

Ecology 2023-2024 Lecture 14 Ecology ´the study of how organisms interact with… 1. other organisms ´intra- & interspecific (biotic interactions) 2. their physical environment (abiotic interactions) ´soil, light, temperature, rainfall, pH, water, topography ´Ecology is studied at many levels: ´organism → population → community → ecosystem → biome → biosphere Ecological levels of study Ecological levels 1. Organism: ´ Adaptations / advantageous traits that are thought to have evolved by natural selection are studied by organismal ecologists. ´ allow organisms to thrive in specific habitats ´ These adaptations may be a. Morphological b. Physiological c. Behavioral Ecological levels 2. Population: ´ ´ ´ a group of organisms of the same species that live in the same area at the same time. The population is the unit of natural selection and evolution. Population ecologists study the characteristics in terms of: a. Size b. Density c. Structure d. Temporal changes serengeti national park Estimates put wildebeest at between 1.3 and 1.7 million Ecological levels 3. Community: ´ includes all of the populations (of different species) that live in a common area ´ Community ecologists focus on: a. interactions between populations b. how these interactions influence the community: ´ interspecific interactions may occur including interspecific competition, predation, mutualism, commensalism, parasitism, etc. Ecological levels 4. Ecosystem: ´Inclusive of all the organisms in an area: ´the community with all the biotic and abiotic interactions that influence that community ´Ecosystem ecologists determine the health of ecosystems by observing the a. flow of energy b. cycling of nutrients African Savannah Ecosystem Freshwater pond ecosystem Ecological levels 5. Biome: ´ aka. a major zone of life or biogeographic region ´ classified according to the predominant vegetation and characterized by adaptations of the organisms that inhabit that particular environment ´ a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment ´ also, areas of plants and animals with similar life forms and similar environmental conditions over the globe Ecological levels 5. Biome: a. Desert b. Tropical rainforest c. Tundra d. Taiga (Boreal forest) e. Savanah f. Temperate deciduous forest g. Aquatic h. Grassland Ecological levels 6. Biosphere: ´ The biosphere, also known as the ecosphere, is the worldwide sum of all ecosystems. It can also be termed the zone of life on Earth. ´ Ecologists working at the biosphere level may study global patterns a. climatology b. species numbers & distribution patterns c. phenomena that affect the entire globe ´ e.g., climate change Biosphere Biome Ecosystem ---------- --------------- Non-living + living ------------------------- Community Population Increasing order of complexity Organism Living Climate cf. weather Weather Climate 1. the day-to-day or short-term condition of the changes in the atmosphere 1. the average of the weather condition of a particular place over a long-term period of decades, (~ 30 years) 2. short-term atmospheric condition of any place, which may vary by time-to-time 2. long-term average atmospheric condition of a place or country 3. affected by temperature, pressure, humidity, cloudiness, wind, precipitation, rain, flooding, ice storms, etc. 3. long term observations of the atmospheric conditions at any location like humidity, temperature, the sunshine, wind, etc 4. may affect the day-to-day occupation 4. significantly affects agriculture, industries, the livelihood of people 5. frequent changes 5. changes are longer term 6. meteorology – study of weather 6. climatology – study of climate Ecotone 1. A transition or boundary between two ecosystems 2. It can be a very gradual or a very sharp a. an area of marshland (wetland ecosystem) between a river and the riverbank b. transitional area of vegetation between such as forest and grassland c. soft bottom to hard bottom in marine communities d. contains species not found in either of the overlapping communities e. transitional area for activities such as courtship, nesting, or foraging for food Ecotone ´ May act as a “buffer-zone” protecting the neighbouring ecosystem from possible environmental damage ´ a wetland area could absorb pollutants preventing them from seeping into a river or estuary ´ The increase in biodiversity associated with ecotones leads to an edge effect Ecotone Source http://www.basic.ncsu.edu/segap/Vertebrate.html Riparian zone 1. An ecotone type bordering bodies of water & land 2. Riparian vegetation contributes shade, food and shelter for aquatic organisms ´ a mixture of vegetation types 3. The riparian zone is also home to many animals that move between land and water, such as insects, amphibians and birds 4. Riparian vegetation reduces erosion and regulates the run-off of water to the stream from the surrounding land 5. The riparian zone acts as a natural sponge, thereby reducing flooding ´ gradually soaking up run-off ´ slowly transferring into the stream Riparian edge effect World Biomes Lecture 15 Major World Biomes ´The biosphere can be divided into relatively large regions called biomes which are of two types: 1. Aquatic biomes 2. Terrestrial biomes Climate as a major determinant of organismal distribution ´ Three main factors affect the distribution of plants and animals over the surface of the globe through the survival, development, and reproduction for different species: 1. Water supply 2. Environmental temperature 3. Seasonal variation Major Biomes in the World Aquatic World Biomes ´Occupy the largest part of the biosphere ´Subdivided based on salinity 1. Marine - average salinity ≥ 3 % 2. Freshwater - average salinity ≤ 1 % 3. Brackish - mixture of marine & freshwater, - salinity is very variable Marine Biomes ´Marine biomes cover about 75% of the earth’s surface and are divided into 3 major zones: 1. Intertidal zone 2. Neritic zone 3. Oceanic zone Marine Biomes – Intertidal Zone 1. Land-sea boundary ´ may be exposed to air at low tide or submerged at high tide 2. Organisms are adapted to harsh conditions of: a. Sandy shoreline b. Rocky coastline c. Mangrove swamps 3. Plants with mostly xerophytic characteristics Marine Biomes - Intertidal Zone Marine Biomes – Neritic Zone 1. Usually warm, clear, shallow waters of tropical and subtropical areas 2. Shallow nearshore waters ´extend from the low tide mark to the edge of the continental shelf ´submerged shelf of land extending into the ocean to about 200 m 3. Relatively stable conditions ´Site for majority of sea life ´ Coral reefs occur within this zone Ø special biomes which provide food and shelter for numerous organisms and protect shorelines from erosion Marine Biomes – Neritic Zone Marine Biomes – Oceanic Zone 1. The region of open sea beyond the edge of the continental shelf (≥104 m) a. Photic zone: Upper regions receive sufficient light to support microscopic plants, animals, fish, and mammals b. Aphotic zone: The lower regions receive little/no light i. nutrient poor and unproductive ii. intense water pressure Lower temperatures Marine Biomes – hydrothermal vents 1. Located in the oceanic zone within the ocean floor 2. Expel superheated water (~350 °C) rich in minerals 3. Chemosynthetic Archaea and some S-bacteria thrive around hydrothermal vents ´ 12H2S + 6CO2 → C6H12O6 + 6H2O + 12S 4. Support squids, tube worms, giant clams and spider crabs Marine Biomes - Hydrothermal vents Hydrothermal vent formation