Biol 1200 exam 2

What is speciation?

The evolutionary process which populations evolve from a common ancestor to form new, distinct species

What is vicariance?

The process of closely related species becoming physically isolated by a geographical barrier, like mountains or a river

What is dispersal?

The movement of organisms from their birthplace to a different location to settle down and reproduce.

What is the difference between dispersal and vicariance?

Dispersal is the result of voluntary migration by species, while vicariance refers to a natural situation that physically divides a species.

What is sympatric speciation?

Speciation that occurs without a physical barrier, but due to other reasons such as natural selection causing the species to breed on different fruits or autopolyploidy

Autopolyploidy

Mistake during meiosis/mitosis that causes the offspring to gain duplicate chromosome sets (gametes are diploid not haploid). Chromosomes come from the same species

Allopolyploidy

Offspring gain duplicate sets of chromosomes from two different species due to a hybridization event, which causes the offspring's chromosomes to be double

Systematics

The study of evolutionary relationships through time for the purpose of classification

What happens when isolated populations come into contact?

The two populations will merge together. Other outcomes include reinforcement, hybrid zones and hybridization

Reinforcement

Natural selection increases the genetic isolation between two populations, not allowing them to interbreed

Hybrid zones

A region where evolutionarily independent species interbreed and create offspring that can only exist within this new hybrid zone.

Speciation by hybridization

When two populations with independent evolutionary lineages come into contact and interbreed, creating hybrid offspring (mules, ligers)

8 classes of the taxonomic hierarchy (Big to small)

Domain, kingdom, phylum, class, order, family, genus, species

Binomial species name of Lutjanus Americanus

Genus: Latjanus, Species name: Lutjanus Americanus

What is a phylogeny?

Evolutionary history of a group of organisms

What is the purpose in constructing phylogenetic trees?

Shows ancestor-descendant relationships among populations or species

Taxonomy

Science of describing and classifying new species

What is a cladogram?

A diagram that shows the evolutionary relationships of organisms by shared derived characteristics (traits)

Why is phylogenetic reconstruction difficult?

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What is an outgroup?

The most distant related species in a cladogram used as a point of reference and comparison

Define cladistics

The biological classification of a group of organisms with shared derived characteristics on a diagram

Constructing phylogenetic trees - Phenetic Approach

Classifying organisms based upon their similarities, like morphological structure (body shape) or other observable traits

Constructing phylogenetic trees - Maximum likelihood

A statistical approach that uses a model of evolution to infer phylogeny

Constructing phylogenetic trees - Cladistic approach

Inferring trees based on clades (synapomorphies) of derived characters to infer phylogeny

Major components of a phylogenetic tree - Branches

Represents the estimated amount of time of evolutionary relationships between a species

Major components of a phylogenetic tree - Nodes

Represents a common ancestor shared by two taxa. Node is caused by divergence from common ancestor through a cladogenic event

Major components of a phylogenetic tree - Tips

Terminal nodes, or the end points (most recent species or mutation; or end of line

What is an ancestral character?

A character trait found in the common ancestor that is present in all the organisms/species in that clade

What is a derived character?

A trait that is derived from a ancestral character, but does not apply to all the groups in a given clade

What is a synapomorphy?

Characters shared by a group of taxa that was derived from a common ancestor. Help to understand evolutionary relationships between two species

What is homology?

Similar traits due to a common ancestor

What is homoplasy?

Shared traits that are independently acquired in unrelated lineages

How to differentiate homology from homoplasy on a tree

Homology is similar traits derived from a common ancestor, homoplasy is similar traits independently acquired (no common ancestor)

Major differences between the three domains of life - Bacteria

Single celled, bacteria do not contain a nucleus, are known to cause bacterial diseases. Can also be an extremophile

Major differences between the three domains of life - Archaea

Single celled, different cell wall and membrane composition than bacteria, more commonly exist as extremophiles in nature than bacteria

Major differences between the three domains of life - Eukaryotes

Multicellular, contain a nucleus

Are prokaryotes monophyletic?

No, they are paraphyletic because their most recent common ancestor are eukaryotes

When did prokaryotes first evolve?

