Unit 3

What is evolution? A change in a population’s genetic composition over time Macroevolution – large-scale patterns of evolution within biological organisms over a long period of time Microevolution – small-scale patterns of evolution within biological organisms over a relatively short period of time

Terms to know Adaptation = an evolutionary modification that improves the chances of survival and reproductive success in a given environment Extinction = the elimination of a species from Earth; occurs when the last individual member of a species dies Gene pool = the total of all genes (genetic information) in a population Natural selection = the tendency of organisms to possess favorable adaptations to their environment to survive and become the parents of the next generation

Theory of evolution - history Charles Darwin – wrote On the Origin of Species in 1859, sailed on the H.M.S. Beagle to the Galapagos Islands, gathered evidence for evolution Jean-Baptiste Lamarck – thought that acquired traits could be inherited, ultimately proven wrong

How does evolution happen? Mutation = change in DNA sequence that affects genetic information Recombination = combining DNA from different sources, usually through sexual reproduction Speciation = formation of a new species; occurs when a population changes so much it can no longer successfully breed with the original species Adaptive radiation = rapid speciation to fill ecological niches; 3 basic types: General adaptation Environmental change Geographic isolation

How does evolution happen? Genetic drift = random change in allele frequencies that occurs in small populations Convergent evolution = organisms not closely related to one another independently acquire similar characteristics in different ecosystems, Ex. wings on birds, bats, and insects Evolutionary 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 fins

How 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 years Punctuated equilibrium = new species arose suddenly in a short period of time (thousands of years) after long periods of stability

Types of natural selection Stabilizing selection Directional selection Disruptive selection

Processes of natural selection Competition – there is a struggle to survive, and competition exists for limited resources Increase 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 generations Exponential population increase – if all offspring survived, there would be astronomical numbers of individuals

Processes of natural selection Individual 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 resources

Phylogenetic tree Tool used to model evolution Can be very broad or very specific Indicate evolutionary relationships between species  branches indicate divergence

Species movements Active movement = walking, running, swimming, flying, etc. Passive movement = using wind for seed dispersal, floating in sea currents Plants 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 area Reasons – redistribution, reduce competition

Survivorship curves Type 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 curves Linear (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 organisms Species richness – number of species Genetic diversity – genetic variety within all populations of that species Ecosystem diversity – variety of interactions among organisms in natural communities

How 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 events Adaptive radiation = diversification of a species or single ancestral type into several forms that are each adaptively specialized to a specific environmental niche, Ex. Darwin’s finches

Types of extinction Local extinction = when a species is no longer found in an area it once inhabited but is still found elsewhere in the world Ecological 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 found Biological extinction = occurs when a species is no longer found anywhere on Earth  Permanent

Endangered vs. Threatened Endangered = has so few individual survivors that the species could soon become extinct over all or most of its natural range Threatened = still abundant in its natural range but is declining in numbers and is likely to become endangered. Examples: grizzly bear, southern sea otter, American alligator

More terms to know Endemic species – found nowhere else on earth Range – the area in which a particular species is found Commercial 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 species Where is declining biological diversity the greatest problem? Florida, California, Hawaii - #1

Types of Speciation Allopatric speciation – populations of a single species are physically separated long enough to evolve into separate species Sympatric speciation – a population of a single species lives in one area but still becomes different species, usually through horizontal gene transfer Parapatric speciation – two populations of a single species live in areas immediately adjacent to each other with little to no contact and evolve into separate species

Estimated Extinction Rates Average annual extinction rate of Mammal and Bird species 8000 B.C - A.D species per – species every 4 years 1900 – species every year 1975several hundred 1985several thousand 1990at least 10, ,000 – 50,000

When is a species extinct? No one has seen it for at least 50 years The last few monitored individuals die Lonesome George

Ten Characteristics of Extinction- Prone Species Found in limited areas Small population size Low population density Large body size Specialized niches and feeding habits --- Giant Panda (bamboo) Low reproductive rates

Ten Characteristics of Extinction- Prone Species Fixed migrations Flyway = An established route that ducks, geese, and shorebirds follow during their annual migrations

Ten Characteristics of Extinction- Prone Species Feed at the top of long food chains or webs Have high economic value to people Need large territory : The California Condor

Human Activities That Increase Extinction Rates Population growth, especially when combined with poverty Habitat 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 patches

Human Activities That Increase Extinction Rates Hunting, poaching Using species as pets/decoration Climate change caused by pollution Introduced species  invasive species

Biodiversity hotspots Relatively 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 Earth’s surface Contains 50% of the Earth’s species

Tropical Deforestation and Degradation Primary Causes Rapid population growth Poverty Exploitive government policies Exports to developed countries Failure to include ecological services in evaluating forest resources Secondary Causes Roads Mining Cattle ranching Cash crops Logging Oil drilling Tree plantations Flooding from dams Unsustainable 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 birds The 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 nature’s ability to replace its species through adaptive radiation?

Overfishing Commercial fishing methods Bycatch - accidental capture of non-target species in fishing gear

Bioinformatics Organizing and storing useful biological information about wild species using a data base Provides computer tools to find, visualize, analyze, and communicate biological information

Conservation Biology The scientific study of how humans impact organism and the development of ways to protect biological diversity

Conservation Biology What are the concepts that guide it? Large habitats are more effective at safeguarding species than several habitat fragments Large 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 Biology Areas 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 Biology 1. Ecosystem Approach In situ conservation Protecting habitats Restoring damaged or destroyed habitats Preserve balanced populations of species in their native habitat Establish legally protected wilderness areas and wildlife reserves Eliminate or reduce the populations of non-native species

Three Techniques of Conservation Biology 2. Species Approach Identify endangered species and give them legal protection Preserve and manage crucial habitats Ex situ conservation Zoos, aquariums, botanical gardens, seed banks Reintroducing endangered species to nature

Three Techniques of Conservation Biology 3. Wildlife Management Approach Manages game species by: Using laws to regulate hunting Establishing harvest quotas Developing population management plans Using international treaties to protect migrating game species such as waterfowl

Wildlife Refuges Teddy Roosevelt established Pelican Island off Florida’s Atlantic coast as the 1 st wildlife refuge to protect the brown pelican (1903) Now have 508 refuges, 85% are in Alaska ¾ are wetlands for protection of migratory waterfowl

Laws, Acts, and Organizations CITES Lacey Act Endangered Species Act Wild Bird Conservation Act Magnuson Fisheries Management and Conservation Act

CITES (1973) Convention on International Trade in Endangered Species An international agreement between governments Its 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 list Requires 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 reasons

Endangered 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 species

Wild Bird Conservation Act Imposed a moratorium on importing rare bird species

Magnuson Fisheries Management and Conservation Act Gives 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 Solutions Biosphere reserves - areas of terrestrial and coastal ecosystems promoting solutions to reconcile the conservation of biodiversity with its sustainable use Reintroduction of endangered species Restoration Ecology

What else can we do? Increase Public Awareness Support Research in Conservation Biology Support Establishment of an International Park System Control Pollution

What else can we do? Give Economic Incentives Fees for Medicinal Drugs Ecotourism Debt for Nature Swap Payments to landowners for protecting endangered species or reduce their property tax