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Biodiversity 3: The Eukarya
Transcript of Biodiversity 3: The Eukarya
This presentation reflects a very brief explanation of the relationships among living organisms. Not all phyla are represented.
The "branches of the tree" only represent general relationships (and a generally accurate phylogeny), not time or abundance or anything else.
The purple arrows (eukarya- plants and animals only) spotlight important evolutionary transitions. Fungi General Characteristics:
eukaryotic, almost entirely unicellular*
mixed nutritional modes General Characteristics:
eukaryotic, multicellular, photoautotrophic
cell walls made of cellulose General Characteristics:
heterotrophic (internal digestion)
no cell walls *EXCEPTION: Seaweeds, Colonial stages of some life cycles Evolution Some Example Protists Autotrophs Heterotrophs Mixotrophs The classification of protists is beyond the scope of this course.
Classification of the Protists is undergoing constant revision.
Relationships among protist lineages are determined through molecular analysis.
You need to know three things:
How to recognize when an organism is a protist
The ancestors of all of the other organisms in the eukarya domain were protists.
The ecological roles that protists play Endosymbiosis has occurred multiple times in the protists. unicellular algae produce most of the oxygen you breathe. The three major divisions of seaweeds are green, red, & brown.
The green seaweeds (chlorophyta) are the ancestors of the plant kingdom Paramecium & Amoeba are two classic examples of hetertrophic protists. The euglena is a protist that can carry out autotrophic and heterotrophic nutrition. Ecology Protists play major roles in aquatic ecosystems as both producers and consumers Protist diseases are common in the developing world, and very difficult to treat (why?) There is a wide diversity of life cycles in protists (shocking, I know).
Many protists have very complex, multi-stage life cycles. Life Cycles Protists alternate between sexual and asexual reproduction strategies Paramecium Plasmodium Kelp Dictyostelium Characteristics: No vascular tissue or seeds
the gametophyte generation is dominant, with a dependent sporophyte Characteristics: Vascular tissue, but no seeds.
Sporophyte is dominant, dependent gametophyte.
Motile, free-swimming gametes. Characteristics: Vascular tissue, seeds develop exposed or in cones
Sporophyte is dominant, microscopic gametophyte
Includes all "evergreen trees" Characteristics: Have flowers. Vascular tissue, seeds develop in floral ovary (fruit)
Sporophyte is dominant, microscopic gametophyte
Classified into 2 major groups: monocots and dicots
Most diverse group of plants (why so successful?) Vascular Tissue! Pollen & Seeds! Flowers & Fruit! What makes a plant? General Characteristics:
eukaryotic, almost entirely multicellular*
Heterotrophic (external digestion)
Cell walls made of Chitin *EXCEPTION: Yeast Evolution Ecology Anatomy & Physiology Arranging the animals: Cephalization! aka: sponges
Asymmetrical, sessile, filter feeders, no tissues aka: jellies, corals, anemones
radially symmetrical, 2 tissue layers, specialized stinging cells aka: worms, lots of worms.
bilateral symmetry, then it depends on the phylum aka: snails, clams, slugs, octopi, etc.
bilateral symmetry, three main body segments (head, viscera, foot)
shell made of CaCO secreted by the "mantle" organ
Wide diversity of feeding strategies aka: crustaceans, insects, arachnids, etc.
bilateral symmetry, three main body segments (head, thorax, abdomen)
exoskeleton made of chitin
Wide diversity of feeding strategies aka: seastars, sea cucumbers, sea urchins, etc.
special derived "pentaradial" symmetry
endoskeleton made of ostia plates
water vascular system for locomotion
predators and filter feeders "spiny skin" "jointed foot" What it is: What it is: What they are: What they are: trypanosoma: sleeping sickness Plasmodium: malaria molecular analysis suggests that plants evolved from green algae Plants grow continuously during their life cycle.
"meristem": permanently undifferentiated tissue. Site of plant growth "Alternation of Generations" Life cycle:
2 multicellular forms (haploid & diploid) Evolutionary trends in plant forms: evolutionary time Tissue that transports water (xylem) and sugar (phloem) throughout the plant. Why does it matter? "Vascular Bundles" of xylem and phloem in a celery stalk Why do they matter? Pollen: a water-free mode of dispersing sperm.
Seeds: a protective, nourishing, dispersive place for early embryo development typical pollen structure: Dandelion seeds are adapted for wind dispersal: "naked seed" gymnosperms include the largest plants on Earth Why do they matter? Flowers: a structure that contains both reproductive organs of the plant and is adapted for pollination.
Fruit: a structure that houses fertilized seeds and aids in their dispersal. "Mmm... Nom Nom Nom!" fruit consumption by animals = seed deposition in fertilizer "Male part" "Female part" Fungi evolved from a heterotrophic protist lineage.
The major divisions of modern fungi are classified by the structures that their spores develop in. Fungi have a very simple anatomy.
