Mississippi State University BIO 1144 - Exam 1

Taxonomy

science of describing, naming, and classifying extant species (those that still exist today) as well as extinct species (those that have died out) + viruses

Systematics

The study of evolutionary relationships among organisms

Taxonomy is hierarchal, and each section is called a:

taxon

All of life is groups into three categories:

1) Bacteria (prokaryotic/no nucleus)

2) Archea (prokaryotic/no nucleus)

3) Eukarya (eukayotic/nucleus)

Supergroup

lies between a domain and a kingdom;

eukaryotic contains 7 supergroups

Binomial Nomenclature

- classification system in which each species is assigned a two-part scientific name

- proposed by Carolus Linnaus in 1753

(ex: Homo sapiens)

Phylogeny

evolutionary history of a species or group of species

How does historical/past Phylogeny different from modern Phylogeny?

historically: morphologically/molecular structures

modern: genetic data (DNA, protein sequences, etc.)

phylogeny tree

branching diagram depicting phylogeny based on information collected and gathered by systematists

- hypothesis of evolutionary relationship among various species

- based on available information

- estimated evolutionary relationships

phylogenetics

science of constructing evolutionary trees

parts of phylogeny/evolutionary tree

how can new species be formed?

anagenesis and cladogenesis

anagensis

evolution of a trait or a species into another over a period of time (single species)

cladogenesis

a species diverges into two or more species

nodes indicate what?

when cladogenesis occurred (diverging of two or more species)

clade

consists of a common ancestral species and all of its descendant species

What are the three taxonomic groups?

1) monophyletic

2) paraphyletic

3) polyphyletic

monophyletic

taxon that is a clade, contains All descendants from last/SAME common ancestor

paraphyletic

group w/ SOME descendants from last common ancestor

polyphyletic

descendants have DIFFERENT last common ancestor

As scientists learn more about evolutionary relationships, taxonomic groups are reorganized to recognize only _____________________ groups

monophyletic

The study of systematics is usually based

on:

morphological or genetic homology

The first studies in systematics focused on ___________________ ___________ of extinct and living species

morphological features

What do we use now in systematics?

molecular features (genetic data, such as DNA sequences or amino acid sequences) to identify and study genetic homologies + propose phylogenetic trees.

horizontal gene transfer / lateral gene transfer

proces in which organisms get genetic material from other organisms WITHOUT being the offspring of that organisms; no sexual reproduction

vertical gene transfer

descent from common ancestor WITH sexual reproduction

4 Members of the domain Eukarya

1) Protists

2) Animals

3) Fungi

4) Plants

All members of the domain Eukarya have a __________________ structure.

eukaryotic

Eukaryotic

"true nucleus"

- nucleus (well defined)

- membrane bound organelles

- divide by mitosis or meiosis

- linear chromosomes

The domain, Archaea and Bacteria, have what type of cell?

prokaryotic

Prokaryotic

"before nucleus"

- no nucleus

- lack mem. bound organelles

- divide by binary fission

- circular chromosome (in nucleoid region)

Bacteria

- data dates back to 3.5 billion years ago

- free living or symbiotic

- uni or multicellular w/ cell differentiation

- some are photosynthetic (cyanobacteria)

- some are causative agents in human disease

Archaea (archaebacteria)

prokaryotic: no nucleus, cytoskeleton, organelles, and are a SINGLE circular chromosome

- share many same genes as the eukaryotic organisms

- ARE NOT disease agents

- often found in harsh, extreme environments

There are currently 3 domains of life. However, what does new data suggest?

New data suggest that Eukaryotes arose from Archaea, so there should be a 2 domain system.

Eukaryotic Diversity: Protist

"catch all category"

- used to describe eurk. org. that are NOT plants, animals, or fungi

- earliest eurk. in fossil records

- most are microscopic

Eukaryotic Diversity: Algae

"plant-like" organism

- 10 groups (autographic)

- uni or multicellular

cell wall = cellulose

Eukaryotic Diversity: Protozoans

"animal-like" organisms

- mostly heterotrophic

- many unicellular

Eukaryotic Diversity: Fungal-Like Protists

- mostly saprotrophic (absorb feeling)

- mostly multicellular

Fungi

- body = mycelium

- "fruiting body" = site of spore production

- cell wall = chitin

- "nature recycle" = decompose

- many parasitic forms

does have several important symbiotic relationships (lichens, mycorrhizae, etc)

Plant Diversity

- evolved from uni/simple multicellular green algal ancestors

- cellulose cell wall

- autotrophic (used chlorophyll A + B)

- starch (food storage compound)

Plants needed special innovations. Why and give examples.

- they had to live on land, so they had to accommodate to a new environment

Ex: Roots, spores, seeds

How many phylas are in the kingdom (of plants)?

