APES - Big Ideas from #2: The Living World - Biodiversity & #9.8-9.9: Invasive & Endangered Species

Genetic Diversity

A measure of genetic variation among individuals in a population.

THINK: Diversity of Genes in a Population = Genetic Diversity

Species Diversity

Number of species in a region or in a specific ecosystem

THINK: Diversity of Species in a Region = Species Diversity

Habitat Diversity

Variation of habitats present in a given ecosystem

THINK: Diversity of Habitats in an Ecosystem = Habitat Diversity

Ecosystem Diversity

Variation of ecosystems present in a given region

THINK: Diversity of ecosystems = Ecosystem Diversity

Relationship between Habitat Diverisity and Species Diversity

There is a DIRECT CORRELATION between habitat diversity and species diversity. Greater Habitat Diversity leads to Greater Species Diversity.

Relationship between Ecosystem Diversity and Habitat Diversity

There is a DIRECT CORRELATION between ecosystem diversity and habitat diversity. Greater ecosystem diversity leads to greater habitat diversity, which in turn leads to greater species diversity.

Specialist Species

Species that can only live under a NARROW range of biotic and abiotic conditions--very specific habitats.

Ex. Herbivores that only consume 1 plant species, such as koalas residing amongst eucalyptus trees, feeding only on eucalyptus leaves.

Generalist Species

Species that can live under a wide range of biotic or abiotic conditions.

Ex. White-tailed deer, as they're able to reside in a wide range of climates throughout the Americas, feeding on a wide variety of different plants.

Ex. Raccoons!

Importance of Genetic Diversity

High levels of genetic diversity (genetic variation) allow for resilient populations, which lead to resilient ecosystems.

Populations are better able to respond to environmental change/disturbances in comparison to populations with lower genetic diversity.

Ex. Populations when they encounter disease

Importance of Habitat Diversity of Specialist and Generalist Species

Habitat Diversity has a DIRECT CORRELATION with Species Diversity.

Each habitat contains some unique specialist species, while various habitats feature generalist species.

When habitat loss occurs, such as due to human activities, the loss of specialist species may occur, which may further lead to the eventual loss of the generalist species.

Given that specialist species can only reside in one habitat, with particular abiotic and biotic conditions, the loss of that unique habitat leads to the loss of specialist species.

As habitat loss continues, with multiple habitats being destroyed, the eventual loss of the generalist species occurs.

Importance of Species Diversity

Species Diversity has a DIRECT CORRELATION with Primary Productivity.

Species Diversity has a DIRECT CORRELATION with Ecosystem Resilience.

Species diversity serves as an indicator for ecosystem health.

THINK:

↑ Species Diversity = ↑ Primary Productivity

↑ Species Diversity = ↑ Ecosystem Resilience

Relationship between Biodiversity and Ecosystem Resilience

There is a DIRECT CORRELATION between Biodiversity & Ecosystem Resilience.

THINK: ↑ Biodiversity = ↑ Ecosystem Resilience

Identify how we can quantify biodiversity in AP Environmental Science.

We can quanity biodiversity via Species Richness and Species Evenness

Species Richness

Total number of different species in a given ecosystem. Generally, High Species Richness serves as a good sign of ecosystem health.

CED (paraphrased from College Board): "Species richness refers to the number of different species found in an ecosystem."

Species Evenness

Relative proportion of individuals within different species in a given ecosystem. Indicates whether a particular ecosystem is numerically dominated by a single species or whether all its species have similar abundances.

↑ High Species Evenness = All species represented by similar number of individuals.

↓ Low Species Evenness = One species represented by many individuals whereas other species are presented by few individuals.

THINK: Balance of species in an ecosystem

Ecosystem Services

Processes by which life-supporting resources such as clean water, timber, and agricultural crops are produced.

Many believe ecosystems have an intrinsic value, regardless of any benefit to humans.,

Provisioning Services

A good produced by an ecosystem that humans can use directly.

Ex. Timber, Food Crops, Medicinal Plants (used for developing pharmaceutical drugs), natural rubbers, furs.

Human Impacts: Overfishing, Deforestation, Pollution can deplete/degrade these natural resources, reducing their availability.

Regulating Services

The benefits ecosystems provide by regulating natural processes. Ecosystem Resilience plays a critical role in regulatory services.

