Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Ch 5 Evolution, Biodiversity, and Population Ecology Part 1: Foundations of Environmental Science Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

This lecture will help you understand: Natural selection How evolution influences biodiversity Reasons for species extinction Ecological organization Population characteristics Population ecology Conservation biology

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Striking gold in Costa Rica Golden toads were discovered in 1964, in Monteverde, Chile The mountainous cloud forest has a perfect climate for amphibians Unfortunately, they became extinct within 25 years -Due to global warming’s drying effect on the forest

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Evolution: the source of Earth’s biodiversity Biological evolution = -genetic change in populations of organisms across generations May be random or directed by natural selection -Natural Selection = -the process by which traits that enhance survival and reproduction are passed on more frequently to future generations -Fitness = -proportion of genes in the next generation

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Understanding evolution is vital It is important for understanding antibiotic and pesticide resistance, agricultural issues, production, medicines, etc. It alters the genetic makeup of a population Organisms adapt to their environment and change over time

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings 10-7 ATB How can high fitness lead to natural selection? Today: -Adaptations, mutations -Various forms of stabilization -Sign into online book (if you didn’t take a book home)

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

10-13 ATB Who wrote “On the Origin of Species”? Today: -Make the house -Keep the ideas flowing

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB What is artificial selection? Give an example Today: -Discuss Darwin’s journey, artificial selection and natural selection -Book: describe some terms

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Natural selection shapes organisms In 1858, Darwin and Wallace both proposed natural selection as the mechanism of evolution: What are factors that lead to evolution? 1.Organisms face a constant struggle to survive and reproduce 2.Organisms tend to produce more offspring than can survive 3.Individuals vary in their characteristics (due to genes and the environment) 4.Many characteristics are inherited by offspring from their parents (better suited traits are passed down in a higher proportion)

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings  Darwin’s voyage aboard HMS Beagle  trip around the world.  Set out to document the “hand of God” in nature.  Collected countless specimens and kept detailed notes  Darwin presented his ideas in the book “On the Origin of Species”

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Darwin studied Finch populations on the various islands

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Artificial selection Artificial Selection = -the process of selection conducted under human direction -For example, artificial selection has led to the great variety of dog breeds

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The development of pesticide resistance in insects is example of real-time evolutionary change. Natural selection is also responsible for: -antibiotic resistance in bacteria -herbicide resistance of weeds

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Evidence of natural selection is everywhere It is evident in every adaptation of every organism Evident in bacteria and fruit flies in laboratories Selective breeding of animals

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Grab a book…define / describe the following in your notes: -Adaptive trait / adaptation -Mutations -Stabilizing, Directional, and Disruptive Stabilization (draw the graph for each) -Artificial selection -Give two examples of how artificial selection has benefitted humans -What is speciation? -Describe the difference between allopatric and sympatric speciation

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB Give one factor that Darwin suggested could lead to evolution Today: -Discuss various selective pressures and mutations

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Genetic variation Adaptive Trait (Adaptation) = -a trait that promotes reproductive success Mutations = -accidental changes in DNA that may be passed on to the next generation -Non-lethal mutations provide the genetic variation on which natural selection acts Sexual reproduction also leads to variation

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Natural selection acts on genetic variation Directional selection = -drives a feature in one direction Stabilizing selection = -produces intermediate traits, preserving the status quo Disruptive selection = -traits diverge in two or more directions If the environment changes, a trait may no longer be adaptive

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Evolution generates biodiversity Biological Diversity = -An area’s sum total of all organisms -The diversity of species Species = -a population or group of populations whose members share characteristics and can freely breed with one another and produce fertile offspring Population = -a group of individuals of a species that live in the same area

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Speciation produces new types of organisms Speciation – -The process of generating new species Allopatric speciation = -species formation due to physical separation of populations (considered the main way in which new species are created) -How can populations become separated?: -glaciers, rivers, mountains

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Another type of speciation Sympatric speciation = -species form from populations that become reproductively isolated within the same area -How / Why? - Feed in different areas, mate in different seasons - Mutations (IE can no longer mate w/ one another)

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Speciation results in diverse life forms Speciation generates complex patterns of diversity above the species level Phylogenetic trees (Cladograms) = Represents the history of species divergence -Scientists can trace when certain traits evolved -Show relationships between species

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB You are a very large, coarse haired mammal. Your other normal sized, regular haired mammal friends all make fun of you. Create a short story to describe the new environmental pressure that causes directional selection, which will, in the end, leave you laughing at all your normal mammal friends. Today: -ATB’s DUE TOMORROW -Discuss extinction -Mass your caterpillars (now, not at the end) -Quiz on the lab background Friday -Water Testing Manuals – give them back if you have them

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Extinction New species can arise, but others go extinct What are some (natural) driving causes of extinction? -Environment changes (species can’t adapt) -Severe weather -Competition (new species) -Massive volcanic eruptions -Meteors Extinction occurs when the environment changes too rapidly for natural selection to keep up -Polar bears?