10

Four Broad Categories of Plants:

1) Non-vascular Plants (Bryophytes / Liverworts, Mosses, and Hornworts)

2) Vascular Seedless Plants (Fern, Horsetails, and Club Mosses / Lycophytes and Pteridophytes)

3) Gymnosperms

4) Angiosperms

Non-Vascular Plants - Liverworts, Mosses, and Hornworts (Bryophytes)

- Lack xylem and phloem tissues

- Lack true roots. Have rhizoids instead.

- require external H2O for reproduction

- produces unicellular SPORES during fertilization

- have an alternation of generations life-cycle where the haploid (1n) gametophyte is the dominant stage as opposed to the diploid (2n) sporophyte.

Non-Vascular Plants Alternation

xylem and phloem

specialized tissues in vascular plants for the transport of food and waters

xylem = water/minerals

phloems = food/solutes

Vascular Seedless Plants (Fern, Horsetails, and Club Mosses / Lycophytes and Pteridophytes)

- fertilization DOES NOT produce seeds

- has xylem and phloem

- 'true' root/leaves/stem system (due to vascularized)

- vascular tissue allows for larger size

- require external H2O for reproduction

- have an alternation of generations life-cycle where the diploid (2n) sporophyte. is the dominant stage as opposed to the haploid (1n) gametophyte

Vascular Seedless Plants Alternation

Gymnosperms

- biggest groups are conifers

- vascular seedless plants, contains xylem and phloem

- seeds are complex characters because they are not enclosed inside a structure; seed has 'survival value'

- contains embryo, stored food, 1 integuments.

- DOES NOT require external H2O for reproduction (uses pollen)

- have an alternation of generations life-cycle where the diploid (2n) sporophyte. is the dominant stage as opposed to the haploid (1n) gametophyte

Gymnosperms Alternation

Angiosperms

- produce flowers, fruits, most advanced vascular tissues and seeds

- seeds are complex character because seed is enclosed in a vessel (fruit). seed has 'survival value'

- Contains embryo, stored food, 2 integuments.

- DOES NOT require external H2O for reproduction (uses pollen)

- have an alternation of generations life-cycle where the diploid (2n) sporophyte. is the dominant stage as opposed to the haploid (1n) gametophyte

- flowers - attract pollinators

- fruits - enclose/protect seeds AND assist with seed dispersal

Angiosperm Alternation

Metazoans/Kingdom Animalia

- >1.7 million

- animals --> monophyletic groups

- 35 phyla

- more similar w/ animal genomes than other kingdoms

Characteristics of Metazoans:

- multicellular

- lack a cell wall

- sexual reproduction: mobile small sperm + immobile large egg

- nervous tissue = complexity

- hox genes

Hox Genes:

series of genes that controls the organs and tissues that develop in various parts of an embryo; patterning the body axis

Common Characteristics of Animals (in Chart)

"Metazoans" means:

multicellular animal

- parazoans - sponges

- eumetazoans - "true" multicellular animals

Differences in Animal Phyla:

1) Body Symmetry

2) Number of Tissue

3) Germ Layers (??)

Body Symmetry: Three Types of Body Symmetry

Asymmetric: display no form/plane of symmetry

Radial Symmetry: divided equally by any longitude plane passing thru the central axis

Bilateral: divided along vertical plan to create 2 halves

- non-identical dorsal

- ventral sides

- anterior (head)

- posterior (backside)

Most animals are:

bilateral (in symmetry)

Tissue

a group of similar cells + extracellular matrix that carry out a open function

- divided on whether or not they have specific functions

Parazoa: Tissue or Not

NO tissue (everything that isn't a parazoa under the Metazoan/Animalia Kingdom have tissue)

Germ Layers

radial and bilateral symmetrical animals differ by embryonic cell layers

Germ Layers of Radial Symmetry?

2 layers: endoderm + ectoderm

Germ Layers of Bilateral Symmetry?

3 layers: endoderm, ectoderm, and mesoderm

- form nucleus + other organs

When does the germ layer develop?

during gastrulation

Blastopore

the opening of the central cavity of an embryo in the early stage of development

Protostomes

blastopore becomes mouth (mouth is formed first)

Deuterostomes

blastopore becomes anus (anus is formed first)

What used to construct phylogenies? What do we use now?

- morphological data (past)

- molecular data (RNA, DNA, proteins, etc) (now)

Body Cavity / Coelom

a fluid or air filled space located between the digestive tract and the outer body wall (for Humans, at least)

Coelom (body cavity) Characteristics

- cushion internal organs

- enables movement

- gives shape + support

- simple circulatory system (fluid)

coelomates (eucoelomates)

organisms w/ true coelom; completely lined w/ mesoderm

- ex: earthworms, snails, starfish

pseudocoelomates

organisms whose coelom only have a partially lined mesoderm

- ex: roundworms

acoelomate

organisms that lack a body cavity; instead posses mesenchyme

- ex: flatworm (only species thus far with this specification)

segmentation

body may divide into segments/regions

(ex: occurs in annelid worms)

This allows specialization of body region

molecular view on animal diversity:

- we use molecular techniques to classify animals

why do we use these molecular techniques?

to compare DNA, RNA, and rRNA/amino acids to classify animals

- closely related organism have fewer differences than more distant relatives

rRNA is better in molecular systematics than other molecular techniques. why?

all organisms have ribosomes

(in fact, the duplication of genes may have evolved from complex body forms (ribosomes basically helped up to evolve!! ... maybe))

phylogenies constructed with rRNA and Hox genes have what properties?