Ex. Climate regulation, Water purification (filtration of water), Pollination

Ex. Sequestration: Humans release around 8 gigatons of Carbon into the atmosphere annually, but 4 gigatons of Carbon are absorbed by ecosystems, with only 4 gigatons of Carbon being added to the atmosphere each year.

Human Impacts: Urbanization, polluton, and land-use changes can reduce nature's ability to regulate climate, water, and air quality

Cultural Services

The non-material/cultural/aesthetic benefits people gain from ecosystems, contributing to our mental health, spiritual well-being, education, and recreation.

Ex. Hiking (Recreation), Camping (Recreation), Aesthetic Value, Outdoor Classrooms (Education), Scientific Research Sites (Education)

Human Impacts Habitat destruction and pollution can reduce access to natural areas, diminishing their cultural and recreational value.

Supporting Services

The natural processes that allow other ecosystem services to occur--the foundation.

Ex. Nutrient Cycling, Primary Production, Habitat provision, Soil formation

Human Impacts: Soil degradation, deforestation, and pollution can disrupt nutrient cycling and energy flow, undermining ecosystem stability.

Describe the results of human disruptions to ecosystem services.

Human activities can impact ecosystems and have negative ecological and economic consequences.

Island Biogeography

The study of how species are distributed and interacting on islands*.

CED: "The study of ecological relationships and distribution of organisms on islands, and of these organisms' community structures."

*Islands can refer to literal islands or terrestrial, isolated habitat islands in a terrestrial landscape.

Colonization (in Island Biogeography)

The process by which new species arrive and establish populations in a habitat where they were not previously found, often from a source area such as the mainland.

2 main rules of Island Biogeography

There is a DIRECT CORRELATION between land size and species richness. Thus, larger islands contain more species than smaller islands.

There is an INVERSE CORRELATION between distance from the mainland and species richness.

THINK:

↑ Land Size = ↑ Species Richness

↑ Distance from Mainland = ↓ Species Richness

Explain the WHY behind the DIRECT CORRELATION between Land Size and Species Richness.

There is a DIRECT CORRELATION between land size and species richness. Thus, larger islands contain more species than smaller islands.

Dispersing species that come from other islands or nearby islands are more likely to find larger islands than smaller islands.

Regardless of latitudes, larger islands support more individuals of a given species than smaller islands due to the increased amount of resources present on the island.

Recall, ↑ Population Size = ↑ Genetic Diversity, which reduces the risk of extinction on the island.

Due to their island size, there are more available ecological niches (Ex. Different food sources for birds on the Galapagos Islands)

Larger islands generally contain a greater variety of abiotic and biotic conditions that supports a greater number of species, as ↑ wider range of environmental conditions, results in more ↑ opportunities for a species to evolvan on the island over time.

Greater ecosystem diversity.

Identify the correlation between island size and the presence of predators

There is a DIRECT CORRELATION between island size and the presence of predators.

Small islands generally do not support larger predators due to the rule of 10% ecological efficiency, as there would be small populations of producers and primary consumers, making it particularly difficult to support populations of secondary and tertiary consumers. In some cases, there may be a complete lack of predators.

THINK: ↑ Island Size = ↑ Presence of Predators

Explain the WHY behind the INVERSE CORRELATION between distance from the mainland and species richness.

There is an INVERSE CORRELATION between distance from the mainland and species richness. Thus, the further the island is from the mainland, the lower the species richness (the number of species) will be.

*While many species can disperse short distances, only few can disperse long distances.*

Suppose 2 islands are the same size, containing the same amount of resources. In that case, the nearer island should accumulate more species than the farthest island as it features a greater rate of immigration by new species.

THINK: ↑ Island Distance from Mainland = ↓ Species Richness

Describe the Model for Island Biogeography

When an island contains very few species, the rate of colonization by new species is expected to be very high.

As the number of species on the island increases, the rate of colonization declines since there are only a few new species that can colonize.

Furthermore, when an island contains very few species, the rate of extinction is expected to be quite low as there should be relatively little competition, predation, or parasitism happening that could cause a species to go extinct.

As the species richness of an island increases, it becomes highly likely that some species will undergo extinction.

The number of species on an island should occur where the two lines intersect, at the equilibrium point.

