Download Radial symmetry

Chapter 17
The Evolution of Animals
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
© 2010 Pearson Education, Inc.
Domain Bacteria
Earliest
organisms
Domain Archaea
The protists
(multiple
kingdoms)
Kingdom
Plantae
Domain Eukarya
The three-domain
classification
system
© 2010 Pearson Education, Inc.
Kingdom
Fungi
Kingdom
Animalia
Figure 14.25
What Is an Animal?
• Animals are:
– Eukaryotic
– Multicellular
– Heterotrophic organisms that obtain nutrients by ingestion
– Able to digest their food within their bodies
• Animal cells lack the cell walls that provide strong support in the
bodies of plants and fungi.
© 2010 Pearson Education, Inc.
• Most animals have:
– Muscle cells
– Nerve cells that control the muscles
© 2010 Pearson Education, Inc.
• Most animals:
– Are diploid
– Reproduce sexually
– Proceed through a series of typically similar developmental stages
© 2010 Pearson Education, Inc.
Early Animals and the Cambrian Explosion
• Animals probably evolved from a colonial flagellated protist that
lived in Precambrian seas about 600–700 million years ago.
© 2010 Pearson Education, Inc.
• At the beginning of the Cambrian period, 542 million years ago,
animals underwent a rapid diversification.
• During a span of about 15 million years:
– All major animal body plans we see today evolved
– Many of these animals seem bizarre
© 2010 Pearson Education, Inc.
Figure 17.4a
Sponges
• Sponges represent multiple phyla.
• Sponges include sessile animals that lack true tissues and that
were once believed to be plants.
• The body of a sponge resembles a sac perforated with holes.
• Choanocyte cells draw water through the walls of the sponge
where food is collected.
© 2010 Pearson Education, Inc.
Pores
Amoebocyte
Skeletal
fiber
Central
cavity
Choanocyte
(feeding cell)
Water
flow
Flagella
Choanocyte
in contact
with an
amoebocyte
Figure 17.8
MAJOR INVERTEBRATE PHYLA
• Invertebrates:
– Are animals without backbones
– Represent 95% of the animal kingdom
© 2010 Pearson Education, Inc.
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
• A second major evolutionary split is based on body symmetry.
– Radial symmetry refers to animals that are identical all around a central
axis.
– Bilateral symmetry exists where there is only one way to split the
animal into equal halves.
© 2010 Pearson Education, Inc.
Radial symmetry. Parts radiate from the center, so any slice
through the central axis divides into mirror images.
Bilateral symmetry. Only one slice can divide left and right
sides into mirror-image halves.
Figure 17.6
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
Cnidarians
• Cnidarians (phylum Cnidaria) are characterized by:
– The presence of body tissues
– Radial symmetry
– Tentacles with stinging cells
© 2010 Pearson Education, Inc.
Mouth/anus
Tentacle
Gastrovascular
cavity
Polyp form
Figure 17.9aa
Mouth/anus
Tentacle
Gastrovascular
cavity
Polyp form
Coral
Hydra
Sea anemone
Gastrovascular
cavity
Mouth/anus
Tentacle
Medusa form
Jelly
Figure 17.9
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
Molluscs
• Molluscs (phylum Mollusca) are represented by soft-bodied
animals, usually protected by a hard shell.
• Many molluscs feed by using a file-like organ called a radula to
scrape up food.
• The body of a mollusc has three main parts:
– A muscular foot used for movement
– A visceral mass housing most of the internal organs
– A mantle, which secretes the shell if present
© 2010 Pearson Education, Inc.
Visceral mass
Coelom
Kidney
Heart
Reproductive
organs
Digestive
tract
Shell
Mantle
Mantle
cavity
Radula
Anus
Gill
Mouth
Foot
Nerve
cords
Digestive
tract
Radula
Mouth
Figure 17.11
MAJOR GROUPS OF MOLLUSCS
Gastropods
Bivalves
(hinged shell)
Cephalopods
(large brain and tentacles)
Snail (spiraled shell)
Scallop
Octopus
Squid
Sea slug (no shell)
Figure 17.12
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
Flatworms
• Flatworms (phylum Platyhelminthes) are the simplest bilateral
animals.
