Bio II Exam #2

Taxonomy

brand of biology concerned with identifying, naming, and classifying species

Taxonomic Naming System

• basis of system introduced by Carolus Linnaeus

• Binomial nomenclature: name listed as: Genus, then species

• capitalize genus, lowercase species

Taxon

• each taxonic unit at any level (family, kingdom, etc.)

Phylogeny

evolution history of a species of a group

Systematics

• discipline of biology that focuses on classifying orgs. and deterrming their evolutionary relationships

Convergent Evolution

• occurs when similar envr. and natural selection produce similar adaptations in orgs. from different evolutionary lineage

• analogy: simliarity due to convergent evolution

Cladistics

• orgs are grouped by common ancestry

Clade

consists of an ancestral species and all its evolutionary descendants

Systematics focuses on two characteristics

1. shared ancestral character

2. shared derived character

Shared Ancestral Character

• common to a particular clade and came from an ancestral, not in the clade (group)

Shared Derived Character

• is common to members of the clade, but not found in a common ancestor

  • it distinguishes clades and thus marks branch points in tree of life

Outgroup

a species from a lineage that is closely related but not related to the group we are studying

Ingroup

the group we are studying

Parsimony

the adoption of the simplest explanation for observed phenomenon

Phylogenic Tree

graphic representation of that evolutionary history

*practice on picture notes*

Sister Groups

come off the same branch, same common ancestor, speciation event

Monophyletic Groups

• includes common ancestor and ALL of its descendants

Paraphyletic Groups

• includes common ancestor and some, BUT not all of its descendants

Polyphyletic Group

Does not include common ancestor, multiple groups w/ different ancestors

Homology

similarities based on evolutionary relationships

Analogy

similarity of function

• due to convergent evolution

Synapomorphy

trait found in two or more taxa that is present in most recent ancestry but not more distant ones

• derived trait

• ancestral traits

Derived Traits

• traits that more than one group have in common

Ancestral Traits

• older traits that species have in common even w/ less related groups

Parsimony

• simplest/ least complex explanation is most likely correct

Prokaryotes

• simple single-celled orgs

• no specialized internal structures (organelles)

• no nucleus

Eukaryotes

• single-celled or multicellular orgs.

• w/ organelles and nucleus surrounded w/ membrane

3 Domains

• Archaea

• Bacteria

• Eukarya

Archaea

• prokaryotes

• have cell wall

• can live in extreme ENVR.

• have DNA and RNA

• have Ribosomes

Bacteria

• prokaryotes

• have cell walls

• DNA and RNA unique

• Ribosomes unique

• cyanobacteria (blue-green algae): photosynthetic bacteria (prokaryotes) earlies photosynthesis occurred here

Eukarya

• some have cell walls

• DNA, RNA, and Ribosomes similar to Archaea

• have a nucleus

Protists/ protista

• was once seen as a kingdom

  • single-cell eukaryotic

  • junk grouping, no longer used

Endosymbiotic Theory Innovation

development of mitochondria

• theory states that mitochondria originated when one cell (Eukaryotic) engulfed bacteria

• bacteria becomes part of cell and lives inside

• host cell provides pyruvate and O2 to bacteria

• bacteria then produces ATP for the cell

• host cell protects bacteria

Symbiosis

• physically close association b/w orgs. of two or more species

• can be positive or negative

Endosymbiosis

• when an org. lives inside the cell of an org. of another species

Mitochondria

• site of aerobic respiration

• organic molecules —> ATP

Endosymbiosis: How Chloroplasts Develop

• cyanobacteria (blue-green algae) engulfed in eukaryotic cell then lives w/in cell

• bacteria provides O2 and Glucose to the cell

• the cell provides CO2 and H2O ( and protection) to the bacteria

• chloroplasts develop

Primary (initial) endosymbiosis creates:

• photosynthesis w/ two membranes

Endosymbiotic Theory (second) endosymbiosis:

• photosynthetic protist is engulfed (eukaryotic)

  • evidence: chloroplasts in some groups have 4 membranes

• nucleus from photosynthetic protist is lost

• organelle has 4 membranes (chloroplasts)

Animal

• multicellular

• heterotrophic eukaryotes that obtain nutrients through ingestion (eating food)