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Some species are more vulnerable to extinction Endemic species = -a species only exists in a certain, specialized area -Very susceptible to extinction -These species usually have small populations Being a specialist leaves an organism more likely to go extinct

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Species’ ranges can be severely restricted Some U.S. salamander species live on top of single mountains Peaks of Otter salamander – Lives in Virginia's Blue Mountains

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Earth has had several mass extinctions Background extinction rate = -extinction usually occurs one species at a time Mass extinction events = -five have occurred in Earth’s history - killed off massive numbers of species at once % of all species went extinct at one time -K-T extinction was the last (Cretaceous–Tertiary - dinosaurs) Humans are causing the sixth mass extinction event -Resource depletion -Population growth -Development / Urbanization

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Ecology is studied at several levels Biosphere = the total living things on Earth and the areas they inhabit Ecosystem = communities and the nonliving material and forces they interact with Community = interacting species that live in the same area

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB What is an endemic species? Today: -Turn in ATB’s -Discuss niche, habitat and population ecology -Lab Quiz tomorrow

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population ecology Community ecology Ecosystem ecology Habitat Selection / Habitat use Habitat Niche Generalist Specialist

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Levels of ecological organization Population ecology = -investigates the quantitative dynamics of how individuals within a species interact Community ecology = -focuses on interactions among species Ecosystem ecology = -studies living and nonliving components of systems to reveal patterns -Nutrient and energy flows

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Organismal ecology: habitat Habitat = -the environment in which an organism lives -Includes living and nonliving elements -Scale-dependent: from square meters to miles (*Your skin vs. the Atlantic ocean) Habitat Selection / Habitat use -Organisms actively select habitat in which to live -each organism thrives in certain habitats, but not in others Availability and quality of habitat are crucial to an organism’s well-being Human developments conflict with this process

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Organismal ecology: niche Niche = -an organism’s use of resources and its functional role in a community -Habitat use, food selection, role in energy and nutrient flow -Interactions with other individuals

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Fundamental Niche -Area organism COULD live, w/ no competition Realized Niche -Area organism DOES live w/ competition -Barnacle Example: Balanus vs Chthamalus

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Specialists vs. Generalists Specialists = -species with narrow niches and very specific requirements -Extremely good at what they do, but vulnerable to change -Examples: -Panda Bear, Koala Generalists = -species with broad niches that can use a wide array of habitats and resources -Able to live in many different places -Examples: -Humans, many omnivores

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings POPULATION ECOLOGY

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics All populations show characteristics that help scientists predict their future dynamics -Numbers can increase, decrease, cycle or remain the same -Passenger pigeon had huge populations in N. America. Hunting / habitat loss lead to extinction

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics Population density = -the number of individuals within a population per unit area -Pros / Cons of high density? -Easier to find mates -Increase in competition -Could lead to higher predator concentrations -Pro’s / Cons of low density? -harder to find mates -plentiful resources and space

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics Population distribution (dispersion) = -spatial arrangement of organisms within an area -Three Types: -Random – -haphazardly located individuals, with no pattern -A tree species in a forest

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings -Uniform – -individuals are evenly spaced due to territoriality -Clumped – -arranged according to availability of resources -Which is most common in nature? -Clumped

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population characteristics – sex ratio Sex ratio = - proportion of males to females -How to maximize population growth if… -Species are monogamous? -50/50 -If species are NOT monogamous? -Need higher # of females

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB What is the difference between a realized and fundamental niche? Today -Lab quiz -Mass the cups -Get your hall decorating stuff Test Tuesday

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB How can comparing a fundamental niche with a realized niche give an insight to the ability of an organism to compete? Today: -Finish notes -Review / review sheet Tuesday -Test Wednesday Mass the cups

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population Characteristics – Age Structure Age Structure = -the relative numbers of organisms of each age within a population -Age structure diagrams (pyramids) = show the age structure of populations -Can be used to predict future growth

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Which will growth decrease? Which will growth explode? Which will have the most stable growth?

