Bio Exam 2

Define speciation

a splitting event that creates two or more distinct species from an ancestral species

Contrast the different species concept

Morphological, biological, phylogenetic

What is morphological species?

Identify species by differences in size, shape and other morphological features

What is biological species?

Based on reproductive isolation – if two different population do not produce viable offspring in nature, then they are considered two species

What is phylogenetic species concept?

– monophyletic group of an ancestral population, all of its descendants and only those descendants

-based on DNA analysis

what are the two types of reproductive isolation barriers?

prezygotic and postzygotic

what is pre-zygotic isolation?

Individuals of different species are prevented from mating successfully

what is postzygotic isolation?

The hybrid offspring do not survive or reproduce.

what are prezygotic isolation barriers?

temporal, habitat, behavioral, gametic barrier, mechanical

what is a temporal barrier?

breeding occurs at different times

what is a habitat barrier?

breeding occurs at different habitats

what is a behavioral barrier?

aren’t attracted to eachother because of behavior

what is a mechanical barrier?

reproductive structures are incompatible

physically can’t reproduce

what is a gametic barrier?

egg/sperm are incompatible

what are postzygotic barriers?

hybrid viability and hybrid sterility

what is a hybrid viability barrier?

when offspring do not develop normally resulting in high mortality

What is a hybrid sterility barrier?

when offspring can’t reproduce

ex: horse + donkey=mule

What are mechanisms that can lead to speciation?

allopatric speciation (occurring through geographic separation) and sympatric speciation (occurring in same geographic area)

Relate evolutionary history to the speciation sequence and species relatedness

• Evolutionary history is the study of how species have evolved over time

  • It involves understanding the relationships between different species and how they are related to one another

• Speciation is the process by which new species arise from existing ones

  • It occurs when populations of a single species become isolated from one another and evolve independently, eventually becoming so different that they can no longer interbreed.

• The sequence of speciation events can be represented using a phylogenetic tree, which shows the evolutionary relationships between different species

  • The more recent the common ancestor of two species, the more closely related they are

  • the more distant they are, the less closely related they are

Compare and contrast sympatric and allopatric speciation

contrasting: allopatric speciation requires geographic isolation, while sympatric speciation does not

• allopatric speciation: isolated populations evolve independently, eventually becoming so different that they can no longer interbreed (driven by natural selection)

• sympatric speciation: occurs when new species are evolved due to polyploidy (cell/organism has more than 2 chromosomes)

  • error in cell division

the same: Both are mechanisms by which new species come from existing ones.

• both involve the formation of new, distinct species from pre-existing ones through reproductive isolation of individuals

Explain the circumstances under which sympatric speciation can occur

• occurs when two groups of the same species live in the same geographic location, but they evolve differently until they can no longer interbreed and are considered different species

• can occur through polyploidy (doubling of chromosomes) or

• disruptive selection (organisms with extreme traits are favored over those with intermediate)

  • ex: beak sizes of finches. due to scarcity of resources, finches with intermediate beak sizes aren’t favored so their generation will die and the population of finches with large and small beaks will rise.

What is taxonomy?

a formal system for naming and classifying species.

the ranks from most general to specific: kingdom, phylum, class, order, family, genus, species

what is systematics?

the study of evolutionary relationship among organisms

What is this part of the cladogram?

nodes; shows ancestors

what is this part of the cladogram?

branches; indicate related groups and their common ancestors

What are these parts of the cladogram?

taxa: any organism at the tip of the tree

What are sister taxas?

taxa that share an ancestor, each other’s closest relative

What are monophyletic (monophyly) groups (or clades)?

a group that includes a single ancestor and all of its descendants

what are paraphyletic (paraphyly) groups?

exclude descendants of common ancestors

What are polyphyletic (polyphyly) groups?

grouping of organisms that does not include the most recent common ancestor of all members of the group

What is a homology?

characteristics similar due to descent from a common ancestor

ex: the wings of birds and bats are homologous because they are derived from the same ancestral tetrapod structure

What is a homoplasy?

characteristics similar due to independent evolution

ex: the wings of birds, bats, and insects are homoplastic because they have similar functions but different evolutionary origins

What is a synapomorphy?

a shared, derived characteristic that is common between an ancestor and its descendants

example: in the clade of terrestrial vertebrates, owls and parrots have the same synapomorphy characteristics of “two legs and two wings” stating they are closely related

What is pleisomorphy?

a character or trait shared by some or all members of a phyogenetic group and their common ancestor but is not unique to that group

what is convergent evolution?

a process in which organisms that are not closely related independently evolve similar features

ex: The Saber-Toothed Tiger and Thylacosmilus possessed giant, downward-curving canines with which they inflicted fatal puncture wounds on prey.