Identify examples of terrestrial, isolated habitat islands, where the theory of Island Biogeography is applicable.

1) Wetlands of different sizes scattered across a terrestrial landscape in Ontario

2) Central Park in NYC

Real-World Applications of Island Biogeography

A larger tract of land will contain more species than multiple smaller tracts that combined form a similar total area. Protecting tracts of habitat islands closer to a large, protected habitat will protect more species than protecting tracts of habitat islands further away.

The theory of island biogeography is taken into consideration, especially in the field of conservation biology/ecology.

The Role of Island Biogeography in Evolution

Species residing in habitat islands are of greater concern as they have often evolved to be specialists, rather than generalists.

WHY: Species on islands are commonly much more isolated than species on the mainland, interacting with a smaller number of species. Due to minimal interactions with other species, island species have developed unique adaptations in response to the selection pressures of the island, resulting in the lack of evolution of predator defenses. The environment may also contain a smaller diversity of food items, so island species may evolve to specialize in the types of food that are present.Under the unique conditions of an island, these specialized evolved responses can increase the evolutionary fitness of the island species, which explains why these adaptations have been preserved.

Ex. Many island species of bird have evolved to build their nests on the ground rather than in trees since there are a lack of nest predators to avoid.

Ex. Some New Zealand island birds have historically lacked predators, losing the ability to fly.

The Role of Island Bioegeography in Evolution, concerning Invasive Species

The specialization of these island species makes them exceptionally vulnerable to invasive species, as they disrupt the island's unique environmental conditions by introducing another biotic factor.

Ex. Brown Tree Snake being introduced to Guam on accident as ships were using the island as a port for transporting goods after WWII. The snakes began to consume several species of native island animals, and

the snake population quickly boomed, eventually leading to the decline of various species.

Range of Ecological Tolerance (AKA The Fundamental Niche)

The range/suite of abiotic conditions under which a species can survive, grow, and reproduce—AKA the Fundamental Niche.

CED: "Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can endure before injury or death results."

Every individual has an optimal environment in which it performs exceptionally well; each species has a range of ecological tolerance.

Both individuals and species have limits to the abiotic conditions tolerable, examples including: Temperature Extremes, Humidity, Salinity, Sunlight, Water flow, pH

Optimal Range

Range where organisms survive, grow, and reproduce

Zone of physiological stress

Range where organisms survive, but experience some stress such as infertility, lack of growth, decreased activity, etc...

Zone of Intolerance

Range where the organism will die

Explain the impact on the organism, given the various zones of ecological tolerance.

As conditions move further away from the ideal, individuals may be able to survive, some even to grow, but not be able to reproduce. Individuals and Species have the greatest evolutionary fitness at the ideal point in the range of ecological tolerance as they are able to survive, grow, and reproduce.

Ex. Plant Responses to Sunlight: Many plant species that grow in open fields thrive in full sunlight but often struggle to photosynthesize in the deep shade of a forest. Conversely, small plants living along the

forest floor are greatly efficient in performing photosynthesis in low light, but perform poorly in the intensive sunlight of an open field.

Explain why the Range of Ecological Tolerance is also known as the Fundamental Niche of Species

Ecological Tolerance is AKA the Fundamental Niche of a Species, as the combination of abiotic factors in a particular environment fundamentally determines whether a species can persist there.

Realized Niche

Realized Niche: The range of abiotic and biotic conditions under which a species actually lives. Once we determine the realized niche of a species, we have a greater understanding of the geographic range of the species.

Geographic Range

Areas of the world in which a species resides.

Differentiate between the Fundamental and Realized Niche

The fundamental niche defines the abiotic limits for a species' presence, with no consideration for the biotic factors.

The realized niche considers both abiotic and biotic factors, such as the presence of competitors, predators, and diseases.

EVALUATE: How could climate change affect a species' ecological tolerance curve?

Shifts in temperature or precipitation could move the environmental conditions outside a species' optimal range, decreasing population size or causing migration/extinction.

Science Practice: 7.A - Describe Environmental Problems

EVALUATE: Why do generalist species have broader ecological tolerance ranges than specialist species?

Generalists can thrive in a wider range of conditions and use diverse resources, while specialists are limited to narrow environmental ranges or food sources.

Science Practice: 1.C - Apply/Explain in Context

Why might a species go extinct when there are significant changes in the environment?

