Chapter 4Biodiversity and Evolution

• Case Study: Amphibians at Risk• Amphibians (___________________, ____________________, & _____________________________________) show great

_______________________________________________________ (6,700-plus species).– Many amphibian populations have _______________________________ or _____________________________

since 1980 (likely due to a combination of ______________________________________________________ _______________________________________________________________________________________________________ ______________________________________________________________________).

– Amphibians are critical species: sensitive ________________________________________________________, prey on/serve as prey for numerous species, sources of ________________________________________.

• How can you study local biodiversity? _____________________________________________________________________ _________________________________________________________________________________________________________________

4.1 What Is Biodiversity and Why Is It Important?• Biological diversity, or biodiversity, is the _________________________________________________________________

_________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________

• Biodiversity is one of ____________________ scientific factors of sustainability.

Components of Biodiversity: Species Diversity• Species diversity describes the ____________________________________________________________________

present in an ecosystem and their _________________________________________ within that ecosystem. • About ________________________________________________ species identified on Earth• Actual total likely ranges from ______________________________________________, may be as many as 100

million

Components of Biodiversity: Genetic Diversity• Genetic diversity is the variety of _______________________________________________________________ or in a

____________________________.– Genetic information gives rise to ___________________________ that are ______________________________

to offspring.– Greater genetic diversity means species have a better chance of _______________________________

& ______________________________________________ to environmental changes.

Components of Biodiversity: Ecosystem Diversity• Ecosystem diversity refers to Earth’s diversity of ________________________________________________________.

– Deserts, grasslands, forests, mountains, oceans, lakes, rivers, and wetlands– Biomes: __________________________________/______________________________________________________ with

distinct _____________________________________ and ___________________________________

Components of Biodiversity: Functional Diversity• Functional diversity is the __________________________________________________________________________________,

such as ____________________________ flow and _________________________________ cycling.

– Concerns ______________________________________________________________ organisms play in their communities and the impact these roles have on the overall ____________________________________• More than one species may ________________________________________________________________.• If an ecosystem contains ____________________ species that ______________________

functional traits, that ecosystem will be ___________________________________________________ ____________________________________________________________ without losing functionality.

Insurance Hypothesis• Biodiversity _____________________________________________________________________________________________ in

their functioning because many species provide _________________________________________________________ of functioning even if others fail.

• Biologically diverse ecosystems are more likely to contain species with _______________________________ _________________________________________________ in the environment.

Biodiversity Builds Natural Capital• Biodiversity is vital to maintaining natural capital that __________________________________________________

____________________________________________________________________________________– Provides __________________________________________________ for resources such as food, medicine,

building materials, fuel– Provides _____________________________________________________________ such as air and water

purification, topsoil renewal, decomposition of wastes, pollination– Allows for _______________________________________________ of new species and ecosystem services

4.2 What Roles Do Species Play in Ecosystems?• Niche

– The ______________________________________________________________ in an ecosystem and everything that affects its __________________________________________ & ______________________________________

• Habitat– The ____________________________________________________________________________ of the species

• Species– May be _________________________________________ with _____________________________ niches, or

_________________________________ with ___________________________ niches

Generalist and Specialist Species• Generalist species (______________________________ niches)

– Eat ___________________________________________ of foods– Can live in a _______________________________________________ of environments– __________________ resource ___________________________________ but _______________ prone to

______________________________• Specialist species (_________________________________ niches)

– Have ___________________________________________ diets– Live in ________________________________________________________________ of habitats

– ___________________________________________________________________ but ________________________ prone to ________________________________________________

A Specialist and a Generalist• What do the colored lines represent on the graph? • What is the significance of the shape of the colored lines?• What are examples of resource use, the variable on the x-axis? • What statement can you make about each species shown in terms of its resource use?

Specialization Reduces Competition– Feeding Niches: Various bird species in a coastal wetland occupy specialized feeding

niches. This specialization reduces competition and allows for sharing of limited resources.– • What do the birds have in common? – • What evidence do you see of specialized niches?

Native and Nonnative Species• Native species

– _______________________________________________________________________________________________________________________________________________________________________________________________________

• Nonnative species – ____________________________________________________ or are introduced (______________________________

or _____________________________________________) into an ecosystem– Can become __________________________________________________

• ____________________________________________/displace native species• ___________________________________________________________ if they find a favorable niche• Often lack _________________________________________ , ________________________________________

faced in native habitat

Keystone Species Play Critical Roles in Their Ecosystems• Keystone species affect the ______________________________________ ___________________________________________

in an ecosystem.– Ecosystem would be ___________________________________________________________________ if keystone

species disappeared• _____________________________________________________________________ of other species

(mountain lions, wolves, sea otters)• May cause ____________________________________________________________________ of dependent

species if drawn to extinction itself

American Alligator as a Keystone Species • The American alligator is a keystone species of subtropical _____________________________________________

in the Southeastern United States.

– ______________________________________________________ provide fresh water, habitat for aquatic life, nesting/feeding sites for other species

– Digging activity maintains _______________________________________________________________– Helps control ___________________________________________________________ populations– Almost hunted to ___________________________________________, endangered species until ___________

(now threatened by ____________________________________________________________________________)

Sharks as Keystone Species• Sharks are keystone species that keep their ecosystems functioning and help ______________________

_____________________________________________of other marine species.– Over a million are killed annually in response to ________________________________________________

________________________________ on shark attacks.– Populations of many shark species are ___________________________________________________, mainly

due to ___________________________________.• As many as _____________________________________________ killed annually• _____________________world’s open-ocean shark ______________________ threatened• Vulnerable due to ________________________________, low _______________________________ rates

The word keystone has applications in other fields. For example, in architecture, keystone is the term used for a stone that is positioned at the top of an arch. It is placed last and locks all the stones in position.

