Conservation Biology Exam 1

drivers of ecosystem deterioration

change in use of land and sea resources, direct exploitation and harvesting of wild populations, climate change, pollution, invasive/alien species

indirect drivers of ecosystem deterioration

demographic and cultural, economic and technological, institutions and governance, conflicts and epidemics (values behaviors)

1st root cause of biodiversity crisis

human population size

• grown by more than 20 billion people in the past 20 years

• us below replacement rate for population maintenance (comes from immigration)

2nd root cause of biodiversity crisis

per capita resource consumption 

• india has highest pop. but low per capita energy use 

• india and Russia use same amt of energy, but Russia has less people

• russia has higher per capita energy use

• largely dictated by society wide indirect drivers

• overexploitation and over hunting of other species at higher rates than they can maintain  

1st documented human caused extinction

dodo bird - hunted by dutch sailors and invasive rats/pigs

size differential defaunation

threat of extinction higher for animals with larger body size 

• loss of large animals has consequences for ecosystems 

• impacts ecological interactions, ecosystem services, disease prevalence, population size

Interdisciplinary but science based

conservation biology is both, includes basic sciences and resource management but also normative discipline (specific values)

conservation biology values

• biological diversity has intrinsic value

• untimely extinction of populations and species should be prevented 

• diversity of species and the complexity of ecological communities should be preserved 

• science plays a critical role in our understanding of ecosystems 

• collaboration among scientists, managers, policymakers, and the public is important and often necessary 

conservation biology goals

• document full range of biological diversity on earth 

• investigate the human impact on species, genetic variation, and ecosystems

• develop practical approaches to prevent the extinction of species, maintain genetic diversity within species, and protect and restore biological communities and their associated ecosystem functions 

what is biological diversity?

• genetic diversity: genetic variation within species (within individuals, and among/within geographically separated populations) 

• species diversity: all species on Earth from the entire phylogenetic tree of life

• ecosystem diversity: all ecosystems (ecological communities and associated abiotic environments) on Earth, including land/oceans/freshwaters

biodiversity

variability among living organisms from all sources including terrestrial, marine, and other aquatic ecosystems and ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems 

morphological species

group of individuals that is distinct in outward appearance according to taxonomists

biological species

group of individuals that can potentially interbreed in the wild and do not breed with individuals of other groups 

• requires thorough study of breeding patterns 

• doesn’t apply to all organisms (e.g. microbes) 

• some plants can breed with other species, hybridize - this definition doesn’t work that well here 

evolutionary species (lineage species concept) 

groups of individuals that share unique similarities in their DNA (and evolutionary history)

• made easier with molecular analysis tools, can compare DNA with modern tech

• useful in identifying cryptic species - species that taxonomists would classify as a single species, but different species when looking at their DNA

Taxonomy

naming and classification of species

three domains of life

• bacteria (pryokarya) 

• archaea 

• eucarya: all organisms with a membrane-bound nucleus in their cells (animals, plants, fungi, protists) 

Eucarya (bottom to top level)

species - genus - family - order - class - phylum - kingdom

methods of measuring species diversity in the wild

• transect method used for sedentary species (eg trees) 

• trapping methods used for small, mobile organisms (eg insects, other invertebrates) 

• aerial surveys (used for large wildlife) 

• electroshocking (like Barry Chernoff used to sample fish in streams) 

Alpha diversity

species richness of organisms in a local community, the number of species found in a local community, such as a lake or meadow

gamma diversity

number of species at a larger geographic scale (region!) that includes multiple local community types (eg mountain range containing forest, meadow, and lake communities) 

beta diversity

the rate of change of species composition (turnover) as one moves across a region, more turnover = greater beta diversity (also habitat diversity) 

beta diversity = gamma diversity/mean alpha diversity 

Endemism

• a species occurs in one geographic areas and nowhere else

• is associated with insular environments, such as oceanic islands

Species diversity index

accounts for the abundance of each species, rather than merely their presence or absence

Shannon diversity index (H)

negative sum of the proportional abundance of each species (i) in the local community (p) multiplied by the natural log of

ecosystem

an ecological community of species that interact (eg food web) in the context of abiotic conditions

• can be great ecosystem diversity even within the same geographic area 

• beta diversity also describes ecosystem diversity 

• important to consider human role in ecosystems & diversity - current conservation biology views people as part of the ecosystem diversity to be conserved 

• humans become a part of ecosystem feedback systems (eg duck/rice/pond example) 

keystone species

high impact, low proportional biomass

dominant (foundation) species

high impact due to high proportional biomass

rare species

low impact and low proportional biomass (often have high extinction risk)

common species

low impact despite high proportional biomass

ecosystem engineers

species that modify the physical environment with large ecological impact - a special case of keystone species (eg beavers, humans) 

ecosystem stability 

properties of the ecosystem (eg species diversity and composition, productivity, carbon sequestration) change little over time, fairly constant 

ecosystem resistance

ability to remain the same state even with ongoing disturbance (eg river ecosystem that retains major ecosystem properties after fertilizer runoff enters it)

ecosystem resilience

ability to return to an original state quickly after disturbance (eg fertilizer runoff changes the abundance and diversity of plants and animals in river ecosystem, but the pre-fertilizer ecosystem properties recover quickly)

economics

study of the transfer of the production, distribution, and consumption of goods and services. Offers a monetary value system that’s clear and meaningful to everyone 

externalities

not all costs are absorbed during the transaction (eg environmental costs like pollution are typically externalities in conventional economics; the costs are borne by biodiversity, ecosystems, the people outside of the transaction  

tragedy of the commons

unregulated exploitation of a resource leads to overexploitation, resulting in the resource being lost to all of society 

