Plant diversity and evolution for life on land
 What was the aquatic ancestor of the land plants?
 green algae (Protista) and plants share the following
derived characters:
 chlorophyll a and b; same accessory pigments (betacarotene)
 cellulose cell walls
 store energy as starch
 similarity of DNA
 What environmental conditions could give a reproductive
advantage to a green algae that could survive better on
land than other individuals?
 avoid grazing herbivores
 shallow water is great place to be (high light) but
individuals rooted in shallow water subject to fluctuating
water levels-constant selective pressure for individuals
who can best survive periods of drying out.
 could new species of algae move onto land today?
 What are the problems faced by an ancestral green algae
exposed to living in air instead of water?
 less support in air than water
 desiccation
 mating; fertilization of eggs and sperm
 What characters evolve to solve these problems?
 support? wood
 desiccation? waxy cuticle plus internal vascular system
 mating? Swimming sperm are a problem
 Not a one step process; some lineages of plants don’t
make a complete transition to land, just like some animal
groups are ‘amphibian’.
What are the major taxa of plants?
 Fig 29.1 Phylogeny of Plants
 Primitive terrestrial plant phyla (Phylum) are small and
restricted to wet sites for reproduction.
 Bryophyta (including liverworts and hornworts) Moss.
 support? Lack vascular system which provides
support in other plants, thus they stay small- desiccation? Incomplete cuticle and are tolerant to
drying out
 sex?
 females retain gametes
 male gametes swim to fertilize egg--need free water for
reproduction
 diploid sporophyte receives nutrients from
gametophyte
 survive in places that stay wet for some extended part
of year—dry out at other times
 Vascular tissues and more complete cuticle results in
adaptive radiation on land of seedless vascular plants.
 3 Phyla: ferns (Pterophyta), horsetails (sphenophyta) and
lycopods (lycophyta)
 support? vascular tissues provide support and
circulation to large body = xylem + phloem
 desiccation? complete cuticle
 reproduction?
 Differs from moss; sporophyte is dominant (2n).
 Similar to moss; gametophyte is free-living, eggs
retained, sperm swim, zygote develops into an embryo
that is nourished by gametophyte.
 Seeds are an evolutionary novelty that results in another
adaptive radiation. What could seed producing plants do
that their ancestors could not? seed
 What could seed producing plants do that their ancestors
could not?
 resource acquired during life of sporophyte cannot be
passed onto its offspring in seedless plants.
 each generation begins from spores carrying nothing
but genetic information—all energy for growth of the
spore into a gametophyte must come thru
photosynthesis
 in contrast, a sporophyte of a seed plant fills a seeds with
energy reserves (fat, starch, or protein) and its embryo
(sporophyte)
 seeds allow colonization of drier habitats for two reasons:
 energy in seed allows rapid early growth and
establishment-provides energy to build photosynthetic
machinery (like getting a loan to build a business)
 swimming sperm eliminated, because now sporophyte
must retain female spores, male spores released as
pollen. Male gametophyte contained within pollen
grain—after pollen carried to female, it produces
sperm.
 What plants produce seeds?
 Gymnosperms and Angiosperms produce seeds
 first appear in fossil record about 300mya during
Carboniferous period (dominant plants were seedless
vascular plants living in large swamps)
 During age of dino’s, 245-65 mya, gymnosperms
dominate

4 extant phyla of gymnos, but we will look at only two:
 Coniferophyta (Conifers)—pines, cedars, redwoods,
spruce
 Cycadophyta (cycads)-
 Flowers are an evolutionary novelty that results in
another adaptive radiation.
 Only angiosperms produce flowers = flowering plants;
evolved from gymnosperm ancestors
 first fossil angiosperms appear about 150 mya and they
are small, herbaceous things—fossil story is less complete
than during swampy periods when seedless plants
dominated; why? seeds allowed colonization of drier
habitats...