Evolved 3.5 billion years ago

How were prokaryotes instrumental in changing the atmosphere?

Evolved to produce oxygen through photosynthesis, allowing for diversification of life

Where can prokaryotes be found?

Omnipresent - Can be found any and everywhere (top of a mountain, bottom of the ocean, hot springs

Why are prokaryotes important?

They act as decomposers, represent a large portion of genetic diversity, useful in bioremediation,

Nitrogen functionality5

All organisms require Nitrogen (N) to synthesize proteins and nucleic acids

Organisms cannot use atmospheric nitrogen (N2) directly; they acquire it through compounds like ammonia (NH3) or Nitrate (NO3).

Bacteria convert N2 into usable compounds

Nitrogen cycle

NO2 (nitrite) produced as a byproduct of bacterial respiration

Nitrite is used as an electron receptor and converted to NO3, for synthetic use by organisms before being converted back to NO2 by bacteria and archaea

What is nitrogen fixation?

The process by which atmospheric Nitrogen (N2) is converted into usable compounds like Ammonia (NH3) or Nitrate (NO3).

Where does nitrogen fixation occur in plants?

Nodules form on the end of roots, which then form a symbiotic (mutually beneficial) relationship with nitrogen fixing bacteria.

What are the basic morphological features of bacteria?

Vary in shape, size and mobility. Can be in the form of rods, spheres, spirals or filaments. Some bacteria are immobile, but others move by swimming or gliding

How does gram-positive bacteria differ from gram-negative bacteria?

Gram positive stain blue; Gram negative stain red. The difference is due to their cell wall structure. Gram positive has a thick cell wall composed of peptodiglycan. Gram negative has a small cell wall encased between two cellular membranes (two phospholipid bilayers)

How do bacteria exchange genetic material and reproduce?

Reproduce by binary fission, exchange genetic material (achieve genetic diversity) by: rapid reproduction, mutations, genetic recombination

Genetic recombination

The combining of DNA from two different sources (horizontal gene transfer) through transformation, transduction and conjugation

Transformation

Takes a piece of DNA floating in it’s environment

Transduction

Through virus

Conjugation

Transferred through tube

Four major modes of prokaryotic metabolism

Photoautotrophy, Chemoautotrophy, Photoheterotrophy, Chemoheterotrophy

Photoautotrophs

Energy source: light, carbon source: CO2. Utilize photosynthesis

Chemoautotrophs

Energy source: Inorganic chemicals (NO3,Fe2), carbon source: CO2

Photoheterotrophs

Energy source: Light, carbon source: organic compounds

Chemoheterotrophs

Energy source: organic compounds, carbon source organic compounds (carbon containing molecules). Humans are an example of chemoheterotrophs

Human/ecological benefits from prokaryotes

Aid in immune system function, food digestion in humans. Useful for bioremediation, decomposition, photosynthesis in the environment

Eutrophication

Nitrogen fixation causes a surplus of nitrogen fertilizer, which runs off into freshwater and marine ecosystems. Results in algal blooms, dead zones and poorer water quality

What domain is eukarya

The domain that contains multicellular and visible organisms like plants, protists, animals, trees and people

What is the endosymbiotic origin of eukaryotes?

An anaerobic eukaryote engulfed an aerobic bacterium which and developed an endosymbiotic relationship.

Evidence of embosymbiotic relationship

Mitochondria are the same size as the average bacterium, replicate with fission, have ribosomes to make their own proteins, have double membranes that is consistent with engulfing theory

Mitochondria are most closely related to what group of bacteria?

Alpha-proteobacteria

What groups are chloroplasts most closely related

Cyanobacteria

What is the difference between primary and secondary endsymbiosis

Primary engulfs a aerobic bacterium, secondary engulfs a photosynthetic protist and loses its nucleus.

Primary has two 2 membranes, secondary has 3-4 membranes

Do protists form a monophyletic group?

No because they are a paraphyletic group because they represent some, but not all, of the descendants of a single common ancestor

What innovative reproductive techniques are first seen in protists?

Sexual reproduction through meiosis and gamete fusion

Haploid and diploid life cycles

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Alternation of generations

The alternation between the sexual phase (haploid gametophyte) and asexual phase (diploid sporophyte) that makes up the life cycle of plants, algae and fungi

What structure produces spores?

