ENGG 413 Topic 1 EVOLUTION, BIOLOGICAL COMMUNITIES, AND SPECIES INTERACTIONS.docx

**ENGG 413 ENVIRONMENTAL SCIENCE AND ENGINEERING** **Main Topic 1: Ecological Concepts** ***EVOLUTION, BIOLOGICAL COMMUNITIES, AND SPECIES INTERACTIONS*** **Evolution Produces Species Diversity** - Each species adapts the environment where it lives. - Examples are **polar bears** living in...

**ENGG 413 ENVIRONMENTAL SCIENCE AND ENGINEERING** **Main Topic 1: Ecological Concepts** ***EVOLUTION, BIOLOGICAL COMMUNITIES, AND SPECIES INTERACTIONS*** **Evolution Produces Species Diversity** - Each species adapts the environment where it lives. - Examples are **polar bears** living in - **sunless, super-cold** arctic winter and - **saguaro cactus** surviving the - blistering temperature and dryness of the desert. Adaptation \- Most important concepts in **biology.** (One of the) \- The **acquisition of traits** that allow a - species to survive in its environment. 2 ways of using the term **"Adapt**" 1\. **Acclimation** -- - When an individual organism can - respond immediately to a changing environment. - when you adjust to a new climate or situation Example: - Keeping a house plant indoors all winter and - then put it out in full sunlight in the spring. - The leaves become damaged or the plant may grow new leaves with thicker cuticles and denser pigments that block the sun's rays. - Although the capacity to acclimate is inherited, houseplants in each generation must develop their own protective leaf epidermis. 2\. **Genetic traits** -- - passed from **generation to generation** and - allow a species to live more successfully in its environment. - This process of adaptation to environment is explained by the ** Evolution** -- - Basic Idea: Species change over generations because individuals compete for scarce resources.  **Natural Selection** -- - process of better-selected individuals **passing their traits** to the next generation.  **Mutations** -- - changes to the **DNA coding sequence** of individuals that occurs occasionally, and the changed sequences are inherited by offspring. **Limiting Factors of Species** - **regulate [how many organism]s live in an ecosystem.** - Pressure and influence to fitness of an individual and - their offspring are exerted by factors such as **environmental.** - With this, species have **limitations** in where they can live. **These limiting factors are:** 1\. **Physiological stress** - due to inappropriate levels of some critical environmental factor, such as moisture, light, temperature, pH, or specific nutrients. 2\. **Competition with other species** 3\. **Predation,** including **parasitism** and **disease** 4\. **Luck.** **Critical Factor** \- According to the **chemist** - **Justus von Liebig** (1840), - the single factor in **shortest supply relative** to demand is the critical factor determining where a species lives. - Temperature, - moisture level, - nutrient supply, - soil and water chemistry, - living space, and - other environmental factors must be at appropriate levels for organisms to persist. **Tolerance Limits** \- **Ecologist Victor Shelford** (**1877-1968**) - expanded **Liebig's principle.** \- He stated that - each environmental factor has both - minimum and maximum levels, - called tolerance limits, - beyond which particular species cannot survive or is unable to reproduce. \- The **single factor** closest to these **survival limits** is the - **critical factor** that **limits** where a particular organism can live. \- In some species, - **tolerance limits** - affect the **distribution of young** differently than they affect **adults.** **Ecological Niche** ** Habitat** -- - the place or set of environmental conditions in which a particular organism lives.  **Ecological Niche** -- - **the position of a species within an ecosystem** - describes both the **role** played by **a species** in a biological community and the set of environmental factors that determine its distribution.  **Charles Elton (1900-1991)** -- British Ecologist - who defined the **concept of niche** in **1927**. - According to him, - each species had a role in a community of species, and - the niche defined its way of obtaining food, the relationships it had with other species, and - the services it provided to its community. -  **G. E. Hutchinson (1903--1991)** -- The American limnologist - who**, thirty years** later, proposed a more biophysical definition of niche. - According to him, every species exists within a range of **physical and chemical conditions** such as - temperature, - light levels, - acidity, - humidity, or - salinity. - It also exists within a set of biological interactions such as - predators and prey present, - defenses, or nutritional resources available. ** Generalists** -- - able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources - species that tolerate a wide range of conditions or exploit a wide range of resources. - Example: Species that - thrive in broad variety of environments such as - weedy species or pests - (rats, cockroaches, or dandelions).  **Specialists** -- species that have a **narrow ecological niche**. - Examples are Giant Panda and Giant Saguaro. **Speciation** **Speciation** - occurs when a group within a species separates from other members of its species and develops its own unique characteristics - The development of a new species. o As a population becomes more adapted to its ecological niche, - it may develop specialized or distinctive traits that eventually differentiate it entirely from its biological cousins. **2 kinds of speciation:** o **Allopatric Speciation** -- - speciation that occurs when populations are **geographically separated.** - when a species separates into **two separate groups** that are **isolated** from **one another** **\*Geographic Isolation** -- - when the **habitat** are far enough apart that population were **genetically isolated;** - they couldn't interbreed with populations on the other **habitat.