Wetland Delineation

• Defines boundary: Wetland vs. Upland

• To be a wetland, requires 3 things

  • Hydrophytic vegetation

    • Plants that have adapted to growing in low oxygen (anaerobic) conditions associated w/ prolonged saturation or flooding

    • Plants species vary in their tolerance of wetland conditions (upland – facultative -- obligate wetland)

  • Hydric soils

    • Soils that have formed under conditions of saturation, flooding or ponding long enough during the growing season to develop anaerobic conditions

  • Evidence of hydrology

    • Standing water, water in shallow-dug hole, high water marks, stained leaves, grass laying down, etc.

• Individuals within a species are typically clumed, with decreasing numbers on extreme ends of environmental gradient

  • State Endangered: threatened with extirpation from the state

  • State threatened: may become endangered with continued stress

  • Species of concern: may become threatened with continued stress

  • Special interest: at the edge of a larger, contiguous range with viable population(s) within core of its range

Dispersal

• Movement away from existing population, or from individual parent

• Affeects pop. distribution, dynamics, geneticsk

• Africanized honey bees are a cross breed of african and european honey bees that have dispersed from Brazil rapidialy making their way to the united states due to their high dispersal rate, high fecundity, and shorter development

Rapid changes in Response to Climate Change

• Organisms began to spread northward about 16,000 years ago following retreat of glaciers

  • Evidence: pollen in lake sediments

  • Some spp. Moved 100 - 400 m/yr

Dispersal in Rivers and Streams

• Macroinvertabrates in streams have mechanisms to allow them to maintain their stream position.

  • Streamlined, flattened bodies

  • Adhesion to surfaces, etc

MISSED CLASS CADEN NOTES

• Population Distribution and Abundance

• 1. Environment limits the geographic distribution of species

• Distribution Limits

  • Organisms can only compensate so much for environmental variation.

  • Although some can migrate

• Tiger Beetle of Cold Climates

  • One species of tiger beetle (Cicindela longilabris) lives at higher latitudes and elevations

  • Prefers lower temperatures

  • Many species of tiger beetles, each with their own requirements

• Distributions of Barnacles

  • Rocky intertidal (high tide to low tide) zone

  • High intertidal area dries every low tide

  • Low intertidal one dries only during lowest tide

  • Patterns of zonation within intertidal zone

  • Chthamalus stellatus in upper levels (drier)

  • Balanus balanoides in middle and lower levels (more moist)

  • Balanus more vulnerable to desiccation, excluding it from the upper intertidal zone

  • Chthamalus excluded from lower areas by competition with Balanus

• 2. On small scales, individuals within a population may show clumped, uniform, or random distribution

• Population Distribution

  • Most populations live in clumps although other patterns occur based on resource distribution.

  • Clumped – E.g., Elephants

  • Uniform – E.g., Creosote bush

  • Random – E.g., Dandelions

  • Clumped

  • Resources tend to be clumped

  • Better protection from predators

  • More likely to eat

  • Easier for mating and nurturing

  • Uniform

  • Common when resources are scarce (this will probably be on Quiz/Exam), and individuals are competing for them

  • Individuals avoid/repel each other

  • Maximizes resource use

  • Random

  • Resources typically uniform in distribution

  • Individuals not attracting, nor repelling each other

  • At large spatial scale ® more environmental variation

  • How might this affect distribution of individuals?

• 3. At a large scale, individuals are clumped (in species with widespread distribution).

• Bird Populations Across North America

  • Christmas bird counts: 346 species showed clumped distributions

  • E.g., American crows congregate in great river valleys in winter

  • Counts also useful for trends

  • Sandhill cranes

  • Overwinter in the south

  • Breed in the north

  • Why do we care?

  • Can look at avian flu

• Plant Distribution and Abundance

  • Typically clumped, with decreasing numbers on extreme ends of environmental variable gradient

• Dispersal of Aquatic Macroinvertebrates

  • Drift: release substrate, travel downstream, settle down again

  • Catastrophic – Moved by a flood or big event

  • Behavioral – Move or stay in place at specific times on purpose (i.e., predators)

  • Constant – Doesn’t matter the time of day, they will move whenever

  • What keeps the upstream reach from becoming devoid of these drifting macroinvertebrates?

  • A lot of the invertebrates gain the ability to fly when they mature, they will fly to where they were produced back upstream to lay their own eggs.

  • Attaching to boats

  • Müller hypothesized populations maintained through balance of downstream and upstream dispersal

  • Müller Colonization cycle

• Population-Level Concepts Important to Conservation Biology

• Geographic range, population distribution, abundance, genetic diversity, dispersal, age distribution, reproductive rates, survivorship

  • Concerned with rare, threatened, endangered species

• Commonness and Rarity

  • Commonness classification based on 3 factors:

  • 1. Geographic Range of Species

  • 2. Habitat Tolerance

  • 3. Local Population Size

  • Non-threatened have extensive geographic ranges, broad habitat tolerances, some large local populations

  • E.g., starlings, red maple, deer mouse

  • All seven other combinations of the three factors create some kind of rarity

  • Rarity I

  • Extensive Range, Broad Habitat Tolerance, Small Local Populations

  • Peregrine falcon

  • Rarity II

  • Extensive Range, Large Populations, Narrow Habitat Tolerance

  • Passenger pigeon

  • Rarity III

  • Restricted Range, Narrow Habitat Tolerance, Small Populations (rarest of rare)

  • California condor

  • Reason numbers so low: poaching, lead poisoning, habitat destruction

  • 22 in 1987 – took ALL in

  • Now: ~300 in wild

• 3/6/23 Lecture

• Community Ecology

• Communities

  • A population is a group of individuals belonging to one species, living together in on area