• Flatworms include forms that are:
– Parasites or
– Free-living in marine, freshwater, or damp habitats
© 2010 Pearson Education, Inc.
• The gastrovascular cavity of flatworms
– Is highly branched
– Provides an extensive surface area for absorption of nutrients
© 2010 Pearson Education, Inc.
Digestive tract
(gastrovascular
cavity)
Nerve cords
Mouth
Eyespots (detect light)
Nervous tissue clusters
(simple brain)
Planarian
Bilateral symmetry
Figure 17.13a
Annelids
• Annelids (phylum Annelida) have:
– Body segmentation, a subdivision of the body along its length into a
series of repeated parts
– A complete digestive tract with
–
Two openings, a mouth and anus
–
One-way movement of food
© 2010 Pearson Education, Inc.
Anus
Brain
Main
heart
Coelom
Digestive
tract
Segment
walls
Mouth
Accessory
hearts
Nerve cord
Waste disposal organ
Blood vessels
Figure 17.15
• The three main groups of annelids are:
– Earthworms, which eat their way through soil
– Polychaetes, marine worms with segmental appendages for movement
and gas exchange
– Leeches, typically free-living carnivores but with some bloodsucking
forms
© 2010 Pearson Education, Inc.
MAJOR GROUPS OF ANNELIDS
Earthworms
Polychaetes
Leeches
Giant Australian earthworm
Christmas tree worm
European freshwater leech
Figure 17.14
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
Arthropods
• Arthropods (phylum Arthropoda) are named for their jointed
appendages.
• There are about one million arthropod species identified, mostly
insects.
• Arthropods are a very diverse and successful group, occurring in
nearly all habitats in the biosphere.
• There are four main groups of arthropods.
© 2010 Pearson Education, Inc.
MAJOR GROUPS OF ARTHROPODS
Arachnids
Crustaceans
Millipedes and Centipedes
Insects
Figure 17.17
General Characteristics of Arthropods
• Arthropods are segmented animals with specialized segments and
appendages for an efficient division of labor among body regions.
© 2010 Pearson Education, Inc.
• The body of arthropods is completely covered by an exoskeleton,
an external skeleton that provides:
– Protection
– Points of attachment for the muscles that move appendages
© 2010 Pearson Education, Inc.
Abdomen
Cephalothorax
(head and thorax)
Antenna
(sensory reception)
Eyes on
movable stalks
Mouthparts (feeding)
Walking leg
Swimming
appendage
Walking legs
Figure 17.18
Two feeding
appendages
Leg (four pairs)
Scorpion
Black widow spider
Dust mite
Wood tick
Figure 17.19
Two feeding
appendages
Leg (three or more pairs)
Antennae
Crab
Shrimp
Crayfish
Pill bug
Barnacles
Figure 17.20
Millipedes and Centipedes
• Millipedes and centipedes have similar segments over most of the
body.
• Millipedes:
– Eat decaying plant matter
– Have two pairs of short legs per body segment
• Centipedes:
– Are terrestrial carnivores with poison claws
– Have one pair of short legs per body segment
© 2010 Pearson Education, Inc.
One pair of legs per segment
Two pairs of legs
per segment
Millipede
Centipede
Figure 17.21
Insect Anatomy
• Insects typically have a three-part body:
– Head
– Thorax
– Abdomen
© 2010 Pearson Education, Inc.
Head Thorax
Abdomen
Antenna
Eye
Mouthparts
Figure 17.22
Insect Diversity
• Insects outnumber all other forms of life combined.
• Insects live in:
– Almost every terrestrial habitat
– Freshwater
– The air
© 2010 Pearson Education, Inc.
Leaf roller
Banded Orange
Heliconian
Giraffe weevil
Peacock katydid
Praying
mantis
Yellow jacket wasp Leaf beetle
Longhorn beetle
Figure 17.23
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
Echinoderms
• Echinoderms (phylum Echinodermata):
– Lack body segments
– Typically show radial symmetry as adults but bilateral symmetry as
larvae
– Have an endoskeleton
– Have a water vascular system that facilitates movement and gas
exchange
• Echinoderms are a very diverse group.