- similar + often agree with those based on morphology (almost all animals have Hox genes)

invertabrates:

- fossils from 570 million - 1.2 billion y.a

- have no backbone

- 90% of animal species

number of main phylas in invertebrates?

10! in this book

(there are actually 34 or 35... science is tricky)

1) Porifera

(sponges)

- lack/no specialized tissue

- asymmetrical body (absent)

- no nervous system

- no body cavity/coelom - acoelomate

- lack segmentation

- lack hox genes

- have choanocytes, specifically flagella cells that act to circulate water for internal cavity to digest food

- filter feeders

2) Ctenophora

(comb jellies)

- earliest diverging animal

- have tissue but no organs

- triploblastic (3 germ lines)

- radial symmetry

- no nervous system

- no body cavity/coelom - acoelomate

- lacks segmentation

- lack hox genes

- hermaphrodites (female and male sexual organs)

- bioluminescence

- use cilia for movement

- use "sticky" tentacles for catch prey

- have larva + adult stage

3) Cnidaria

(jellyfish, coral, etc)

- have tissue but no organs

- radical

- no nervous system

- diploblastic (2 germ lines)

- no body cavity/coelom - acoelomate

- lacks segmentation

- nermocytos: stinging structures that capture food

- have two forms: Medusa (adult) and Polyp (young)

4) Platyhelminthes

(flatworms, tapeworms)

- have organs

- bilateral

- nervous system (nerve net)

- triploblastic (3 germ layers)

- no body cavity/coelom - acoelomate

- lacks segmentation

- one opening (mouth = open + entry); protostomes

- free living + parasitic forms

5) Rotifera

- have organs

- bilateral - simple brain

- nervous system

- triploblastic (3 germ layers)

- pseudocoelom

- lacks segmentation

- separate mouth + anus

6) Bryozoa + Brachiopods

- have organs

- bilateral

- nervous system, but reduced

- triploblastic (3 germ layers)

- coelomates

- lacks segmentation

- complete gut track - protostomes

7) Mollusca

(snails, slugs, etc)

- have organs

- bilateral

- have a nervous system

- triploblastic (3 germ layers)

- coelomates

- lacks segmentation

- complete gut track + protostomes

8) Annelida

(segmented worms)

- have organs

- bilateral

- have a nervous system (enhanced)

- triploblastic (3 germ layers)

- coelomates

- have segmentation

- complete gut track + protostomes

9) Nematoda

(roundworms)

- have organs

- bilateral

- have a nervous system (enhanced)

- triploblastic (3 germ layers)

- pseudocoelom

- lacks segmentation

- complete gut track + protostomes

- some are parasites

10) Arthropoda

(arachnids, crustaceans, insects)

> 1,000,000 species; most diverse

- have organs

- bilateral

- have a nervous system

- triploblastic (3 germ layers)

- coelomates

- has segmentation

- complete gut track + protostomes

- complex brain

- hardened exoskeleton - chitin

11) Echinodermata

(starfish, sea urchins)

- have organs

- bilateral larvae, radial adults

- has a nervous system (simple)

- triploblastic (3 germ layers)

- coelomates

- lacks segmentation

- complete gut track + deuterostomes

Phylum: Chordates

- deuterostome

- complete gut tract

- exoskeleton; always internal with muscle attached for permitting movement

- eucoelomate

- triploblastic

- bilateral symmetry

Four Critical Innovations for the Body

1) Notochord

2) Dorsal

3) Pharyngeal gill/silts

4) Postanal Tail

(featured at some point in history)

1) Notochord

- stiff yet flexible cartilaginous supporting rod along dorsal axis

- provide skeletal support for early diverging chordates

- replaced by jointed "backbone"

2) Dorsal Hollow Nerve Cord

- differs for nerve cord of non-chordates

- expanded at anterior end

- replaced by "brain"

3) Pharyngeal gill pouches/silts

- pharynx: back of mouth

- filter feeding pouches (early diverging chordates)

- gills for gas exchange is for aquatic vertebrates

- those that do not fully form + modify are for terrestrial

4) Postanal Tail

- extend past posterior anus

- locomotions (aquatic chordates)

- variety of function

- non chordates = end of body (for anus)

Humans Development/Evolution of Four Innovations:

1) notochord = replaced as series of bony elements (vertebrates)

2) nerve cord = dorsal/hollow w/ large brain capacity

3) pharyngeal pouches = slits lost during development EXCEPT the one that formed the Eustachian tubes (auditory; ear to throat)

4) postanal tail = post anus tail regressed to form 1 vertebra = the tailbone / coccyx