What happens to the rest of the arch if you take the keystone out? How does this concept relate to a keystone species in an ecosystem?

Indicator Species Serve as a Biological Smoke Alarm• An indicator species is sensitive to changes in an ecosystem.

– Presence or absence indicates the __________________________________or characteristics of certain

___________________________________________________________________________– Some _________________________________________ species are good indicator species (Case Study)

• ____________________________________________________ factors: virus, fungal disease, parasites• _____________________________________________________ factors: habitat loss, pollution,

climate change

4.3 How Does the Earth’s Life Change Over Time?• The ________________________________________________________________ is demonstrated in the process of

natural selection.– Explains how life on Earth ________________________________________________________ due to changes

in the _______________________________________________________________________– ___________________________________________________________________________________________________ that

explains how life has changed on Earth• Population evolution occurs through _____________________________________________________.

– Gives individuals genetic traits that _____________________________________________________________ to survive and _____________________________________________________________________

Biological Evolution by Natural Selection Explains How Life Changes Over Time• Biological evolution

– Process by which species __________________________________________________________________, occurs within ____________________________________________________________________ generation to generation

• Natural selection– Individuals with traits that ________________________________________________________________ are

more likely to ______________________________________ and _______________________________ these traits.• ____________________________ (bones, teeth, shells, leaves, seeds, impressions)

Evolution Depends on Genetic Variability• Genetic variability

– ________________________________________________________________________ of individuals in population– Primarily results from __________________________________ (_________________________________ changes

to DNA sequence in genes)• Can result in ____________________________________traits• Some ___________________________, some ________________________, some _______________________

Evolution Depends on Natural Selection• _______________________________________________

– Any heritable trait that gives individual some ____________________________________________________ in population

• Genetic _________________________________________– The ability of one or more organisms in a population to _________________________________________

designed to kill the population – Develops in __________________________________ and ________________________________ species because

they ___________________________________ produce ___________________________ numbers of offspring (antibiotic-resistant bacteria)

Adaptation Through Natural Selection Has Limits• Limiting factors for adaptation:

– Organisms can only adapt to a ______________________________________________________________________ if the necessary genetic traits are __________________________________________________________ in a population’s gene pool.

– Even if a beneficial heritable _____________________________________________________ in a population, the population’s ability to adapt may be limited by its _____________________________________ __________________________________________.

4.4 What Factors Affect Biodiversity?

• As environmental conditions change, ____________________________________________ is determined by the ___________________________ between formation of _________________________________________ and the ____________________________________________ of existing species.

• ______________________ has caused loss of biodiversity:– By causing __________________________________________ of species – Through ______________________________________________________________________________ needed for

development of new species

How Do New Species Arise?• Speciation occurs when _____________________________________________________________________________________

_______________________________________________________________.– Species are considered different when ____________________________________________________________

_______________________________________________________________

Geographic and Reproductive Isolation• Geographic isolation

– Occurs when groups of the same population become physically isolated (by _________________ ______________________________________________________________________) from one another over time

• Reproductive isolation – Occurs when ________________________________________________________________________________ operate

independently in the gene pools of geographically isolated populations

Geographic Isolation Can Lead to Reproductive Isolation

All Species Eventually Become Extinct• Extinction occurs when a species _____________________________________________________________

(_______________________ ____________________________).• A species facing a crisis may:

– ________________________________ to the new changes in the environment– _________________________________ to a new geographic location that is more suitable to their

lifestyle– _______________________________________________

Endemic Species Are Very Vulnerable to Extinction• Found in only _______________________________________________________________________ areas, making it

___________________________ for them to migrate or adapt during ____________________________________________ environmental conditions

• Many endangered endemic species are ___________________________________________________.

Background Versus Mass Extinction• ____________________________________________________ eventually become extinct.• Background extinction rate: ________________________________________________________________________________

__________________________________________________________________________ (less than 1 species per million)• Mass extinction : ___________________________________________________________________________________

• Often ___________________________________________________________________ tied to major widespread environmental change

• Current mass extinction may be occurring as a result of _________________________________ ________________________________________

A Short History of Mass Extinctions• __________________________ & __________________________________ evidence indicate that there have probably

been _____________ mass extinctions during the past ____________________________________________ years.• These mass extinctions have been followed by an _________________________________ in species diversity.

– New species _____________________________________________________________________________________ or to ____________________________________________________________________________________ ones.

Are We Experiencing the Next Mass Extinction?• Evidence suggests that ______________________________________________________on average through time

has ________________________________________________ of extinction.• However, scientists now think we may be experiencing the beginning of a ___________________________

_________________________________ that is the result of _____________________________________________________.

Humans Select Species’ Traits• Artificial selection

– Selectively ______________________________ or __________________________________________ between genetic variations of the same species

– Takes ____________________, ____________________________________________________ of years * Genetic engineering (GMOs)

– _________________________________________________________________________________ for desired traits– ___________________________________________________________ between different species that would

not ________________________________________ in nature– ________________________________________________________________ (new DNA sequences)