© 2010 Pearson Education, Inc.
Sea star
Tube feet
Sea urchin
Sea cucumber
Sand dollar
Figure 17.25
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
SO…….
We are cousins with a
Starfish?
© 2010 Pearson Education, Inc.
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
METAMORPHOSIS
Blastula
(cross section)
Digestive tract
Outer cell layer
(ectoderm)
Larva
Inner cell layer
(endoderm)
Internal sac
© 2010 Pearson Education, Inc.
Early gastrula
(cross section)
Later gastrula Future middle
(cross section) layer of cells
(mesoderm)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-8
© 2010 Pearson Education, Inc.
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
21%
6%
14%
48%
11%
Living
Vertebrates
© 2010 Pearson Education, Inc.
VERTEBRATE EVOLUTION AND
DIVERSITY
• Vertebrates have unique endoskeletons composed of:
– A cranium (skull)
– A backbone made of a series of bones called vertebrae
© 2010 Pearson Education, Inc.
Tunicates
Figure 17.28b
Mouth
Tail
Lancelet
Figure 17.28a
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.29
(a) Hagfish (inset: slime)
Jawless
Figure 17.30a
Jawless
(b) Lamprey (inset: mouth)
Figure 17.30b
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
© 2010 Pearson Education, Inc.
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.29
The two major groups of living fishes are the:
Cartilaginous fishes (sharks and rays) with a flexible
skeleton made of cartilage
Lateral line
(c) Shark, a cartilaginous fish
Figure 17.30c
And bony fishes with a skeleton reinforced by hard
CALCIUM
Operculum
Lateral line
(d) Bony fish
Figure 17.30d
Amphibians
• Amphibians:
– Exhibit a mixture of aquatic and terrestrial adaptations
– Usually need water to reproduce
– Typically undergo metamorphosis from an aquatic larva to a terrestrial
adult
© 2010 Pearson Education, Inc.
(a) Tadpole and adult golden palm tree frog
Red-eyed tree frog
Texas barred tiger salamander
(b) Frogs and salamanders: the two major groups of amphibians
Figure 17.31
• Amphibians:
– Were the first vertebrates to colonize land
– Descended from fishes that had lungs and fins with muscles
© 2010 Pearson Education, Inc.
Lobe-finned fish
Early amphibian
Figure 17.32
• Terrestrial vertebrates are collectively called tetrapods, which
means “four feet.”
• Tetrapods include:
– Amphibians
– Reptiles
– Mammals
© 2010 Pearson Education, Inc.
Reptiles
• Reptiles (including birds) and mammals are amniotes, which
produce amniotic eggs that consist of a fluid-filled shell inside of
which the embryo develops.
© 2010 Pearson Education, Inc.
• Reptiles include:
– Snakes
– Lizards
– Turtles
– Crocodiles
– Alligators
– Birds
© 2010 Pearson Education, Inc.
• Reptile adaptations to living on land include:
– Amniotic eggs
– Scaled, waterproof skin
© 2010 Pearson Education, Inc.
• Nonbird reptiles are ectotherms, sometimes referred to as “coldblooded,” which means that they obtain their body heat from the
environment.
• A nonbird reptile can survive on less than 10% of the calories
required by a bird or mammal of equivalent size.
• Reptiles diversified extensively during the Mesozoic era.
• Dinosaurs were the largest animals ever to live on land.
© 2010 Pearson Education, Inc.
• Birds have many adaptations that make them lighter in flight:
– Honeycombed bones
– One instead of two ovaries
– A beak instead of teeth
• Unlike other reptiles, birds are endotherms, maintaining a
warmer and steady body temperature.
© 2010 Pearson Education, Inc.
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
© 2010 Pearson Education, Inc.
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.29
Mammals
• The first true mammals:
– Arose about 200 million years ago
– Were probably small, nocturnal insect-eaters
• Most mammals are terrestrial although dolphins, porpoises, and
whales are totally aquatic.
