http://pinker.wjh.harvard.edu/photos/santa_barbara_california/pages/Santa%20Barbara%201.htm

Vertebrate Evolution

Chapter #1 – The Diversity, Classification, and Evolution of Vertebrates, pg. 2 – 15.

Chapter #2 – Vertebrates and Basic Structure, pg. 19 – 45.

Chapter #3 – Early Vertebrates, Jawless and Jawed Vertebrates, pg. 47 – 73.

Amphibians

Figure 6.1 – Vertebrate Biology

Liss = smooth (greek – referring to skin)

Amphibia = double life (greek – referring to metamorphosis)

Jurassic(before break-up of Pangea) Long hind limbs

Short, stiff bodies

Equal-sized limbsLong, slender bodies

No limbsLong, slender bodies

HOP

WADDLE

SLITHER

What is a (Liss)Amphibian?

Shared Derived Characteristics of Amphibians:

1) Smooth, Moist Skin:

• Absence of bony / keratinized scales (exception = caecilians)

• Absence of keratinized, true claws• Mucous glands (prevent desiccation / slippery / disease-free)

Other Methods for Controlling Water Loss:

1) Behavioral Modifications:

3) Permeable Bladder:

Store dilute urine; “Canteen” away from water

2) Pelvic Patch:

Highly vascularized skin; absorbs majority of water

Cool, wet nights Warm, dry nights

Example:

Puerto Rican Coqui

Amphibians

1) Smooth, Moist Skin:

• Absence of bony / keratinized scales (exception = caecilians)

• Absence of keratinized, true claws• Mucous glands (prevent desiccation / slippery / disease-free)

• Poison glands:

• Produce diverse array of chemicals

• Concentrated on dorsal surface

Tarichatoxin (newts)

Water-soluble alkaloid(blocks Na+ channels)

Batrachotoxin(dart-poison frogs)

Lipid-soluble alkaloid(Blocks closing of Na+ channels)

Sequestered via diet

Epibatidine(dart-poison frogs)

Lipid-soluble Alkaloid(Blocks Ach receptors)

Non-addictivepainkiller

Shared Derived Characteristics of Amphibians:

Amphibians

2) Multiple Methods of Respiration:

• Cutaneous – Gas exchange occurs across moist skin• Buccopharyngeal – Gas exchange occurs in buccal cavity / pharynx• Pulmonary – Gas exchange occurs in paired lungs (too small for all gas exchange)

• Gills – Larval forms and neotenics (neoteny = adults that retain juvenile characteristics)

3) Pedicellate Teeth:

• Crown and base of tooth separated by uncalcified dentine / fibrous tissue

Amphibians

Shared Derived Characteristics of Amphibians:

Teeth break easily – continuously replaced

• May allow for “flex” of tooth for prey handling (all carnivores)

4) Green Rods: • Distinct type of retinal cell

• Hue discrimination in dim light?

5) Unique Hearing Adaptations:

• Operculum – Columella Complex: • Two bones in middle ear that transmit sound to inner ear (via oval window)

• Dual high / low frequency system• High frequency (> 1000 Hz) = vibration of columella alone (air)

• Frogs (needs tympanum for amplification); Vocalization• Low frequency (< 1000 Hz) = vibration of operculum-columella unit (ground)

• Vibration via leg bones / scapula (activated via opercularis muscle)

• Frogs & Salamanders; Predator / prey detection• Inner Ear:

Amphibian papillae: Hair cell system – detects

low frequencies

Basilar papillae: Hair cell system –

detects high frequencies

Amphibians

Shared Derived Characteristics of Amphibians:

6) Levator bulbi muscle:

Amphibians

Shared Derived Characteristics of Amphibians:

• Bulges eye outward; increases buccal cavity

Salamanders (10 families; ~ 515 species):

Order: Caudata (“Tailed Ones”)

Diversity:

• First appearance in fossil record = Jurassic

Evolution associated w/ cool, wet forests

* (~ 245 sp.)

North American = 9 of 10 families (5 endemic)

• Neotropic = greatest # of species

All from single family

(Plethodontidae ~ 145 sp.)