• sometimes market value of a species does not favor its conservation (eg trophy hunting - the rarer the trophy to kill, the more people are willing to pay for it) 

environmental economics 

values components of the environment in analyzing effects of environmental phenomena (eg global warming) on conventional economic systems (eg insurance costs, agricultural production, etc)

• extends traditional economic thinking to aspects of the environment

• however it struggles in that it still is not really accounting for the non-monetary value of other parts of the environment, which is where ecological economics comes into play

ecological economics

much more academic than practiced in economic system

• integrates ecology and economics with the goal of sustainability for humans and biodiversity/ecosystems 

• revolutionary in introducing new valuation systems to public policy 

instrumental

the value that is a means to an end, has some utility

use-value vs non-use value

benefits are gained by those assigning value (use) or not (non-use)

• something you’re getting a practical benefit from

• a value that is recognized for what it is giving you

direct use 

benefits are gained via consumption or production (marketable commodities, such as food, medicine, fiber, lumber)

indirect use

benefits gained not by harvesting or destroying the resource (ie recreation, education, research, scenic amenities, ecosystem services) 

option value

prospect of future uses to new people (new medicines, future food, future genetic resources)

non-use existence value

how much people are willing to pay to protect a species just so they can know it exists

intrinsic value

assigning value as an end in itself

• humans don’t have to be around to assign value, they have inherit value for themselves

ecotourism

ideally, economic benefits of tourism increase conservation value within conventional economies (local and global)

• people will want to protect tigers in their community because they attract tourists and bring in money

ecosystem services: provisioning

material or energy outputs of an ecosystem (food, medicine, raw materials - direct use value provided by an ecosystem) 

ecosystem services: regulating

maintenance of a habitable environment by an ecosystem (air, water purification, nutrient cycling, climate regulation, pollination, pest control - indirect use value provided by an ecosystem) 

ecosystem services: cultural

how an ecosystem provides intellectual, spiritual, aesthetic value (art, design, science, religion - indirect and non-use value provided by an ecosystem) 

pollinator biodiversity

bees and other native pollinators are responsible for fruit and seed production, a service that would be practically impossible to replicate 

• positive relationship between wild bee visitation rates and fruiting rates for flowers

• example of a regulating ecosystem service, and an indirect use value

• also a direct use value as a provisioning ecosystem service when crops are involved 

wetland ecosystem services

sequestration of atmospheric carbon, food productivity, barrier to floodwater, plants take up toxins and excess nutrients 

burden of proof

placed on conservationists (have to prove that this shouldn’t be done for reasons x, y, z) while intrinsic value system places burden of proof on developer (have to prove how much it is worth in economic benefits to destroy an ecosystem, endanger its species, etc) 

US National Environmental Policy Act (NEPA)

requires environmental assessments or environmental impact for federal actions regarding the environment, requires reconciling instrumental and intrinsic values 

US endangered species act 

rare in public policy bc it assumes intrinsic value of species 

environmental impact assessments

estimating environmental consequences of a development project

• risks are determined by federal, state, and local laws that grant protection to species/environmental factors (clean water, anti-pollution, etc) 

cost-benefit analysis

economic benefits of projects are usually weighed against estimated environmental costs in approval of development projects at local and regional levels of government

precautionary principle

choosing not to go forward with a development project when experts estimate there are significant risks to the environment (better safe than sorry)

• erring on the side of caution 

• more in the EU than the US

relational value system

more meaningful to individuals than either instrumental or intrinsic value systems

• better captures value of cultural ecosystem services 

• easier for individuals to relate to 

intrinsic vs instrumental vs relational

• intrinsic: moral, ethical, religious 

• instrumental: direct use, indirect use, option value, non-use

• relational: personal and cultural identity, social responsibility, historical and education, biophilia, aesthetic 

  • has more to do with the human experience/the existence of humans and our social systems than intrinsic value 

anthropocentrism

moral consideration applies to human beings only

biocentrism

moral consideration applies to human and non-human beings (eg animals)

ecocentrism

moral consideration applies to biodiversity, ecosystems, and everything that inhabits them

globally extinct

no member of the species is found alive anywhere (ie dodo bird)

extinct in the wild 

live individuals of species are only in captivity or human-controlled situations (ie California condor during late 1980s)

locally extinct

extinction of one or more local populations, but other populations exist elsewhere

functionally extinct

populations reduced to such low abundance that their role in ecosystems is negligible (ie Chinese river dolphin) 

island habitat (risk factor for global extinction) 

many endemic species, few populations, small population size, evolved in ecosystems with limited threats from predators, pathogens, and competitors 

hunting or harvesting by people (risk factor for global extinction) 

human efficiency and population density places intense harvesting pressure on populations 

large body size (risk factors for global extinction)

body size trades off with population size and reproductive rate, such that reduced populations of large bodied species cannot easily recover

