CAMPBELL BIOLOGY TENTH EDITION Reece Urry Cain Wasserman Minorsky Jackson 28 Protists Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick
Living Small Even a low-power microscope can reveal a great variety of organisms in a drop of pond water Protist is the informal name of the group of mostly unicellular eukaryotes Advances in eukaryotic systematics have caused the classification of protists to change significantly Protists constitute a polyphyletic group, and Protista is no longer valid as a kingdom
Figure 28.1 1 μm
Figure 28.1a Trumpet-shaped protists (Stentor coeruleus)
Concept 28.1: Most eukaryotes are single-celled organisms Protists are eukaryotes Eukaryotic cells have organelles and are more complex than prokaryotic cells It is important to bear in mind that The organisms in most eukaryotic lineages are protists, and Most protists are unicellular
Structural and Functional Diversity in Protists Protists exhibit more structural and functional diversity than any other group of eukaryotes Though most protists are unicellular, there are some colonial and multicellular species Single-celled protists can be very complex, as all biological functions are carried out by organelles in each individual cell
Protists, the most nutritionally diverse of all eukaryotes, include Photoautotrophs, which contain chloroplasts Heterotrophs, which absorb organic molecules or ingest larger food particles Mixotrophs, which combine photosynthesis and heterotrophic nutrition
Some protists reproduce asexually, while others reproduce sexually, or by the sexual processes of meiosis and fertilization
Four Supergroups of Eukaryotes It is no longer thought that amitochondriates (lacking mitochondria) are the oldest lineage of eukaryotes Many have been shown to have mitochondria and have been reclassified Our understanding of the relationships among protist groups continues to change rapidly One hypothesis divides all eukaryotes (including protists) into four supergroups
Figure 28.2 Excavata 5 μm Archaeplastida 20 μm 50 μm Diplomonads Parabasalids Euglenozoans Excavata Stramenopiles Alveolates Rhizarians Amoebozoans Opisthokonts Green algae Diatoms Golden algae Brown algae Dinoflagellates Apicomplexans Ciliates Forams Cercozoans Radiolarians Red algae Chlorophytes Charophytes Land plants Slime molds Tubulinids Entamoebas Nucleariids Fungi Choanoflagellates Animals SAR clade Archaeplastida Unikonta SAR Clade 100 μm 50 μm Unikonta 100 μm
Figure 28.2a Diplomonads Parabasalids Euglenozoans Excavata Stramenopiles Alveolates Rhizarians Diatoms Golden algae Brown algae Dinoflagellates Apicomplexans Ciliates Forams Cercozoans Radiolarians SAR clade Green algae Red algae Chlorophytes Charophytes Land plants Archaeplastida Amoebozoans Opisthokonts Slime molds Tubulinids Entamoebas Nucleariids Fungi Choanoflagellates Animals Unikonta
Figure 28.2aa Diplomonads Parabasalids Euglenozoans Excavata Stramenopiles Alveolates Rhizarians Diatoms Golden algae Brown algae Dinoflagellates Apicomplexans Ciliates Forams Cercozoans Radiolarians SAR clade
Figure 28.2ab Green algae Red algae Chlorophytes Charophytes Land plants Archaeplastida Amoebozoans Opisthokonts Slime molds Tubulinids Entamoebas Nucleariids Fungi Choanoflagellates Animals Unikonta
Figure 28.2b Excavata 5 μm SAR Clade 50 μm Archaeplastida 20 μm 50 μm Unikonta 100 μm 100 μm
Figure 28.2ba Excavata 5 μm Giardia intestinalis, a diplomonad parasite
Figure 28.2bb SAR Clade 50 μm Diatom diversity
Figure 28.2bc SAR Clade 100 μm Globigerina, a rhizarian in the SAR clade
Figure 28.2bca SAR Clade 100 μm Globigerina, a rhizarian in the SAR clade
Figure 28.2bcb SAR Clade
Figure 28.2bd Archaeplastida 20 μm 50 μm Volvox, a colonial freshwater green alga
Figure 28.2bda Archaeplastida 50 μm Volvox, a colonial freshwater green alga
Figure 28.2bdb Archaeplastida 20 μm
Figure 28.2be Unikonta 100 μm A unikont amoeba
