Exam 2: BIO 322

What are the 2 broad conservation approaches?

Systems approaches + Single-species approaches

What are the main criteria for selecting protected areas?

Richness + Endemism + Threats + Irreplaceability + Ecoregions + Regional focus

What is species richness?

Number of different species in an area

What is endemism?

Species restricted to a particular geographic area

What is the original definition of a biodiversity hotspot?

a biogeographic region with a high concentration of endemic species that is facing severe habitat loss and human threat

What is the biodiversity hotspot approach?

Protect areas with highest endemic biodiversity + greatest threats

What are Key Biodiversity Areas (KBAs)?

Extension/refinement of the biodiversity hotspot approach

What are the 5 KBA categories?

Threatened biodiversity + Geographically restricted biodiversity + Ecological integrity + Biological processes + Irreplaceability

What is the habitat loss approach?

Prioritize areas based on fraction of native habitat lost or altered

What is irreplaceability?

Measure of how essential an area is for meeting conservation targets

What can make an area irreplaceable?

Evolutionarily unique organisms + Rare ecosystems + Rare processes

What is the ecoregion approach?

Protect as many different habitat types as possible

What is the regional approach?

Protect ecosystem services within a geographically and politically connected region

What is gap analysis?

Finding gaps in current conservation coverage to identify areas for new reserves

What data can gap analysis use?

Species ranges + Costs + Threat levels + Other spatial data

What is complementarity?

Protected areas together meet biodiversity targets with little overlap

What is the goal of complementarity?

Maximum biodiversity protection + Minimum redundancy

What is GIS?

Geographic Information System that combines multiple spatial data layers

What data layers can GIS use for conservation?

Species + Habitat + Climate + Protected areas + Threats

What are the 4 main steps of conservation planning?

Identify targets + Inventory targets/threats + Set goals + Design protected-area network

What is an indicator species?

Usually a sensitive or endemic species used to measure conservation success

What is a flagship species?

Culturally important or charismatic species used as a conservation target

What is an umbrella species?

Species whose protection benefits many other organisms

What makes a good conservation goal?

Specific + Measurable + Attainable + Relevant + Time-based (SMART)

What methods help determine how much conservation is enough?

Population viability + Minimum viable population + Habitat fragmentation analyses

What are general rules of reserve design?

Larger + Close together + Clustered + Corridors + Minimize edges

What is the SLOSS debate?

Whether a Single Large Or Several Small reserves are better

What factors determine the best SLOSS strategy?

Nestedness + Edge effects + Connectivity

When may a single large reserve be better?

Species are nested + Lower edge:interior ratio + Greater connectivity

Why are corridors important especially with climate change?

provide safe pathways for plants and animals to move across fragmented landscapes as temperatures and habitats shift due to climate change

What are the five main perils of small populations?

Demographic stochasticity + environmental stochasticity + Allee effect + genetic drift + inbreeding

How does population size relate to extinction risk?

Smaller population sizes generally have a much higher risk of extinction than larger one

What is demographic stochasticity?

Chance variation in survival and/or reproduction among individuals within a population + variation in the population's sex ratio

Why is demographic stochasticity especially dangerous for small populations?

Small populations are more affected by random variation because each individual contributes more to the population's survival and reproduction

When is demographic stochasticity generally not a major concern?

When BOTH the number of females and number of males are greater than 20

What is the formula for extinction probability from demographic stochasticity?

Probability of extinction = (1 - s)^N + s = probability of individual survival + N = population size

What is environmental stochasticity?

Random variation in environmental conditions that affects reproduction or survival + examples include temperature

How does environmental stochasticity relate to population size and geographic range?

It can affect populations of all sizes but has larger impacts on small populations + it has a greater impact when a species has a small geographic range

What is an example of environmental stochasticity causing extinction?

Heath hen + hunting and habitat destruction restricted it to Martha's Vineyard + random fire

What is the Allee effect?

A positive relationship between population size and individual reproduction or survival + small populations may grow more slowly than large populations

What can cause an Allee effect?

Difficulty finding mates or pollinators + reduced cooperative hunting + reduced protection from predators + disrupted social interactions

What is an extinction vortex?

A cycle where population decline makes a population increasingly vulnerable to additional threats + those threats cause further decline + the downward spiral can eventually lead to extinction

How can multiple threats create an extinction vortex?

One event reduces population size + the smaller population becomes more vulnerable to genetic and ecological problems + these problems cause further population decline + repeated declines can lead to extinction

Why is genetic diversity important in conservation?