Mycellium: the loose, thread-like body of the fungus.
Fruiting body: develops from mycellium to produce spores. A "fairy ring" of mushrooms (all one organism) that forms as mycellium radiates outward: Fungi reproduce sexually and asexually.
Immediately after fertilization ("plasmogamy"), fungi undergo meiosis ("karyogamy") and return to the haploid condition Fungi are major decomposers of other organisms. pennicillium mold on an orange 3 Examples of Fungal Plant Diseases Some fungi exist in interesting symbiotic relationships a lichen is a relationship between a fungus and an algae leaf-cutter ants cultivate a fungus that produces an antibiotic Fungi can also be parasites, causing disease and even "stalking" prey. To The Chordates!
(more next time) How is the Eukaryotic domain of life organized?
What are the characteristics of eukaryotes that are used to classify them? Learn your floral anatomy! Animals evolved from a group of protists called "Choanoflagellates" Early events in development are a major dividing line between animal phyla The organization of the body cavity (if it exists) is another major identifying trait of animals Porifera are the most basal (evolutionarily basic) organisms that we classify as animals.
Choanocytes: "Collar cells" responsible for moving water through the sponge and filtering out food. Cnidarians are predators and filter feeders.
Nematocyts: stinging barb organelles that cnidarians use to paralyze prey.
Cnidarians have two tissue types. Why does it Matter? the concentration of sensory organs in the anterior ("head") of the organism.
necessitates bilateral symmetry spicules give sponges structure Cnidarians come in two major forms jellyfish are only one group of cnidarians Coral consist of many individual polyps living colonially We're not really interested in keeping all worm phyla straight.
You need to know three groups of worms: Phylum Platyhelminthes: The "Flatworms"- Acoelomates Phylum Nematoda: The "Roundworms"- Pseudocoelomates Phylum Annelida: Segmented worms- Coelomates Planaria is a typical example of a playtyhelminthe Acoelomates do not have a body cavity.
This is the most primitive 3-germ layer animal body plan. this is a pretty marine flatworm Blood flukes and Tapeworms are good examples of parasitic flatworms Pseudocoelomates have a body cavity that is lined by 2 different tissue layers (mesoderm and endoderm) C. elegans is a roundworm that is widely used to study animal development. Trichinella is a parasitic roundworm that lives in mammalian muscle tissue (most notably pork) leeches are another well-known group of parasitic roundworms Coelomate organization has a true body cavity lined entirely by one germ layer (mesoderm).
This allows organs to be suspended in the cavity, and protected.
All phyla that we will look at from this point onward are coelomates. Earthworms are very typical annelids, though there are many marine annelids, as well. Bottom line:
You should be familiar with general characteristics and example organisms of these three worm phyla.
You should be able to explain the differences in body plans shown in these phyla.
That's it. The structure of a mollusc's shell is useful for keeping the different groups separate. Gastropods have a one-peice shell (or no shell at all) Bivalves have a 2-piece shell Cephalopods have mostly lost their shells.
They have the largest brain:body ratio of any invertebrate animals Chitons have a series of interlocking plates Though plentiful in terms of diversity, molluscs have suffered more recorded extinctions than any other phylum of organisms (why?) Arthropods are the most abundant phylum of animals.
There are more arthropods than all other species of animal combined. Crustaceans:
common aquatic arthropods.
Usually 10 legs (some have 8 or 12) The arthropod exoskeleton gives them very clear body segmentation Trilobites: a very common arthropod fossil Arthropods undergo a very dramatic metamorphosis when moving from larval form to adult form Some example arthropods: Insects:
very common terrestrial arthropods
"God has an inordinate fondness for stars and beetles."
-JBS Haldane (evolutionary biologist) Arachnids:
another group of very common terrestrial arthropods
8 legs Echinoderms are only found in aquatic environments.
Their radial symmetry is a special, derived kind that splits their body segments into 5 identical sections.
They are the first group of deuterostomes that we have encountered. Seastars have typical echinoderm anatomy 6 kinds of echinoderms sea stars sea cucumbers brittle stars sea urchins sea lillies sea daisies Echinoderms have amazing regenerative ability. One arm of a sea star can give rise to an entire organism Identify members of all of the groups that were discussed in this presentation if given information about their characteristics.
Explain why the particular example organisms discussed in this presentation belong in particular groups.
Identify the characteristics most useful for grouping members of each kingdom discussed in this presentation.
Explain the evolutionary trends demonstrated in the plants and animals.
Explain the advantages and tradeoffs of the strategies and adaptations that were discussed in this presentation.
Explain why the phylogeny discussed in this presentation is hypothetical and subject to continuing revision. Since their divergence, the eukaryotes have evolved into four major groups (tradiationally refered to as kingdoms) 3 Amoeba eating!
(now with 200% more epic music!) It makes me want to Sing and Dance! Not Just Nematodes!
(ALERT: AWESOMENESS!) Pneumatocysts are cool!