Endosymbiosis in Eukaryotic Evolution There is now considerable evidence that much protist diversity has its origins in endosymbiosis Endosymbiosis is a relationship between two species in which one organism lives inside the cell or cells of the other organism (the host)
Mitochondria and plastids are derived from prokaryotes that were engulfed by the ancestors of early eukaryotic cells Mitochondria evolved once by endosymbiosis of an alpha proteobacterium Plastids evolved later by endosymbiosis of a photosynthetic cyanobacterium The ancestral host cell may have been an archaean or a protoeukaryote, from a lineage related to, but diverged from archaeal ancestors
Plastid Evolution: A Closer Look Mitochondria arose first through descent from a bacterium that was engulfed by a cell from an archaeal lineage The plastid lineage evolved later from a photosynthetic cyanobacterium that was engulfed by a heterotrophic eukaryote The plastid-bearing lineage of protists evolved into photosynthetic protists, red and green algae
Figure 28.3 Membranes are represented as dark lines in the cell. Cyanobacterium Red alga Secondary endosymbiosis Dinoflagellates Plastid 1 2 3 Primary endosymbiosis Stramenopiles Nucleus Heterotrophic eukaryote One of these membranes was lost in red and green algal descendants. Secondary endosymbiosis Secondary endosymbiosis Plastid Euglenids Green alga Chlorarachniophytes
Figure 28.3a Primary endosymbiosis Membranes are represented as dark lines in the cell. Cyanobacterium Red alga 1 2 3 Nucleus Heterotrophic eukaryote One of these membranes was lost in red and green algal descendants. Green alga
Figure 28.3b Secondary endosymbiosis Dinoflagellates Red alga Plastid Stramenopiles
Figure 28.3c Secondary endosymbiosis Plastid Euglenids Green alga Chlorarachniophytes
Video: Volvox Colony
Video: Volvox Daughter
Video: Volvox Flagella
Video: Volvox Inversion 1
Video: Volvox Inversion 2
Video: Volvox Sperm and Female
Video: Amoeba
Video: Amoeba Pseudopodia
Like cyanobacteria, plastids of red algae and green algae have two membranes Transport proteins in the membranes of red and green algae are homologous to those found in cyanobacteria
On several occasions during eukaryotic evolution, red and green algae underwent secondary endosymbiosis, in which they were ingested by a heterotrophic eukaryote For example, chlorarachniophytes likely evolved when a heterotrophic eukaryote engulfed a green alga The engulfed cell contains a vestigial nucleus called a nucleomorph
Figure 28.4 Inner plastid membrane Nucleomorph Outer plastid membrane Nuclear pore-like gap
Figure 28.4a Inner plastid membrane Nucleomorph Outer plastid membrane Nuclear pore-like gap
Concept 28.2: Excavates include protists with modified mitochondria and protists with unique flagella The clade Excavata is characterized by its cytoskeleton Some members have an excavated feeding groove This group includes the diplomonads, parabasalids, and euglenozoans
Figure 28.UN02 Diplomonads Parabasalids Euglenozoans Excavata SAR clade Archaeplastida Unikonta
Diplomonads and Parabasalids These two groups lack plastids, have modified mitochondria, and most live in anaerobic environments Diplomonads Have reduced mitochondria called mitosomes Derive energy from anaerobic biochemical pathways Have two equal-sized nuclei and multiple flagella Are often parasites, for example, Giardia intestinalis
Parabasalids Have reduced mitochondria called hydrogenosomes that generate some energy anaerobically Include Trichomonas vaginalis, the pathogen that causes yeast infections in human females
Figure 28.5 Flagella Undulating membrane 5 μm
Euglenozoans Euglenozoa is a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites The main feature distinguishing them as a clade is a spiral or crystalline rod inside their flagella This clade includes the kinetoplastids and euglenids
Figure 28.6 Flagella 0.2 μm 8 μm Crystalline rod (cross section) Ring of microtubules (cross section)