• reproduce diploid offspring w/ haploid gametes (egg and sperm)

• form blastula: hollow ball of cells

• have gastula stage w/ endoderm, mesoderm, and ectoderm

• larva look like immature individual that looks different from adult

Blastula

hollow ball of cells

Gastrula

an early stage in animal embryonic development that follows the blastula. During this phase, the single-layered, hollow sphere of cells (the blastula) rearranges into a multilayered cup-shaped structure. This creates the three primary germ layers that will eventually form all the tissues and organs in the adult body

Endoderm

• holds innermost linings

• turns into digestive tract

Mesoderm

• forms muscles and most internal organs (middle layer)

Ectoderm

• outer covering

• turns into central nervous system

Metamorphisis

• larva to adult transformation

Body Plan Categorizing

• radial symmetry

• bilateral symmetry

• variation in tissue organization

Radial Symmetry

• body parts radial from the center like spokes of a bike wheel

• same on every side

Bilateral Symmetry

• mirror imaging on right and left of body

  • anterior end: head

  • posterior end: tail

  • dorsal: back

  • ventral: underside/ belly/ bottom

  • both sides same down the middle

Eumetazoa

• clade of “true animals” those w/ true tissues AKA all animals but sponges

Bilateria

• clade w/ animals w/ bilateral symmetry

Lophotrochozoan

• clade of animals with bilateral symmetry that include flatworms, annelids, mollusks

Ecdysozoa

• have external skeletons that must be shed for the animals to grow

• invertebrate animals that includes arthropods (insects, spiders, crustaceans) and nematodes (roundworms)

Deuterostomia

• includes echinoderms and chordates who go through deuterostome development

• characterized by their blastopore becoming their anus during embryonic development

4 Characteristics of Animals

1. multicellular

   • cells lack cell walls

   • have extensive extracellular matrix: fibers, membranes, collagen that gives cells structures and holds them together

2. heterotrophs

   • consume something else to gain energy, digest internally (except starfish)

3. mobile at some point in its life

   • for sessile adults, larva generally mobile

4. all animals other than sponges have nerve and muscle cells

Steps of Embryotic Development

1. fertilization

2. zygote created

3. cell division

4. blastula (hollow ball of cells) is created

5. gastrulation happens (cell folds inward to create pore/ cavity)

6. creates gastrula (cup shaped embryo w/ external opening: blastopore)

Tissues and levels of tissue

• tissue: groups of cells that function as a unit

• no tissue: sponges

• diploblastic

  • has endoderm: inner level (digestive)

  • has ectoderm: outer layers ( skin and nervous system)

  • ex: jellyfish

• triploblastic (most groups in animals)

  • endoderm

  • ectoderm

  • mesoderm: everything else (circulatory system, muscle, internal structure)

Development of the Digestive Tract (blastopore)

• only for triploblastic orgs.

• protostome: first mouth

• deuterostomes: second mouth

Protostome

• blastopore forms into mouth

• means first mouth

  • spiral cleavage: first row of cells is off-set from next set

Deuterostomes

• blastopore forms into anus instead of mouth

• means second mouth

  • radial cleavage: rows stacked on each other

Body Cavity and types

• body cavity: where organs are held

  • true coelom

  • pseudocoelom

  • acoelomate

  • hydrostatic skeleton

True Coelom

• both inside and outside of body cavity is line w/ mesoderm

Pseudocoelom

• there is no layer of mesoderm tissue on inside

Acoelomate

• no body cavity, it is solid inside

Hydrostatic Skeleton

• coelom gets filled up with organs and water

  • body wall (creates pressure)

  • fluid-filled pseudocoelom

  • muscles: cause shape change by contracting

• ex: earthworm

Phylum Porifera

• sponges

• earlies animals to appear in the fossil record

• suspension feeders

• no tissues

• sessile ( don’t move)

• no symmetry

• no gut formation

• no coelom

Choanocytes

• specialized cells found in sponges that are used to feed

Asexual Reproduction

• producing clones (genetically identical to parents)

  • parthenogenesis: diploid eggs (mitosis) develop with no fertilization

  • budding: “falls off the parent”