** - the physical separation of populations of organisms from one another due to **geographical barriers.** o **Sympatric Speciation** -- - speciation that occurs within one geographic area. - splitting of an **ancestral species** into two or more reproductively isolated groups without geographical isolation of those groups. \***Behavioral Isolation** -- - when **two identical species** live in similar habitats but have **different mating calls**. - This difference is enough to prevent **interbreeding.** - the act of mixing different species or varieties of animals or plants and thus to produce hybrids. - **when species are reproductively isolated from others due to differences in behavior.** ** Directional Selection** -- - the **shift toward** one extreme of a trait. - occurs when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other. - type of natural selection in which **one extreme phenotype** is favored over **both** the other **extreme and mode**rate phenotypes **Taxonomy** - The study of types of - organisms and - their relationships. - With this, organisms can be traced which - common ancestors they have descended. - the classification of living and extinct organisms **Binomials** - also called - **Scientific** or - **Latin Name** o Identify and describe species using - Latin or Latinized nouns and - adjectives, or - names of people or places. o Scientists communicate using - **scientific name**s instead of - common names like lion, dandelion, or ant to avoid confusion. **Species Interactions** - **mutualism,** - **commensalism,** - **competition, and** - **predation** \- **Competition** - leads to resource allocation. - organisms that strive for the - same resources in the same place \- **Predation** is an - important type of selective pressure. - biological interaction where one organism, - the **predator,** kills and eats - another organism, its **prey** \- **Symbiosis** - benefits both species involved. - plants or animals of different species may be - dependent on one another for survival.  **Competition** \- A type of **antagonistic relationsh**ip within a biological community. TRIVIA: **antagonistic relationship** - Those in which one organism nourishes themself by harming another organism, in particular by parasitism or predation. \- **Organisms compete** for resources that are in - limited supply such as energy and matter in usable forms, living space, and specific sites to carry out life's activities. \- **Competition** - shapes a species population and biological community by - causing individuals and species **to shift their focus** from - one segment of a resource type to another. **Types of competition:**  **Intraspecific competition** -- - competition among members of the - same species. ((**cospecifics**))  **Interspecific competition** -- - competition between members of - different species. **Predator** - Any organism that **feeds directly** on another living organism, whether or not this - kills the prey. \- Herbivores, carnivores, and omnivores, which feed on live **prey,** are **predators.** \- **Predation** - is a powerful but **complex influence** on species populations in communities. **Predation affects:** 1\. All stages in the life cycles of - predator and prey species. 2\. Many specialized - **food-obtaining** mechanisms. 3\. The evolutionary adjustments in - behavior and body characteristics that - help **prey** avoid being eaten and help **predators** more efficiently **catch their prey**. **Symbiosis** \- Two or more species **live intimately together**, with their fates linked. \- **Symbiotic relationships** - often enhance the survival of **one or both partners.** **Types of Symbiosis:**  **Mutualism** -- - type of symbiosis in which **both members' benefits**. (e.g. Dogs and Humans) - the host and a symbiont, where both organisms benefit and - **no** one is **harmed.**  **Commensalism** -- - type of symbiosis in which - **one member** clearly **benefits** and the - other apparently is neither benefited nor harmed. - (e.g. a spider building a web on a tree)  **Parasitism** -- - a form **predation** may also be considered symbiosis because of the - dependency of the parasite on its host. - (fleas and mosquitoes feed on blood from other organisms  **Endosymbiosis** -- - one species living **inside** another one. - (e.g. Protozoans that live inside termites and help them digest wood)  **Ectosymbiosis** -- - one species living on the **surface** of the other species. - (e.g. Lice that feed on the skin, blood, or oil secretions of the host) Keystone Species - Plays a critical role in a - **biological community** that is - out of proportion to its abundance. - Thought to be the **top predators** like lions, wolves, and tigers that - limited **herbivore abundance** and reduced the **herbivory of plants.** - Scientists now recognize that - **less-conspicuous species** also play - **keystone roles.** - **Keystone species** hold together the **complex web** of relationships in an ecosystem.  **Community Properties** \- species **abundance and diversity** as well as the trophic relationships that the members of a community establish - **Productivity** is a - measure of **biological activity**. - **Abundance** and **diversity** measure - the **number and variety** of organisms. - **Resilience and stability** make - communities resistant to disturbance. Primary Productivity - The **rate of biomass production.** - An indication of the - **rate of solar energy conversion** to - **chemical energy.