Figure 28.6a 0.2 μm Crystalline rod (cross section) Ring of microtubules (cross section)
Kinetoplastids Kinetoplastids have a single mitochondrion with an organized mass of DNA called a kinetoplast Free-living species are consumers of prokaryotes in freshwater, marine, and moist terrestrial ecosystems
Some species are parasitic Kinetoplastids in the genus Trypanosoma cause sleeping sickness in humans Another pathogenic trypanosome causes Chagas disease
Figure 28.7 9 μm
Trypanosomes evade immune responses by switching surface proteins A cell produces millions of copies of a single protein The new generation produces millions of copies of a different protein These frequent changes prevent the host from developing immunity
Euglenids Euglenids have one or two flagella that emerge from a pocket at one end of the cell Some species can be both autotrophic and heterotrophic
Figure 28.8 Long flagellum Eyespot Short flagellum Contractile vacuole Light detector Nucleus Chloroplast Euglena (LM) 5 μm Plasma membrane Pellicle
Figure 28.8a Long flagellum Eyespot Euglena (LM) 5 μm Contractile vacuole Nucleus Chloroplast Plasma membrane
Video: Euglena
Video: Euglena Motion
Concept 28.3: The SAR clade is a highly diverse group of protists defined by DNA similarities The SAR clade is a diverse monophyletic supergroup named for the first letters of its three major clades stramenopiles, alveolates, and rhizarians This group is one of the most controversial of the four supergroups
Figure 28.UN03 Diatoms Golden algae Brown algae Dinoflagellates Apicomplexans Ciliates Forams Cercozoans Radiolarians Stramenopiles Alveolates Rhizarians Excavata SAR clade Archaeplastida Unikonta
Stramenopiles The stramenopiles clade includes some of the most important photosynthetic organisms on Earth Most have a hairy flagellum paired with a smooth flagellum Stramenopiles include diatoms, golden algae, and brown algae
Figure 28.9 Smooth flagellum Hairy flagellum 5 μm
Diatoms Diatoms are unicellular algae with a unique twopart, glass-like wall of silicon dioxide
Figure 28.10 40 μm
Video: Diatoms Moving
Video: Various Diatoms
Diatoms are a major component of phytoplankton and are highly diverse Fossilized diatom walls compose much of the sediments known as diatomaceous earth After a diatom population has bloomed, many dead individuals fall to the ocean floor undecomposed
This removes carbon dioxide from the atmosphere and pumps it to the ocean floor Some scientists advocate fertilizing the ocean to promote diatom blooms and the movement of carbon dioxide from the atmosphere to the ocean floor
Golden Algae Golden algae are named for their color, which results from their yellow and brown carotenoids The cells of golden algae are typically biflagellated, with both flagella near one end All golden algae are photosynthetic, and some are mixotrophs Most are unicellular, but some are colonial
Figure 28.11 Flagellum Outer container Living cell 25 μm
Brown Algae Brown algae are the largest and most complex algae All are multicellular, and most are marine Brown algae include many species commonly called seaweeds
Giant seaweeds called kelps live in deep parts of the ocean Brown algal seaweeds have plantlike structures: the rootlike holdfast, which anchors the alga, and a stemlike stipe, which supports the leaflike blades Similarities between algae and plants are examples of analogous structures
Figure 28.12 Blade Stipe Holdfast
Alternation of Generations A variety of life cycles have evolved among the multicellular algae The most complex life cycles include an alternation of generations, the alternation of multicellular haploid and diploid forms Heteromorphic generations are structurally different, while isomorphic generations look similar
The diploid sporophyte produces haploid flagellated spores called zoospores The zoospores develop into haploid male and female gametophytes, which produce gametes Fertilization of gamates results in a diploid zygote, which grows into a new sporophyte
