Biodiversity and Evolution

Biodiversity and EvolutionUnit 3What is evolution?A change in a populations genetic composition over timeMacroevolution large-scale patterns of evolution within biological organisms over a long period of timeMicroevolution small-scale patterns of evolution within biological organisms over a relatively short period of timeTerms to knowAdaptation = an evolutionary modification that improves the chances of survival and reproductive success in a given environmentExtinction = the elimination of a species from Earth; occurs when the last individual member of a species diesGene pool = the total of all genes (genetic information) in a populationNatural selection = the tendency of organisms to possess favorable adaptations to their environment to survive and become the parents of the next generationTheory of evolution - historyCharles Darwin wrote On the Origin of Species in 1859, sailed on the H.M.S. Beagle to the Galapagos Islands, gathered evidence for evolutionJean-Baptiste Lamarck thought that acquired traits could be inherited, ultimately proven wrongHow does evolution happen?Mutation = change in DNA sequence that affects genetic informationRecombination = combining DNA from different sources, usually through sexual reproductionSpeciation = formation of a new species; occurs when a population changes so much it can no longer successfully breed with the original speciesAdaptive radiation = rapid speciation to fill ecological niches; 3 basic types:General adaptationEnvironmental changeGeographic isolationHow does evolution happen?Genetic drift = random change in allele frequencies that occurs in small populationsConvergent evolution = organisms not closely related to one another independently acquire similar characteristics in different ecosystems, Ex. wings on birds, bats, and insectsEvolutionary relay = Independent species acquire similar characteristics through their evolution in similar ecosystems but not at the same time, Ex. sharks and prehistoric ichthyosaurs both grew dorsal finsHow does evolution happen?Parallel evolution = when two independent species evolve together at the same time and in the same ecosystem and acquire similar characteristics, Ex. placentals and marsupials Gradualism = slow, gradual development of a species over millions of yearsPunctuated equilibrium = new species arose suddenly in a short period of time (thousands of years) after long periods of stabilityTypes of natural selectionStabilizing selectionDirectional selectionDisruptive selection

Processes of natural selectionCompetition there is a struggle to survive, and competition exists for limited resourcesIncrease in phenotypic adaptations variations that are advantageous to the individual in terms of survival allow more organisms possessing the trait(s) to survive, reproduce, and pass on the characteristic(s) to future generationsExponential population increase if all offspring survived, there would be astronomical numbers of individualsProcesses of natural selectionIndividual variations There is variation in offspring. For natural selection, the variations must be gene expressed and be capable of being inherited.Limited resources Earth has finite resourcesPhylogenetic treeTool used to model evolutionCan be very broad or very specificIndicate evolutionary relationships between species branches indicate divergence

Species movementsActive movement = walking, running, swimming, flying, etc.Passive movement = using wind for seed dispersal, floating in sea currentsPlants in particular have evolved several structures for dispersal through air/water currents, animal digestive tracts, adhesion, etc.Migration = seasonal movement of a population to a different areaReasons redistribution, reduce competitionSurvivorship curvesType I = high survival rates for early and middle life, rapid decline in later life (ex. humans)Type II = roughly constant mortality rate at all stages of life (ex. some species of birds)Type III = high death rate for early and middle life, high survival rate in later life (ex. octopus)

Population curvesLinear (straight line)J curve (exponential)S curve (exponential, then levels off)Carrying capacity = how many individuals can be supported by an ecosystem

