Download What really are reptiles and amphibians?

Questions? common tree snake, Dendrelaphis
punctulatus (Australia)
Integrating Conservation in Agriculture
EFB 496 (2 credits)
The Roosevelt Wild Life Station is offering an intensive spring break field course on
conservation in agricultural landscapes to seniors of any major. Space for 10 students is
available. Selection will be highly competitive.
Students will advise landowners on how to improve the biodiversity value of their
property and suggest ways to enhance beneficial interactions between wild species and
agricultural production.
Topics covered in this course will include:
- ecological monitoring - biodiversity survey techniques - invasive species management
- sustainable harvest and marketing of native species - the economics of conservation
- a wide array of ecologically-conscientious land management and farming techniques
Students MUST be available on the following dates to participate:
February 5: Introductory lunch with landowners (1 pm – 3pm)
March 11-19: Spring break field trip to study sites
May 11: Thank you dinner with landowners (time TBA)
*Students will also meet regularly at a TBA time before and after the spring break trip.
Contact Sam Quinn to apply ([email protected]; Illick 254). Deadline Jan 20 to apply.
Herps Field Course: Peru
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Learn about the natural history, anatomy, ecology, and conservation of Neotropical reptiles and
amphibians while staying at an active research field station in Peru. This course will give
participants advanced training in field techniques relevant to tropical biology research, with special
emphasis on field exercises over classroom-based lectures.
Students will use drift fence and leaf litter sampling, make audio recordings, conduct transects,
and much more. We will also read and discuss selected literature on tropical ecology, applied
research, and conservation issues pertinent to the the Madre de Dios region of Peru and beyond.
COURSE DATES
May 25th – June 7th, 2017
REGISTRATION
Course size is limited, spots are filled on a rolling basis until April 17th, 2017
COURSE FEE
$2100 (includes all meals and lodging at the field station, as well as transportation from Puerto
Maldonado to the field site and back)
MORE INFORMATION
https://fieldprojects.org/participate/courses-2/field-herpetology
LOCATION
This course will be held at the Los Amigos Biological Station, situated between the Madre de Dios
and Los Amigos Rivers on terra firme forest rising above the floodplain. This field station lies
within the buffer zone of Manu National Park, which was recently declared the world’s top
biodiversity hotspot, due in no small part to having the largest number of amphibian and reptile
species on the planet.
Origins of tetrapods
= origins of the
amphibians
Origins and evolution of
the major extant groups…
Outline of today’s lecture
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Brief (very)
introduction to
phylogenetic analyses
Origin of tetrapods
Origin of amphibians
The three major
amphibian clades
Current Linnaean Classification
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Evolutionarily speaking, “herpetiles” are a somewhat
unnatural grouping of rather different animals
Kingdom Animalia
Phylum Chordata
Subphylum Vertebrata
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Class Agnatha: Fish lacking jaws
Class Chondrichthyes: Cartilaginous fish
Class Osteichthyes: Bony fish
Class Amphibia
Class Reptilia
Class Aves
Class Mammalia
Fishes
Phylogentic systematics (see Ch. 2)
 Phylogenetic systematics (cladistics)
emphasizes the importance of
evolutionary relationships
 Shared derived characters
(synapomorphies) are used to
identify clades and infer the order in
which they branched
 Parsimony is an assumption built
into phylogenetic models (assumes
simplest possible path). “Occam’s
Razor”
Phylogentic systematics (see Ch. 1)
A monophyletic lineage (clade) is
composed of an ancestor and all of its
descendants. Only monophyletic lineages are
recognized in phylogenetic systematics
A polyphyletic group consists of
distantly related taxa whose last common
ancestor is not a member of the group
A paraphyletic group includes all of the
descendants of a common ancestor minus
one or more monophyletic groups
Polyphyletic group
Polyphyletic group
Reptilia is a paraphyletic group if
birds are excluded
“non-avian reptiles”
Last terminology:
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Amphibia and
Mammalia
are sister groups.
They
are adjacent branches
on the cladogram
Mammalia is an
outgroup to
Reptilia. It is outside
of the
reptile clade.
Where did amphibians (and all
vertebrate tetrapods) arise?