Plants, like algae and moss, or fungi, like mushrooms

Sporophyte

What do spores grow into?

Through mitosis, spores grow into haploid gametophyte

Mycelium

What structures produce gametes?

Angiosperms (vascular, flowering plants) sperm,egg

What do gametes grow into?

Through meiosis, gametes grow into diploid sporophytes

What are the ecosystem services of fungi?

Digest cellulose and lignin from wood to obtain sugar and small organic compounds

Advantages and disadvantages of hyphae

High surface area of hyphae allows the fungi to efficiently absorb nutrients and water; this high surface area also makes the fungi prone to drying out (desiccation)

Hyphae

Branching filaments that make up mycelium

Mycelia

The cumulative network of a bunch of hyphae cells

Advantages of mycelia

Helps to close the energy cycle by decomposing organic matter into compounds that are used by the soil.

What are mycorrhizal fungi?

A species of fungi that form a mutualistic relationship with a plant, improving nutrients, growth and water absorption

How do fungi decompose plant tissue?

Fungi secrete an enzyme that breaks down lignin and cellulose, converting complex carbon sources into glucose

How does fertilization of fungi cells occur?

Fusion of cells or fusion of nuclei from fused cells

What is plasmogamy in fungi?

fusion of the cellular contents of two hyphae but not of the two haploid nuclei) results in dikaryotic hyphae in which each cell contains two haploid nuclei, one from each parent.

What is karyogamy in fungi?

The fusion of two haploid nuclei to form a diploid nucleus, or a zygote,

Analysis of sediments shows that Death Valley, California, was once a large, continuous complex of lakes and marshes. Today it is a desert with tiny, isolated springs. Each spring has its own species of desert pupfish. This is an example of which concept?

Vicariance

In North America, fly populations that are adapted for laying their eggs in apples rather than hawthorn fruits are diverging into separate species-even though apples were introduced just a few hundred years ago. Which of the following facts is most important in making this divergence possible?

These flies mate on the fruit that they feed on

The pollen from one orchid species fertilizes a closely related orchid and the resultant progeny has the chromosome of both species. You know that this individual is a(n):

Allopolyploid

Presume the following genetic data: Base#: 123 456 789

ancestral population: TTT CAT CCA

descendant population #1: TTG CAT CCG

descendant population #2: TTT CAA CCG

Which base numbers represent synapomorphies?

Base 3 and 6

Consider the wings of bats and birds. What two biological structures/characteristics describe their relationship?

Their limbs are homologous; Their wings represent homoplasy

Recent work has shown that homologous genes are involved in the early development of ray-finned fish fins and tetrapod limbs. Does this data support the data in the fossil record or conflict with it?

Support- If limbs and fins are homologous, they should arise from homologous genes

You find a euphorbia species that looks very similar to a cactus. These plants are in separate families. Which of the following would convince you that the similar appearance of these plant families was homologous?

You learn that the two plant families had a common ancestor with these traits

You find a new species of bacterium and determine that it is comprised of cells that are Gram-positive. Which of the following traits would you expect to observe in your new discovery?

A thick wall composed of peptidoglycan

What would you expect to occur if a new virus emerged that killed the bacteria and archaea that nitrificate NO2– into NO3–?

A decrease in atmospheric N2

A polytomy on a phylogenetic tree represents

Insufficient data to determine lineage relationship

A potential source of confusion in constructing a phylogeny tree is similarity between organisms that is due to

Convergent evolution

What is the principle of maximum parsimony

The preferred tree is the one that minimizes the amount of evolutionary change

What do sister taxa represent?

Groups of organisms that share an immediate common ancestor

The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds and mammals are the result of?

Homoplasies

What evidence suggests that limbless bodies are the result of convergent evolution of snakes and lizards?

Snakes and lizards with limbless bodies evolved from different ancestors of legged lizards

When using a cladistic approach to systematics, which of the following is considered most important for classification?

Shared derived characters

Which of the following types of taxa are problematic when the goal is to construct phylogenies that accurately reflect evolutionary history?

Polyphyletic and Paraphyletic taxa