Exam 4 - Organizing Species, Protists, Plants

What is taxonomy?

A field of biology concerned with identifying, naming, and classifying species.

What is phylogenetics?

The scientific study of evolutionary relationships among lineages and species.

Phylogenetic tree

Hypothetical evolutionary history showing the relationships between phylogenies

Outgroup

Species/lineage not closely related to any other member of the group understudy

Sister groups

Two lineages that emerge from the same mode

Derived character

A trait shared by all members of clade that evolved in that clade’s common ancestor

Monophyletic group

A group including an ancestral derived character with all of its descendants

Polyphyletic group

A set of organisms that are grouped together based on similar traits, but do not include their most recent common ancestor.

Ex: Elephants, rhinoceroses, hippopotamuses, and tapirs and are group together in a single category because they share specific traits such as

• Thick skin

• Large heavy bodies

• Herbivorous diets

What is the assumption of parsimony?

The simplest explanation that fits the evidence is the best one

What are derived traits?

Traits different from those of the group’s ancestor

The best phylogeny is the one that requires the ______ ______ _______

Fewest evolutionary changes

Homologous structures indicate _____ ______

Evolutionary relationships

Ex: Shared bone structure across reptiles, birds, and mammals

Analogous structures indicate fulfilling a similar __________ ____

Environmental niche

Ex: Appear via either convergence or reversal

Convergence

Developing similar structures due to pressures from environmental niche

Reversal

Loss of structure due to pressures from environmental niche

All organisms use the same:

• Energy molecule

• Nucleotides

• Cell cycle

• Phospholipid cell membranes

• Oxygen for respiration

• 20 amino acids

All organisms are descended from a _____ _____?

Common ancestor

What is a cladogram?

Represents a hypothesis of relationships among organisms

What are some of the eukaryotic traits?

• Multiple linear chromosomes inside a nucleus

• Membrane-bound organelles

• Mitochondria or mitochondria-derived organelles

What is the endosymbiont hypothesis?

Mitochondria and chloroplasts evolved from bacteria

What are some of the general protist traits?

• Variety of organization strategies

  • Unicellular

  • Some are colonial (living as a collection of independent cells)

  • Multicellular

• Most have typical eukaryotic organelles

List some more of the general protist traits

• Most have a protective layer on their cell surface

• Variety of locomotive strategies

  • Swimming with flagella

  • Swimming using cilia

  • Crawling around using pseudopods

  • Some don’t move at all

List some more of the general protist traits

• Majority are free-living and aquatic

• Some live in moist soil

• Some live on or inside other organisms

List some more of the general protist traits

• Most reproduce asexually when conditions are favorable then switch to sexual reproduction

• Variety of lifecycles

  • Some are haploid

  • Some are diploid

  • Multicellular algae alternates between haploid and diploid forms

What are excavates? (Protist)

• Unwalled cells with 1+ flagella

• Have an “excavation” groove for feeding

What does the SAR supergroup stand for?

S: Stramenopiles

A: Alveolates

R: Rhizaria

What are characteristics of stramenopiles?

• Have short anterior flagellum with hairlike extensions

• Most are photosynthetic

What are the characteristics of the diatom lineage within stramenopiles?

They are photosynthetic with silica shell

What are the characteristics of brown algae and what group do they belong in?

• Multicellular and photosynthetic

• Stramenopiles

What are the characteristics of water molds and what group do they belong in?

• Heterotrophic parasites with cellulose cell walls

• Stramenopiles

What are the characteristics of alveolates?

Have sacs beneath their plasma membrane (may be empty or contain cellulose)

What are the characteristics of ciliates and what group do they belong in?

• Heterotrophs covered in cilia

• Have two nuclei (macro & micro)

Alvelolates

What are the characteristics of dinoflagellates lineage and what group do they belong in?

• Have two flagella

Alveolates

What are the characteristics of apicomplexans lineage and what group do they belong in?

Parasites with a secretory vesicle complex on their cell apex

What are the characteristics of Rhizaria?

Nearly all are single-celled, marine heterotrophs with a protective shell

What are the characteristics of foraminifera lineage and what group do they belong in?

• Shell is made of calcium carbonate

• Most settle on bottom of the ocean among sediments

Rhizaria

What are the characteristics of radiolaria lineage and what group do they belong in?

• Shell is made of silica

• All live suspended in ocean water column (planktonic)

Rhizaria

What are the characteristics of Archaeplastids?

• Have cellulose cell walls and chloroplasts with two membranes

What are the characteristics of radiolaria lineage and what group do they belong in?

• Chloroplasts have chlorophyll a and red accessory pigments

Archaeplastids

What are the characteristics of green algae lineages and what group do they belong in?

• Chloroplasts have both chlorophyll a and chlorophyll b

  • Land plants evolved from within these lineages

Archaeplastids

What are the characteristics of amoebozans?

• Heterotrophs that moves using cytoplasm extensions (pseudopods)

• Amoebas lineage

  • Single-celled

  • Most are predators, some are parasites

What are the characteristics of amoebas lineage and what group do they belong in?

• Single-celled’

• Most are predators, some are parasites

Amoebozoans

What are the characteristics of slime molds lineage and what group do they belong in?

• Live as an aggregation of individual cells (cellular) or as a multinucleated mass (plasmodial)

Amoebozoans

What are the characteristics of opisthokonts?

• Heterotrophs

• Choanoflagellates lineage

  • Most are single-celled with a flagellum surrounded by a “collar” or threadlike projections

  • Animals evolved from within this lineage

What are the general plant traits?

• All are multicellular

• All have cell walls made of cellulose

• All have chloroplasts with two membranes

• All store sugars as starch

• All form and develop their embryos within a chamber composed of maternal tissues (embryophytes)