Boyer paper

• extinctions were not random with respect to body size

• Regression trees show major predictors of extinction risk (e.g. we can see on the phylogenies that most ground nesting species went extinct)

• pre-historic extinction bias towards ground-nesting and large-bodied bird species + wave of extinction coinciding with Polynesian colonization is evidence of extinction due to hunting, invasive rats and pigs, and possibly habitat loss

7 forms of rarity (function of population size, geographic range, and habitat specificity)

only common/not rare species has a large geographic range, large population size in some place, and a broad habitat specificity

additional risk factors for extinction

• large home range: habitat loss especially detrimental (ie jaguar)

• slow reproduction: population cannot easily recover 

• limited dispersal ability: climate change and habitat loss  

• seasonal migration: habitat loss in multiple places

• low tolerance for disturbance: most typical 

• permanent or temp aggregations: threats can affect a large fraction of the population 

• no prior contact with people: less tolerance for human disruption 

• close relatives that are recently extinct of threatened with extinction 

environmental stochasticity (special problems of small populations)

change in average birth or death rates from year to year because of random changes in environmental conditions that affect population size as a whole (in theory all individuals in a population have an equal probability of being affected by environmental stochasticity) 

• Example: a severe winter in 2009-2010 brought wild horse population dangerously close to extinction

demographic stochasticity (special problems of small populations)

variation in individual reproduction and mortality rates due to chance events that alter demographic composition of the population (eg sex ratio of males to females - reproductive rates might be limited to low number of females) 

• Example: Spanish imperial eagle population sex ratio biased when population was small. In this species, mature individuals breed in large populations, resulting in more equal sex ratio. But in small populations, mature individuals leave, immatures breed and this produces mostly male offspring.

genetic stochasticity (special problems of small populations)

chance events influence which alleles are passed on to the next generation (genetic drift)

• in small populations the chance of losing alleles due to drift is much higher than the chance of gaining alleles due to mutation or gene flow 

• genetic drift: the random change in allele frequencies from one generation to the next due to chance 

• Example: in fruit flies, larger populations kept greater genetic (nucleotide) diversity than smaller populations

effective population size (N2)

number of breeding individuals in the population

Allee effect

population growth that is positively density-dependent because survival or reproduction depend on living in a group 

Example: Antarctic fur seals had higher pup survival rates when populations were larger, despite increased competition for food.

extinction vortex concept

reduction in population size can dramatically increase local extinction risk

ecological footprint

number of global hectares needed to support an average citizen

• varies among nations 

• positively correlated with Human Development Index, a commonly used measure of standard of living

• global distribution of CO2 emissions varies widely by country

Cardinale reading: biodiversity loss and its impact on humanity

grassland prairies, experimental grassland plots at cedar creek, MN - lots of experiments done on impacts of/on biodiversity since the 1990s, article reviews the research

• Biodiversity loss reduces the efficiency of ecosystem function in a nonlinear way

• From textbook example: more diverse plots (with more species richness) grew more than less diverse plots (total number of plants is constant across plots)

ecosystem function

resource capture, biomass production, decomposition, nutrient recycling 

biological diversity

variation in genes, species, functional traits

identity effects

ecosystem response is driven by a few functionally dominant species

• curve decelerates quicker between original species richness and plant biomass, ecosystem function is “maxed out” sooner

diversity effects

complementarity among species with different functional traits (eg resource partitioning, positive interactions) drives ecosystem response 

• steeper curve between species richness and plant cover (more diversity of species continues to drive increases in plant cover for longer, until ecological redundancy is reached - ecosystem “maxes out” after a greater number of species in the ecosystem)

portfolio effect

diversity increases ecosystem stability

• greater ecosystem stability (reduced variation in function) with increased species richness 

contributing factors to emergence of infectious disease

land use changes, agricultural intensification, food industry changes, bushmeat trade

biodiversity effect on incidence of disease

biodiversity increasing incidence of disease:

• higher diversity of species could host higher diversity of diseases 

• more possible sources of disease and places for transmission to occur 

• animal diversity is greater in the tropics - lots of diseases come from the tropics (larger scale phenomenon) 

biodiversity decreasing incidence of disease:

• at smaller scales: dilution effect 

complementarity among plant species

might partly indicate complementarity among soil pathogens, which control plant biomass in a species-specific and density-dependent manner

identity effects

host identity determines “host competence” or “dilution potential"

• some species make better hosts of disease than others, and the aggregate effect of host competence traits among species (community competence) determines disease transmission or dynamics (epidemiology) 

host dilution potential 

identity effects drive the relationship between host diversity and disease prevalence