** **Net Primary Production** - The **energy left** after **respiration** is. **Abundance and Diversity** \- **Abundance** - expression of the **total number of organisms** in a biological community. \- **Diversity** - measure of the **number of different species**, ecological niches, or genetic variation present. - The abundance of a **particular species** often is inversely related to the - total diversity of the community. \- **Communities** with a **very large number of species** often have only a few members of any given species in a particular area. \- **Diversity decreases** but **abundance** within species **increases** as we go from the - equator toward the poles. **Ecological Structure** \- **Ecological structure** - **patterns of spatial distribution** of individuals and populations within a community, as well as - the **relation of a particular community** to its surroundings. \- At the local level, even in a **relatively homogeneous environment**, - individuals in a single population can be distributed - randomly, clumped together, or in **highly regular patterns.** \- In **randomly arranged populations**, - individuals live wherever resources are **available.** \- **Ordered patterns** may be - determined by the physical environment but are more often - the result of **biological competition.** **Resilience and Stability** **Stability** - ability of a system to **[return]** to the **same equilibrium** state after a **temporary disturbance**. **Resilience** - ability of systems to **absorb change and disturbance** and **still maintain** the same relationships between populations or state variables. \- Many **biological communities** tend to - remain relatively stable and **constant over time.** \- **Robert MacArthur (1955)** - a graduate student at **Yale,** - proposed that the - **more complex and interconnected a community** is, - the **more stable** and r**esilient** it will be - in the **face of disturbance.** Three kinds of **stability or resiliency** in ecosystems: 1\. **Constancy** -- - lack of fluctuations ( continual change) in composition or functions -  person never stops doing something and always follows the routine. 2**. Inertia --** - resistance to perturbations - (A small change in a physical system, most often in a physical system at equilibrium that is disturbed from the outside) - the delay or slowness in the response of an ecosystem to certain factors of change 3**. Renewal** - ability to - **repair damage** **after disturbance** **Edges and Boundaries** **­-Edge Effects.** \- The **boundary** between - one habitat and its neighbors - is an important aspect of community structure. - These relationships are called \- The **edge of a patch** **of habitat** is - sometime relatively sharp and distinct. \- In moving from a **woodland patch** into a grassland or cultivated field, you sense a dramatic change from the cool, dark, quiet forest interior to the windy, sunny, warmer, open space of the meadow. \- In other cases, one **habitat type** intergrades very gradually into another, so there is no distinct border. \- **Ecotones** are what the ecologists call the - **boundaries between adjacent communities**. \- **Closed Community** - a community that is **sharply divided** from its neighbors. \- **Open Community** - a community with **gradual or indistinct** boundaries over which **many species cross.** \*Often this distinction is a **matter of degree or perception**. **Dynamic and Changing Communities** \- Some **biological communities** are **dependent** on - periodic disturbance. \- **Introduced species** can - cause profound community change. **Ecological Succession** \- **Climax Community** is the community that - developed **last and lasted the longest**. \- **Ecological Succession** is the - history of community development. When a **succession** occurs, organisms occupy a - **site and change** the environmental conditions. **2 kinds of succession:** 1\. **Primary succession** - - Land that is **bare of soil** (a sandbar, mudslide, rock face, and volcanic flow) is colonized by living organisms - where **none lived** before. **2. Secondary succession** - When an - existing community is **disturbed**, - a **new one develops** from the - biological legacy of the old. \- **Ecological development or facilitation** -- - In both kinds of succession, when organisms **change the environment** by - modifying soil, light levels, food supplies, and microclimate, - the change permits new species to colonize and - eventually replace the previous species. **- Pioneer species** -- - In **primary succession** on land, the - first colonists (microbes, mosses, and lichens) - that can withstand a harsh environment with few resources. An example of **primary succession**, shown in five stages (left to right). Bare rocks are colonized by lichens and mosses, which trap moisture and build soil for grasses, shrubs, and eventually trees. **Disturbance** \- Any force that **disrupts** the - established patterns of species diversity and - abundance, community structure, or community properties. \- **Disturbances on earth**: - landslides, mudslides, hailstorms, earthquakes, hurricanes, - tornadoes, tidal waves, wildfires, and volcanoes. \- **Animals** can cause **disturbance** too. **- Disturbance-adapted species** -- - species that can survive **periodic disturbance** - (survive fires underground, or resist the flames, and then reseed quickly after fires). **Introduced Species** **Requirements of Succession.** \- **Continuous introduction** of new community members and - the **disappearance of previously existing species** are - New species move in as conditions become suitable; others die or move out as the community changes. **- New species** can be introduced - after a stable community already has become established. Some of them **cannot compete** with **existing species** and - fail to become established. Others are able to fit into and - become part of the community, defining ***[new ecological niches.]*** \- If an **introduced species** - **preys** upon or competes more successfully with one or more **populations** that are **native to the community**, - the **entire nature** of the **community** **can be altered.**