Figure 28.13 Haploid (n) Diploid (2n) Sporangia 10 cm Mature female gametophyte (n) Developing sporophyte Zygote (2n) FERTILIZATION Sporophyte (2n) Female Egg MEIOSIS Gametophytes (n) Sperm Zoospore Male
Figure 28.13a-1 Haploid (n) Diploid (2n) Sporangia Sporophyte (2n) Female Egg MEIOSIS Gametophytes (n) Zoospore Male Sperm
Figure 28.13a-2 Haploid (n) Diploid (2n) Sporangia Mature female gametophyte (n) Developing sporophyte Zygote (2n) FERTILIZATION Sporophyte (2n) Female Egg MEIOSIS Gametophytes (n) Sperm Zoospore Male
Figure 28.13b 10 cm
Alveolates Members of the clade Alveolata have membraneenclosed sacs (alveoli) just under the plasma membrane The alveolates include Dinoflagellates Apicomplexans Ciliates
Figure 28.14 0.2 μm Flagellum Alveoli Alveolate
Figure 28.14a 0.2 μm Flagellum Alveoli
Dinoflagellates Dinoflagellates have two flagella and each cell is reinforced by cellulose plates They are abundant components of both marine and freshwater phytoplankton They are a diverse group of aquatic phototrophs, mixotrophs, and heterotrophs Toxic red tides are caused by dinoflagellate blooms
Figure 28.15 Flagella (a) Dinoflagellate flagella 3 μm (b) Red tide in the Gulf of Carpentaria in northern Australia
Figure 28.15a Flagella (a) Dinoflagellate flagella 3 μm
Figure 28.15b (b) Red tide in the Gulf of Carpentaria in northern Australia
Video: Dinoflagellate
Apicomplexans Apicomplexans are parasites of animals, and some cause serious human diseases They spread through their host as infectious cells called sporozoites One end, the apex, contains a complex of organelles specialized for penetrating host cells and tissues Most have sexual and asexual stages that require two or more different host species for completion
The apicomplexan Plasmodium is the parasite that causes malaria Plasmodium requires both mosquitoes and humans to complete its life cycle Approximately 900,000 people die each year from malaria Efforts are ongoing to develop vaccines that target this pathogen
Figure 28.16 Inside mosquito Inside human Merozoite Sporozoites (n) Liver Liver cell MEIOSIS Oocyst Zygote (2n) Merozoite (n) Red blood cells Red blood cell Apex 0.5 μm FERTILIZATION Gametes Gametocytes (n) Haploid (n) Diploid (2n)
Figure 28.16a-1 Inside mosquito Inside human Liver Liver cell Zygote (2n) Merozoite (n) Red blood cells FERTILIZATION Gametes Gametocytes (n) Haploid (n) Diploid (2n)
Figure 28.16a-2 Sporozoites (n) MEIOSIS Inside mosquito Oocyst Zygote (2n) Merozoite (n) Inside human Red blood cells Liver Liver cell FERTILIZATION Gametes Gametocytes (n) Haploid (n) Diploid (2n)
Figure 28.16b Merozoite Apex Red blood cell 0.5 μm
Ciliates Ciliates, a large varied group of protists, are named for their use of cilia to move and feed They have large macronuclei and small micronuclei Genetic variation results from conjugation, in which two individuals exchange haploid micronuclei Conjugation is a sexual process, and is separate from reproduction, which generally occurs by binary fission
Figure 28.17 50 μm Contractile vacuole Cilia Oral groove Cell mouth Micronucleus Macronucleus Food vacuoles (a) Feeding, waste removal, and water balance. MEIOSIS Conjugation Asexual reproduction Compatible mates Diploid micronucleus The original macronucleus disintegrates. Haploid micronucleus Diploid micronucleus MICRO- NUCLEAR FUSION (b) Conjugation and reproduction.
Figure 28.17a 50 μm Contractile vacuole Cilia Oral groove Cell mouth Micronucleus Macronucleus Food vacuoles (a) Feeding, waste removal, and water balance.
Figure 28.17b-1 Compatible mates MEIOSIS Conjugation Asexual reproduction Diploid micronucleus Haploid micronucleus (b) Conjugation and reproduction.
Figure 28.17b-2 Compatible mates MEIOSIS Conjugation Asexual reproduction Diploid micronucleus The original macronucleus disintegrates. Haploid micronucleus Diploid micronucleus MICRO- NUCLEAR FUSION (b) Conjugation and reproduction.
