Evolution & Biodiversity. Unit 3 Chapter 5 & 12

Transcription

1 Evolution & Biodiversity Unit 3 Chapter 5 & 12

2 Types of Biodiversity: Species (# of species) Genetic (Variety of genes) Ecological (Variety of ecosystems) Functional (Variety of processes)

3 1.9 million species identified ~10-14 million estimated to exist

4 Evidence indicates that earth s life is the result of about 1 billion years of chemical evolution followed by 3.7 billion years of biological evolution p.88

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6 Knowledge about earth s early life comes from fossils, chemical analysis, ice cores, & DNA analysis Fossil record is incomplete? Why? We only have fossils of 1% of all species that lived on earth. Biological Evolution by Natural Selection Explains How Life Changes over Time POPULATIONS evolve by becoming genetically different Fossil = Physical evidence of ancient organisms Fossil record = entire body of fossil evidence

7 Microevolution: change in a population s gene pool over time. Well-supported theory; documented in bacteria, pests, viruses, etc.

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9 Macroevolution: long-term, large-scale evolutionary changes through which new species form from ancestral species Studied using fossils & comparative morphology A lot more debatable

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11 Evolution occurs when 1. Genetic variation exists Due to Random shuffling of alleles during sexual reproduction Mutations: random changes in structure or number of DNA molecules o Result of random mistakes during DNA replication, X- rays, Radiation, Man-made chemicals, or random mistakes during DNA replication & cell division o Mutations in parents get passed on to progeny can be harmful, harmless, or beneficial

12 2. Nature Selects Individuals (Natural Selection) Environmental pressure causes organisms better adapted to survive to reproduce & make offspring with the same traits Requirements: 1.Genetic variability in trait 2.Trait is heritable 3.Individuals with trait leave more offspring Natural selection causes adaptations to become more common in succeeding populations Adaptations can be: Physical Physiological/ Chemical Behavioral

13 ALLOPATRIC SPECIATION Geographic isolation: physical isolation of populations for a long period(volcanic eruption, advancing of glaciers, changes in sea level, etc.) Reproductive isolation: mutations & natural selection in isolated pops lead to inability to produce viable offspring Two species One species

14 Myths about Evolution Survival of the fittest is not survival of the strongest Organisms do not develop traits out of need or desire No grand plan of nature (random) Humans will not develop skin resistant to UV radiation, lungs that filter air pollution, or livers that detoxify pollutants (genetic trait has to be present to begin with &we reproduce slowly so it takes thousands to millions to adapt through natural selection)

15 Coevolution:When 2 species interact over time, they can change the direction of each other s evolution Adaptations are refined in this ongoing coevolutionary contest Moths develop ears to detect & evade 2. Moths developed high frequency clicks to jam bats echolocation system Bats use echolocation 3. Bats switch frequency 5. Bats stop making sounds & follow clicks

16 Human-Caused Evolution: Artificial selection: selective breeding for traits Genetic engineering: genetically-modified organisms (GMOs) Ex: Bt corn; insulin-making bacteria (Biofarming); Golden Rice (vitamin A); bacteria that extract minerals i.e. Cu; cold tolerant plants cows that give more milk food crops w/higher yields

17 Species Diversity Richest environments: Tropical rain forests Coral reefs Large tropical lakes Ocean bottom Species Role or Niche includes Adaptations Role it plays in matter cycles and energy flow Range of tolerance to env. conditions (temp. & water availability) Types & amounts of resources used Interactions with other species

18 Two Types of Species with Respect to Niches: Generalist species have Broad Niches Live in many habitats, eat variety of food, tolerate wide range of environmental conditions Rats & mice Coyotes Deer

19 Two Types of Species with Respect to Niches: Specialist species have Narrow Niches Live in one type of habitat, eat few types of food, tolerate narrow range of environmental conditions More prone to extinction Tiger salamander Giant panda Red cockaded woodpecker

20 Specialized feeding niches of coastal birds reduces competition and allows for sharing of limited resources

21 Adaptive Radiation can result in Specialists Adaptive radiation: evolutionary divergence of a single species into a variety of species when new niches are available Left: honeycreepers on Hawaii Right: finches on Galapagos

22 Species Can Play Five Major Roles within their Environment: Indicator species: provide early warning of damage to a community Frogs, butterflies, birds Special Focus: Amphibian Decline According to the IUCN, about 32% of all known amphibian species are threatened with extinction, and populations of 43% of the species are declining Frogs are sensitive to environmental disruption at various points in their life cycle Eggs have no protection from UV radiation or pollution Adults absorb pollutants through skin

23 Amphibian Decline Causes include: Habitat loss & fragmentation Climate change Increased UV radiation Viral & Fungal Diseases: Chytrid fungus Pollution: pesticides (atrazine) Overhunting (frog legs) Nonnative predators & competitors Why should we care: indicators, role as predators, pharmaceuticals

24 Keystone species: have a large effect on the types and abundances of other species Top predators, pollinators; Ex: American alligator, honey bees, sea otter Foundation species: enhance their habitats, which benefit others Ex: Alligators, beavers, elephants

25 Biodiversity Loss: Extinction: loss of a species Local = extirpation Biological = lost forever Background extinction: typical extinction b/c not all life can sustain on earth Mass extinction: significant rise in extinction rates above the background Widespread/ global event in which 25-70% of species are lost 3-5 have occurred over past 500 million years (last one 65 m.y.a) Can lead to adaptive radiations (taking advantage of opportunities) Human-Caused Biodiversity Loss: Before humans rate was 1 extinction per million species per year Extinction rate now 10,000 species per million Some saw we re currently in the 6 th Mass Extinction

26 Some Species are More Prone to Extinction: Slow reproducers Specialized niche Top predator Commercially valuable Need large territories back-terrapin.html

27 Loss of Biodiversity: Why Should We Care? 1. Species provide natural capital and services Pollination, Pest control, chemical cycling, etc. 2. Most species contribute economic services Plants for food, fuel, lumber, medicine Ecotourism 3. Many people believe species have an intrinsic right to exist

28 How Humans Decrease Biodiversity: HIPPCO Habitat destruction/ fragmentation = Biggest threat Invasive species Pop growth Pollution Climate change Overexploitation: overharvesting & poaching

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30 re/lessons/the-pythonproblem/videosegments/5699/

31 Solutions: CITES: Convention on International Trade in Endangered Species Bans the hunting, capturing, & selling of threatened species Endangered Species Act of 1973 Goal: Identify and protect endangered species in the U.S. and abroad Started w/ 92 US species Currently protects ~1,550 species in US ( National Marine Fisheries Service for ocean species U.S. Fish and Wildlife Service for all others

32 Solutions: Wildlife Refuges & Botanical Gardens First one was Pelican Island est by T. Roosevelt Captive breeding in zoos & aquariums Egg pulling Artificial insemination Embryo transfer Use of incubators Cross-fostering

33 Pelican Island National Wildlife Refuge The Pelican Island National Wildlife Refuge in Florida was America s first National Wildlife Refuge. It was established in 1903 to help protect the brown pelican and other birds from extinction. In 2009, the brown pelican was removed from the U.S. endangered species list.

34 Sustaining Biodiversity