Extinction of Species Final

Why is maintaining genetic diversity important?

Maintain adaptability:

Some alleles that are not important now may become important as the environment changes.

2 ways to define genetic diversity within a population

number of alleles for a gene OR heterozygosity

Heterozygosity

proportion of individuals that are heterozygotes

Only source of new genetic variation (alleles) in populations

Mutations in sex cells

4 Processes that Determine Levels of Genetic Diversity in a Population

Genetic drift

Mutation

Gene flow

Natural selection

Effective Population Size

The number of breeders contributing genes to subsequent generations

Why is effective population size lower than actual population size?

– Population fluctuations

– Unequal sex ratios

– Unequal reproductive success

Inbreeding depression

Loss of fitness as a result of increased homozygosity from inbreeding

3 Conservation Strategies for Inbred or Low-diversity Populations

• Minimize size and duration of bottlenecks

• Maintain/promote “gene flow” among populations

• Intentionally mate individuals from genetically distinct populations (Genetic Rescue/Translocations)

50/500 rule

50 individuals are needed to avoid short-term genetic diversity loss (inbreeding)

500 individuals are needed to avoid long-term genetic diversity loss (actual number may be as high as 5000)

2 ways to maintain gene flow

Protect landscape connectivity

Build habitat corridors

Outbreeding depression

Loss of fitness due to crossing between two genetically distinct populations

Hybridization

mating between different species or two genetically distinct populations that produces ‘hybrid” offspring, regardless of fertility of offspring

Introgression

Genetic transfer between species due to hybrid individuals back-crossing with one of their parent species.

2 ways hybrid zones are maintained in nature

Hybrids are less fit than parents - but populations keep being established via dispersion

OR

Hybrids are more fit than parents when living in “transitional” environment between the habitat of the two parents.

Simple genetic approach to detect hybridization

Examine a locus where two species are have completely different alleles.

Why is hybridization a getting worse with humans?

Human-caused habitat and climate change have resulted in distributional changes and expansions for many species

Genetic extinction:

Fertile hybrids replace one or both parental species through the formation of hybrid swarms

Hybrid swarms

Populations or species where every individual is a hybrid to some degree.

Hybrid vigor:

Opposite of outbreeding depression. When hybrids have higher fitness than either parent.

General strategy for dealing with hybrids

remove hybrids when the cause is humans, but leave alone when hybridization is natural.

Why Conserve Distinct Groups of Individuals (“Conservation Units”) (2 reasons)

1. Groups may have distinct morphological or genetic differences

2. Groups may have unique social or economic value

5 different conservation units

Species

Subspecies

Distinct population segments

Evolutionary significant units

management groups

What conservation units can and cannot be listed under the ESA

Can: Species, Subspecies, Distinct population segments

Cannot: Evolutionary significant units, Management groups

Cryptic species

Morphologically similar but genetically unique species. ex. elephants

2 criteria for discerning a “distinct population segment”

Discreteness: How different is the population (group) from to the rest of the species?

Significance: How important is the population (group) segment to the species to which it belongs?

What is a “management unit”

Populations that are isolated and will not be naturally re-established if they go extinct.

Tend to be genetically unique due to low gene flow

Is there a formal definition for “subspecies”

No - generally just refers to a population “on its way” to specieshood.

Many unique morphological and genetic differences

California gnatcatcher genetic studies

Looked for genetic differences between coastal and other subspecies

First - found no differences in 9 “neutral” loci

Reanalysis - showed that there are 2 or 3 differences actually

Why should the coastal gnatcatcher be a separate subspecies?

Genetic differences (2 or 3 found in 9 neutral loci)

Breast coloration differences

Occupies a different ecological setting than other subspecies

3 reasons turtles are overkilled

Consumption of adult and eggs

Pet trade

Road fatality

Turtle TSD

Temperature-dependent sex determination

Warmer = more females

Blanding turtle distribution

Some states have 100s, others have 100,000s'

Considered “threatened” or “endangered” in a state-by-state basis

Why was the de-listing of the blanding turtle in wisconsin proposed?

High number of observed occurrences

Despite a high number of occurences, why are blanding turtles threatened?