© 2010 Pearson Education, Inc.
• Mammalian hallmarks are:
– Hair
– Mammary glands that produce milk, which nourishes the young
© 2010 Pearson Education, Inc.
• There are three major groups of mammals:
– Monotremes, egg-laying mammals
– Marsupials, pouched mammals with a placenta
– And eutherians, placental mammals
© 2010 Pearson Education, Inc.
MAJOR GROUPS OF MAMMALS
Monotremes
(hatched from eggs)
Echidna adult
and egg
Marsupials
(embryonic at birth)
Eutherians
(fully developed at birth)
Kangaroo newborn and mother
Wildebeest newborn
and mother
Figure 17.35
• Eutherian placentas provide more intimate and long-lasting
association between the mother and her developing young than do
marsupial placentas.
© 2010 Pearson Education, Inc.
© 2010 Pearson Education, Inc.
THE HUMAN ANCESTRY
• Humans are primates, the mammalian group that also includes:
– Lorises
– Pottos
– Lemurs
– Tarsiers
– Monkeys
– Apes
© 2010 Pearson Education, Inc.
Lemurs, lorises,
and pottos
Ancestral
primate
Tarsiers
Apes
Gibbons
Anthropoids
Old World monkeys
Monkeys
New World monkeys
Orangutans
Gorillas
Chimpanzees
Humans
Figure 17.36
• Primates are distinguished by characteristics that were shaped by
the demands of living in trees. These characteristics include:
– Limber shoulder joints
– Eyes in front of the face
– Excellent eye-hand coordination
– Extensive parental care
© 2010 Pearson Education, Inc.
Ring-tailed
lemur
Tarsier
Black spider monkey
(New World monkey)
Patas monkey (Old World monkey)
Gorilla (ape)
Orangutan (ape)
Gibbon (ape)
Chimpanzee (ape)
Human
Figure 17.37
The Emergence of Humankind
• Humans and chimpanzees have shared a common African
ancestry for all but the last 5–7 million years.
© 2010 Pearson Education, Inc.
Some Common Misconceptions
• Chimpanzees and humans represent two divergent branches of the
anthropoid tree that each evolved from a common, less
specialized ancestor.
• Our ancestors were not chimpanzees or any other modern apes.
© 2010 Pearson Education, Inc.
• Human evolution is not a ladder with a parade of fossil hominids
(members of the human family) leading directly to modern
humans.
• Instead, human evolution is more like a multibranched bush than
a ladder.
• At times in hominid history, several different human species
coexisted.
© 2010 Pearson Education, Inc.
0
?
Homo
Homo
neanderthalensis sapiens
Paranthropus
boisei
0.5
1.0
1.5
Millions of years ago
2.0
2.5
Homo erectus
Paranthropus
robustus
3.0
3.5
Homo
habilis
Australopithecus
africanus
4.0
4.5
5.0
5.5
Australopithecus
afarensis
6.0 Ardipithecus
ramidus
Figure 17.38
• Upright posture and an enlarged brain appeared at separate times
during human evolution.
• Different human features evolved at different rates.
© 2010 Pearson Education, Inc.
Australopithecus and the Antiquity of Bipedalism
• Before there was the genus Homo, several hominid species of the
genus Australopithecus walked the African savanna.
• Fossil evidence pushes bipedalism in A. afarensis back to at least
4 million years ago.
© 2010 Pearson Education, Inc.
(a) Australopithecus (b) Ancient footprints
afarensis skeleton
(c) Model of an
Australopithecus
afarensis male
Figure 17.39
Homo Habilis and the Evolution of Inventive Minds
• Homo habilis, “handy-man”:
– Had a larger brain, intermediate in size between Australopithecus and
modern humans
– Walked upright
– Made stone tools that enhanced hunting, gathering, and scavenging on the
African savanna
© 2010 Pearson Education, Inc.
Homo Erectus and the Global Dispersal of Humanity
• Homo erectus was the first species to extend humanity’s range
from Africa to other continents.