Amphibians

• Primarily holarctic distribution:

Salamanders (10 families; ~ 515 species):Morphology / Locomotion:

• Presence of tail (larvae / juveniles / adults)

• 4 equally-sized limbs (extend at right angle from body)

• Size range = 3 cm to >1 m

Chinese Giant Salamander

Adults retain:

laterally compressed tail / flattened head

functional lateral line system

external gills (not always…)

• Paedomorphosis widespread (aquatic life)

• Anguilliform locomotion (walking-trot / swim)

Respiration:

• Aquatic = primarily gills (some cutaneous)

• Cryptobrachidae = large skin folds

• Terrestrial = lungs (50%) / skin (50%)

Plethodontidae = lungless

skin (10%) & buccopharynx

(90%)Hypothesis:

Evolved in fast, cold water ( O2)

Lungs disadvantageous (buoyancy)

Amphibians

Salamanders (10 families; ~ 515 species):Diet / Prey Capture:

• Generalist carnivores (primarily invertebrates)

• Aquatic = mouth gape• Suction pulls prey into oral cavity

• Terrestrial = Thick, sticky tongue grabs prey

• Works will with gills / gill slits (one-way flow)

• Tongue = broad, flat, immobile

• Plethodontidae: Projective

tongueWhy Plethodontids?

Buccal pump not necessary for breathing(no lungs)

Hyoid bone specialized for projectingthe tongue (elongated / lightened)

http://autodax.net/feedingmovieindex.html

Cryptobrachus alleganiensismovie

Taricha torosamovie

Hydromantes platycephalusmovie

Amphibians

Salamanders (10 families; ~ 515 species):Sensory Systems:

• Aquatic:• “Taste” chemicals in water• Vibrations – Retain lateral line system

• Terrestrial:• Smell – Olfactory epithelium (volatile)

• Smell – Vomeronasal organ (Non-volatile)

• Sexually dimorphic (larger in males)

• Courtship / Identification (species / sex / individual)

• Highly advanced in Plethodontidae• Nasolabial Grooves = Non-ciliated grooves; upper lip to nares

• Aids in collection / delivery of chemical cues (capillary action)

• Sexually dimorphic (esp. during reproductive season)

Amphibians

• Hearing – limited high frequency (no ear drum); primarily ground vibration• Vision – acute; especially in plethodontidae

• Eel-like; lack hind limbs (lack pelvic girdle)

• Paedomorphic; gills present

Morphology:

Amphibians

Habitat:

• Swamps / lakes / marshes (slow-moving water)

• Nocturnal• Vocalization

Sirenidae (sirens):

Aquatic:SE United States / NE Mexico

Aquatic:Central China / Eastern United States

Cryptobranchidae (Hellbenders):

• Dorsal-ventral compressed body (paedomorphic)

• Multiple folds in skin (cutaneous respiration)

Morphology:

Habitat:

• Clear, cold mountain streams / lakes• Severely reduced ranges (loss of habitat)

Reproduction:• External fertilization; female nest guarding

Reproduction:

• External fertilization; Males = “den masters”

• largest individuals• live 50+ years

Amphibians

• Eel-like; maintain four reduced limbs• Paedomorphic; lack gills (lungs present)

Morphology:

Habitat:

• Sluggish streams / rivers; swampsReproduction:• Internal fertilization; female nest guarding

• terrestrial egg-laying• aestivate

Aquatic:SE United States

Amphiumidae (Amphiums):

• Paedomorphic; feathery gills / caudal fins

Morphology:

Habitat:

• Lakes / streams• Limestone caves (drastic reduction in numbers)

• dissection specimen• nocturnal

Reproduction:

• Internal fertilization; ♂ / ♀ nest guarding

Proteidae (Waterdogs):

Aquatic:Eastern United States / SE Europe

• Constriction at tail base = tail autotomy• Very costly (tail = large fat reserve)

• ~ 10 – 12% tail regeneration (~ 2 years)

Anatomy:

• Prefers cool forests with litter / dead trees• Tolerates logging better than most plethodons

Plethodontidae (example = Ensatina escholtzii):

Habitat:

• Mating begins (Nov.) and ends (March) with rains• ♂ use hedonic glands / pheromones to attract ♀

Reproduction:

• Methods of pheromone administration:• Slap ♀ nares with hedonic gland (video)

• Innoculate ♀ with sharp teeth• Elaborately patterned courtship “dance”

• “Tail straddle-walking” (unique to plethodons) • ♂ repeats dance (~ 1 – 5 hours)

• Pathway / movement unique to each species

Amphibians

Terrestrial:North / Central / South America & Europe

Pheromone:

Chemical cue that affects thebehavior and / or physiology

of a conspecific

• ♂ lays down spermatophore; ♀ picks it up (video)

Reproduction:

• ♀ guards eggs ( predation / fungal infection)

• Direct development of eggs (~60 – 120 days)

Growth / Maturation:• Sexual Maturation ~ 4 years• Life Span ~ 10 years (best guess)

Amphibians

Terrestrial:North / Central / South America & Europe

Plethodontidae (example = Ensatina escholtzii):

Sperm Cap

Gelatinous Base

• ♀ lay 8 – 12 eggs (~ 5 mm)• Terrestrial – in logs; under logs; in burrows

• Cold, clear streams / seepages / waterfalls• Very desiccation intolerant

• Low heat tolerance (susceptible to logging)

Rhyacotritonidae: (example = Rhyacotriton olympicus)

Amphibians

Terrestrial:NW United States

• Full metamorphosis• No operculum / opercular muscle ( hearing)

• Highly reduced lungs (cutaneous respiration)

Anatomy:

Habitat:

Growth / Maturation:• Sexual Maturation ~ 4 years• Life Span ~ 10 years (best guess)

Reproduction:

Anti-predator Display

• Internal fertilization• Spermatophore deposition

• Tail-wagging display• Aquatic egg-laying

• No nest guarding

Larval Anatomical Specializations:

Pond Larvae Stream Larvae

AmbystomatidaeSalamandridae

Dicamptodontidae RhyacotritonidaePlethodontidae

• High body profile• broad tail fin extending up to head• long, plume-like gills• Only front legs at hatching

• Depressed body profile• Narrow tail fin (not onto trunk)

• Short, thread-like / curly gills• All four legs at hatching

Amphibians

• Prefer older growth forests during “newt” phase

• Flashes tail & brightly colored stomach

Warning Coloration:

Salamandridae (example = Taricha granulosa):

• Tarichatoxin (non-protein – VERY poisonous)

• Neurotoxin – blocks NA+ channels (paralysis)

• Small dose lethal to birds / mammals

Chemical Defense:

Habitat:

Red-spotted Garter Snake“The Arms Race”

• Large dose lethal to humans

Amphibians

Terrestrial:North America / Europe / NW Africa / Asia

http://evolution.berkeley.edu/evolibrary/article/biowarfare_01

Assignment:

Questions Posted on Class Website…

• Adults migrate to ponds / lakes (1 – 3 weeks prior)

• Breeding from April – July (annual / biannual)

• ♂ release pheromone (hedonic gland)

Reproduction:

• ♂ lays down spermatophore

• ♀ lay 200 – 375 eggs• Incubation ~ 20 – 35 days

Growth / Maturation:• Metamorphosis ~ 4 – 5 months

• Amplex with ♀ (ward against rivals)

• ♀ signals willingness to mate by raising head

Amphibians

Salamandridae (example = Taricha granulosa):

Terrestrial:North America / Europe / NW Africa / Asia

• Sexual Maturation ~ 4 – 5 years• Life Span ~ 20 – 25 years

• Damp coniferous forests (near streams / seeps)

• Paedomorphic = moving water• Diet: Opportunistic feeders (sit-and-wait)

Dicamptodontidae: (example = Dicamptodon tenebronsus)

Amphibians

Terrestrial:NW United States / SW Canada

• Full metamorphosis / facultative paedomorphosis

• Large (up to 30 cm SVL)

• Well-developed lungs / blade-like teeth

Anatomy:

Growth / Maturation:• Metamorphosis ~ 2 years• Sexual Maturation ~ 2 years• Life Span = long-lived…

Reproduction:• Internal fertilization

• Breeding occurs in waterWill eat small mammals• Eggs (~ 200) deposited singly

wood / rocks in water (female nest-guarding)

Habitat:

• Wide range of habitats (grasslands forests)

• Subterranean (“mole” salamanders)

• Close to water (~ within 100 m)

• Enter torpor during winter (below frost line)

Ambystomatidae: (example = Ambystoma macrodactylum

Amphibians

Terrestrial:Western North America

• Full metamorphosis / paedomorphosis (rare)

• Stout-bodied; thick-tailed

Anatomy:

Growth / Maturation:• Metamorphosis ~ 2 years

Reproduction:• Earliest amphibian breeders (Pacific Northwest)

