Global Ecosystems

Biodiversity

Biodiversity is the variety and variability of living organisms and the ecological systems they belong to.

Genetic Attributes

Differences in genes and alleles

Phenotypic Attributes

Differences in observable traits (ie. size, shape, color)

Phylogenic Attributes

Differences in evolutionary history and relationships

Functional Attributes

Differences in the roles organisms perform in ecosystems

Abundance and Distrbution

How many organisms exist and where they occur, including how those patterns change over time and space

Pattern

A non-random, repetitive arrangement or distribution. It describes what we observe.

Ex., where species live, which regions have more species, and how species are distributed across islands.

Process

A mechanism or cause that helps explain a pattern. It describes how or why the pattern happens.

Ex.,natural selection, speciation, extinction, dispersal, climate, and interactions between species.

Morphological Species Concept

Species are distinguished by differences in their physical form and structure.

- Useful when organisms can be identified by visible features.

- Can be difficult when individuals of one species look different or different species look very similar.

Example: Two groups of organisms have consistently different physical structures, so scientists classify them as separate species.

Main question: What physical traits distinguish the organisms?

Biological Species Concept

A species consists of natural populations that can interbreed and are reproductively isolated from other such groups.

Reproductive isolation means populations do not successfully reproduce with one another to produce fertile offspring under natural conditions.

- Focuses on interbreeding and reproduction.

- Limitations: it is difficult to apply to fossils, organisms that reproduce asexually, or populations that are geographically separated.

Example: Two populations that no longer produce fertile hybrids under natural conditions may be considered separate species.

Main question: Can they interbreed and produce fertile offspring under natural conditions?

Phylogenetic Species Concept

A species is the smallest group of organisms that can be identified as distinct based on its pattern of ancestry and descent.

- Focuses on evolutionary relationships and diagnosable differences.

- Helps scientists classify organisms using evidence about their evolutionary history.

Example: A group of organisms forms a distinct evolutionary lineage that can be distinguished from other groups.

Main question: Can they be identified as a distinct evolutionary lineage?

Systematics

The study of biological diversity and relationships among organisms.

Taxonomy

Identifying, naming, and describing organisms.

Phylogeny

The evolutionary history and relationships of organisms or groups.

Classification

Organizing organisms into groups based on shared characteristics or relationships.

Scientific Name

The formal name assigned to a species.

Plants

Generally multicellular, photosynthetic autotrophs that use sunlight and resources such as water and carbon dioxide to make food.

Animals

Multicellular heterotrophs that obtain energy by consuming other organisms or organic material.

Fungi

Obtain nutrients by absorbing them from organic material, often by decomposing dead or decaying organisms.

Protista and Monera

…

Organism

An individual living thing.

Example: One oak tree or one bird.

Population

A group of individuals of the same species in a particular area.

Example: All individuals of one bird species living in a particular forest.

Community

Groups of different species that occur together in space and time and may interact.

Example: Trees, birds, insects, fungi, and other organisms living in a forest.

Ecosystem

The interacting biotic and abiotic components of a particular environment.

Example: A forest community together with its soil, water, light, air, and temperature.

Biotic

living components of an environment, such as plants, animals, fungi, and bacteria.

Abiotic

nonliving physical and chemical components, such as water, light, soil, temperature, and minerals.

Habitat

the place where an organism lives.

Microenvironment

The immediate environment experienced by an organism.

Not the same as niche

Community Structure

the types of species present, their forms, and their trophic roles and interactions.

Natural History

Natural history is the study of organisms in their environments, using methods that tend to be more observational than experimental.

It helps scientists understand how life and biodiversity have changed through time.

Natural history can involve observing organisms in the field, recording where they live, comparing species, examining fossils, and studying how organisms relate to their surroundings.

Observation vs Experiment

Observation: recording what happens in nature without deliberately manipulating the situation.

- Experiment: changing or controlling one or more factors to test how they affect an outcome.

Natural history often emphasizes observation, but observation and experiments can complement one another.

Cambrian Explosion

A period of geologically rapid diversification of many animal groups. Your slides connect it with changes in oxygen, environmental conditions, predator–prey relationships, shells, swimming, and the filling of ecological niches.

Fossil Record

Preserved evidence of past life. Fossils help scientists investigate which organisms lived in the past and how life changed over time.

Evolution

Change in inherited characteristics of populations across generations. Evolution explains how life changes; natural history examines those changes in the context of the history of life and Earth.

Biological Evolution

inherited changes in populations across generations.

Seasonality

recurring changes associated with seasons, such as temperature or growing-season length

Erosion

the movement of soil or rock by water, wind, ice, or other forces.

Weathering

the breakdown of rock material.

What limits a species’ geographic range?

1) Physical Environment 2) Biological Interactions 3) Disturbances

A species' geographic range is the area in which it occurs.

The range can be limited by factors such as temperature, water availability, nutrients, competition, predation, and events that change or damage habitats.

Often, several factors interact. A species may tolerate a certain temperature but still be unable to occupy an area because a competitor excludes it or the necessary habitat is absent.

