1. Phylogeny and Systematics
Ch. 25

2. Phylogeny
Evolutionary history of a species or group of related species
Reconstructing phylogeny is part of the scope of systematics
Systematics—the study of biological diversity in an evolutionary context

3. Phylogenetic Trees
Diagrams that trace evolutionary relationships as best as they can be determined
Systematist use evidence from:
Fossil record
Phenotypic appearances
Molecular biology
Comparison of nucleic acid sequences/amino acid sequences
DNA sequence analysis—identifying & comparing homologous sequences
Species diverge as changes (genetic mutations) occur

5. Taxonomy
Branch of biology concerned with naming and classifying the diverse forms of life
Scientific name of an organism = binomial system
Genus / species

6. Phylogenetic trees reflect the hierarchical classification

7. Cladistic Analysis Synonymous with phylogenetic systematics
Clade=evolutionary branch
Classifying organisms according to the order in time that branches arose along a dichotomous tree
Cladogram

9. Analyzing the taxonomic distribution of homologies enables us to identify the sequence in which derived characters evolved during vertebrate phylogeny.
Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

10. Kingdom: Plantae Plant Diversity
Ch. 29 & 30

11. Land plants evolved from green algae
Green algae called charophyceans are the closest relatives of land plants
Four key traits in common:
Rose-shaped complexes for cellulose synthesis
Peroxisome enzymes
Structure of flagellated sperm
Formation of a phragmoplast
Supported by genetic similarites in both their nuclear and chloroplast genes

12. Adaptations Enabling the Move to Land
In charophyceans a layer of a durable polymer called sporopollenin prevents exposed zygotes from drying out
The accumulation of traits that facilitated survival on land may have opened the way to its colonization by plants

13. Land plants possess a set of derived terrestrial adaptations
Many adaptations emerged after land plants diverged from their charophycean relatives
Five key traits appear in nearly all land plants but are absent in the charophyceans:
Apical meristems
Alternation of generations
Walled spores produced in sporangia
Multicellular gametangia
Multicellular dependent embryos

14. Plant Characteristics
Multicellular eukaryotes
Photosynthetic autotrophs
Chloroplasts with photosynthetic pigments
chlorophyll, carotenoids
Cell walls contain cellulose
Excess glucose stored as starch in plastids

15. Life Cycles of Plants: Alternation of Generations
Gametophyte—multicellular individual with haploid cells
Produce haploid cells that fuse to form zygotes
Sporophyte—multicellular individual with diploid cells
Develop from the zygotes that are formed

16. Gametophyte Phase
Dark round structures are antheridia or archegonia of the fern gametophyte (x12)
The fern sporophyte grows from a fertilized egg in an archegonium on the gametophyte. (x12)

17. Sporophyte Phase Fern Fiddleheads Sori on Fern Leaf
Fern Leaf with Sori

18. Plant Phylogeny
Origin of plants from aquatic ancestors— Ordovician period (475mya)
Cuticle formation and jacketed gametangia
Vascular tissue with conducting cells
Diversification of seedless vascular plants—Devonian period (400mya)

19. Plant Phylogeny Origin of the seed—Devonian period (360mya)
Seed = plant embryo packaged with food store and protective coat
Gymnosperms—early seed plants—naked seeds
Emergence of flowering plants—Cretaceous period (130mya)
Angiosperms—plants bear seeds inside flower’s protective ovaries

21. Classification of Plants I
Nonvascular Plants (Bryophytes)
Division Bryophyta (mosses)
Division Hepatophyta (liverwarts)
Division Anthocerophyta (hornwarts)
Characteristics:
Small herbaceous plants (nonwoody)
No vascular tissue, so relies on diffusion and capillary action to get water
Need water to reproduce
Gametophytes—larger and longer-living than sporophytes
Sporophytes—typically present only part of the time
Gametangia protect developing gametes
antheridium—produce flagellated sperm
archegonium—produce single egg

22. Division Bryophyta (mosses) Spongy mat—can absorb and retain water
Grips substratum with rhizoids (cellular filaments)

23. Bryophyta The green leafy structures are gametophytes.
The brown structures are sporophyte stalks and spore capsules.

24. Life Cycle of Moss

25. Division Hepatophyta (liverworts)
Division Hepatophyta
(liverworts)
Sporangia have coil-shaped cells that spring out and disperse spores
LIVERWORT SPOROPHYTE

26. Division Anthocerophyta
Sporophytes are horn-shaped, elongated capsules that grow from the mat like gametophyte
Photosynthetic cells have only one large chloroplast
sporophyte
gametophyte
Division Anthocerophyta
(hornworts)
hornwort Phaeoceros

27. Classification of Plants
Vascular Plants
Seedless Vascular Plants
Division Lycophyta (lycophytes)
Division Sphenophyta (horsetails)
Division Pterophyta (ferns)
Characteristics:
Sporophytes are the larger generation
Gametophytes are tiny plants that grow on or below the soil surface
Terrestrial Adaptations:
Roots-transport water
Cellulose (structure support)
Vascular tissue-xylem (water) and phloem (food)
Pollen-eliminates need for water in reproduction
Increased dominance of diploid sporophyte

