Unit 3 - Quiz 1

3 types of biodiversity

Genetic, species, habitat/ecosystem

Genetic Diversity

• Variation in DNA of a species (important for adaptation + evolution)

• Genes make species more/less susceptible to disease

Species Diversity

Variety of species in an ecosystem

Habitat/ecosystem diversity

• Variety of habitats in region

• Different niches (roles that can be played in an ecosystem)

Why does large populations = high genetic diversity?

• Some individuals may survive new diseases, drought or temp change

• Survivors reproduce, population adapts over time

Population Bottleneck

Sudden reduction in population size

Effect of population bottleneck

• Loss of alleles

• Reduced genetic diversity

• Lower ability to adapt

Ecosystem Resilience

Ability to recover from disturbances (when multiple species perform similar ecological roles)

If one species declines during a disturbance:

1. Another species may increase

2. Ecosystem functions may continue

3. Overall productivity remains stable

What can happen if a species gets wiped out in an ecosystem with great species diversity

Another species may be able to take over the niche

Biodiversity Hotspots

Tropical rainforest

Coral reefs

Coastal ecosystems (marshes, wetlands, estuary)

Low disturbance effect

Dominant species outcompete others

lower biodiversity

High disturbance effect

Too many species eliminated

lower biodiversity

Moderate disturbance effect

Prevents dominance

highest biodiversity

Intermediate Disturbance Hypothesis

Moderate disturbance can increase biodiversity by preventing one species from dominating

How does habitat loss reduce biodiversity

1. Specialist species disappear first

2. Large predators decline

3. Generalist species eventually decline

→ Lower species richness, population fragmentation, reduced genetic diversity

What species are affected by habitat Loss Fragmentation

species with large territorial requirements

Fragmentation

Large habitat separated into small parts by urbanization, agriculture, etc.

What factor defines the difference between specialists and generalists

Ability to respond to changes (how adaptable)

Narrow vs Broad niche habitat specialist or generalist?

Narrow - specialist

Broad - generalist

Adaptability habitat specialist or generalist?

Less adaptable - specialist

More adaptable - generalist

Likeliness to go extinct habitat specialist or generalist?

More likely - specialist

Less likely - generalist

Resources habitat specialist or generalist?

Specific set - specialist

Variety - generalist

Tolerance habitat specialist or generalist?

Sensitive to change - specialist

Tolerant - generalist

When conditions are constant, who has the advantage, specialists or generalists?

Specialists

When conditions are inconsistent, who has the advantage, specialists or generalists?

Generalists

Koalas and pandas specialist/generalist

Specialists

Rats and racoons specialists/generalists

Generalists

Species richness

r - total number of diff species found in an ecosystem

Species evenness

Balance of individual organisms between different species (comparing population sizes)

Dominance indices

quantifies dominance of one or few species in a community

Information indices

related to concept of unknown/uncertainty

Simpson’s Index

Probability that 2 random individuals belong to same species in an ecosystem

Population will never be below ____

What resources can handle

Biotic Potential

max rate at which pop can increase under ideal conditions

Biotic potential in reality

populations rarely grow at biotic potential

Density Dependent factors examples

Competition, predation, disease, parasitism

Density independent factors examples

Drought, flood, wildfires, extreme temperatures

3 periods in logistic growth

Equilibrium = population aligns with carrying capacity

Slow growth → natality slightly above mortality

Fast growth → natality significantly above mortality

What does logistic curve look like

Population overshoot

Population grows above carrying capacity

Effect of population overshoot

• Resource depletion

• Habitat degradation

• Increased or decreased capacity

What 3 things can happen after a population overshoot

1. Population crash

2. Carrying capacity decreases over time (can also be due to natural factors)

3. Population recovers

Can carrying capacity change?

Yes - if limiting factors change

What factors cause differences in reproductions

• Energy usage/availability

• Trade off between quantity vs quality of offspring

K selected species survivorship type

I or II

Fewer offspring K/r selected

K

Smaller body size K/r selected

r

Long lifespan K/r selected

K

High comp for resources K/r selected

K

Early maturity + shorter lifespan K/r selected

r

Lower comp for resources K/r selected

r

Some reproduce only once in life K/r selected

r

Larger body size K/r selected

K

More than one reproductive event K/r selected

K

Many offspring per reproductive event K/r selected

r

Low energy investment K/r selected

r

Delayed maturity in offspring K/r selected

K

Slow growth in population K/r selected

K

High infant mortality in population K/r selected

r

Population increases rapidly in favorable conditions K/r selected

r

Population colonizes disturbed/new habitats quickly K/r selected

r

Population recovers slowly after major decline K/r selected

K

Population in stable environments K/r selected

K

Survivorship

Probability or proportion of individuals in population surviving to specific age

Survivorship Curve

Line that shows survival rate of cohort (same-aged individuals) from birth → death

Type I survivorship type + organisms

K-selected, most mammals

Type 1 survivorship curve

High survivorship early due to parental care

High survivorship mid-life due to large size + defensive behavior

Low survivorship late due to old age

Type II survivorship type and organisms

K, r

birds, rodents, songbirds

Type II survivorship curve

Steady decrease in survivorship

Constant mortality rate regardless of age

Type III survivorship type and organisms

r

insects, plants, fish, trees

Type III survivorship curve

Low survivorship due to no/little parental care

Low survivorship mid-life, few survive and steady decline

High survivorship late when adulthood is reached

Factors in ecological tolerance

Temp, salinity, water flow rate, sunlight, pH, dissolved O2

Range of ecological tolerance

Minimum - dead, zone of intolerance

→

Zone of stress - species rare

→

Optimal

→

Zone of stress - species rare

→

Maximum - dead, zone of intolerance

Generalists’ tolerance curve

Wide curve

Specialists’ tolerance curve

Skinny curve

Eco tolerance applies to species, individuals, or both?

Both

Types of species found in low pollution water

Abundant pollution-sensitive organisms

Same or higher amount of pollution-tolerant organisms

Types of species found in increasing pollution water

Pollution sensitive species decline/disappear

Pollution tolerant species increase

Bioindicator

Organism whose presence, absence, abundance, health gives info about environmental conditions

• Often aquatic macro invertebrates

Biotic index relationship

Higher index = poorer water quality