The Devonian opportunity
The Devonian opportunity
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Late Devonian ~ 375 MYA, a diversity
of shallow aquatic habitats developed (warm, no glaciers)
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This generated a variety of unexploited microhabitats
Detritus from terrestrial and wetlands vegetation provided a base
for increasingly complex food webs
Exploitation of these new habitats was driving
force behind the evolution of the tetrapods
Refinements and variations of the
adaptations that enabled tetrapods
to use these new habitats enabled
them to expand onto the land
Tiktaalik
Why lobe-finned fish?
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Free-swimming predators of shallow waters and
adapted to living on the water’s edge.
Likely had “preadaptations” for terrestrial life
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Limb-like structures (paired, lobed fins) used for stalking
prey in shoreline vegetation
May have used fins to prop up and respire in shallow
stagnant pools
How do we know tetrapods are descended
from lobe-finned fish?
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labyrinthodont teeth = maze or labyrinth pattern
of tooth surface.
This character is not shared with other fishes
Icthyostega is a “stem tetrapod” basically a fish with legs
What transitions to
terrestriality were
required?
Or
How do you get
from fish to
tetrapod?
Or
“Exaptations”
Respiration
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Air breathing:
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Lungs were already present in many bony fishes (e.g. the
Dipnoi or lungfish)
Coping with anoxic waters
A passive pump mechanism (gulping and diving
head-first) was replaced with a buccal-force pump
(mouth opens, floor drops, mouth closes, floor
raised, air forced into lungs)
Morphology
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Fins to limbs — joints formed in “legs” and digits
formed from fin rays
Support system changed — no longer supported by
buoyancy in water (density water = 1 g/cm3; air =
0.001 g/cm3)
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Vertebral column and limb girdles become more robust.
Feeding
Suction feeding no longer possible
 Skull and vertebral column become mobile
 Elongated jaws
develop
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Other changes…
 A rudimentary ear develops from vestigial
fish jaw bones
 Nasal passages develop for respiration and
olfaction
 Skin thickens to protect from desiccation
and abrasion
The origin of modern amphibians
“The origin of lissamphibians has been hotly debated in the last few
years, and the number of hypotheses about their origin has not
decreased despite several detailed phylogenetic analyses.”
Marjanovic and Laurin 2007
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Confusion: soft-bodied , do not preserve
well
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Recent perspective: A stem batrachian from the Early Permian of Texas and
the origin of frogs and salamanders. Nature 453, 515-518 (22 May 2008)
Primitive amphibians:
Lepospondyls
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Labyrinthodont teeth
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Simple, spool-shaped vertebrae;
bony cylinders around the
notochord
Diverse body forms (e.g. some with
limbs others without)
Generally small (a few cm - 1m)
Held niches of modern
salamanders, caecilians, and lizards
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Primitive amphibians:
Temnospondyls
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Labyrinthodont teeth
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Resemble large salamanders, crocodiles
Complex vertebrae consist several
separate elements
Size ranges from 20 cm – 3 m
Numerous sharp, conical, teeth, and
the large fangs suggest that they
were predators
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Siderops
Temnospondyls and lepospondyls of
the Late Paleozoic
Monophyletic within the temnospondyls?
Rhipidistian
crossopterygian
lobe-finned fish
Lepospondyls
Temnospondyls
Gymnophiona
Anura
Caudata
Monophyletic within lepospondyls?
Rhipidistian
crossopterygian
lobe-finned fish
Lepospondyls
Temnospondyls
Gymnophiona
Anura
Caudata
Diphyletic (two separate ancestries) with caecilians within
the lepospondyls and salamanders and frogs within the
temnospondyls?
Rhipidistian
crossopterygian
lobe-finned fish
Lepospondyls
Temnospondyls
Gymnophiona
Anura
Caudata
Figure 2.9 Three hypotheses for
the origins of modern amphibians
A
phylogenetic
expression of
previous
points
Carboniferous:
Age of Giant Amphibians
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Increasingly warm, with moist terrestrial
environments
Highly favorable environments for amphibians
360 to 286 MYA
Gerobatrachus (early Permian, ~290 MYA)
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The earliest fossil that can be clearly assigned to an
extant lissamphibian clade
“frogamander”
discovered in
Texas
Triadobatrachus (early Triassic, 245 MYA)
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Sister taxon to Anura (frogs and toads)
“Protofrog”
discovered
in Madagascar
Slow subsequent radiations
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These early amphibians radiated later in the
Cretaceous and Paleocene (50-150 MYA) to
generate many of the extant amphibian families.