(a) Changes are too rapid for species to respond

(b) Unable to shift their distributions: Lack of favorable environments nearby to which species can move to match their ecological tolerance.

(c) Attempt to shift distributions made with resistance: "If there is an alternative favorable environment to which a species could move, the alternative favorable environment may be occupied by other species against which moving populations cannot successfully compete."

Identify the relationship between Genetic Diversity and Ecological Range of Tolerance.

There is a DIRECT CORRELATION between genetic diversity and ecological range of tolerance.

THINK: ↑ Genetic Diversity = ↑ Range of Ecological Tolerance

Periodic Disturbance

Disturbances that occur regularly

Ex. Day-night Cycle, Monthly cycles of Moon's effect on ocean tides

Episodic Disturbance

Disturbances that occur semi-regularly

Ex. Cycles of high and low rain that occur every 5-10 years.

Random Disturbance

Disturbances that have no regular pattern; irregular.

Ex. Volcanic eruptions, hurricanes

Justify whether ecosystem disruptions can occur twice at a particular location.

Technically, yes, but the probability of it occurring twice is low.

Ex. Fires, hurricanes, tsunamis, and droughts happen every year somewhere in the world, potentially completely changing the ecosystem for many years, but rarely hit the exact location for multiple years consistently.

However, forest fires can occur at the same locations with some regularity. After a forest fire, coniferous trees have very little burnable material left on the ground. However, each year after the fire, the forest floor continues to accumulate conifer needles and dead branches until there's enough to feed another fire.

Identify the correlation between duration and the sptial extent of disruptions.

There is a DIRECT CORRELATION between duration and the spatial extent of eruptions.

Thus,

Longer durations result in a greater spatial extent and impact on the areas affected by the disruptions.

Shorter durations result in shortened spatial extent and minimal impact on the areas affected by the disruptions.

Ecosystem Resistance

In an ecosystem, a measure of how much a disruption can affect the flows of energy and matter.

The ecosystem has a HIGH resistance when a disruption influences populations and communities but has NO effect on the overall flows of energy and matter.

The ecosystem has a LOW resistance when a disruption influences populations and communities but has a SIGNIFICANT effect on the overall flows of energy and matter.

Ecosystem Resilience

The rate at which an ecosystem returns to its original state after a disruption.

The ecosystem is HIGHLY resilient if it returns to its original state relatively rapidly.

The ecosystem is LOWLY resilient if it returns to its original state relatively more slowly.

*Often dependent on specific interactions of the biogeochemical and hydrologic cycles.

Ex. As human activity has caused an increase in global atmospheric Carbon Dioxide concentrations, terrestrial and aquatic ecosystems have increased the amount of carbon they absorb. Through this method, the Carbon Cycle collectively has offset some of the changes we may expect from increases in atmospheric Carbon Dioxide concentrations, including global climate change.

Ex. When a drought occurs, the soil may dry out, hardening to such an extent that when it eventually rains, the soil isn't able to absorb as much water as it did before the drought.

The soil changes in response to the drought, leading to further drying and intensification of the drought damage. In this case, the hydrologic cycle does not relieve the effects of the drought, instead forming a positive feedback loop in the system, amplifying the situation, making it worse.

Identify where we get the long-term data for temperature

The long-term data for temperature comes from foraminifera exoskeletons found in ocean sediments.

Identify the long-term source for atmospheric Carbon Dioxide levels

The long-term source for atmospheric Carbon Dioxide levels is Ice Cores.

Identify what type of measurements must be used to determine historic climates

Indirect measurements must be used to determine historic climates

Ice Core

Long tubes of ice extracted from the frozen regions of the world, which scientists use to conduct chemical analysis to capture changes in the atmosphere, regarding the composition of greenhouse gases.

Identify 3 reasons that Earth's climate has changed over geological time

Reasons Earth's climate has changed over geological time include increased carbon dioxide levels, shifts in solar radiation, and changes in volcanic activity and plate tectonics.

Describe why sea levels have varied on Earth over time

Sea levels have varied on Earth over time due to global warming, as the melting of ice releases stored freshwater into rivers and streams, which contribute to rising sea levels. Similarly, during ice ages, freshwater has been stored in ice, contributing to declining sea levels.