Sexual Reproduction

• production of haploid gametes (meiosis)

• gametes fuse to create diploid zygote

  • mixing of alleles

• external fertilization

• internal fertilization

External Fertilization

• eggs and sperm are out in open ENVR (usually water) they fertilize

• only option if sessile

• need lots of gametes

Internal Fertilization

• sperm fertilizes egg inside the female

• must find mate

• moving is dangerous

• has an increase chance of fertilization compared to external

Asexual vs. Sexual Reproduction

• asexual: faster, more reproduction

• sexual: good for adaptation and variation

Ganglia

group of nerves

Purpose of Nerves

1. coordinate movement of muscles

2. sensory: react to world (senses and impulses)

3. process information

Alignment of Nerves

1. nerve net: mesh-like nervous system made of interconnected neurons that lack a brain

   1. ex: cnidarians (worms) have this

2. central nervous system: central nerve cord w/ off shoots

Phylum: Ctenophores

• comb jellies

• real tissue

  • diploblastic

  • muscle and nerve tissues

• gut formation

  • gastrulation (gut)

  • mouth only (no anus)

• no body cavity

• radial symmetry

• predators: prey stick to mucus on body or sticky substance produced by colloblasts (cells) on tentacles (eat small crustaceans and even fish)

• movement: rows/ combs of cilia

• ecological importance: invasive ones can cause collapse of fisheries

  • food for other orgs: jellyfish, sea turtles

Phylum: Cnidaria

• jellies, sea anemones,, corals, hydra

• tissues

  • diploblastic

• gut formation

  • mouth only

• no body cavity

• radial symmetry

• body forms

  • polyp: sessile, generally asexual

  • medusa: free flotation, sexual

• more info

  • gastrovascular activity

  • muscles and nerve net

  • cnidocyte (singing cell)

Phylum: Mollusca

• class Cephalopoda: (head foot): squid, octopuses, nautilus

• mantle lined w/ muscles (contracts and expels water out of system)

• fast swimmers

• have tenticles

• very developed eyes ( can camouflage)

Type of Life Cycles (3)

• direct

• indirect

  • metamorphosis

  • embryogenesis

Direct Development

• newborn young look similar to adults

• ex: grasshopper (baby —> adult)

Indirect Development

• individual undergo a dramatic change (metamorphosis) during their life cycle

• ex: butterfly (egg to caterpillar to butterfly)

Metamorphosis

• transforms larva into juveniles which

  • look like adults

  • live in the same habitats and eat the same foods

  • are still sexually immature

• incomplete: egg to baby org then grows to adult ( larva looks like adult)

• complete: larva to pulpa to adult (larva looks complete different than adult)

Embryogenesis

• produce larva, which

  • look radically different from adults

  • live in different habitats and eat different foods

Protostomes

• first gastrulation becomes mouth

• spectacularly diverse

  • of the 30 animal phyla described, 22 abundant are protostomes

  • about 1.2 million out of 1.5 million have been named arthropod

• vast majority of animal species are protostomes

• two major subgroups inlcuded:

  • lophotrochozoan: include mollusks and annelid worms

  • ectozoan: include arthropods

Water to Land Transition

• fossil indicate that protostome lineage originate in the ocean

• protostomes made this transition multiple times as they diversify

• transition independently from eachother

Challenges of Land

• gas exchange

  • across skin (high surface area to volume useful)

  • internal gills

• desiccation (dry out on land)

  • need moist envr.

  • created waxy later hold moisture (ex: insect)

  • egg protection or resistance (thick membrane or shells)

• support

  • size limits on land

  • gravity on land US water

Advantages on Land

• available resources (lots of it)

• fewer predators

Lophotrochozoan

• name was inspired by presence of feeding structure called lophopore

  • specialized structure that rings the mouth of the animals and functions in suspension feeding

Phylum: Platyhelminthes

• class turbellaria: flatworms

  • mostly free-living (aquatic and land)

  • high SA:V

• class Trematoda: flukes

  • parasites

  • suckers (to stick to things)

  • complex life cycles

• class cestode: tapeworms

  • parasites

  • scolex: shark hooks on head to live inside orgs.