What is parsimony?

most likely explanation is the simplest one

Watch Khan Academy phylogeny tree video

how are fossils formed?

when an organism dies and is quickly buried by sediment.

what is the punctuated equilibrium?

change occurs rapidly and in brief geological events

What is adaptive radiation?

rapid increase in the number of species with common ancestor, characterized by great ecological and morphological diversity…which leads to speciation

1. mass extinction events

2. colonization events

3. evolutionary innovations

Describe long-term patterns of speciation and extinction

extinction rates have been higher than speciation rates throughout Earth’s history

• has led to a decline in Earth’s species over time

speciation rates have been high during environmental change

• when new habitats/resources become available, organisms may evolve new adaptions that allow them to use the resources more efficiently

Identify when major mass extinctions have occurred

end Ordovician: occurred about 444 million years ago and 85% of species were lost

late Devonian: occurred about 375 million years ago, about 75% of all species were lost

end Permian: occurred about 250 million years ago and 96% of species were lost

end Triassic: occurred about 200 million years ago and about 80% of species were lost

end cretaceous: occurred 65 million years ago and resulted in the loss of dinosaurs

Describe the structures and organization of prokaryotic cells

• cells that lack a nucleus

• cytoplasm

• chromosome (DNA)

  • singular

• nucleoid

• plasmids-sites for manufacturing proteins

• cell wall

• plasma membrane

Describe the evolutionary relationships between, bacteria, archaea, and eukarya

• bacteria/archea are prokaryotic (lack a nucleus)

  • differ in the types of RNA polymerases they use to transcribe DNA into RNA

• eukarya evolved from archaea through endosymbiosis (when one organism lives inside another)

• eukarya and archea are more related

Contrast the mechanisms of DNA exchange in Bacteria

1. conjugation-physical contact through pilus

2. transformation- pickup genetic information from cells around in the environment

3. transduction-DNA is accidentally moved from one bacterium to another by a virus.

Explain the evidence that microbial life was present on earth 3 billion years ago

1. microfossils in rocks that are about 3.5 billion years old

   -represent modern-day tiny bacteria

2. scientists also found evidence in billions of years of sulfur isotope ratios

   -life thrived in ancient oceans

Describe how different types of energy led to diversification

energy diversification is the process of using a variety of energy sources minimize risk and increase energy security.

1. renewable energy sources: solar, wind, and hydroelectric

2. nuclear power

Describe the functional diversity of prokaryotic life

a big part of the diversity is based on metabolic diversity

metabolism= the chemical reactions occurring within the cell that convert molecules into other molecules and transfer energy in living organisms

what is aerobic respiration?

cellular respiration that takes place in the presence of oxygen

what is anaerobic respiration?

cellular respiration that occurs in the absence of oxygen

what are the classification methods for prokaryotes?

morphology (shape) and gram staining

What shape is coccus?

circular

What shape is bacillus?

cheeto puff

what shape is coccobacillus?

jellybean

what shape is vibrio?

boomerang

what shape is fusiform bacillus?

olive garden breadstick

what shape is spirillum?

long curvy noodle

What shape is spirochete?

a worm

when bacteria clumps together in the form streptococci…it looks like:

what bacteria clumps together in the form staphylococci, it looks like:

grapes

What are extremophiles?

live in extreme environments:

-freezing to hot temps

-super salty water

-very acidic

-1 mile deep into earth

Apply evolutionary concepts to explain rapid drug resistance exhibited by prokaryotes/Describe the properties of prokaryotes that facilitate their rapid evolution

1. rapid reproduction because of their small size

2. horizontal/lateral gene transfer-allows successful genes to pass quicker

3. asexual reproduction-cloning themselves perfectly

Describe how viruses are classified

shapes and the Baltimore system

-Baltimore system=different types of nucleic acids/modes of replication

Describe the general characteristics of viruses

-high mutation rates

-have a capsid (genome packaged inside protein coat), envelope (lipid membrane)

autotrophs

self-synthesized from C02, CH4, or other simple molecules

heterotrophs

from molecules produced by other organisms

phototrophs

from sunlight

chemoorganotrophs

from organic molecules

chemolithotrophs

from inorganic molecules