Occurances may be from male-biased or all-male populations

Ultimately, observed populations are not viable long-term

What changed after the blanding turtle was de-listed?

Harvesting was already outlawed, but no obligation to minimize take (ex. incidental)

No more population monitoring

Loss of information on declining populations

2 impacts of roads on blanding turtle population viability

More male-skewed sex ratios: females crossed roads more and got hit

Loss of heterozygosity: loss of genetic diversity due to decreased effective population size.

Bottom-up trophic effects

Loss of a bottom trophic species causes coextinctions as animals that rely on that food go extinct as well.

Top-down trophic effects

Loss of a top trophic species causes a trophic cascade which changes the populations of lower trophic levels.

Competitive release

Loss of a species causes an increase in all the species it competed with for food.

Rise of mesopredators

Effect of species loss on invasibility

Less biotic resistance - ecosystem is more vulnerable to invasive species

Effects of species loss on infectious disease

Population of a disease reservoir or vector may increase

Greater disease presence and transmission.

Effects of species loss on mutualisms

Loss of mutualistic relationships may jeopardize other species

Ecosystem functioning

What an ecosystem does:

Carbon storage

Nutrient cycling

Biomass production

Ecological state:

What an ecosystem is:

Dominant vegetation

Disturbance regimes

Trophic regulation

Ecosystem services

What an ecosystem provides us:
Regulating (air quality, flood control)

Provisioning (food, fiber, energy)

Cultural (recreational, spiritual)

Who are the carnivores?

Mammals of the order Carnivora

Meat eaters or omnivores

Why are carnivores susceptible to the “evil septet”? (5)

Body size

Trophic position - Rarity, Prey biomass

Large home territory

Low reproductive rates

Social behaviors

5 ecosystem services provided by carnivores

• Increase primary productivity

• Enhance biodiversity

• Pest control

• Buffer against climate change

• Regulate diseases

Economic value of carnivores (2) and cost (1)

Tourism

Regulation of damaging species

BUT - livestock depredation is a cost

4 conservation strategies for large carnivores

Reducing conflict non-lethally

Education and tolerance

Habitat connectivity

Hunting for conservation?

3 major ways to provide habitat for wild species

Protection (usually best)

Management

Restoration

Two Main Roles of Protected Areas

1. Represent region’s biodiversity

2. Separate this biodiversity from processes that threaten its persistence.

• Maintain services and biodiversity

Strict Nature Reserve

Category 1a

Protected area managed for biodiversity protection and scientific study

Wilderness Area

Category 1b

Protected area managed mainly for wilderness protection

National Park

Category II

Protected area managed mainly for ecosystem protection and recreation

Natural Monument

Category III

Protected area managed mainly for conservation of specific natural features

Habitat/Species Management Area

Category 4

Protected area managed mainly for conservation through management intervention

Protected Landscape/Seascape

Protected area managed mainly for landscape/seascape conservation and recreation

Managed Resource Protected Area

Protected area managed mainly for the sustainable use of natural ecosystems

How to select protected areas

SELECT areas to achieve full representation of biological diversity within a system of protected areas

Biodiversity “Hot Spots” - high species diversity, endemism, and levels of threat

Importance of spatially designing protected areas

SPATIALLY DESIGN areas to ensure long-term viability of the biodiversity occurring in the selected areas

Role of small wildlife reserves

Might hold important or endemic species

Accommodate important stages in species life history

Can exist in developed landscapes

Importance of corridors/stepping stones

• Daily movements

• Annual migration

• Permanent immigration and emigration

• Range shifts in response to climate change

• Increases range of large species

Disadvantages of habitat corrodors

• Facilitates spread of disease, fire, exotic species, etc.

• Are they used?