  • Interactions

  • Competition

  • Predation

  • Symbiotic relationships

  • Competition (this will be on Exam 2) is an interaction between individuals of the same or different species, in which the fitness of one is lowered by interaction with the other over a limited resource

• Mechanisms of Competition

  • 1. Interference competition

  • Direct, aggressive interaction between individuals

  • E.g., Big horn sheep

  • 2. Exploitation competition

  • Indirect interaction between individuals through limited resource (i.e., compete through mutual effects on resource)

  • E.g., Sea anemones (limited space)

• Types of Competition

  • 1. Intraspecific

  • Competition with members of own species

  • May involve interference or exploitation

  • 2. Interspecific

  • Competition between individuals of different species

  • May involve interference or competition

• Intraspecific Competition Among Plants

  • More intense at higher population densities

  • Lower growth rates and mortality

  • Self-thinning (within a species):

  • 1000s seeds ® 100s seedlings ® 10s trees

  • Can competition go on indefinitely?

  • Outcome will depend on

  • Nature of limitation (resource-wise)

  • Nature of the overlap

  • Adaptive ability of species involved

• Key Concept

  • A niche reflects the environmental requirements of a species

  • Grinell 1917, and Elton 1927

  • Niche: An organism’s ecological role

  • How it responds to distribution of resources, competitors, predators

• Niche

  • Odum, 1959

  • Niche: An organism’s ecological role plus its habitat

• Interspecific Competition in Paramecia

  • Gause (1934) studied interspecific competition in two closely related species of paramecium

  • Gause: Two species so similar that they compete for the same limited resource(s) cannot coexist

• Principle of Competitive Exclusion (Created by Gauss)

  • Two species with identical niches cannot coexist indefinitely

  • One will be a better competitor, have higher fitness, and exclude the other

  • How do we know when niches are identical?

  • How many factors determine a niche?

• 3/7/23 Lecture

  • Hutchinson, 1957

  • Niche: n-dimensional hyper-volume (space)

  • n: number of environmental factors important to survival nd reproduction of a species

  • This one is the most accurate

• Fundamental vs. Realized Niche

  • Fundamental niche: represents the range of conditions and resources within which a species can persist (ideally)

  • Competitors can resist distribution of a species to some smaller part of the fundamental niche – Realized niche

• Niche Overlap in Flour Beetles

  • Tribolium beetles infest stored grain products

  • Hot-wet favors T. castaneum

  • Cool-dry favors T. confusum

  • Interspecific competition restricts niches

• Niche Overlap in Barnacles

  • Role of environment in determining distribution

  • Desiccation: Chthalamus more tolerant than Balanus

  • Does not entirely account for pattern

  • Competition and predation restrict fundamental niche to smaller realized niche

• Key Concept

  • Competition can result in evolution of niches

• Competition and Niches

  • Two possible outcomes of competition between species with identical niches:

  • 1. Extinction, or exclusion of one species

  • 2. Change in one species to use different resources (“Ghost of competition past”)

  • Species can become resource specialists, minimize niche overlap

  • Species can be generalists with high overlap, and competition

• Resource Partitioning

  • Galapagos finches

  • Grant (1986) found differences in beak size among closely related ground finches

  • Beak size related to diet

  • 1977 drought: only hard, large seeds

  • In G. fortis (medium-sized beaks/seeds), mortality was highest in those with smaller beaks

• Character Displacement

  • Interspecific competition can lead to directional selection that reduces niche overlap

  • Differences among similar species whose geographic distributions overlap are accentuated where they co-occur, and minimized (harder to tell spp. apart) where they do not overlap

  • Allopatric – live in different areas – do not overlap

  • Sympatric – same area – do overlap

• Directional Selection

  • Directional selection favors an extreme phenotype

• Character Displacement in Appalachian Lizards

  • Plethodon hoffmani and P. cinereus morphology similar in allopatric populations

  • In sympatric populations: differences in jaws

  • P. hoffmani larger, for larger prey

  • P. cinereus smaller, for smaller prey

• Predation

  • Predators kill and consume other organisms

  • Includes herbivory: plants

  • The one that does the eating is the predator

  • The one that is eaten is the prey

  • Potent factor in natural selection

• Predator Adaptations

  • Acute senses

  • Speed and agility

  • Lie-in-wait ambush mechanisms

  • Lure mechanisms (Aggressive mimicry)

  • Claws, teeth, fangs, stingers, poison

Prey adaptation

• Alarm call: to bring in a mob (crows), or alert others to hide (ground squirrels)

• Mullerian Mimicry: two or more species that are harmful and look similar

• Batesian mimicry: A harmless species looks like a harmful species

• Cryptic coloration: Blend in with the background (Camouflage)

• Warning coloration: Poison; brightly colored

• Having quills, repellents, Expel fluids (toxic, or hot)

Cycles of Abundance in Snowshoe Hares and Their Predators

• Lynx are specialized to hunt these Hares; when hare numbers go up the lynx numbers will shortly follow and vice versa

• These Hare number and lynx numbers are controlled by food Bottom-up

• Other predators will also eat hares when they are abundant including coyotes Predation is 60-98% Top-down

• Climate change will mess up when they are changing colors causing increased predation

Herbivory

• Primary producers as prey

  • Plants

  • Algae

Herbivorus Stream Insect and Its Algal Food

• Influence of caddisfly on algal Biomass

Symbiotic Relationships

• Paratisitim: one is harmed and the other benefits

• Commensalism: One benefits, the other is not harmed, but does not