• The global dispersal began about 1.8 million years ago.
© 2010 Pearson Education, Inc.
• Homo erectus:
– Was taller than H. habilis
– Had a larger brain
– Gave rise to Neanderthals
© 2010 Pearson Education, Inc.
The Process of Science:
What Did Neanderthals Look Like?
• Observation: Geneticists noted that a gene mclr has a large effect
on human hair and skin pigmentation.
• Question: What form of the gene would be found in
Neanderthals?
• Experiment: The mclr pigment gene was isolated from
Neanderthal DNA.
© 2010 Pearson Education, Inc.
• Results:
– The Neanderthal gene contained a mutation not found in modern humans.
– Human cells engineered to carry the Neanderthal version of the gene
reacted in ways that suggests that Neanderthals had red hair and pale skin.
© 2010 Pearson Education, Inc.
Figure 17.40
The Origin and Dispersal of Homo Sapiens
• The oldest known fossils of our own species, Homo sapiens:
– Were discovered in Ethiopia
– Date from 160,000 to 195,000 years ago
© 2010 Pearson Education, Inc.
• DNA studies strongly suggest that all living humans can trace
their ancestry back to a single African Homo sapiens woman who
lived 160,000 to 200,000 years ago.
© 2010 Pearson Education, Inc.
• Fossil evidence suggests that our species emerged from Africa
in one or more waves.
• The oldest fossils of H. sapiens outside of Africa are 50,000 years
old.
• The oldest fossils of humans in the New World are uncertain, but
are at least 15,000 years old.
© 2010 Pearson Education, Inc.
• The global consequences of human evolution have been
enormous. Humans can:
– Defy our physical limitation
– Shortcut biological evolution
– Change the environment to meet our needs
© 2010 Pearson Education, Inc.
Figure 17.42
Tuesday Apr 1 : Chap 15
Thursday Apr 3 : Chap 16
Tuesday Apr 8 : Chap 17
Tuesday Apr 10 : Chap 17
Tuesday Apr 15 : Exam #3
covering all Evolution
Chap 13, 14, 15, 16, 17
What's your favorite
animal?????
© 2010 Pearson Education, Inc.
Biology Tutoring
HSEC building, room A-129
Biology
Thursday 1 pm – 4 pm
Saturday 12:00 pm – 3 pm
Tuesday EXAM #3
Chap 13, 14, 15, 16, 17
What's your favorite animal?????
© 2010 Pearson Education, Inc.
Tuesday Nov 5 : Chap 15
Thursday Nov 7 : Chap 16
Tuesday Nov 12 : Chap 17
Tuesday Nov 14 : Chap 17
Tuesday Nov 19 : Exam #3
covering all Evolution
Bring Scantron + pencil
Chap 13, 14, 15, 16, 17
© 2010 Pearson Education, Inc.
Domain Bacteria
Earliest
organisms
Domain Archaea
The protists
(multiple
kingdoms)
Kingdom
Plantae
Domain Eukarya
The three-domain
classification
system
© 2010 Pearson Education, Inc.
Kingdom
Fungi
Kingdom
Animalia
Figure 14.25
• Chordates consists of three groups of invertebrates:
– Lancelets are bladelike animals without a cranium.
– Tunicates, or sea squirts, also lack a cranium.
– Hagfishes are eel-like forms that have a cranium.
• All other chordates are vertebrates.
© 2010 Pearson Education, Inc.
Fishes
• The first vertebrates were aquatic and probably evolved during
the early Cambrian period, about 542 million years ago. They:
– Lacked jaws
– Are represented today by hagfishes
© 2010 Pearson Education, Inc.
Characteristics of Chordates
• Chordates (phylum Chordata) all share four key features that
appear in the embryo and sometimes the adult:
– A dorsal, hollow nerve cord
– A notochord
– Pharyngeal slits
– A post-anal tail
© 2010 Pearson Education, Inc.