It provides long-term evolutionary potential + evolutionary flexibility to respond to changes such as epidemics and climate change + improves short-term individual and population fitness

What is polymorphism?

The number of loci for which more than one allele exists

What is heterozygosity?

The average percentage of loci that are heterozygous OR the average percentage of individuals heterozygous at a particular locus

How does population size affect loss of heterozygosity?

All populations lose heterozygosity over time + small populations lose heterozygosity faster

Why do small isolated populations tend to lose genetic diversity?

Mutations are rare + gene flow is limited or nonexistent + genetic diversity can be lost through selection

What is genetic drift?

Change in allele frequencies by chance unrelated to the alleles themselves + generally causes loss of heterozygosity and increased homozygosity

Why is genetic drift stronger in small populations?

Random sampling has a larger effect when there are fewer individuals + chance loss or reproduction of individuals can greatly change allele frequencies

What is the bottleneck effect?

A sudden reduction in population size that causes loss of alleles and reduces overall genetic variation + can result from disasters

How do the size and duration of a bottleneck affect genetic diversity?

Both matter + smaller and longer bottlenecks cause greater loss of genetic diversity + populations that rebound quickly retain more diversity

What is the founder effect?

Genetic drift that occurs when a small number of individuals establish a new population + the new population may have different allele frequencies and lower genetic diversity than the source population

What is inbreeding?

Mating between related individuals + becomes more common in small populations + reduces heterozygosity because relatives are more likely to share the same alleles

What is inbreeding depression and why does it occur?

Reduced fitness of offspring due to inbreeding + occurs because genetic diversity decreases

What is genetic rescue?

Improving population fitness by interbreeding with immigrant individuals + gene flow introduces genetic diversity into a population

What is effective population size (Ne)?

The size of an ideal population that would lose genetic diversity at the same rate as the real population

What is the relationship between Ne and N?

Ne is almost always smaller than N + Ne is typically about 10–20% of N

What are the 5 assumptions of an ideal population?

Discrete generations + random mating + equal sex ratio + random family sizes + constant population size

What three major factors affect Ne?

Sex ratio + mating structure/reproductive success + variation in population size through time

How does sex ratio affect Ne?

A more even sex ratio produces a larger Ne closer to N + an uneven sex ratio lowers Ne

What equation calculates Ne from the numbers of males and females?

Ne = (4NmNf)/(Nm + Nf) + Nm = number of males + Nf = number of females

How does variation in reproductive success affect Ne?

Greater variation in reproductive success lowers Ne because fewer individuals contribute disproportionately to the next generation

How does population size variation through time affect Ne?

Large fluctuations lower Ne + small generations act like bottlenecks and disproportionately reduce genetic diversity

Why is the harmonic mean used when estimating Ne across generations?

It weights small population sizes more heavily + reflects the strong genetic effects of population bottlenecks

What is the harmonic mean formula used for population size?

HM = t / Σ(1/Ni) + t = number of time points + Ni = population size at time i

What is the geometric mean used for in population biology?

Describing proportional population growth + it gives the equivalent constant proportional growth rate

What does the 100/1000 rule state?

Ne > 100 is needed to reduce short-term inbreeding + Ne > 1000 is needed to maintain long-term genetic diversity and evolutionary potential

What was the older 50/500 rule?

Ne = 50 for short-term protection from inbreeding depression + Ne = 500 for long-term protection from genetic drift

How can you estimate N from Ne if no species-specific information is available?

Assume Ne is about 10–20% of N + therefore N is approximately 5–10 times Ne

What is minimum viable population (MVP)?

The minimum number of individuals N having a 95% chance of persisting for 50–100 years

What general conclusion can be made about MVP size?

MVP varies among species + most species likely require at least a few thousand individuals + there is no simple universal MVP

Using the 100/1000 rule

what N is approximately needed for long-term evolutionary potential?

What are three major methods for estimating population size?

Census + relative abundance + mark-recapture

What is a census?

Counting all individuals in a population

What is relative abundance?

Estimating abundance in a sampled area and using it to estimate abundance across the larger area

What is the mark-recapture formula for estimating population size?

N = (m × s)/r + m = originally marked + s = total captured later + r = marked individuals recaptured

What assumptions must be met for mark-recapture estimates to be reliable?

Marks do not affect recapture or survival + marked individuals mix into the population + captured individuals are representative + population is closed + marks are not lost

How can conservation biologists estimate population trends through time?

Historical population records + reconstructing past population size from modern allelic diversity + or both methods

What is population viability?

The inverse of extinction risk/probability + a viable population has a low risk of extinction