What could flowering plants do that their non-flowering
seed plant anscestors could not?
 flowering plants are insect pollinated—some secondarily
wind pollination, but it appears to be convergent
evolution due to similar environmental conditions
 what’s advantage of insect pollination?
 for wind pollination it helps to be tall and have plants
around you be the same species
 woody gymnosperms were major diet of sauropod
dinos then transition to ceritopcians and low grazers.
What were they grazing on? both small gymnosperms
and angiosperms.
 gymnosperms are not well adapted for grazing, but
herbaceous angiosperms are for several reasons:
 grazing tolerant
 grow and reproduce in short time, perhaps
escaping from herbivores by luck.
 insect pollination allows for a population of
scattered, low growing individuals
Diversity of animals
 Diverse…1 million named species, and many more
unnamed species
 35 phyla most of which are invertebrates
 most phyla are aquatic, only 2 phyla are completely
terrestrial
Phylogeny of animals
 probably monophyletic with a colonial protist as
ancestor
 Cambrian Explosion: all 35 phyla appear over 5-10
million year period 545 mya ( beginning of Cambrian)
 Fossils are rare, but occur under some conditions:
Burgess Shale is cambrian-contains all 35 phyla and
perhaps more
 Evolutionary novelties probably fuel the cambrian
explosion, but its not clear what they are (HOX genes)
 environmental changes could also be important; i.e.,
rising oxygen content of atmosphere could allow for
more active animals such as predators.
 phylogeny based on comparative anatomy (analogy and
homology) and embryonic development
 will not stress characters associated with embryonic
development and body plans; rapidly changing views
due to molecular phylogenies
Evolutionary trends in the Animals, Fig 32.8
 radial to bilateral symmetry (Fig 32.5)
 cephalization
 complete gut (hydra)
 circulatory system
 segmentation
Survey of major phyla of animals- (you are responsible for
phyla discussed in class or seen in lab; although I won’t test you over Class
names, the text under class contains information you are responsible for)
 Cnidaria (jellyfish, coral, hydras, sea anemones)
 diverse (10,000 species) and common in marine
environments; freshwater hydras too
 evolutionary advances over sponges: radial symmetry;
have tissues but, lack of organ systems—early branch of
animal evolution
 body plan: gut with single mouth/anus = gastrovascular
cavity
 surrounded by tentacles that capture and move prey to
gut.
 have muscle fibers and nerve fibers, but no
muscle/nervous systems
 medusa: free swimming with tentacles down. Hydra
sessile with tentacles up.
 cnidocytes are stinging cells used in prey capture:
contain nematocysts-a coiled thread that explodes out of
cnidocytes and stings/harpoons or tangles up prey.
 Platyhelminthes (flatworms, flukes, tapeworms-
represent 4 classes with flukes in 2 classes)
 diverse (20,000 species) in marine, freshwater, parasitic,
damp terrestrial
 advances: bilaterally symmetrical—what does it mean to
be bilaterally symmetrical? cephalization, directional
movement, more complex sensory systems and muscle
systems
 primitive characters: gastrovascular cavity with
mouth/anus-finely branched throughout body to
distribute food,
 no circulatory system-constrains them to simple, flat
forms
 Nematoda (round worms)
 diverse (80,000 species), abundant, and common in all
wet places: water, wet soils, living plant and animal
tissues.
 advances:
 complete digestive tract;
 psuedocoelom-fluid filled cavity between outer body
wall and gut that acts as blood-vascular system to
distribute nutrients and to cushion organs
 Mollusca (snails and other gastropods, clams, octopus
and squid)
 50,000 species in marine
 foot, viseral mass, mantle that secretes shell, radula
 Class: Gastropoda
 radula for scraping algae, plants, or predation
 torsion and usually single shell
 slugs and sea slugs
 some terrestrial species
 Bivalvia
 two shell halves
 filter feeders
 Cephalopoda
 squids include largest invertebrate species
 well developed sensory organs and brains
 Annelida
 15,000 species; 3 classes-earthworms, marine worms,
leeches
 two evolutionary innovations
 1. segmented bodies with some organs repeated in
each segment, i.e., excretory tubes, lateral veins,
muscles
 specialization of segments in digestive system: mouth
pharynx, esophagus, crop, gizzard, intestine
 2. Coelom or body cavity for organs. Protects internal
organs, and allows muscle contraction for movement
not to disrupt internal organs.
 closed circulatory system with hemoglobin in blood; uses
wet skin to absorb oxygen
 Arthropoda
 1 million species-most successful animal group in
numbers of species and individuals
 key to success?