Figure 28.17c 50 μm
Video: Paramecium Vacuole
Video: Paramecium Cilia
Video: Vorticella Cilia
Video: Vorticella Detail
Video: Vorticella Habitat
Rhizarians Many species in the rhizarian clade are amoebas Amoebas are protists that move and feed by pseudopodia, extensions of the cell surface Rhizarian amoebas differ from amoebas in other clades by having threadlike pseudopodia Rhizarians include radiolarians, forams, and cercozoans
Radiolarians Marine protists called radiolarians have delicate, symmetrical internal skeletons that are usually made of silica Radiolarians use their pseudopodia to engulf microorganisms through phagocytosis The pseudopodia of radiolarians radiate from the central body
Figure 28.18 Pseudopodia 200 μm
Forams Foraminiferans, or forams, are named for porous, generally multichambered shells, called tests Pseudopodia extend through the pores in the test Many forams have endosymbiotic algae
Foram tests in marine sediments form an extensive fossil record Researchers can use measures of the magnesium content in fossilized forams to estimate changes in ocean temperature over time
Figure 28.19
Cercozoans Cercozoans include most amoeboid and flagellated protists with threadlike pseudopodia They are common in marine, freshwater, and soil ecosystems Most are heterotrophs, including parasites and predators
Paulinella chromatophora is an autotroph with a unique photosynthetic structure called a chromoatophore This structure evolved from a different cyanobacterium than the plastids of other photosynthetic eukaryotes
Figure 28.20 Chromatophore 5 μm
Concept 28.4: Red algae and green algae are the closest relatives of land plants Plastids arose when a heterotrophic protist acquired a cyanobacterial endosymbiont The photosynthetic descendants of this ancient protist evolved into red algae and green algae Land plants are descended from the green algae Archaeplastida is the supergroup that includes red algae, green algae, and land plants
Figure 28.UN04 Chlorophytes Charophytes Red algae Green algae Land plants Excavata SAR clade Archaeplastida Unikonta
Red Algae Red algae are reddish in color due to an accessory pigment called phycoerythrin, which masks the green of chlorophyll The color varies from greenish-red in shallow water to dark red or almost black in deep water Red algae are usually multicellular; the largest are seaweeds Red algae are the most abundant large algae in coastal waters of the tropics
Figure 28.21 Bonnemaisonia hamifera 20 cm 8 mm Dulse (Palmaria palmata) Nori
Figure 28.21a Bonnemaisonia hamifera 8 mm
Figure 28.21b 20 cm Dulse (Palmaria palmata)
Figure 28.21c Nori
Figure 28.21d Nori
Green Algae Green algae are named for their grass-green chloroplasts Plants are descended from the green algae Green algae are a paraphyletic group The two main groups are the charophytes and the chlorophytes Charophytes are most closely related to land plants
Most chlorophytes live in fresh water, although many are marine Other chlorophytes live in damp soil, as symbionts in lichens, or in environments exposed to intense visible and ultraviolet radiation
Larger size and greater complexity evolved in chlorophytes by 1. The formation of colonies from individual cells 2. The formation of true multicellular bodies by cell division and differentiation (e.g., Ulva) 3. The repeated division of nuclei with no cytoplasmic division (e.g., Caulerpa)
Figure 28.22 2 cm (a) Ulva, or sea lettuce (b) Caulerpa, an intertidal chlorophyte
Figure 28.22a 2 cm (a) Ulva, or sea lettuce
Figure 28.22b (b) Caulerpa, an intertidal chlorophyte
Most chlorophytes have complex life cycles with both sexual and asexual reproductive stages
Figure 28.23 Flagella 1 μm Cell wall Nucleus + Gamete (n) + Cross section of cupshaped chloroplast (TEM) Zoospore ASEXUAL REPRODUCTION Mature cell (n) FERTILIZATION SEXUAL REPRODUCTION + Zygote (2n) Haploid (n) Diploid (2n) + MEIOSIS
Figure 28.23a-1 Zoospore ASEXUAL REPRODUCTION Mature cell (n) Haploid (n) Diploid (2n)
Figure 28.23a-2 + Gamete (n) + Zoospore ASEXUAL REPRODUCTION Mature cell (n) FERTILIZATION SEXUAL REPRODUCTION Zygote (2n) + Haploid (n) Diploid (2n) + MEIOSIS
Figure 28.23b Flagella 1 μm Cell wall Nucleus Cross section of cupshaped chloroplast (TEM)
Video: Chlamydomonas
