ch. 21 and 11; conservation, biodiversity, and evolution and its processes

exam 2

species diversity

the number of species in a given area

ecosystem diversity

number of ecosystems in a given area

species richness (diversity) and the factors that affect it

* solar energy
* evolutionary history
* disturbances

solar energy

more direct sunlight = more plant/animal diversity

evolutionary history

the length of time a species has been present in an ecosystem

longer evolutionary history = healthier relationships = more diversity

disturbances

regular, moderate disturbances maintain high levels of diversity

biogeographic hotspots

characterized by a certain number of endemic species

endemic species

they aren’t found anywhere else on the planet

describing at risk species: threatened

at risk of becoming endangered in the future

describing at risk species: endangered

risk becoming extirpated or extinct in the future

describing at risk species: extirpated

extinct in part of its range

describing at risk species: extinct

no longer present

extinction events: background extinction

* occurs at a constant rate

effected by:
* population size; small population is more vulnerable
* geographic range; small range is more vulnerable
* niche: generalized/specialized; specialized is more vulnerable

extinction events: mass extinction

50% or more taxa must be destroyed, caused by natural disaster

taxa

a taxonomic group of any rank such as a species, family, or class

current threats to biodiversity

* global warming
* habitat loss
* overharvesting
* intro of exotic species
* removal of natural predators

global warming

organisms can move into new areas where they have no evolutionary history; intro of new diseases (human/animal/crop)

habitat loss

loss of habitat (ex. deforestation)

overharvesting

upsetting evolutionary history because we are removing a species

intro of exotic species

move into area where there’s no evolutionary history (ex. feral cats are responsible for dramatic decline of songbirds)

removal of natural predators

removal of species upsets evolutionary history (ex. snakes)

density independent factor

any force that affects the size of a population of living things regardless of the density of the population

density dependent factor

have either a positive or negative correlation to population size (ex. disease, competition, predation)

middle (dark) ages

* not a lot of writing
* catholic church is supreme authority
* king appointed by god
* socioevonomic position is the will of god
* benedicts rule
* charlemagne
* immigration of islamic people to spain, bring golden age with them, reintroduce wisdom of the ancient greeks back into europe

benedicts rule

all monks are required to read and write so they could make copies of the bible

charlemagne

established schools in the abbeys

golden age

wisdom of ancient greeks is reintroduced into europe

renaissance

* rebirth of education in all fields
* humanist movement

humanist movement

celebrate the unique potential of the human mind, believed you can change socioeconomic position through education

reformation

* monks see discrepancies (inconsistencies) between what the bible says and what the church does
* leads to the protestant reformation

enlightenment

thomas paine: wrote book “age of reason”

* reason is the supreme authority
* encouraged people to seek the gods divine order in nature
* these two ideas were popular in the upper class and in monasteries
* theologian/scientist/naturalist role was also popular

scale of nature

classification system that ranks organisms based on usefulness to humanity. placement is ranked

(ex. 1. gods, 2. people, 3. horses, 4. goods, 5. mice, etc)

carl von linne/carolus linnaeus

* father of taxonomy (classification)
* binomial nomenclature (genus and specific epithet)
* updated scale of nature to reflect god’s divine order
* based on anatomical similarities and differences
* relationships were correct most of the time
* darwin later applies concept of “relativeness of species” to his theory of evolution

james hutton

* geologist
* presented ideas on gradualism
* removed supernatural elements from the equation
* proposed earth was much older than what was commonly thought
* darwin will apply concept of slow constant change to living organisms

gradualism

large geographic features are the result of natural processes occurring slowly and at a constant rate over many years

jean baptiste lamarck

* evolutionary theory
* first person to propose a mechanism for evolution (how it works)

evolutionary theory: use and disuse

traits that are essential for survival become amplified, traits that are not become vestigial

evolutionary theory: inheritance of acquired characteristics

proposed parents acquire traits over course of their lifetime (not true, genes dictate what we are); then the parents pass their traits to their offspring (true)

darwin used some of these concepts such as:

* traits that are necessary for survival
* traits being passed from parent offspring

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georges curvier

* father of paleontology (fossils)
* studied fossils from plaster mines; each layer of plaster has a different fossil community
* first to propose organisms can become extinct
* darwin replies with concepts of extinction
* catastrophism

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catastrophism

god wiped out the existing community and replaced it with a new creation

charles lyell

* geologist
* revises buttons gradualism
* uniformitarianism
* darwin applies concept of continuous change in the future to living organisms

uniformitarianism

large geographic features are product of natural processes occurring at a slow constant rate. these slow constant processes continue into the future

charles darwin

* went to medical school
* studied beetles
* dropped out of med school
* went to divinity school
* continued studying beetles
* after graduating, he travels on beagle as “companion to the captain” (to map coastline of south america)
* collects plants, animals, and fossils of south america
* studies paf rest of his life
* embodies the scientist/naturalist/theologian role

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what did darwin see?