• Migrate to breeding ponds (fidelity - ♂ arrive first)

• Eggs (~ 100 – 400) deposited in clusters

Habitat:

Cannibalisticlarvae

• Sexual Maturation ~ 3 – 5 years• Life Span ~ 10 years

Caecilians (6 families; 180 species):• Long, slender body; small dermal scales• Legless; no post-anal tail• Most species blind as adults

• Specialized sensory tentacles (snout)

Order: Gymnophiona (“Naked snake”)

Tropics (S. America / Africa / S.E. Asia)

Fossorial / Aquatic

• Diet = small insects / earthworms

Life History:• Very little known about courtship• Internal fertilization (via intromittent organ)

• 75% viviparous (live young - matrotrophic)

• Initial nutrition = yolk• Subsequent nutrition = “uterine milk”• Breath via fetal gills• Young caecilians 30 – 60% adult BL!

• 25% oviparous (lay eggs – may brood eggs)

Amphibians

Frogs (29 families; ~ 4800 species):

Order: Anura (“Without Tail”)

Diversity: First appearance infossil record = Jurassic

North American = 10 or 29 families

• Neotropic = greatest # of species

* (~ 1100 sp.)

Most Diverse Family

Leptodactylidae ~ 1100 sp.

Amphibians

• Ubiquitous (except Antarctica):

Morphology:• Body specialized for jumping:

• Hind legs elongated; tibia / fibula fused• Large pelvis; short vertebral column• Urostyle (Fused posterior vertebra)

• Size variable (1/2” 1 ‘)

Amphibians

Frogs (29 families; ~ 4800 species):

Locomotion:

Jumping Frogs

Long hind limbs

Hopping Frogs

Short limbs / Robust body

Semi-aquatic Frogs

Webbed feet / stream-linedArboreal Frog

Slim waist / long legs

Toe Pads:

Viscous mucus = “sticky”

Vocalization:

• Associated with reproduction (advertisement calls)

• Identify species / sex of caller

• Vocalization is a tradeoff:• Costs:

1) Vocalization energetically expensive

2) Vocalization announces location

• Can function in mate choice (e.g., male size)

Amphibians

Frogs (29 families; ~ 4800 species):

Pacific Tree Frog

Bullfrog

Spadefoot Toad

Tungara Frogs:

“Whine – cluck”

Females prefer / bats prefer

“Whine”

Females / bats less preference

“Whine – cluck” only observedwhen large choruses present

• Benefits:

Reproduction:

• Fertilization primarily external• Amplexus: Embrace of male and female frog

• Brings cloacae in close proximity (fertilization)

Amphibians

Frogs (29 families; ~ 4800 species):

Inguinal Amplexus

• Mating systems:

1) Explosive Breeders (season = few days)

• Temporary aquatic habitats

Axillary Amplexus

• May last hours to several days

Fertilization canoccur internally…

• Large aggregations; limited mate choice

2) Prolonged Breeders (season = months)

• Males defend territories• Males out-number females; strong mate choice

Reproduction:

Amphibians

Frogs (29 families; ~ 4800 species):

• Egg Development:

Directly in water Vegetation over water(egg protection)

Foam Nest(egg protection)

Bromeliad Nest(egg protection)

(tadpole protection)

Direct Development(egg protection)

(tadpole protection)

• Parental Care (common):

Guard Eggs

Carry Eggs(Mid-wife Toad ♂)

Internal Brooding(♀ Gastric Brooders)

Carry Eggs / tadpoles(Sirinam Toad ♀)

Viviparous(Morogoro Tree Toad)

Tadpoles:

Amphibians

Frogs (29 families; ~ 4800 species):

• Aquatic larval stage of frogs

Still Water:

Ovoid bodiesTails with large fins

Fast Water:

Stream-lined bodiesSmall tail fins

• Advantages:

1) Exploit non-adult resources• Tadpoles = aquatic / herbivores• Adults = terrestrial / carnivores

2) Efficient eating machines (rapid growth)

Metamorphosis: (3 stages)

Premetamorphosis• Increase in size

• Little change in form

Prometamorphosis• Hind legs appear

• Rapid decline in growth

Metamorphic Climax• Fore legs appear

• Tail regresses

• Mouth broadens; long short gut; degeneration of gills; dermal gland formation

• Triggered by thyroid hormone

• Short, powerful limbs; tubercle present• Robust body; pointed head (cornified tip)