Dorsal,
hollow
Notochord
nerve cord
Brain
Muscle segments
Mouth
Anus
Post-anal
tail
Pharyngeal
slits
Figure 17.27
• Another chordate characteristic is body segmentation, apparent in
the:
– Backbone of vertebrates
– Segmental muscles of all chordates
© 2010 Pearson Education, Inc.
• Cartilaginous and bony fishes have a lateral line system that
detects minor vibrations in the water.
• To provide lift off the bottom:
– Cartilaginous fish must swim but
– Bony fish have swim bladders, gas-filled sacs that make them buoyant
© 2010 Pearson Education, Inc.
The Evolution of Primates
• Primates evolved from insect-eating mammals during the late
Cretaceous period.
© 2010 Pearson Education, Inc.
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
© 2010 Pearson Education, Inc.
Figure 17.5
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.UN16
Obesity Rates Are Rising in Developing Countries
(Nov. 11) -- Obesity is often thought of as a Western problem brought on by prosperity.
But as fortunes rise in developing nations and more and more people begin to adopt an
American-style diet, American-style health problems are spreading as well.
In a report from the Lancet medical journal, the Organization for Economic Co-operation
and Development found that obesity levels are rising throughout developing countries -up to 50 percent of adults in a group of nations that includes Russia, China, Brazil, South
Africa and Mexico. Mexico and South Africa were both well above the average.
The report's authors recommend government spending on regulation, media campaigns,
food labeling and subsidies for healthy foods. They argue that any costs incurred would be
more than offset by long-term reductions in health care spending.
The increase in over-nutrition across the world hasn't led to comparable decreases in
under-nutrition, either. While the U.N. Food and Agricultural Organization did find that
hunger had decreased in 2010, a report last month still found that 925 million people
around the world have chronic hunger, a figure they called "unacceptable."
© 2010 Pearson Education, Inc.
Feds: Put rare Hawaii dolphin on endangered list
Nov 16, 2010
HONOLULU (AP) - The federal government is recommending that
a small population of dolphins living near Hawaii be placed on the
endangered species list.
The National Marine Fisheries Service said Tuesday it's identified
29 threats to the population's survival.
The agency is due to post its recommendation in the Federal
Register on Wednesday.
The species is called the "false killer whale" even though it's a
dolphin and doesn't look like a killer whale.
An agency study published in August says the small population is
in danger of inbreeding and of getting caught on fishing lines.
False killer whales are found in tropical and temperate waters
worldwide. But scientists estimate only about 150 or 170 live in
waters up to 87 miles off Hawaii.
© 2010 Pearson Education, Inc.
Giant Flying Lizard Could Cross Whole Continents
(Nov. 15) -- Coast-to-coast nonstop flights. Not bad for a giant lizard.
According to a new study published by palaeontologists in England and the
United States, not only did the giraffe-sized lizard, known as pterosaur, fly, it
flew incredibly long distances.
''These creatures were not birds, they were flying reptiles with a distinctly
different skeletal structure, wing proportions and muscle mass, " Witton told The
Telegraph. ''They would have achieved flight in a completely different way to birds
and would have had a lower angle of takeoff and initial flight trajectory. The
anatomy of these creatures is unique.'‘
While birds developed light, hollow bones in order to fly, pterosaurs needed
stronger, reinforced skeletons to support their rough-and-tumble methods of
flight.
Once it was aloft, the soaring creature could remain airborne for hundreds of
miles, sometimes even spanning whole continents, the study says.
© 2010 Pearson Education, Inc.
• Lampreys:
– Are vertebrates
– Have a cranium
– But lack jaws
© 2010 Pearson Education, Inc.
Tenth of Quirky Creature's Active Genes Are Foreign: Believed to 'Ingest' DNA
from Other Simple Organisms Nov. 15, 2012
Up to 10 per cent of the active genes of an organism that has survived 80 million years without sex
are foreign, a new study from the University of Cambridge and Imperial College London reveals.
The asexual organism, the bdelloid rotifer, has acquired a tenth of its active genes from bacteria
and other simple organisms like fungi and algae.