Many extant amphibian families are essentially
unchanged for epochs
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Pipidae, Pelobatidae = 150 million years!
local red-spotted newt genus (Notophthalmus) unchanged
for 20 million years!
Extant amphibian diversity
Pyron & Wiens (2013) Large-scale phylogenetic analyses reveal the
causes of high tropical amphibian diversity. Proc R Soc B 280:
20131622.
Subclass Lissamphibia – living amphibians
(two other subclasses now extinct)
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Liss = smooth (refers to
smooth scaleless skin)
Amphi = double
Bios = life
Extant amphibians fall into one
of three orders –
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Anura (frogs, including toads)
Caudata or Urodela
(salamanders, including newts)
Gymnophiona or Apoda (the
limbless caecilians)
Traits of the Lissamphibia
Smooth skin
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Especially in larvae – 2-3 layers
Site of gas exchange
Permeable to water
Contains poison glands (granular), pheromone
glands (hedonic glands), and mucous glands
Traits of the Lissamphibia
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Therefore, need high levels of humidity or a fully
aquatic environment to live (some exceptions)
Reason for nocturnality, precipitation association,
seasonality
Traits of the Lissamphibia
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Shell-less eggs
Traits of the Lissamphibia
Generally eggs laid in water, hatch into larvae,
and metamorphose into a morphologically distinct
adult form.
Australian gastric brooding frog
Traits of the Lissamphibia
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Three-chambered heart
with two atria and one
ventricle
atria
ventricle
Pedicellate teeth (crown of teeth is separated
from the root by a zone of fibrous tissue)
Ability to elevate the eye (with
levetator bulbi muscle)
Operculum
• small bone in the
skull
• linked to shoulder
girdle by the
opercularis muscle
• Hearing? Balance?
• Fused to the
columella (ear
bone, stapes) in
most anurans)
• Not in caecilians,
some salamanders
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To here!
Thurs Lab
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Relocated:
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To 220 Illick from 238
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Much nicer
Bigger
More convenient
220 is just up the hall from 238, same
side
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ESF
Herpetology
Club!
Order Anura – frogs and toads
or “tail-less amphibians” ~6,000 species
Size range
considerable…
West African goliath frog, Conraua goliath
Tiny frog claimed as world's
smallest vertebrate
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Paedophryne amauensis (Sumatra)
Frog or toad?
Bufo bufo - common toad
Rana temporaria - common frog
Atelopus zeteki - Panamanian golden “frog”
Anuran traits
 Fore- and hind-limbs usually of unequal size - hind
limbs are elongated and modified for jumping
 Tail in larval form lost as adult
Figure 1.3 Anuran body forms
Anuran skeleton
Head and trunk
fused
Fused radius
and ulna
Urostyle
Fused tibia and
fibula
Anurans typically have external fertilization and
lay eggs…
…but there is a wide diversity of reproductive
modes among anurans
Ancestral mode
Tadpoles
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Many are herbivorous,
omnivorous
“basically a swimming
sieve attached to a gut”
Origins
Photo: Eiko Jones
High rates of predation
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Typically less than 10% of
tadpoles reach metamorphosis
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Highly unusual in
rapid
transformation
from prey to
predator (e.g.,
with Odonates)
Transition away from water
Parental care
usually none
but sometimes
Direct development
Egyptian mythology
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In Egypt the frog was associated
with Heket, the goddess of
fertility and childbirth
Frog shaped knives placed on the
bellies of pregnant women and
newborn babies were believed
to protect the children
"Double, double, toil and trouble, fire
burn and cauldron bubble - fillet of
fennel, snake, toad, adder's fork, lizard's
leg..." Macbeth
Toads in potions and spellcraft
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Toads as witch’s “familiars”
Witches concocted brews from frogs,
toads and snakes, often referred to as
“Toad Soup”
Secrete a thick, white substance
(bufotenine/bufotoxin) from skin
glands when provoked (toxic and
hallucinogenic components)
The toxin (C24H34O5) is called
bufagin, or more colloquially, toads'
milk
Toad licking
“Profound alteration of
consciousness within a few
seconds of exhaling. I relax
into a deep, peaceful
interior awareness. There is
nothing scary about the
effects and no sense of
toxicity. I try to describe my
feeling but am unable to
talk for the first five minutes
and then only with some
difficulty. This is a powerful
psychoactive drug, one that
I think would appeal to most
people who like the effects
of hallucinogens. For the
next hour I feel slow and
velvety, with a slight
pressure in my head. No
long-lasting effects to
report.” (A.T. Weil)
Weil AT, Davis W (1994) Bufo alvarius: a potent
hallucinogen of animal origin. Journal of
Ethnopharmacology 41:1-8
Bufotenine (5-OH-DMT)
is Schedule I in the
United States. This means
it is illegal to manufacture,
buy, possess, or distribute
(sell, trade or give) without
a DEA license. Not
available by prescription.