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Birth and death rates Crude birth/death rates = -rates per 1000 individuals Survivorship curves = -the likelihood of death varies with age

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Survivorship curves -Type I: More deaths at older ages -Humans, elephants -Type II: Equal number of deaths at all ages -Birds, honeybees -Type III: More deaths at young ages -Plants, fish

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Survivorship curves -How does parental care influence this? -More care = less fatality in young

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Four factors of population change Natality = -births within the population Mortality = -deaths within the population Immigration = -arrival of individuals from outside the population Emigration = -departure of individuals from the population Growth rate formula = -(Crude birth rate + immigration rate) - (Crude death rate + emigration rate) = Growth rate

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Exponential population growth Steady growth rates cause exponential population growth -Something increases by a fixed percent -Graphed as a J-shaped curve Exponential growth cannot be sustained indefinitely -It occurs in nature with a small population and ideal conditions

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Limiting factors restrain growth Limiting factors = -physical, chemical and biological characteristics that restrain population growth -Water, space, food, predators, and disease Environmental resistance = -All limiting factors taken together

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB In which survivorship curve does most of the organisms die at older ages? What does this tell us about parental care? Today: FIRST - Finish notes -Pop. Effects on limiting factors and reproductive strategies SECOND - Mass your chrysalis TEST – Wednesday (review sheet due)

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Carrying capacity Carrying capacity = -the maximum population size of a species that its environment can sustain -An S-shaped logistic growth curve -Limiting factors slow and stop the exponential growth Carrying capacity changes Humans have raised their carrying capacity by decreasing the carrying capacity for other species

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Perfect logistic curves aren’t often found

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population density affects limiting factors Density-dependent factors = -limiting factors whose influence is affected by population density -Increased risk of predation and competition for mates occurs with increased density Density-independent factors = -limiting factors whose influence is not affected by population density -Events such as floods, fires, and landslides

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Biotic potential and reproductive strategies vary Biotic potential = -the ability of an organism to produce offspring K-selected species = -animals with long gestation periods and few offspring -Have a low biotic potential -Stabilize at or near carrying capacity -Good competitors r-selected species = -animals which reproduce quickly -Have a high biotic potential -Little parental care

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Describe two density-dependant factors that could affect a population Today: -Review sheet / Test  Thursday -Get a lap top…start graphing your data in excel -Friday  Dr. Hu coming to speak.

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings K-selected vs. r-selected species

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Population changes affect communities As population in one species declines, other species may appear Human development now displaces other species and threatens biodiversity -As Monteverde dried out, species from lower, drier habitats appeared -But, species from the cloud-forest habitats disappeared

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Challenges to protecting biodiversity Social and economic factors affect species and communities -Nature is viewed as an obstacle to development -Nature is viewed as only a source of resources -Human population growth pressures biodiversity

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Preserving biodiversity Natural parks and protected areas help preserve biodiversity -Often, they are underfunded -Ecotourism brings jobs and money to developing areas

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings ATB

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Which of the following is NOT a part of the process of natural selection? a) Organisms struggle to survive b)Organisms limit the number of young they produce c) Individuals vary in their genetic characteristics d)Some individuals are better suited to their environment than others

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Disruptive selection would result in which of the following? a)Dogs with black coats evolving whiter coats in colder areas b)Red and white flowers interbreeding, producing pink flowers c)Fish evolving bigger eyes as the water gets muddier d)A population of birds, some with thicker beaks that eat seeds and others with thinner beaks that eat insects

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Biological diversity includes all of the following, except: a)Species diversity b)Genetic diversity c)Population diversity d)Community diversity e)All of these are included in the concept of biodiversity

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Sympatric speciation would occur in.... a) One population that mates in May, and another that mates in June b) Two populations separated by the Mississippi River c) Two populations separated by a glacier d) Two populations separated by the Rocky Mountains

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Which of these species is least vulnerable to extinction? a) A species with a population size of 50 individuals b) A species distributed throughout the United States c) A species that eats only river snails d) A species that lives on mountaintops

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review An ecosystem is defined as: a) The total living things on Earth b) Members of the same population that can interbreed c) Interacting species in an area d) Species and the nonliving material they interact with

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Viewpoints Should we care whether a species goes extinct? a)Yes, because all life is important and valuable b)Yes, because we are causing this wave of extinction, so we should fix it c)We should not, because it’s natural d)I don’t care; it really does not affect me

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Viewpoints Do you think humans are subject to limiting factors and, ultimately, a fixed carrying capacity? a)Yes, although we have raised the carrying capacity, there are limits to the number of humans the Earth can support b)Yes, but technology will keep raising the carrying capacity, so it’s not much of a problem c)No, humans are no longer constrained by environmental limits, due to our technology and ability to manipulate the environment d)I don’t care; it really does not affect me

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data Which of the following graphs shows a population that will have fewer individuals in the future? (a)(c)(b)(d)

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data Which type of distribution is a result of individuals guarding their territory? a) Random b) Uniform c) Clumped d) None of these

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data What does this graph show? a)The effects of carrying capacity on population growth b)A population that keeps growing c)The effects of exponential growth d)The effects of increasing carrying capacity