Concept 28.5: Unikonts include protists that are closely related to fungi and animals The supergroup Unikonta includes animals, fungi, and some protists This group includes two clades: the amoebozoans and the opisthokonts (animals, fungi, and related protists) The root of the eukaryotic tree remains controversial It is unclear whether unikonts separated from other eukaryotes relatively early or late
Figure 28.UN05 Slime molds Tubulinids Entamoebas Nucleariids Fungi Choanoflagellates Animals Excavata SAR clade Archaeplastida Unikonta
Figure 28.24 Results Choanoflagellates Common ancestor of all eukaryotes Animals Fungi Amoebozoans Diplomonads Euglenozoans Unikonta Excavata DHFR-TS gene fusion Stramenopiles Alveolates Rhizarians Red algae Green algae Plants SAR clade Archaeplastida
Amoebozoans Amoebozoans are amoeba that have lobe- or tube-shaped, rather than threadlike, pseudopodia They include slime molds, tubulinids, and entamoebas
Slime Molds Slime molds, or mycetozoans, were once thought to be fungi DNA sequence analyses indicate that the resemblance between slime molds and fungi is a result of convergent evolution Slime molds include two lineages, plasmodial slime molds and cellular slime molds
Plasmodial Slime Molds Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange
Figure 28.25 Zygote (2n) FERTILIZATION Feeding plasmodium Mature plasmodium (preparing to fruit) 4 cm Flagellated cells (n) Amoeboid cells (n) Germinating spore Spores (n) Young sporangium Mature sporangium MEIOSIS Haploid (n) Diploid (2n) Stalk
Figure 28.25a-1 Feeding plasmodium Mature plasmodium (preparing to fruit) Young sporangium Mature sporangium Haploid (n) Diploid (2n) Stalk
Figure 28.25a-2 Feeding plasmodium Mature plasmodium (preparing to fruit) Flagellated cells (n) Amoeboid cells (n) Germinating spore Spores (n) Young sporangium Mature sporangium Haploid (n) Diploid (2n) MEIOSIS Stalk
Figure 28.25a-3 Zygote (2n) FERTILIZATION Feeding plasmodium Mature plasmodium (preparing to fruit) Flagellated cells (n) Amoeboid cells (n) Germinating spore Spores (n) Young sporangium Mature sporangium Haploid (n) Diploid (2n) MEIOSIS Stalk
Figure 28.25b 4 cm
At one point in the life cycle, plasmodial slime molds form a mass called a plasmodium (not to be confused with malarial Plasmodium) The plasmodium is not multicellular It is undivided by plasma membranes and contains many diploid nuclei It extends pseudopodia through decomposing material, engulfing food by phagocytosis
Cellular Slime Molds Cellular slime molds form multicellular aggregates in which cells are separated by their membranes Cells feed individually but can aggregate to migrate and form a fruiting body Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity
Figure 28.26-1 Spores (n) Emerging amoeba (n) 600 μm Solitary amoebas (feeding stage) (n) ASEXUAL REPRODUCTION Aggregated amoebas Fruiting bodies (n) Migrating aggregate 200 μm Haploid (n) Diploid (2n)
Figure 28.26-2 600 μm Spores (n) Emerging amoeba (n) Solitary amoebas (feeding stage) (n) ASEXUAL REPRODUCTION Aggregated amoebas FERTILIZATION SEXUAL REPRO- DUCTION Zygote (2n) MEIOSIS Amoebas (n) Fruiting bodies (n) Migrating aggregate 200 μm Haploid (n) Diploid (2n)
Figure 28.26a 200 μm
Figure 28.26b 600 μm
Tubulinids Tubulinids are a diverse group of amoebozoans with lobe- or tube-shaped pseudopodia They are common unicellular protists in soil as well as freshwater and marine environments Most tubulinids are heterotrophic and actively seek and consume bacteria and other protists
Entamoebas Entamoebas are parasites of vertebrates and some invertebrates Entamoeba histolytica causes amebic dysentery, the third-leading cause of human death due to eukaryotic parasites
Opisthokonts Opisthokonts include animals, fungi, and several groups of protists
Concept 28.6: Protists play key roles in ecological communities Protists are found in diverse aquatic and moist terrestrial environments Protists play two key roles in their habitats: that of symbiont and that of producer
Symbiotic Protists Some protist symbionts benefit their hosts Dinoflagellates nourish coral polyps that build reefs Wood-digesting protists inhabit the gut of termites
Figure 28.27 10 μm