Physical Resources that affect organism distribution

Radiation or light: provides energy for photosynthesis and affects organisms that depend on light.

- Water: needed for many biological reactions and processes.

- Carbon dioxide (CO₂): used in photosynthesis.

- Mineral nutrients: including nitrogen and phosphorus.

- Space: organisms need suitable places to grow, live, reproduce, or establish themselves.

Water availability is affected partly by soil type and root systems. Carbon dioxide for photosynthesis is obtained from the atmosphere.

Environmental constraints are conditions or resource limits that restrict an organism's survival, growth, reproduction, or distribution.

Temperature

- Latitude: affects the amount and angle of solar energy received.

- Winds and ocean currents: transport heat and influence regional temperatures.

- Altitude and topography: higher elevations are generally cooler; landforms can also affect local conditions.

Precipitation

- Atmospheric pressure belts: influence the rising and sinking of air, which affects cloud formation and rainfall.

- orographic effect: mountains force air to rise, changing its temperature and moisture.

Orographic Effect and Rain Shadow

When moist air reaches a mountain, it rises and cools. Cooling can lead to condensation and precipitation on the windward side. As the air descends on the leeward side, it warms and becomes drier, creating a rain shadow.

- Windward side: faces the incoming wind; often wetter.

- Leeward side: sheltered from the incoming wind; often drier.

- Rain shadow: a relatively dry area on the leeward side of a mountain range.

Environmental Gradient

A gradual change in an environmental factor across space, such as temperature, moisture, or elevation. Different species may occur along different parts of the gradient because their tolerances differ.

Weathering and Soil

Weathering is the breakdown of rock material.

- Physical or mechanical weathering: breaks rock into smaller pieces without changing its chemical composition.

- Chemical weathering: changes the minerals or chemical composition of rock through reactions.

Soils can differ even in nearby locations because of differences in parent rock, water, climate, topography, and biological activity. Soil differences can affect water retention and the nutrients available to organisms.

Photsynthesis

Captures energy from sunlight, Produces sugars/food, Uses CO2, releases O2, Requires light for process

Photosynthesis converts energy from sunlight into chemical energy stored in carbohydrate molecules, such as sugars.

Cellular Respiration

Releases usable energy from food molecules, uses food molecules, produces CO2, uses O2 in aerobic respiration, and can occur in light or darkness

Cellular respiration breaks down food molecules to release usable energy for cellular activities.

Energy Flow and Nutrient Cycling

Energy flow describes how energy moves through an ecosystem, entering largely as sunlight and passing among organisms through feeding relationships.

Nutrient cycling describes how matter, such as nitrogen and phosphorus, moves between organisms and the nonliving environment and is reused.

Trophic Levels

an organism's feeding position in an energy-transfer system.

Producers/Autotrophs

Make organic food, usually through photosynthesis

Primary Consumers

Feed on producers

Secondary and higher-level consumers

Feed on other consumers

Decomposers

Organisms such as fungi and bacteria break down organic material and return nutrients to the environment. Decomposition connects with every trophic level, not just the final consumer.

Trophic chain or Food chain

a sequence showing who obtains energy from whom.

Example of a simple chain: grass → grasshopper → frog → snake.

The arrows indicate the direction of energy transfer: from the organism being eaten to the organism that eats it.

Food Web

a network of interconnected food chains, showing the multiple feeding relationships in a community.

Evolution

organisms share ancestors, and inherited characteristics change across generations.

happens in populations across generations, not because an individual decides to change during its lifetime.

Microevolution vs Macroevolution

small-scale evolutionary change within a population

large-scale evolutionary patterns and changes over many generations

DNA

the molecule that carries hereditary information.

Gene

a section of DNA associated with a functional product; your lecture describes genes as DNA sections that code for proteins.

Allele

a version of a gene

Trait

a characteristic of an organism, such as a particular seed shape.

Genetic Variation

differences in genetic material or alleles among individuals or populations.

Gene frequency/Allele frequency

how common a particular allele is within a population.

Inheritance

the transmission of genetic information from parents to offspring.

Mutation

A change in DNA

-Substitution: one DNA unit is replaced by another

- Insertion: DNA units are added.

- Deletion: DNA units are removed.

Genetic Drift

Genetic drift is a random change in allele frequencies from one generation to the next.

It differs from natural selection because drift is based on chance, not on whether a trait improves survival or reproduction.

Founder Effect

Example of genetic drift (1/2)

A small group separates from a larger population and starts a new population. The new group carries only some of the original population's genetic variation, so alleles that were uncommon in the original group can become common in the new one.

Bottleneck Effect

Example of genetic drift (1/2)

A population becomes much smaller, leaving a limited set of survivors. The survivors' alleles make up much of the genetic variation in the later population.

Natural Selection

Natural selection occurs when inherited traits that improve survival and reproductive success become more common across generations.

1. Variation: individuals in a population differ.

2. Heredity: some differences are passed from parents to offspring.

3. Differential reproduction: individuals with certain inherited traits leave more offspring than others.

Gene Flow

Gene flow is the transfer of genetic variation from one population to another, often when individuals migrate and reproduce in a different population.