What is biodiversity?The number and variety of organismsSpecies richness number of speciesGenetic diversity genetic variety within all populations of that speciesEcosystem diversity variety of interactions among organisms in natural communitiesHow has it changed?Background extinction = the ongoing extinction of individual species due to ecological or environmental factors such as climate change, competition, disease, loss of habitat, etc.Mass extinction = the extinction of a large number of species over a short period of time, thought to be due to catastrophic global eventsAdaptive radiation = diversification of a species or single ancestral type into several forms that are each adaptively specialized to a specific environmental niche, Ex. Darwins finchesTypes of extinctionLocal extinction = when a species is no longer found in an area it once inhabited but is still found elsewhere in the worldEcological extinction = when there are so few members of a species left that it can no longer play its ecological roles in the biological community where it is foundBiological extinction = occurs when a species is no longer found anywhere on Earth Permanent Endangered vs. ThreatenedEndangered = has so few individual survivors that the species could soon become extinct over all or most of its natural rangeThreatened = still abundant in its natural range but is declining in numbers and is likely to become endangered. Examples: grizzly bear, southern sea otter, American alligatorMore terms to knowEndemic species found nowhere else on earthRange the area in which a particular species is foundCommercial extinction - depletion of the population of a wild species used as a resource to a level at which it is no longer profitable to harvest the speciesWhere is declining biological diversity the greatest problem? Florida, California, Hawaii - #1Types of SpeciationAllopatric speciation populations of a single species are physically separated long enough to evolve into separate speciesSympatric speciation a population of a single species lives in one area but still becomes different species, usually through horizontal gene transferParapatric speciation two populations of a single species live in areas immediately adjacent to each other with little to no contact and evolve into separate speciesEstimated Extinction RatesAverage annual extinction rate of Mammal and Bird species8000 B.C - A.D. 16001 species per 1000 1600 19001 species every 4 years1900 19751 species every year1975several hundred1985several thousand1990at least 10,000200020,000 50,000When is a species extinct?No one has seen it for at least 50 yearsThe last few monitored individuals dieLonesome George http://www.youtube.com/watch?v=wDYqZncKNNc

Ten Characteristics of Extinction-Prone SpeciesFound in limited areasSmall population sizeLow population densityLarge body sizeSpecialized niches and feeding habits --- Giant Panda (bamboo)Low reproductive ratesTen Characteristics of Extinction-Prone SpeciesFixed migrations Flyway = An established route that ducks, geese, and shorebirds follow during their annual migrations

Ten Characteristics of Extinction-Prone SpeciesFeed at the top of long food chains or websHave high economic value to peopleNeed large territory : The California Condor

Human Activities That Increase Extinction RatesPopulation growth, especially when combined with povertyHabitat destruction such as deforestation, draining swamps, etc.Habitat fragmentation the breakup of large areas of habitat into small, isolated patches, makes it difficult for reproduction to occur between populations in different patchesHuman Activities That Increase Extinction RatesHunting, poachingUsing species as pets/decorationClimate change caused by pollutionIntroduced species invasive speciesBiodiversity hotspotsRelatively small areas of land that contain an exceptional number of endemic species and are at high risk from human activities, ex. tropical rainforest

How important is the rainforest?Covers 7% of the Earths surfaceContains 50% of the Earths species

Tropical Deforestation and DegradationPrimary CausesRapid population growthPovertyExploitive government policiesExports to developed countriesFailure to include ecological services in evaluating forest resourcesSecondary CausesRoads MiningCattle ranchingCash cropsLoggingOil drillingTree plantationsFlooding from damsUnsustainable peasant farming

What happens when tropical rainforests are destroyed?Birds that migrate from North America to the rain forest in Central America and the Caribbean have been declining in numbers faster than other migratory birdsThe forest itself generates much of the rainfall in tropical rain forest. If half of the existing rain forest in the Amazon region of South America were to be destroyed, precipitation in the remaining forest would decrease.