  • no mouth (absorb nutrients through skin)

• KNOW:

  • most are parasites

  • live in mammals

  • number of them have unique life cycles

Phylum: Annelida

• segmented worms

• earthworms, leeches, tube worms

• symmetry: bilateral

• tissues: triploblastic

• gut formation: protostome

• body cavity: coelomate

• body plan: segmentation (repeated body structures)

  • closed circulatory system

  • parapodia: appendages with bristle like structures

  • hydrostatic skeleton: allows swimming and digging

• reproduction

  • asexual: fragmentation

  • sexual: polychaeta (separate sexes)

Annelid Groups

1. class polychaeta (many bristles)

2. class Oligochaeta ( earthworm and relatives)

3. class Hirudinea: leeches

Phylum: Mollusks

• snails, slugs, oysters, clams, octopuses squid

• symmetry: bilateral

• tissues: triploblastic

• gut formation: protostome

• body cavity: coelomate

• body plan:

  • muscular foot ( muscular hydrostat= solid muscle)

  • hydrostatic skeleton uses water to create internal pressure ( allow movement)

  • we use bones

  • we use muscle alone

• open circulation system:

  • heart pumps blood through gill and into open hemocoel

Mollusk Groups

1: class gastropoda: snail and slugs

• stomach foot

• single shell

• radula ribbon like with tiny teeth scraping

2:class Bivalvia: scallops, clams, oysters,

• foot

• siphon: pull and filter water

3. Cephalopoda (head foot)

• squids, octopuses, nautilus

• mantle lined w/ muscle that contracts and expels water out of siphon

  • tentacles

  • fast swimmers

  • developed eyes

Phylum: Nematodes

• roundworms (unsegmented worms)

• symmetry: bilateral

• tissues: triploblastic

• gut cavity: protostome (mouth first)

• body cavity: pseudocoelomate ( lack fully lined coelom)

• no appendages

• elastic cuticle (molted)

• no specialized systems for exchanging gases through circulating nutrients

• parasites

  • heartworm, hookworms, guinea worms

• free-living

  • very abundant in soils

  • decomposers, predators (bacteria, small protists, plants)

Phylum Arthropoda

• insects, arachnids, crustaceans, and others

• symmetry: bilateral

• tissues: triploblastic

• gut formation: protostome

• body cavity: coelomate

• segmentation

  • specialized body sections (head, thorax, abdomen)

• hardened exoskeleton

  • chitin (polysaccharide) some hardened with CaCO3 (crustaceans)

• jointed appendages:

  • arthro (joint) poda (foot)

• Chelicerata (two body sections)

  • cephalothorax and abdomen

  • 6 pairs of appendages

  • ex: horseshoe crabs, arachnids

• class: Myriapoda (many)

  • order Diplopoda

    • millipedes

    • herbivore

  • order chilopod

    • predator

    • centipedes

    • carnivores

• class crustaceans

• class insects

Deuterostomes

• phylum Echinodermata (sea star, sea urchin, sea cucumber)

• symmetry: bilateral larva

• tissues: triploblastic

• gut formation: deuterostome

• body cavity: coelomate

• endoskeleton

• water vascular system: eject stomach digest value

• tube feet

Phylum: Chordata

• tunicates, lancelets, vertebrates

• symmetry: bilateral

• tissues: triploblastic

• gut formation: deuterostome

• body cavity: coelomate

• characteristics:

  • dorsal: hollow nerve cord

  • notochord (flexible rod)

  • pharyngeal gill slits

  • muscular post anal

Phylum: Craniates

• cranium (bone or cartilage)

• increase brain complexity

• sensory organs on head

• hagfishes:

  • ~ 40 species

  • cartilaginous skull: lack jaws, vertebrate

  • marine scavengers

  • slime glands

  • primative cranial

Vertebrates

• endoskeleton

• bone and cartilage

• spinal cord

• vertebral column

• vertebrae

  • ex: lampreys

    • primitive vertebrates

    • lack jaws

    • larvae are suspension feeders

    • many adults parasitic: feed on blood and tissues of other fishes

Fish-Tetrapod Transition

• aquatic to terrestrial

• lobe fins to limbs

• gills lost

• neck (lift head to breath and look around over time)

• bones diversify to digits