Some protists are parasitic Plasmodium causes malaria Pfiesteria shumwayae is a dinoflagellate that causes fish kills Phytophthora ramorum causes sudden oak death P. infestans causes potato late blight, which contributed to the Irish famine of the 19th century
Figure 28.28
Photosynthetic Protists Many protists are important producers that obtain energy from the sun In aquatic environments, photosynthetic protists and prokaryotes are the main producers In aquatic environments, photosynthetic protists are limited by nutrients These populations can explode when limiting nutrients are added
Figure 28.29 Other consumers Herbivorous plankton Carnivorous plankton Prokaryotic producers Protistan producers
Biomass of photosynthetic protists has declined as sea surface temperature has increased Growth of phytoplankton communities relies on nutrients delivered from the ocean bottom through the process of upwelling Warm surface water acts as a barrier to upwelling
If sea surface temperature continues to warm due to global warming, this could have large effects on Marine ecosystems Fishery yields The global carbon cycle
Figure 28.30 Ocean region NI NP EP A NA EA Arctic (A) North Atlantic (NA) Equatorial Atlantic (EA) South Atlantic (SA) North Indian (NI) South Indian (SI) North Pacific (NP) Equatorial Pacific (EP) South Pacific (SP) SI (a) S SP 2.50 1.25 0.00 1.25 2.50 Sea-surface temperature (SST) change ( C) SA (b) Southern (S) 0.02 0.01 0.00 0.01 0.02 Chlorophyll change (mg/[m 2 yr])
Figure 28.30a NP EP A NA NI EA SI S SP SA (a) 2.50 1.25 0.00 1.25 2.50 Sea-surface temperature (SST) change ( C)
Figure 28.30b Ocean region Arctic (A) North Atlantic (NA) Equatorial Atlantic (EA) South Atlantic (SA) North Indian (NI) South Indian (SI) North Pacific (NP) Equatorial Pacific (EP) South Pacific (SP) Southern (S) 0.02 0.01 0.00 0.01 0.02 Chlorophyll change (mg/[m 2 yr]) (b)
Figure 28.UN01a Wheat mitochondrion A. tumefaciens C. testosteroni E. coli M. capricolum A. nidulans Wheat mitochondrion 48 38 35 34 34 A. tumefaciens 55 57 52 53 C. testosteroni 61 52 52 E. coli 48 52 M. capricolum 50 A. nidulans
Figure 28.UN01b Wheat, used as the source of mitochondrial RNA
Figure 28.UN06 Eukaryote Supergroup Major Groups Key Morphological Characteristics Specific Examples Excavata Diplomonads and parabasalids Modified mitochondria Giardia, Trichomonas Euglenozoans Kinetoplastids Euglenids Spiral or crystalline rod inside flagella Trypanosoma, Euglena SAR Clade Stramenopiles Diatoms Golden algae Brown algae Hairy and smooth flagella Phytophthora, Laminaria Alveolates Dinoflagellates Apicomplexans Ciliates Membrane-enclosed sacs (alveoli) beneath plasma membrane Pfiesteria, Plasmodium, Paramecium Rhizarians Radiolarians Forams Cercozoans Amoebas with threadlike pseudopodia Globigerina Archaeplastida Red algae Phycoerythrin (photosynthetic pigment) Porphyra Green algae Plant-type chloroplasts Chlamydomonas, Ulva Land plants (See Chapters 29 and 30.) Mosses, ferns, conifers, flowering plants Unikonta Amoebozoans Slime molds Tubulinids Entamoebas Opisthokonts Amoebas with lobeshaped or tube-shaped pseudopodia (Highly variable; see Chapters 31 34.) Amoeba, Dictyostelium Choanoflagellates, nucleariids, animals, fungi
Figure 28.UN06a Eukaryote Supergroup Major Groups Key Morphological Characteristics Specific Examples Excavata Diplomonads and parabasalids Modified mitochondria Giardia, Trichomonas Euglenozoans Kinetoplastids Spiral or crystalline rod inside flagella Trypanosoma, Euglena Euglenids SAR Clade Stramenopiles Diatoms Hairy and smooth flagella Phytophthora, Laminaria Golden algae Brown algae Alveolates Dinoflagellates Apicomplexans Membrane-enclosed sacs (alveoli) beneath plasma membrane Pfiesteria, Plasmodium, Paramecium Ciliates Rhizarians Radiolarians Amoebas with threadlike pseudopodia Globigerina Forams Cercozoans
Figure 28.UN06b Eukaryote Supergroup Major Groups Key Morphological Characteristics Specific Examples Archaeplastida Red algae Phycoerythrin (photosynthetic pigment) Porphyra Green algae Plant-type chloroplasts Chlamydomonas, Ulva Land plants (See Chapters 29 and 30.) Mosses, ferns, conifers, flowering plants Unikonta Amoebozoans Slime molds Tubulinids Amoebas with lobeshaped or tube-shaped pseudopodia Amoeba, Dictyostelium Entamoebas Opisthokonts (Highly variable; see Chapters 31 34.) Choanoflagellates, nucleariids, animals, fungi
Figure 28.UN07