What happens when tropical rainforests are destroyed?As the land became drier, organisms adapted to moister conditions would be replace by organisms able to tolerate the drier conditions. Many endemic species would become extinct.Disruption of the evolutionary process. Tropical Rainforest has supplied the base of ancestral organism from which adaptive radiation occurs.Are we eliminating natures ability to replace its species through adaptive radiation?OverfishingCommercial fishing methodsBycatch - accidental capture of non-target species in fishing gear

BioinformaticsOrganizing and storing useful biological information about wild species using a data baseProvides computer tools to find, visualize, analyze, and communicate biological informationConservation BiologyThe scientific study of how humans impact organism and the development of ways to protect biological diversity

Conservation BiologyWhat are the concepts that guide it?Large habitats are more effective at safeguarding species than several habitat fragmentsLarge areas of habitat typically have the potential to support greater species richness.It is better if areas of habitat for a given species are located close together rather than far apart.Conservation BiologyAreas that are inaccessible to humans are better than human accessible areas.It is more effective and more economical to preserve intact ecosystems in which many species live than to work on preserving individual species one at a time.Higher priority is given to preserving areas that are more biologically diverse than others. (Remember the Hot Spots?)

Three Techniques of Conservation Biology1. Ecosystem ApproachIn situ conservation Protecting habitatsRestoring damaged or destroyed habitatsPreserve balanced populations of species in their native habitatEstablish legally protected wilderness areas and wildlife reservesEliminate or reduce the populations of non-native speciesThree Techniques of Conservation Biology2. Species ApproachIdentify endangered species and give them legal protectionPreserve and manage crucial habitatsEx situ conservationZoos, aquariums, botanical gardens, seed banksReintroducing endangered species to natureThree Techniques of Conservation Biology3. Wildlife Management ApproachManages game species by:Using laws to regulate huntingEstablishing harvest quotasDeveloping population management plansUsing international treaties to protect migrating game species such as waterfowlWildlife RefugesTeddy Roosevelt established Pelican Island off Floridas Atlantic coast as the 1st wildlife refuge to protect the brown pelican (1903)Now have 508 refuges, 85% are in Alaska are wetlands for protection of migratory waterfowlLaws, Acts, and OrganizationsCITESLacey ActEndangered Species ActWild Bird Conservation ActMagnuson Fisheries Management and Conservation ActCITES (1973)Convention on International Trade in Endangered SpeciesAn international agreement between governmentsIts aim is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.Lacey Act (1900)The Act prohibits trade in wildlife, fish, and plants that have been illegally taken, possessed, transported or sold. Thus, the Act underscores other federal, state, and foreign laws protecting wildlife by making it a separate offense to take, possess, transport, or sell wildlife that has been taken in violation of those laws.Endangered Species Act (1973)Endangered or threatened species cannot be hunted, killed, collected or injured in the United States.

Endangered Species Act (1973)There are over 1100 species on the list 60% are plants and 40 % are animals. Hawaii leads this list (298+). Each year about 85 species are added to the listRequires all commercial shipments of wildlife and wildlife products enter or leave the country through one of nine designated ports.Endangered Species Act (1973)National Marine Fisheries Services (NMFS) identifies and list endangered and threatened ocean species.U.S. Fish and Wildlife Service (USFWS) identifies and list all other endangered and threatened species.Adding or removing a species from the list must be based on biology, not economic or political reasonsEndangered Species Act (1973)Forbids federal agencies to carry out, fund, or authorize projects that would either jeopardize, destroy or modify the critical habitat.Fines and jail sentences can be imposed on private lands to ensure protection of the habitats of endangered speciesWild Bird Conservation ActImposed a moratorium on importing rare bird species

Magnuson Fisheries Management and Conservation ActGives the federal government authority to manage fisheries in the zone between 3 and 200 miles off the U.S. shore. There is no limit on the number of U.S. fishing vessels, but quotas can be imposed on the quantity of fish taken.Other SolutionsBiosphere reserves - areas of terrestrial and coastal ecosystems promoting solutions to reconcile the conservation of biodiversity with its sustainable use

Reintroduction of endangered speciesRestoration Ecology

What else can we do?Increase Public AwarenessSupport Research in Conservation BiologySupport Establishment of an International Park SystemControl Pollution

What else can we do?Give Economic IncentivesFees for Medicinal DrugsEcotourismDebt for Nature SwapPayments to landowners for protecting endangered species or reduce their property tax