28. Division Lycophyta (lycophytes)
Low-growing plants with rhizomes and true leaves
Some are epiphytes (use another organism as a substratum
Lycopodium
annotinum
Rhizome: stem like part of the plant from which the leaves grow
Order Isoetales Quillworts

29. Division Sphenophyta (horsetails) sporangia
sporangia
Division Sphenophyta
(horsetails)
Sphenophytes consist of only one genus, Equisetum, with about thirty living species known worldwide
Homosporous-bisexual gametophyte produces egg and sperm

30. Division Pterophyta (ferns)
Most diverse seedless vascular plants
Fronds-compound leaves
Homosporous
Sporangia borne on underside of specialized sporophylls
Water necessary for fertilization
Sporophyte develops within archegonium

32. 3 Variations on Alternation of Generations in Plants

33. Evolution of Roots Roots are organs that anchor vascular plants
They enable vascular plants to absorb water and nutrients from the soil
Roots may have evolved from subterranean stems

34. Evolution of Leaves
Leaves are organs that increase the surface area of vascular plants, thereby capturing more solar energy that is used for photosynthesis
Leaves are categorized by two types:
Microphylls, leaves with a single vein
Megaphylls, leaves with a highly branched vascular system
According to one model of evolution, microphylls evolved first, as outgrowths of stems

35. Classification of Plants II
Vascular Plants
Seed Plants
Gymnosperms
Division Coniferophyta (conifers)
Division Cycadophyta (cycads)
Division Ginkgophyta (ginkgo)
Division Gnetophyta (Gnetae)

36. Seeds Replace Spores
Relatively harsh terrestrial environment led to development of resistant structures for the dispersal of offspring
Seeds more hardy because of multicellular nature
Seed = sporophyte embryo + food supply surrounded by protective coat
Seed plants are heterosporous
Megasporangia produce megaspores  female gametophyte
Microsporangia produce microspores  male gametophyte

37. Heterospory: The Rule Among Seed Plants
Seed plants evolved from plants with megasporangia, which produce megaspores that give rise to female gametophytes
Seed plants evolved from plants with microsporangia, which produce microspores that give rise to male gametophytes
cavehill.uwi.edu/FPAS/bcs/bl14apl/pter3.htm
Micrograph of Selaginella

38. Ovules and Production of Eggs
An ovule consists of a megasporangium, megaspore, and one or more protective integuments
Gymnosperm megaspores have one integument
Angiosperm megaspores usually have two integuments

39. Pollen and Production of Sperm
Microspores develop into pollen grains, which contain the male gametophytes
Pollination—transfer of pollen to the part of a seed plant containing the ovules
Dispersal by air or animals
If a pollen grain germinates, it gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovule

40. The Evolutionary Advantage of Seeds
A seed develops from the whole ovule
A seed is a sporophyte embryo, along with its food supply, packaged in a protective coat
commons.wikimedia.org/wiki/Image:Avocado_seed...

41. Division Coniferophyta (conifers)
Araucaria cunninghamii. The hoop pine. Lake Tinaroo Falls Dam, Queensland, Australia.
Largest division of Gymnosperms
-most are evergreens: pines, spruces, firs, larches, yews, junipers, cedars, cypresses, and redwoods

42. Yosemite National Park, Mariposa County, California.
Sequioadendron giganteum. The Giant Sequoia.
Yosemite National Park, Mariposa County,
California.

43. Division Coniferophyta (conifers)
Needle-shaped conifer leaves are adapted to dry conditions
thick cuticle covers the leaf
stomata are in pits, reducing water loss

44. Division Coniferophyta (conifers)
Mature ovulate cones and seeds

45. Heterosporous- both male and female gametophytes develop from different types of spores on separate cones

47. Division Coniferophyta (conifers)
Cedrus deodora. Near Placerville

48. Division Cycadophyta (cycads)
Living fossils—Jurassic Period is sometimes called the "Age of Cycads"

49. Division Cycadophyta
(cycads)
Cycas revoluta

50. Division Ginkgophyta (ginkgo)
Ginkgo biloba
Division Ginkgophyta (ginkgo)

51. Division Gnetophyta (Gnetae) Ephedra andina. Mormon tea
Division Gnetophyta
(Gnetae)
Ephedra andina.
Mormon tea

52. Classification of Plants II
Vascular Plants
Seed Plants
Angiosperms
Division Anthophyta (flowering plants)

53. Reproductive adaptations of angiosperms include flowers and fruits
Angiosperms are flowering plants
These seed plants have reproductive structures called flowers and fruits
They are the most widespread and diverse of all plants

54. Division Anthophyta (flowering plants) Sunflower
California Poppy
Sunflower
Indian Paintbrush in Grand Canyon.
Division Anthophyta
(flowering plants)

56. Fruit develop from the ovary

57. Fruits
A fruit typically consists of a mature ovary but can also include other flower parts
Fruits protect seeds and aid in their dispersal
Mature fruits can be either fleshy or dry

58. Fruits Various fruit adaptations help disperse seeds
Seeds can be carried by wind, water, or animals to new locations

59. The Angiosperm Life Cycle
In the angiosperm life cycle, double fertilization occurs when a pollen tube discharges two sperm into the female gametophyte within an ovule
One sperm fertilizes the egg, while the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food-storing endosperm
The endosperm nourishes the developing embryo

60. The Angiosperm Life Cycle