BSCI 160 Exam 3

Analagous Structures

Similar structure without having a common ancestor

Homologous Structures

Structures in different species that are similar because of common ancestry.

Ways to create Tree of Life

Fossil Analysis, Phylogenetic Analysis (DNA analysis, Cladograms)

Phylogeny

Branches and connections on the Tree of Life

Cladogram

Diagram that estimates the phylogeny

Cladistics

A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa.

Clade

A group of species that includes an ancestral species and all its descendants.

Synapomorphy

shared derived trait

Monophyletic

ALL descendants came from one common ancestor, the same as a clade, which implies a close relationship. (Ex: Mammals)

Polyphyletic

Pertaining to a group of taxa that includes distantly related organisms but does not include their most recent common ancestor. (Ex: birds + bats)

Paraphyletic

Consists of an ancestral species and some, but not all, of its descendants. Not used in cladistics. (Ex: Reptiles)

Two principal methods for reconstructing phylogeny

Outgroup Analysis, Parsimony

outgroup analysis

distinguishing derived from primitive similarity

Parsimony

Cladogram requiring the fewest evolutionary changes is preferred.

Biological Species Concept (BSC)

Species is a group of populations whose members have the potential to produce viable, fertile offspring.

Hybrids

Offspring that area mix of two different species. (Liger, Donkey)

BSC Limitations

Difficult to apply in cases of fossils, does not apply to asexual organisms

other speciation models

Morphological (looks at structural similarities), Phylogenetic (smallest group on tree), Ecological (viewed in terms of niche)

Prezygotic Barriers

prevent formation of a zygote or fertilized egg. (Habitat isolation, Temporal isolation, Behavioral isolation, Mechanical Isolation, Gametic Isolation)

Postzygotic Barriers

Prevent the hybrid zygote from developing into a viable, fertile adult. (Lower fitness, offspring infertility, generational infertility)

Allopatric Speciation

The process of speciation occurs with geographic isolation. (Founder's Effect + Natural Selection)

Reinforcement

Hybrids are usually inviable, so nature favors assortative mating. (Mating with your own kind)

Fusion

Fit hybrids mate and make the two species one.

Sympatric Speciation

The formation of new species in populations that live in the same geographic area.

Allopolyploidy

polyploidy resulting from contribution of chromosomes from two or more species

Adaptive Radiation

The diversification of a group of organisms into forms filling different ecological niches.

Evolution

Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.

Basic Evolutionary Mechanisms

Mutation, Genetic Drift, Migration, Natural Selection

Macroevolution

Evolutionary change above the species level. Patterns of broad scale change, diversification and extinction.

Anagenesis

Single species evolves into a different species

Cladogenesis

Branching evolution occurs when a new species branches out from a parent species.

Gradualism

A proposed explanation in evolutionary biology stating that new species arise from the result of slight modifications (mutations and resulting phenotypic changes) over many generations.

Stasis

Long period of subtle evolutionary change. Caused by stabilizing selection, lack of change in environment.

Punctuated Equilibrium

The pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change. (Note: "Brief" period can still be more than a million years)

Mosaic Evolution

A phenotypic pattern that shows how different traits of an organism, responding to different selection pressures, may evolve at different rates

Cambrian Explosion

A burst of evolutionary origins when most of the major body plans of animals appeared in around 50 million years; due to high oxygen levels. Example of "rapid evolution"

Ecological Opportunity for rapid diversification

Extrinsic: creation of new niches

Intrinsic: New "innovations" like flowers or wings

Evolutionary Novelty methods

Exaptation, Duplication, Serial Homology, Heterochrony, Lateral Gene Transfer, Homeotic Genes

Exaptation

The process in which existing structures take on new functions through descent with modification. (Ex: wings were originally heat collection devices.)

Duplication

Duplicated genes can form novel functions

Serial Homology

Repetitive segments in the same organism can specialize.

Heterochrony

Evolutionary change in the timing or rate of an organism's development.

Lateral Gene Transfer (LGT)

The transfer of genes between lineages that are not descended from one another. (Ex: human mitochondria and mitochondrial DNA)

Homeotic Genes

Genes that determine basic features of where a body part is. (HOX genes)

Early Earth

Formed 4.5 bya, very hot, low oxygen

Introduction of Oxygen

Came from photosynthetic bacteria 2.5 bya, proof in banded iron formation

Prokaryotes

Dominant life form on Earth, high metabolic diversity, simple structure, began 3.8 bya

Prokaryotes vs. Eukaryotes

No nuclear envelope

No membrane bound organelles

Circular DNA (not wrapped around histones)

Binary Fission

Lateral Gene Transfer

Gram-positive Bacteria

Have peptidoglycan cell wall

Prokaryote genome

small, diverse, haploid, no sex

Plasmid

A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome

Mechanisms of Lateral Gene Transfer in Bacteria

transformation, transduction, conjugation

Transduction

genes via virus (bacteriophage)

Conjugation

Exchange of plasmids from live bacteria

Transformation

genes from environment like dead bacteria

Metabolism

All of the chemical reactions that occur within an organism, requires energy and carbon

Enery source

phototrophs (light) and chemotrophs (chemical compounds)

Carbon Source

autotrophs (CO2), heterotrophs (consume organic compunds)

Glycolysis

the breakdown of glucose by enzymes, releasing energy

aerobic respiration

Respiration that requires oxygen, yields lots of ATP

Archaea

One of two prokaryotic domains, the other being Bacteria.

Methanogens

Archaea that release methane, a greenhouse gas. Oxygen will kill them

Halophiles

"salt-loving" archaea that live in environments that have very high salt concentrations

Thermophiles

Archaea that thrive in very hot environments, such as volcanic springs.

Acidophiles

Achaea that live in pH below 1.0

Origin of Eukaryotes

Autogenous Theory: evolved from ancestral prokaryote

Endosymbiosis Theory: Eukaryotes came from one organism living inside another (mitochondria & chloroplasts)

secondary endosymbiosis

when a living cell engulfs another eukaryote cell that has already undergone primary endosymbiosis

Protists

A eukaryotic organism that cannot be classified as an animal, plant, or fungus.

Eukaryotes

protists, plants, animals, fungi

Plant origins

Closest relatives of modern plants are green algae (E.g. Charophytes), chlorophyll, cell wall, starch

Charophyceans

A member of the green algal group that are considered the closest relatives of the land plants.

Reasons why life in water is easy

Lots of nutrients

supported against gravity

gametes transported via water

no desiccation (removal of water)

Why leave da water?

direct sun

new nutrients on land

abundant CO2

new niches

Land evolution of plants

in response to what they do not have on land

4 radiations of land plants

Nonvascular, ferns, gymnosperms, angiosperms

sporophyte

The stage in the life cycle of a plant in which the plant produces spores.

gametophyte

The stage in the life cycle of a plant in which the plant produces gametes.

Nonvascular plants (bryophytes)

Do not have vascular tissues to conduct water and provide support (moss)

Ferns

seedless vascular plants

Gymnosperms

A plant that produces seeds that are exposed rather than seeds enclosed in fruits. (Conifers)

Angiosperms

flowering plants (extremely successful)

Cuticle

A waxy covering on the surface of stems and leaves that acts as an adaptation to prevent desiccation in terrestrial plants.

xylem and phloem

2 types of vascular tissue

Role of fruits

Promote dispersal

3 origins of multicellularity

animals, plants, fungi

Metazoans

animals

Origin of Metazoans

come from protists, multicellularity independent from fungi and plants

Porifera (sponges)

lack true tissues; have choanocytes and amoebocytes, asymmetry, asexual reproduction