* paf that were unlike anything in europe


* pafs are more similar to each other than anything occupying similar niches in europe (relatedness)
* earthquake, landslide, volcanic eruption; coastline changed dramatically- saw uniformitarianism firsthand
* island biogeography
* galapagos

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island biogeography

islands are a good place to see evolution in action

* must be enough from mainland to prevent back and fourth traffic
* island must be right size, have the right amount of resources: population reaches K (carrying capacity) quickly, but can live long enough for adaptations to appear

carrying capacity (K)

number of organisms in a population that the environment has the resources to support

* changes constantly
* depends on limiting factors

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galapagos

* finches- each island has a unique community of finches: some have same seed-eating black as those on mainland; others show beak adaptations
* giant tortises
* aquatic vegetarian iguanas

darwin’s descent with modification: observation 1

all populations have the reproductive ability to increase in size of the generations

darwin’s descent with modification: observation 2

eventually there will be more organisms in a population than the available resources can provide for

darwin’s descent with modification: inference 1

individuals within a population will eventually compete for resources

darwin’s descent with modification: observation 3

within a population, most individuals will have the same traits, which are heritable

darwin’s descent with modification: observation 4

these traits occur in slightly varied forms (polymorphisms)

polymorphisms

occurrence of different forms among members of a population

darwin’s descent with modification: inference 2

some phenotypes give an advantage to the individual, allowing an increased ability to survive and reproduce (differential reproductive success)

phenotype

observable characteristics

differential reproductive success

provides statistical evidence of natural selection; some phenotypes give an advantage to the individual, allowing an increased ability to survive and reproduce

darwin’s descent with modification: conclusion

individuals with differential reproductive success will produce more offspring, increasing the numbers of individuals carrying the alleles that confer this advantage

alleles

two or more alternative forms of a gene that arise by mutation and are found at the same place on the chromosome

natural selection

shift in allele frequency, this is darwin’s descent with modification

alfred wallace

* conducted similar study in the east indies
* independently developed same theory of natural selection as darwin
* doesn’t receive credit for natural selection because darwin had 30 years of research compared to wallace’s 2 years

what is evolution?

* microevolution
* macroevolution
* artificial selection

microevolution

* shifts in allele frequency in the gene pool of a population
* this is something you can see
* (BB, Bb, bb)
* low level species → species change


1. natural selection
2. mutation
3. gene flow
4. genetic drift
5. non-random mating

microevolution: 1. natural selection

an organism has a trait that confers an advantage and increases survivorship, therefore produces more offspring carrying that trait, differentiating reproductive success

microevolution: 2. mutation

copying errors that occur during meiosis (the formation of gametes)

* probably a “neutral” mutation- doesn’t affect function of gene product
* maybe positive (favored by selection) or negative (disfavored)
* HOX GENES
* evolutionary biologists propose all the animal diversity on the planet is the product of mutation

hox genes

control embryonic development in animals

microevolution: 3. gene flow

organisms leave one population and join another, taking their genes with them

microevolution 4. genetic drift

something happens that dramatically reduces population size and changes the gene pool from that of the “parent” population

two types:

* bottleneck
* founder effect

genetic drift: bottlenecking

most of population dies; the survivors have a dramatically different gene pool (ex. disease)

genetic drift: founder effect

a segment of a population gets separated from the main population, this segment has a dramatically different gene pool (ex. the amish)

microevolution: 5. non-random mating

not all males get to make- some males are disproportionately represented in the gene pool