Bdelloid rotifers are best known for going 80 million years without sex, as they have evolved
to reproduce successfully without males. Many asexual creatures go extinct without the
benefit of traditional genetic evolution. However, bdelloids have flourished by developing
ingenious ways of overcoming the limitations of being asexual.
Bdelloids have also developed the fascinating ability to withstand almost complete desiccation
when the freshwater pools they typically live in dry up. They can survive in the dry state for many
years only to revive with no ill effect once water becomes available again.
"We were thrilled when we discovered that nearly 10 per cent of bdelloids' active genes are
foreign, adding to the weirdness of an already odd little creature," said Professor Alan Tunnacliffe,
lead author of the study from the University of Cambridge. "We don't know how the gene transfer
occurs, but it almost certainly involves ingesting DNA in organic debris, which their
environments are full of. Bdelloids will eat anything smaller than their heads!"
Because some of the foreign genes are activated when the bdelloids begin to dry out, the
researchers believe that the genes play a role in bdelloids' ability to survive desiccation.
For the study, the researchers extracted all of the messenger RNA (genetic code similar to DNA
which provides a blueprint for the creation of proteins) from bdelloid rotifers and sequenced each
message, creating a library of the animal's active coding information. Using a supercomputer, they
then compared these messages with all other known sequences and found that in many cases
similar sequences had been found in other organisms.
© 2010 Pearson Education, Inc.
Henley hit by 'mutant super rat' invasion
Researchers found the picturesque riverside Oxfordshire area has been inundated with dozens of the pests,
which carry a poison-resistant gene.
Experts say that despite appearing the same as their non-mutant counterparts, they are resistant to pest
controls because of their genetic mutation.
"All rats tend to carry various diseases,” said Dr Alan Buckle, from the University of Reading.
“The reason we need to get rid of them is because they transmit diseases from themselves to humans and
farm animals.
Dr Buckle, who led the study, added: "These anticoagulant-resistant rats carry the same diseases as other
rats carry but are very difficult to control."
The team used new DNA techniques to determine the prevalence of rats with the poison-resistant gene.
Dr Buckle, a research fellow, said there stronger poisons would control the super-rats but were currently
illegal.
"We're not allowed to use them because the regulatory body is worried about their effects on wildlife,” he
said.
Dr Buckle said this caused the greatest concern because the rats carry illnesses such as Weil's disease, which
can be passed on to humans.
It has flu-like symptoms initially but can lead to jaundice in the kidneys.
He added: "If Weil's disease is not treated it's very serious. About 40 to 50 people in the UK catch it every
year."
Weil's disease is a waterborne bacterial infection linked to the urine of infected rats, which killed Andy
Holmes, the Olympic rowing champion in 2010.
But animal welfare groups believe poisons, or rodenticides, are detrimental to wildlife.
It is estimated that there are up to 10.5 million rats in Britain and in areas in which resistance exists almost
three in four carry the rodenticide resistant gene.
© 2010 Pearson Education, Inc.
Novel Genetic Patterns May Make Us Rethink Biology and Individuality
Nov. 7, 2013
Professor of Genetics Scott Williams, PhD, of the Institute for Quantitative Biomedical Sciences
(iQBS) at Dartmouth's Geisel School of Medicine, has made two novel discoveries: first, a person
can have several DNA mutations in parts of their body, with their original DNA in the rest -- resulting
in several different genotypes in one individual -- and second, some of the same genetic mutations
occur in unrelated people. We think of each person's DNA as unique, so if an individual can have
more than one genotype, this may alter our very concept of what it means to be a human, and
impact how we think about using forensic or criminal DNA analysis, paternity testing, prenatal
testing, or genetic screening for breast cancer risk, for example. Williams' surprising results indicate
that genetic mutations do not always happen purely at random, as scientists have previously
thought.
Genetic mutations can occur in the cells that are passed on from parent to child and may cause
birth defects. Other genetic mutations occur after an egg is fertilized, throughout childhood or adult
life, after people are exposed to sunlight, radiation, carcinogenic chemicals, viruses, or other items
that can damage DNA. These later or "somatic" mutations do not affect sperm or egg cells, so they
are not inherited from parents or passed down to children. Somatic mutations can cause cancer or
other diseases, but do not always do so. However, if the mutated cell continues to divide, the
person can develop tissue, or a part thereof, with a different DNA sequence from the rest of
his or her body.