Migration

The movement of organisms for short-term or long-term durations, usually caused by natural disturbances such as seasonal changes.

Identify 3 reasons for a population to migrate

Three reasons a population would migrate include temperatures that are complacent with a species' ecological tolerance, food supply, and water supply.

Identify and justify what seasonal disruptions favor.

Seasonal disruptions favor migrations, as some disruptions are cyclic, such as seasonal changes in temperature, which are associated with seasonal changes in food abundance. Thus, seasonal disruptions serve as common causes of animal migration in search of more abundant food.

Identify an example of a short-term migration.

The movement of grazing animals up and down a mountainside during alternating periods of snowfall and snowmelt as they aim to find grasses to graze on.

Identify an example of a long-term migration.

Many North American bird species fly south in the fall in search of more abundant food and fly back north in the Spring when the northern westerly winds start warming, generating new food sources in the form of plants and insects.

Intermediate Disturbance Hypothesis

Ecosystems experiencing intermediate levels of disturbance will favor a higher level of diversity of species than those with high or low (extreme) disruption levels.

Explain what ecosystems experience where disturbances are rare, concerning the Intermediate Disturbance Hypothesis

Ecosystems in which disturbances are rare experience intense competition among species, leading to the eventual dominance of the ecosystem by only a few highly competitive species.

Explain what ecosystems experience where disturbances are frequent, concerning the Intermediate Disturbance Hypothesis

Ecosystems in which disturbances are frequent experience only a few species with high population growth rates that can counter the effects of frequent disturbance and prevent species extinction.

Identify what ecosystems experience where disturbances occur at an intermediate level

At an intermediate level of disturbance, many more species are capable of persisting.

Explain an example of the Intermediate Disturbance Hypothesis using the Marine algae along the Coast of New England. You may use a numbered list instead of a paragraph form.

Ex. Marine algae that spend their lives attached to rocks along the rocky coast of New England:

1) In these areas, common periwinkle snails are present, eating multiple species of marine algae.

2) When few snails are present, they only eat a small amount of the marine algae, representing a small disturbance.

3) Under these conditions, only a few algal species—the most competitive ones dominate the rocks.

4) In areas containing high densities of snails, a significant amount of marine algae is consumed, representing a high disturbance. In this case, only the most unpalatable algal species can remain.

5) When snails are present at an intermediate density, there is too much consumption by snails for the best competitors to dominate and the other species being near driven extinct. Thus, the intermediate snail density favors 12 species of algae remaining on the rocks.

6) Thus, the greatest diversity of species can occur when ecosystems experience an intermediate frequency of disturbance.

Evolution

A change in the green pool over time from generation to generation, due to the 5 mechanisms of evolution. It is essentially a change in the genetic makeup/composition of a population over time and is supported by a variety of evidence. It is the process that causes biodiversity.

Microevolution

Evolution at the population level—change over time in allele frequencies in a population.

Ex. Allele frequencies in a population alter over time and thus the phenotype, such as the color of eyes, differs significantly across generations due to a change in allele frequencies, caused by the mechanisms of evolution.

Macroevolution

Evolution that gives rise to new species, genera, families, classes, or phyla—a broad pattern of evolution above the species level.

Ex. Origin of new groups of organisms, such as mammals or flowering plants.

Identify who is affected by evolution

Evolution affects populations, not individuals.

Artifical Selection

The process by which humans have modified other species over many generations by selecting and breeding individuals possessing desired traits. As a result, crops, livestock animals, and pets often bear little resemblance or similarity to their wild ancestors.

Ex. Dog breeds—derived from wolves

Identify the 5 mechanisms of Evolution

1) Natural Selection

2) Genetic Drift

3) Mutations

4) Non-Random Mating/Sexual Selection

5) Gene Flow

Natural Selection

Organisms that have beneficial adaptations suited for a particular environment have a greater chance of survival and reproduction. It is the ONLY mechanism of evolution that causes adaptations.

Notes...

1) Natural Selection is a process of editing, not a creative mechanism.

2) Evolution by Natural Selection may occur rapidly (ex. few years or decades)

3) Natural Selection favors adaptations depending on time and environment.