Morphology:

Amphibians

Habitat:

• Sub-humid areas; surface after heavy rains

• Single species • Unique tongue

• Highly variable (10 mm 250 mm)

Morphology:

Reproduction:• Explosive breeder; aquatic tadpole

Reproduction:

• External / internal fertilization• Aquatic tadpoles / direct development

• Among largest• Many nocturnal

Rhinophrynidae: (Burrowing Toad)

FossorialNorth America / Central America

Leptodactylidae (Neotropical frogs):

TerrestrialNorth / Central / South America

Habitat:

• Variable:• Leaf litter layer • Fully aquatic

• Arid regions• High plateaus

Morphology:

Amphibians

• Commensal assoc. with spiders

Microhylidae: (Microhylid frogs)

Terrestrial / Fossorial / ArborealUbiquitous

• Relatively small; highly aposematic

Morphology:

Reproduction:

• Explosive breeders / prolonged breeders• Aquatic tadpoles / direct development

Reproduction:

• Most lack amplexus• Small clutches; parental care

• Introduced to Hawaii

Habitat:

• Tropical rainforests

• Highly variable (10 mm 100 mm)

Habitat:• Variable (Arid deserts Wet rain forests)

Dendrobatidae (Poison-dart frogs):

TerrestrialCentral / South America

• Poisonous

Morphology:

Amphibians• Tongueless• Model lab organism

Pipidae: (clawed frogs)

AquaticSouth America / Africa

Reproduction:

• Aquatic tadpoles / direct development

• Dorso-ventrally compressed body• Limbs splayed laterally; large, webbed feet

Habitat:

• Almost every type of body of water

Cane Toad (Bufo marinus)

No native toad species

~ 100 Marine toadreleased…

1935

1) Prolific breeders (~ 33,000 eggs)

2) Tolerance for temperature / salinity

3) All stages of life poisonous (bufotoxin)

4) Generalist diet (including cat food)

“… one of the 100 worst invasive species worldwide.” Invasive Species

Specialist Group

• Trap / hand catch frogs• Biocontrol (virus)

• Males have tail-like intromittent organ• Highly vascularized cloacal extension

• Tympana absent; do not call

Anatomy:

• Swift mountain streams with cobbled substrate• Primarily aquatic; terrestrial after heavy rains

Ascaphidae (example = Ascaphus truei):

• Internal fertilization (only frog species…)• Inguinal amplexus; ♂ “tail inserted into ♀ cloaca

Reproduction:

• Small clutches of large eggs (place under rocks)

• Tadpoles have suction disks / reduced fins

Amphibians

Aquatic:Northwest United StatesHabitat:

Growth / Maturation:• Metamorphosis ~ 2 – 3 years• Sexual Maturation ~ 8 – 9 years• Life Span ~ 12 – 20 years

• Keratinous, spade-like metatarsal tubercle

Anatomy:

• Found in sagebrush country (shallow burrows)

• Over-winter in self-made burrows (~ 1 m deep)

Pelobatidae (example = Scaphiopus intermontana):

• Explosive breeding; permanent / ephemeral waters• 300 – 500 eggs / female; hatch = 2 – 4 days

Reproduction:

Amphibians

Terrestrial:North America / Europe / Asia / Africa

Growth / Maturation:

• Metamorphosis ~ 1 month

• Sexual Maturation ~ 1 – 2 years• Life Span ~ 10 – 13 years

Habitat:

• Rotund body; short legs; large eyes• Glandular, tuberculate skin

• Survive osmotic stress via urea in body fluids

• Bidder’s Organ: Rudimentary ovary (on male testis)

• Rotund body; dull coloration• Prominent skin glands (toxic - peptides)

Anatomy:

• Various elevations; Close water contact• Over-winter in existing burrows near / in water

Bufonidae (example = Bufo boreas):

• Prolonged breeders; ♂♂ actively search out ♀♀

• Males lack call; “chirp” = release call • ~ 6000 eggs / clutch; laid in double row strings

Reproduction:

Amphibians

Terrestrial:Cosmopolitan

Growth / Maturation:

• Metamorphosis ~ 1 – 2 months

• Sexual Maturation ~ 4 – 6 years• Life Span ~ 10 – 15 years

Habitat:

• Relatively small: 1 – 2 inches in length• Toe discs present• Polymorphic colors; change with temp / humidity

Anatomy:

• Low shrubbery during wet season• Over-winter in moist, cool retreats during winter

Hylidae (example = Hyla regilla):

• Migration to breeding ponds triggered by warm, winter rains

• ♂♂ enter pond, begin calling (attract ♀♀; warn ♂♂)

Reproduction:

Amphibians

Primarily Arboreal:North / Central / South America

Growth / Maturation:

• Metamorphosis ~ 2 months

• Sexual Maturation ~ 1 – 2 years• Life Span ~ ???

