Todayfinish biodiversity (Chapter 23)start conservation biology (Chapter 25)Wednesdayconservation biologyFridayquiz!conservation biologyMondayhistorical biogeography (Chapter 24)Wednesdayecosystem management (outside reading)

Conservation Biology - a mission-oriented science that focuses on protecting and restoring biodiversity

BiodiversityAll forms of lifeAll levels of organization (subpopulation to biosphere)All interactions among forms of life and the environment

Where is the biodiversity?

Endemic species restricted to a small regionisolated areas (islands, mountain ranges)product of unique habitat, climate features

Biodiversity hotspots - areas with a high concentration of endemic species, experiencing rapid habitat loss

Hotspots:1.4% of the land area44% of vascular plant species35% of terrestrial vertebrate species

But20% of the human population, which isgrowing at 1.8% per year (vs. 1.3% worldwide)each hotspot has already lost 70% of its vegetation

Current Status of Biodiversity1.4 million described species, possibly 10 million in total

Background extinction rate rate of species loss in the absence of human activitiesfossil record: species survive 1-10 million yearsone year: one species has a 1 in 1-10 million chance of going extincttotal: 1 extinction per year

Mass extinction loss of large number of speciesusually due to catastrophic volcano or meteor impactvery rare (5 times in 3 billion years)

Current rate of extinction???

Some estimates for current rate:1 species per hour1 million species total, so far10% of all species so far8.8% of all species27,000 species per year20% of neotropical plant species100 to 10,000 times the background rate

Numbers of threatened/endagered species:5,188 vertebrates (9%)1,992 invertebrates (0.17%)8,321 plants (2.89%)2 lichens (0.02%)

Since 1600, ~1000 species have gone extinct (probably many more)

Why do species go extinct?

2 separate processes:Something causes a large population to decline.

Small populations go extinct.

Causes of species declinesHabitat destruction and fragmentationIntroduced speciesExploitation and overharvestingPollutionClimate change

USA

Habitat destruction and fragmentation

Fragmentation disruption of extensive habitats into small, isolated patches

Relaxation loss of species from isolated habitats over timeAreaS

Edge effects negative impacts adjacent to habitat boundaries

Forest edges:more sunlightdryinghigh windstree mortalityinvasive speciesmore predators

Core areaEdge area Core area part of a patch not impacted by edge effects

Patch size is not always the best predictor of patch quality

Introduced speciesHumans are constantly moving species between continents, islandsdeliberate or accidental

Most serious impacts on islandslow species diversityfew native predatorsanimals lack anti-predator defenses, resistance to diseases

Characteristics of invasive speciespioneer specieshigh dispersal ratesfound in disturbed habitats, butsome can invade undisturbed communities

Why are invasives successful?no diseases, herbivores, parasites, predatorsbetter competitors than native species

Introduced diseases exploit lack of evolved resistanceDutch elm disease American elmChestnut blight American chestnutavian malaria Hawaiian birdsRinderpest African ungulateschytrid fungus amphibians

Net result of invasive specieshomogenize ecological communities around the worlddrive native, endemic species extinct

Exploitation and overharvestDirect exploitation for foodoverfishingbycatch in fisheries killing non-target species (birds, marine mammals)bush meat harvest of wild animals for foodcan be sustainable, but often notthreatens many large mammals, primates

Global trade in wildlifebirds, orchids, cactus, primates captured for gardens, pets, zoos, etc.

Many species driven extinct before hunting/harvest regulations were in placepassenger pigeon, island tortoises, marine mammals

ExamDefinitions, compare-contrast 5 points each (20 points per page)5 questions 12 points per questionbonuses 3 points eachdropped the question with the lowest score

Average grade = 86

Causes of species declinesHabitat destruction and fragmentationIntroduced speciesExploitation and overharvestingPollutionClimate change

PollutionMost important for aquatic systemschemical pollutantsacid precipitationBioaccumulation process by which toxin concentrations increase in living tissuesconcentrations increase through the food chain

Climate change

Why do small populations go extinct?

Demographic stochasticity chance events that occur at small populations sizefailure to breed or survivefailure to find a mateskewed sex ratio

Dusky Seaside Sparrow

Environmental effects unpredictable events that reduce survival or reproductiondroughts, floods, fires, storms

Genetic effects at small population sizeinbreedinggenetic driftrandom mutations

Extinction vortex combination of genetic, environmental and demographic factors that drive a small population to extinction

Heath hen1700 throughout the northeast coast1907 50 left on Marthas Vineyard1915 2000 birds1916 fire1917 goshawk invasion1920s poultry disease1927 13 birds, mostly malesMarch 11, 1932 last known sighting

Minimum viable population smallest population has a specified probability of surviving for a certain timeusually 95% chance of surviving for 100 yearsHow big?at least 50 individuals to avoid demographic stochasticityat least 500 individuals to avoid genetic effectsrealistically > 1000 but varies by species

Reasons for protecting biodiversity

Intrinsic valuable for its own sake

Instrumental beneficial to humans

Instrumental Reasons for Protecting BiodiversityEconomic benefitsfooddrugscultivated cropsecotourism

Ecosystem services quantifiable services that an ecosystem provides to humans often very valuable economically

Examples:moderating climatesmitigating floods and droughtseliminating waste and toxinspest controlpollination

PollinatorsInsects pollinate 2/3 of crop species~25% of foods consumedU.S.: $20 to 40 billion in agriculture

Evidence that many pollinators are decliningbatshoneybees hummingbirds

Maintenance of ecosystem functionHow many species can you safely remove?How do you ensure maximum productivity in managed or natural ecosystems?

More diverse ecosystems are more stable

Diversity-productivity relationshipHow are plant species richness and primary productivity related?

3 possibilities:

Why would productivity increase with richness?Greater odds of encountering a super-productive speciesComplementarity use of different resources by different species