Toad Stones
Sweet are the uses of
adversity,
Which, like the toad, ugly
and venomous,
Wears yet a precious jewel
in his head;
And this our life, exempt
from human haunt,
Finds tongues in trees,
books in the running
brooks,
Sermons in stones, and
good in everything.
William Shakespeare, As You
Like It (Duke Senior at II, i)
If
swallowed,
it was a
certain
antidote
against
poison
Order Caudata (or Urodela)
newts and salamanders
“bearing a tail” ~650 species
Figure 1.2 Salamanders occupy
aquatic, terrestrial, and arboreal
habitats
All are
“salamanders”
Size range
considerable…
dwarf salamander
(Nototriton sp.), Costa Rica
Chinese giant salamander (Andrias davidianus)
Newt or salamander?
But newts are in the family
Salamandridae … so are ‘true
salamanders’!
Generally, salamanders
lacking costal grooves with
rough / drier skins are
referred to as newts
New discoveries
2016-2017
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Crocodile newts
(Vietnam)
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Luristan newt (4
streams, n Iran)
Traits of Caudates
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Have four limbs usually of equal size (with the
exception of sirens), a tail, and elongated body
Generally fossorial (live in soil or leaf litter)
or aquatic
The most prolific group
(Plethodontidae) is lungless —
• Skin is a site of gas exchange
• Use hyoid apparatus to project
tongue and capture prey
Fertilization is internal
Aquatic and terrestrial eggs
Larvae are stream-lined
and carnivorous
Paedomorphosis is common
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In paedomorphosis is a form of heterochrony, where
adults are aquatic and retain traits of juveniles
obligate
facultative
Proteus
Necturus
Ambystoma tigrinum
Salamanders
 “Salamander” is derived from an
Arab-Persian word which means
“lives in fire”
Why?
immune to fire, and could
extinguish fire with skin
secretions?
 Skins, bodies, and body parts of
salamanders still used in traditional
medicine.
Torched newts are sometimes sold in
Asia as aphrodisiacs.
A “salamander”…
Order Gymnophiona (or Apoda)
caecilians: ~200 species
restricted to the tropics
caecilian, Muquinqui, north Sao Tome
Pronunciation of caecilian
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“Sicilian”
“Say-cilian”
Greek words γυμνος (gymnos, naked) and οφις (ophis, snake)
Latin word caecus, meaning "blind", referring to the small or
sometimes nonexistent eyes
Figure 1.4 Caecilians are
elongate, legless amphibians
Characteristics
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“without legs” = apoda
subterranean diggers
eyes may be covered by
skin or even bone
tentacle of head serves as a
chemosensory organ to detect
underground prey
encircling primary grooves = annuli, with
dermal (bony) scales often lie deep
within the tissues of each annular groove
Caecilian reproduction
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Internal fertilization
Viviparity common –
young 30-60% of female’s
body size when born
Initial growth of fetuses supported by yolk sac,
embryos feed on uterine milk secreted from the
epithelial wall of oviduct
Obscure, uncommon and
poorly studied
Not much interaction, not much
folklore, except…
Origins of
tetrapods and
amphibians
End…