Habitat:

• ~ 500 - 750 eggs / clutch; ~ 3 clutches / season

IndicatorSpecies

• Mid-sized body: 2 - 3 inches in length• Long rear legs; exceptional leaping ability• Presence of vocal sacs dependent on sub-species

Anatomy:

• Require riparian vegetation near ponds / streams• Move into upland forest outside of breeding season

Ranidae (example = Rana Aurora ):

• Reproduction occurs November – April (assures cold water)

• Extensive migrations to breeding sites not uncommon

Reproduction:

Amphibians

Terrestrial:Cosmopolitan

Growth / Maturation:

• Metamorphosis ~ 3 – 4 months

• Sexual Maturation ~ 2 – 3 years• Life Span ~ 10 years

• ~ 200 - 1000 eggs / clutch; attached to aquatic vegetation

Habitat:

Red located on lower abdomen / hind limbs

Believed to be inspiration for Twain’s"The Notorious Jumping Frog

of Calveras Country"

Amphibians

Global Distribution of Amphibians

Amphibian Decline:

• Nearly 1/3 of amphibian species are threatened (~ 2000 species)

• ~ 150 species believed extinct over the past several years

• 43% of all species declining in population (< 1% show increases)

Global Distribution of Threatened Amphibians

• Regions:• Latin America (largest #)

• Caribbean (largest %)

• Madagascar• Eastern Australia• Central / Southern China• West Africa

Why are populationsdeclining?

(7 major hypotheses…)

Amphibians

Amphibian Decline - Reasons:

1) Habitat Changes:

Habitat Destruction:

Complete elimination of ecosystemleading to total loss of biological function

California red-legged frog

Habitat Alteration:

Changes to ecosystem thatadversely affect function

Habitat Fragmentation:

Populations isolated due toremoval of linking habitat

Amphibians

Amphibian Decline - Reasons:

1) Habitat Changes:

Habitat Destruction:

Complete elimination of ecosystemleading to total loss of biological function

California red-legged frog

Habitat Alteration:

Changes to ecosystem thatadversely affect function

Habitat Fragmentation:

Populations isolated due toremoval of linking habitat

2) Introduced Species:

Sunfish vs. Red-legged Frog / Pacific Tree Frog Bullfrog vs. Anything that moves

Amphibians

Amphibian Decline - Reasons:

3) Overexploitation:

4) Climate Change:

Red-legged Frog:Prized for legs

(~ 80,000 harvested / year)

Illicit Pet Trade(Goliath Frog ~ $3000)

• Education (e.g., dissection)

• Research• Bait

Breeding earlier than usual…

Wood Frog – New York Great-crested Newt

Drought

Amphibians

Amphibian Decline - Reasons:

5) UV Radiation:

Pacific Tree Frog:Developmental and physiological abnormalities and reduces larval

survival

6) Chemical Contamination:Atrazine (herbicide):

Disrupts steroidogenesis resulting in demasculanization and hermaphroditism

Acidification:

Reduced hatching success

Nitrogen Pollution:

Reduced feeding activity, swim less vigorously,Display disequilibrium, development malformations

7) Disease:

Common FrogVirus

Yellow-legged FrogBacteria

Western ToadWater Mold

Pacific Tree FrogTrematodes

Amphibians

Amphibian Decline - Reasons:

5) UV Radiation:

Pacific Tree Frog:Developmental and physiological abnormalities and reduces larval

survival

6) Chemical Contamination:Atrazine (herbicide):

Disrupts steroidogenesis resulting in demasculanization and hermaphroditism

Acidification:

Reduced hatching success

Nitrogen Pollution:

Reduced feeding activity, swim less vigorously,Display disequilibrium, development malformations

7) Disease:

Common FrogVirus

Yellow-legged FrogBacteria

Western ToadWater Mold

Pacific Tree FrogTrematodes

Synergisms most likely at work…