• Cost

• Ecological traps

“paper parks”

Parks that only exist on paper

Not properly protected

Illegally hunted, logged, exploited

How can success of nature parks cause a problem

economic benefits of protected areas can act as a magnet for people

puts more pressure on resources

3 Advantages of Single-species Management

• Addresses causes declines for threatened species

• Strong history and methodological basis

• Conserving species can benefit ecosystems

2 Disadvantages of Single-species Management

• Bias due to the ‘‘cute and cuddly syndrome’’

• May not address ecosystem-level problems – and even exacerbate them

2 advantages of ecosystem management

• Addresses ecosystem-level problems important for human well-being

• Can benefit multiple, rather than a single species

2 disadvantages of ecosystem management

• Ecosystems are big and complicated

• May negatively impact rare or specialized species

How does fire increase biodiversity?

creates a “mosaic” of habitat types

Example of species vs ecosystem conservation from lecture

Fuels (ecosystem) management simplifies owl habitat - could exacerbate declines

Fuels treatment vs severe fire impact on spotted owls

Severe fires are bad for owls

Severe fuels treatment is bad for owls

BUT - the benefits of reducing fires outweigh the harms of some fuels treatment

flagship species

Charismatic species that foster public interest in conservation of ecosystems

umbrella species

benefit many species as well as ecosystem function/services

Role of International Institutions in conservation (4)

Address global conservation issues that transcend national borders

Exert international pressure on recalcitrant nations

Facilitate sharing of costs and benefits of conservation

Allow for exchange of information and technology

3 approaches to international conservation

International conservation organizations

International treaties and conventions

International biodiversity databases

4 limitations to international conservation

Limited engagement by some nations

Conflicting agendas and priorities

Large inequities between nations

Enormous costs

Role of governments in conservation (5)

Economic policies

Enact legislation

Undertake large-scale activities

Support conservation research and education

Manage publicly-owned resources

4 problems with protected areas in the Global South

• Conservation too often highly coercive, rooted in colonialism (esp. in Africa)

• Prohibitions on resource use sometimes cause impoverishment & suffering

• Little sense of ownership by local people

• Local govt has limited capacity to control resource use in PAs

5 examples of community-based conservation

Community engagement in ecotourism

Community-based agroforestry around protected areas with Certified products

Sustainable harvest of forest products, game or fish within protected area

Community-managed low-impact logging

Indigenous reserves (combining development and conservation across large scale) – South America

Vulnerability factors of farmers on edge of protected area in east africa (high population)

• Risky place to farm - elephant and wildlife damage

• Limited capacity to cope - little savings

• Immigrant population - low connection to local communities

Community-based strategies at Kibale, Uganda (East Africa. many people, few elephants)

Improve local support for park

1. Allow communities to extract non-timber forest use in the Park

2. Tourism revenue sharing

Reduce conflict

1. Barriers and trenches

2. Legalize hunting of ‘vermin’: bushpigs & baboons

Community-based strategies in Zimbabwe (few people, many elephants)

Make wildlife an asset, not a liability.

Auction off animals living on communal lands to safari hunters

What is a conservation NGO?

Private, non-profit guided by a clear conservation-related mission

Do a lot of NGOS focus on endangered species?

No - only very few

What is a big way that new conservation NGOs form?

Division of large groups into smaller

Divisions within organization spawned a new organization with a related but distinct mission

5 things NGOs can do

1. Provide services to members

2. Represent members’ views

3. Provide oversight of public institutions (watchdogs)

4. Take direct conservation action

5. Flexibility to undertake activities governments can’t (or won’t)

The Three Components of Sustainable Development

Environmental

Social

Economic

Unsustainable vs Sustainable Agricultural Practices

Unsustainable:

• Heavy use of pesticides and fertilizers

• Monocultures

Sustainable:

• Organic farming

• Nitrogen fixers

• Shade-grown crops

Unsustainable vs Sustainable Livestock Production

Concentrated animal feeding operation (CAFOs) VS Natural rangeland

Grazing in riparian habitats VS Grazing excluded from riparian habitat

Unsustainable vs Sustainable Fisheries

Long-lining (high bycatch) vs pole-fishing (low bycatch)

Unsustainable vs Sustainable Timber Extraction

Large-scale even-aged management VS Uneven-aged management

IMPACT model of human impact on climate

Impact = Population x Consumption/Person x Damage/consumption

IMpact = Population x Affluence x Technology

Is sustainability expensive?

Yes, but the cost of dealing with environmental impacts if we continue to do nothing will be much higher