 1. retain advances of annelida: segmented, coelom
segmented (allows specialization of groups of
segments)
 2. jointed appendages-legs, feeding sensory
perception-- preadaptation for land
 3. exoskelton made of chitin and protein; protection—
preadaptation for land and muscle attachment
 exoskelton has advantages (above) but also limitations
 doesn’t grow so must molt
 limits size because its heavy and there is no internal
support
 well developed heads with sense organs
 gas exchange through gills or trachea
 Spiders and other chelicerates--Class Arachnida
(spiders, ticks, mites, scorpions) + some related marine
classes of chelicerates too
 all have chelicerae or fangs (most anterior
appendages)
 predators
 two body parts-cephlathorax with 6 pairs of
appendages (chelicerae, pedipalps, 4 pairs of legs) and
abdomen
 several pairs of eyes (4)
 Insects, millipedes and centipedes-Class Insecta
 mandibles instead of fangs,
 antennae and compound eyes
 millipede-like fossils from 450 mya colonizing land
following plants
 insects appear 400mya
 evolutionary novelty of insects: flight
 adaptive radiation greater than any other group of
organisms
 well developed organ systems: nervous system,
muscles, excretory
 metamorphosis is complete in some Orders,
incomplete in others
 separate male and female sexes, fertilization internal
as with all terrestrial groups, whether invert, vert or
plant
 look over Orders of insects in Table 33.6
 Crustaceans
 mostly aquatic; terrestrial groups of spiders and
insects have lost appendages, but most crustaceans
retain appendages on most segments
 pill bugs are terrestrial crustaceans
 lobsters, crayfish are big
 planktonic species: copepods, marine species
Evolution of animal life on land
 support and mobility on land
 waterproof outer layer and other water conserving
mechanisms
 circulatory system to move water and nutrients internally
 reproduction without water
Phylum Chordata Fig. 34.1
 includes 3 subphyla: 2 invertebrates and 1 vertebrate;
grouped together based on 4 characters (often present
only in embryonic stages)
 1. notochord- a stiff flexible rod running down the dorsal
side
 2. hollow dorsal nerve cord- forms from inrolled
ectoderm; unique from nerve cords in other phyla; forms
brain and spinal cord
 3. pharengeal gill slits-pharnyx is the muscular part of
the digestive tube just after the mouth; it has slits to
outside of body; function to allow water out of mouth for
filter feeding.
 4. muscular postanal tail
Subphyla: Vertebrata
 characters that distinguish vertebrates probably
associated with increased activity and size
 1. increased cephalization
 2. cranium and vertebral column replace notochord;
associated with increased size and mobility
 axial skeleton (supports limbs or fins) provides
support for greater activity
 bone or cartilage
 3. adaptations of digestive, respiratory, circulatory
systems to provide energy for more active life style (=
predatory)
Phylogeny of Vertebrates
 derived characters in Phylogeny in Fig 34.7
Class Agnatha
 jawless fish-like vertebrates
 most lived 400-500mya, but some extant forms
 hagfish, lamprey
 suck blood, suspension feed (like lancelets), detritus
 lack paired appendages (no axial skeleton)
 retain notochord
 pharengeal gill slits, mouth is simply the muscular
opening of the digestive tube-no jaws
 what does it mean to be primitive?
 primitive does not = bad or non-adaptive
 a novel trait may allow radiation into unexploited
habitats, but does not have to eliminate the more
primitive trait.
 an improvement of a trait is likely to result in the
replacement of more primative trait.