Gene flow can make populations more genetically similar by moving alleles between them.

Artificial Selection

Artificial selection occurs when humans choose which organisms reproduce based on desired traits.

Speciation

Speciation is the process through which new species originate from ancestral populations.

1. Populations of one ancestral species become separated or experience different conditions.

2. Genetic differences accumulate through mechanisms such as mutation, drift, selection, and changes in gene flow.

3. The populations become increasingly different.

4. If they become reproductively isolated, they may be considered separate species under the biological species concept.

Ecotype

A genetically differentiated subpopulation adapted to particular physical environmental conditions

Disruptive Selection

A form of natural selection that favors individuals with extreme versions of a trait over individuals with intermediate versions.

Connection between evolution and biodviersity

Three fundamental processes that explain biodiversity patterns:

Evolution and speciation- change populations over generations; speciation produces new species. These processes can increase the number of species.

Extinction-the disappearance of a species. It removes species from biodiversity.

Dispersal- occurs when individuals move away from their immediate parental environment and become less aggregated. It affects where organisms occur and which places populations can colonize.

Extinction

Extinction is the disappearance or termination of a species when no living individuals remain.

Extinction is a natural part of life's history, but extinction rates differ greatly across species and periods.

Background Extinction vs. Mass Extinction

Background: Extinctions affecting one or a few species in a particular place or period; Often occurs as part of ongoing changes in environments and biological interactions

Mass: A large proportion of species disappear over a relatively short geological interval; Affects many groups or lineages across broad areas

5 Mass Extinctions

Ordovician–Silurian 440 million years ago; Major glaciation and falling sea levels

Late Devonian Starting about 360 million years ago; Low oxygen in ocean bottom waters and changes in carbon accumulation

Permian–Triassic About 250 million years ago; “Great Dying”; massive volcanism and major environmental changes

Triassic–Jurassic About 200 million years ago Volcanic activity; extinction opened ecological opportunities for dinosaurs

Cretaceous About 65 million years ago; in the slides Asteroid or comet impact associated with the Yucatán Peninsula in Mexico

Mass Extinction Drivers

- Ice ages and rapid climate change.

- Asteroid impacts and their effects on climate.

- Massive volcanic activity, atmospheric particulates, and sulfur dioxide.

What causes extinction?

environmental change and shifts in biological interactions

- A climate change that makes a habitat unsuitable.

- Loss of a necessary food source.

- Competition or predation that reduces a population's success.

- A specialized habitat disappearing.

- Small population size, which can make a species more vulnerable to environmental changes.

Human-Associated Threats related to a possible 6th mass extinction

- Habitat destruction.

- Habitat fragmentation.

- Pollution.

- Overharvesting.

- Invasive species.

- Climate change.

Endemic Species

An endemic species occurs naturally only within a particular geographic region.

Ex. Madagascar Lemurs; different species adapted to using different parts of a tree

Endemism is often associated with geographic isolation because isolated areas can develop distinctive species that occur nowhere else.

Island Biogeography

Studies patterns of species richness on islands and how these patterns relate to immigration, extinction, island size, and isolation

How does species richness on islands reflect a balance between immigration and extinction?

- Immigration: organisms arrive from another area.

- Extinction: species disappear from the island.

- Species richness: the number of species present.

- Isolation: how separated an island is from other areas that can supply organisms.

Why do large islands close to the mainland tend to have greater biodiversity than small, isolated islands?

- Larger islands can support more habitat and resources.

- Islands closer to a mainland are easier for organisms to reach.

- Immigration can add species, while extinction can remove them.

Scientific Method

Involves systematic observation, measurement, data collection, and experiments, along with the formulation, testing, and modification of hypotheses.

Data

observations or measurements collected for a study

Observation

Information gathered by examining a phenomenon.

Hypothesis

A proposed explanation that can be tested using evidence.

Prediction

An expected result if a hypothesis is correct.

Experiment

A test in which researchers examine what happens under specified conditions.

Evidence

Observations, measurements, or results used to evaluate an explanation.

Mechanical

The process or cause that produces an observed result.

Theory

A broad explanatory framework supported by evidence. In science, a theory is not merely a guess.

S. J. Gould's essay on continental drift

- Evidence is the information supporting or challenging an explanation.

- Theory is an explanatory framework that makes sense of evidence and explains how or why something happens.

Continental Drift

The theory that continents were once joined and have since moved apart to their present positions.

Pangaea

Pangaea was the supercontinent that joined most of Earth's major landmasses before they separated and drifted apart. The continental drift idea helps explain why continents that are now far apart can share geological features, fossils, or related organisms.

Geological Evidence

Evidence for continental drift (1/4); Continents' outlines and geological features fit together in ways consistent with former connections. the distribution of earthquakes.

Paleontological Evidence

Evidence for continental drift (1/4); Paleontology is the study of past life, particularly through fossils. Similar fossils on continents now separated by oceans support the idea that those landmasses were once connected.

Ex. The fossil record of Glossopteris