4) Evolution is a blend of chance and "sorting" (Chance, as in the creation of new genetic variations - mutations and Sorting, as in Natural Selection, favors certain alleles over others depending on selection pressures). Due to this sorting process, the outcome of Natural Selection is NOT random. It increases the frequencies of alleles that provide greater evolutionary fitness, leading to adaptative evolution

Identify various examples of Natural Selection

1) Sickle Cell Anemia (Sickle Cell Trait is Selected For)

2) DDT Resistance in Insects

3) Peppered Moth

4) Rock Pocket Mice

Identify the evolutionary mechanism that causes adaptations.

Natural Selection is the only mechanism of evolution that causes adaptations.

Genetic Drift

A random change in allele frequencies in a population, especially significant in smaller populations. Exemplifies the bottleneck effect and the founder effect.

Summarize the effects of Genetic Drift

1) Genetic Drift is significant in small populations

2) Genetic Drift can cause allele frequencies to change at random.

3) Genetic Drift can lead to a loss of genetic variation in populations.

5) Genetic Drift can cause harmful alleles to become fixed.

Bottleneck Effect

A sudden change/disruption in the environment, such as a fire or flood, may drastically reduce the population.

Ex. A deer may be in the wrong place at the wrong time, and due to that unfortunate circumstance, die.

Founder Effect

When few individuals become isolated from a larger population, this small group may establish a new population with a different gene pool from the initial, source population. These individuals get isolated and act as "founding fathers."

Gene Flow

The movement of alleles into or out of a population due to the migration of individuals or gametes, which can increase genetic diversity and reduce genetic differences between populations.

THINK: Migration of Alleles

Mutations

A random change in an organism's DNA that can introduce new alleles into a population, providing raw material for evolution.

Identify the relationship between population size and the amount of mutations present.

There is a DIRECT CORRELATION between population size and the amount of mutations present. Generally, larger populations result in more opportunities for mutations to appear in them.

If a mutation improves evolutionary fitness, it will be favored by Natural Selection.

Determine whether every mutation leads to the formation of a new species

No. Most mutations are neutral or minor. Speciation typically requires isolation and time.

Non-Random Mating/Sexual Selection

When individuals select mates based on phenotype or relatedness, which can shift allele frequencies. Includes assortative mating and inbreeding.

Evolutionary Fitness

Ability of an organism to survive and reproduce fertile offspring.

THINK: Survival AND reproduction.

Evolutionary fitness can be measured by the reproductive success of an organism (production of offspring).

Dependent on specific environmental conditions.

An individual's fitness is relative to environmental conditions, as favorable adaptations can change in response to environmental changes, influencing selection pressures.

Adaptation

A trait that improves an individual's evolutionary fitness.

Speciation

The process by which one species splits into two or more species.

Allopatric Speciation

Gene flow is interrupted when a population is divided into geographically isolated subpopulations. It can occur without geologic change, such as through colonization.

THINK: Speciation due to Geographic Isolation

Sympatric Speciation

Subset of population forms without geographic separation, involving reproductive barriers. It can occur if gene flow is reduced by various factors.

THINK: Speciation with no geographic isolation but rather caused by reduced gene flow without geographic separation.

Identify the various facotrs that can reduce gene flow

Various factors that can reduce Gene Flow include: Polyploidy, Sexual Selection, and Habitat Differentiation

*May also promote Allopatric Speciation

Concerning the pace of evolution, identify what type of evolution natural selection and artificial selection cause in broad, elementary terminology.

Natural Selection generally causes SLOW evolution. Artificial Selection generally causes RAPID/FAST evolution

Punctuated Equilibrium

Evolution occurs rapidly after a long period of stasis, or NO EVOLUTION.

Gradualism

Evolution occurs gradually, slowly over hundreds of thousands or millions of years.

Adaptive Radiation

Evolution of new species allowing empty, unfilled ecological roles/niches to be filled.

Describe how adaptations arise in a population

Adaptations arise in a population as a result of selection pressures, due to Natural Selection.

Selective pressure

Any biotic/abiotic factors in the environment that influence survivability and reproductive success.

Ex. Temperature of an environment, as it directly influences enzyme function, behavior, and habitat range.

Explain how environmental change can lead to the evolution or extinction of a species

An environmental change can lead to the evolution or extinction of a species depending on its response to selective pressures, acted on by natural selection.

Ecological Succession

The predictable replacement of one group of species by another group of species over time.