* male competition
* female mate choice

both competition and mate choice lead to SEXUAL SELECTION

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non-random mating: male competition

males fight to establish dominance- the most dominant male mates

non-random mating: female mate choice

females pick the most suitable man (ex. tropical birds)

sexual selection

a trait confers an advantage (not in survivorship, but in differential reproductive success). it can’t increase survivorship because then it would be natural selection

non-random mating: sexual selection in terms of survivorship

* may NOT affect survivorship (ex. size of rams horns doesn’t affect him)
* may negatively affect survivorship (ex. peacock feathers make them more susceptible to predators

macroevolution

an accumulation of microevolutionary events resulting in large scale change

* can’t see it, takes too long
* class → class (ex. fish → amphibian)


1. fossil record
2. biogeography
3. comparative anatomy
4. embryology
5. molecular biology

macroevolution: 1. fossil record

fossils and fossilization, any representation of ancient life

* fossilization is uncommon. populations represented by fossils were probably large healthy and strong

fossil record: types of fossils

* body fossils: represent the body of the organism
* shows posture, how they moved, age, and disease
* trace fossils: non-body
* ex. fossil burrow, tracks, and excrement
* tell about paleoecology

paleoecology

what the environment was like at the time

fossil record: how does fossilization take place?

1. organism must die in a manner that the carcass is protected from scavengers
2. bacteria will eat the soft body parts
3. time passes, each layer of sediment represents a flood. soil accumulated on top of bones, weight of soils destroys MOST of the organic material. minerals in soil replace organic material- bone becomes rock
4. more time passes, geological upheaval and erosion reexpose fossil to air. it erodes just like the rocks around it

fossil record: how are fossils dated?

1. relative dating: date based on position of fossil in soil OR compare its position to that of an INDEX FOSSIL
2. radiometric dating: doesn’t work on fossils because most of the organic material is gone. instead scientists use potassium dating to date volcanic ash in soil

index fossil

an organism of which the dates are known (younger or older)

fossil record: what do fossils show us?

anatomical change over time

fossil record: what is the missing link?

(ex. btwn fish and amphibians)

* scientists rely on transitional fossils, even though that particual species doesnt represent the “link”
* evidence of large populations of transitional forms indicates that these organisms thrived and were successful as transitional forms
* this means that the transition is possible, it doesn’t matter if its the link
* ex. penguins, birds that can’t fly but are large healthy and successful. on the other hand, manatees are not large healthy and successful

macroevolution: 2.

biogeography and continental drift

alfred wegener

* german weatherman
* WWI- in a german submarine he mapped the ocean floor. saw the mid-atlantic ridge. noticed that the continents line up on the mar
* 1915- origin of contains and oceans, outlines theory of continental drift
* proposed continental drift was: continents float on the crust and plough through the crust like a ship plows through ice
* like remark- sound idea, but fault mechanism
* generally dismissed
* correct about continents being in constant motion

biogeography and continental drift: plate tectonics

states that the crust is divided up into large continuous (touching) plates. the plates are in constant motion


1. subduction zones
2. spread zones

plate tectonics show us we can see how fossil communities change when land masses are connected and separated

plate tectonics: subduction zones

when two plates collide, the more dense plate will subduct (go beneath) the other. the less dense plate goes up (mountains)

plate tectonics: spread zones

two plates separate. magma comes up to fill the gap. the force of the magma pushes up both plates (mountainous ridges)

macroevolution: 3. comparative anatomy

homologous and analogous structures and morphological convergence or divergence

comparative anatomy: homologous structures

structures may look the same of may look different BUT the underlying structure is the same

* indicative of common ancestry
* divergence

comparative anatomy: divergence

if they look different its because they’re adapted for different niches

comparative anatomy: analogous structures

looks the same BUT the underlying structure is different

* not indicative of common ancestry
* convergence

comparative anatomy: convergence

they look the same because they have adapted to similar niches (flightless birds are NOT an example of convergence, they are all related). (ex. shark tail moves side to side, whale tail moves up and down)

macroevolution: 4. embryology

states the more closely related two species, the more similar their patterns of embryological development

macroevolution: 5. comparative biochemistry

determines relativeness of species by studying the nucleotide sequence of a gene directly OR study the amino acids of the resulting proteins/enzymes

* the more closely related to species, the more similar their sequences
* often the genes for the proteins in the electron transport chain. it is “highly conserved” in all species meaning it cannot take a lot of mutation and its under the same selection pressure
* its a statistical analysis, a computer does it which removes human bias
* depends on selection pressure
* difficult to know which gene or protein is most appropriate to use