Topic 5.3 Classification of biodiversity essential idea: Species are named and classified using an internationally agreed system UNDERSTANDINGS: The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses. When species are discovered they are given scientific names using the binomial system. Taxonomists classify species using a hierarchy of taxa. All organisms are classified into three domains. The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species. In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species. Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species. Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.

Topic 5.3 Classification of biodiversity essential idea: Species are named and classified using an internationally agreed system Applications and skills: Application: Classification of one plant and one animal species from domain to species level. Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta. Application: Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda and chordata. Application: Recognition of features of birds, mammals, amphibians, reptiles and fish. Skill: Construction of dichotomous keys for use in identifying specimens.

Classification of Plants Topic 5.3 Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.

Eukaryotic Tree of Life “PROTISTS” PLANTAE FUNGI ANIMALIA (sea urchins, sea stars, vertebrates) Deuterostomes (worms, arthropods, mollusks) Protostomes (liverworts, mosses) Bryophyta (anemones, jellyfish) Cnidaria (flowering plants) Angiosperms Diplomonads Kinetoplastids Apicomplexans Dinoflagellates Phaeophyta (brown algae) (water molds) Oomycota Rhodophyta (red algae) Chlorophyta (green algae) Pteridophyta (ferns) Gymnosperms Amoebozoans Zygomycota Ascomycota Basidiomycota (sponges) Porifera Euglenids Ciliates Diatoms

What Are the Major Groups of Plants? Two major groups of land plants arose from ancient green algal ancestors The nonvascular plants (called bryophytes) require a moist environment to reproduce, and therefore they straddle the boundary between aquatic and terrestrial life The vascular plants (called tracheophytes) have been able to colonize dry habitats

The Evolutionary Tree of Some Major Plant Groups Nonvascular plants Vascular plants bryophyta seed plants Liverworts Mosses Filocinophyta coniferophyta Angiospermophyta Flowers and fruits Seeds and pollen True vascular tissue and lignin Ancestral green alga Fig. 21-4

Nonvascular plants (Bryophyta) Mosses are the most diverse, and some have a waterproof covering that retains moisture, permitting them to invade drier areas, such as deserts, bare rock, and northern and southern climes where humidity is low and water scarce Mosses of the genus Sphagnum are common in northern regions of the world Accumulations of dead mosses form peat, which is used as a fuel

Nonvascular Plants Fig. 21-5

Vascular plants have conducting cells that also provide support distinguished by specialized groups of tube-shaped conducting cells cells are impregnated with the stiffening agent lignin Vascular plants can be divided into two groups: seedless vascular plants and the seeded plants

seedless vascular plants (Filocinophyta) include ferns have swimming sperm and require water for reproduction do not produce seeds, but propagate by spores

Ferns (Filocinophyta) are broad-leaved and more diverse With 12,000 species, ferns are the largest and most diverse group of seedless vascular plants Their well-developed, broad leaves emerge from coiled fiddleheads Ferns are the only seedless vascular plants that have broad leaves Reproduction in ferns requires water

The seed plants aided by two important adaptations: pollen and seeds Pollen grains are tiny male gametophytes that carry sperm-producing cells They are dispersed by wind or pollinators They eliminate the need for sperm to swim to the egg Seeds have three components: an embryonic sporophyte plant, a food supply for the embryo, and a protective outer coat

Coniferophyta nonflowering seed plants evolved earlier than the flowering plants first fully terrestrial plants to evolve, most of these early gymnosperms are now extinct A conifer tree develops male and female cones Male cones are relatively small and produce pollen Female cones consist of numerous woody scales arranged spirally around a central axis

Angiospermophyta flowering seed plants produce flowers and fruits They are the most diverse and widespread of all plants, with more than 230,000 species broad range in size The smallest is duckweed (3 mm in diameter) The largest is the eucalyptus tree (100 meters in height)

Flowers attract pollinators Flowers are reproductive structures in which both male and female gametophytes are formed Flowers are believed to have evolved when gymnosperm ancestors formed an association with animals Animals benefited by eating some of the protein-rich pollen Plants benefited by using animals as pollinators

Fruits encourage seed dispersal Fruits are mature ovaries that contain developing seeds Various fruit adaptations help disperse seeds Edible fruits entice animals to eat them (seeds pass through the digestive tract unharmed) Burrs cling to animal fur Winged fruits are carried through the air