Class Chondrichthyes-Sharks and rays
 Sharks are primitive too, they have been dominate sea
predators for 425-450 my
 cartilaginous fish
 not all predators; some are suspension feeders on
plankton: rays and whale sharks
 teeth are modified scales; scales tooth-like pegs
 senses of sharks include
 lateral line system, a row of tiny organs sensitive to
pressure changes—to detect presence of prey ; may
attract sharks to sites of helicopter sea rescues
 olfactory sense excellent
 electric field receptors on snout,
Class Osteichthyes-Bony fish
 most species of all vertebrates (30,000)
 bony scales
 lateral line system too, you can see opening running
down side of fish
 4-5 pairs of gills covered by operculum
 muscular operculum pumps water over gills
 swim bladder: air filled sac controls buoyancy
 ray-finned fishes and lobe-fined fishes
Class Amphibia
 4000 species
 365 mya first amphibians appear
 3 orders: frogs; salamanders; caecilians
 you see these in lab
Amniotic egg found in all remaining classes
 birds, reptiles and mammals are monophyletic group:
the amniotes, but its traditional to consider them as 3
classes
 amniotic membranes allow gas exchange but prevent
desiccation
(fig 34.19)
 4 membranes in all, the one surrounding the embryo =
amnion
 embryo develops within fluid filled amnion
Class Reptilia
 7000 species
 reptile covered with waterproof coating: made of
protein keratin
 most lay eggs, but some viviparous
 ectothermic
 appear 300mya;
 huge radiation 200-65 mya that resulted in dinosaurs
 modern orders:
 turtles (Chelonia)
 lizards and snakes (Squamata)
 alligators and crocidilia (Crocodilia)
Class Aves
 evolved during dinosaur radiation; retain scaled legs
 Archaeopteryx from 150mya in Jurassic
 feathers, teeth, tail
 some specimens were classified as small dinos until
reexamined and feather traces found
 characteristics associated with flight make birds unique
and traditionally classified in their own class
 light honeycombed bones
 endothermic,
 4 chambered heart
 excellent vision
 adaptation examined in lab
 8600 species today
Class Mammalia
 mammals present during dino age, just not dominant
 220mya appear in fossil record
 4500 species today
 unique characters
 hair
 mammary glands that produce milk
 most don’t lay eggs
 endothermic with 4 chambered heart
 3 major groups:
 monotremes lay eggs similar to reptile eggs
 secrete milk from glands on venter
 australia and new guinea
 marsupials-opossums, kangaroos, koalas (fig. 34.31)
 babies born tiny and complete their development in
pouch
 placental complete embryonic development in uterus, joined to
mother by placenta
 major orders of placental mammals in Table 34.1
 Primates represent one order
 ancestors were small tree-dwellers (arboreal); appear
55mya (fig 34.35)
 suborders: prosimii (lemurs, tarsiers) and anthropoidea
(monkeys, apes)
 human evolution is under intense study
 is it gradual phyletic change or are there many extinct
offshoots?
 Fig 34.38. branching tree indicate that several humanlike species coexisted at the same time; i.e.,
neanderthals and cro-magnon man fossils are found in
caves in europe at same time 60,000 to 35,000 yrs ago
 multiregional vs out-of-africa Fig 34.41
Fungi
 What are fungi?
 terrestrial
 multicellular,
 heterotrophic by absorption
 eukaryotic
 Ecological roles
 decomposers
 symbiotic relationships with other organisms
 mycorrhizae
 lichens
 gut symbionts
 plant parasites
 animal parasites
 Morphological adaptations
 yeasts -unicellular
 molds - masses of hyphae and mycelia
 Reproduction
 classification based on details of reproduction
 life cycle: haploid most of the time
 grow through mitosis as hyphae in soil, tree, etc.
 reproduce by producing spores asexually or sexually
 sexual reproduction occurs when hyphae from two
different individuals fuse (plasmogamy), followed by
fusion of the nuclei (karyogamy).