"We are in reality diverse beings in that a single person is genetically not a single entity -- to be
philosophical in ways I do not yet understand -- what does it mean to be a person if we are variable
within?" says Williams, the study's senior author, and founding Director of the Center for Integrative
Biomedical Sciences in iQBS. "What makes you a person? Is it your memory? Your genes?" He
continues, "We have always thought, 'your genome is your genome.' The data suggest that it is not
completely true.”
© 2010 Pearson Education, Inc.
Sperm
MEIOSIS
Egg
Adult
Key
Haploid (n)
Diploid (2n)
Figure 17.2-1
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
Key
Haploid (n)
Diploid (2n)
Figure 17.2-3
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
Blastula
(cross section)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-4
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
Blastula
(cross section)
Early gastrula
(cross section)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-5
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
Blastula
(cross section)
Outer cell layer
(ectoderm)
Inner cell layer
(endoderm)
Internal sac
Early gastrula
(cross section)
Later gastrula Future middle
(cross section) layer of cells
(mesoderm)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-6
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
Blastula
(cross section)
Digestive tract
Outer cell layer
(ectoderm)
Larva
Inner cell layer
(endoderm)
Internal sac
Early gastrula
(cross section)
Later gastrula Future middle
(cross section) layer of cells
(mesoderm)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-7
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
METAMORPHOSIS
Blastula
(cross section)
Digestive tract
Outer cell layer
(ectoderm)
Larva
Inner cell layer
(endoderm)
Internal sac
Early gastrula
(cross section)
Later gastrula Future middle
(cross section) layer of cells
(mesoderm)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-8
Endangered Limpets (Sea Snail) Change Sex to Improve Their Chances of Survival
Nov. 12, 2013
The Ribbed Mediterranean Limpet is one of the most endangered invertebrates of the Mediterranean Sea and is
classed as being in danger of extinction. Researchers at the Spanish National Museum of Natural Sciences have
discovered their reproductive strategy, consisting in changing sex from male to female and vice versa, which
improves their ability to adapt to changes in their environment.
"One of the problems involved in the recovery of the Patella ferruginea is the lack of knowledge regarding basic
aspects of its biology. This is the first time we have encountered this part of its reproductive strategy on an
experimental basis," Javier Guallart, main author of the project and researcher at the Spanish National Museum of
Natural Science, said.
According to the scientist, the ribbed limpet had until now been believed to be a protandric hermaphrodite species.
"As a reproductive strategy, this term means that youngsters, when they reach sexual maturity, do so as males
and then, at some point during their vital cycle, change sex and become females."
This occurs often in molluscs and, in particular, in limpets. However, this conclusion has normally been based on
indirect information. "For example, it is based on the fact that smaller specimens tend to be male and larger ones
tend to be female," adds Guallart.
In order to confirm that they really do change sex, in 2006 a complex task began, involving sexing a number of
specimens and returning to do it again a year later, during the next reproductive period (this species only
reproduces once a year), to check whether they had changed sex.
"This may seem simple, but it is not. Sexing specimens means separating them from the substratum during the
time of the year in which they are mature, between October and November, handling them and performing a small
biopsy with a syringe to take a small sample of gonad in order to establish the sex according to the sample
extracted (oocytes or sperm)," outlines the author.
The specimens were then returned to the coast, in the same place they were captured and this was done so they
could adhere to the substratum, enabling them to continue with their way of life.
In 2007 we discovered that a specimen previously sexed as male in 2006 was now a female, which meant this
was the first direct and unprecedented proof of a sex change in the Patella ferruginea.
The work carried out between 2007 and 2008 also brought about further developments. On the one hand, it was
confirmed that a number of specimens previously sexed as male were now females and a new unusual
development was unearthed: a female had become a male between consecutive reproductive periods.
© 2010 Pearson Education, Inc.
© 2010 Pearson Education, Inc.