Endocrine Axis:
HP-prolactin/growth
Negative and positive
Endocrine regulation:
1. Larval growth high:
+ve PrL, -ve TRH inhibited
Metabolic effect
Growth hormones
Endocrine Axis
Thyroid-Growth
+ve
+ve Prl
-ve
3. Prl
2.Growth
drops
slows
T3 -ve
Endocrine T3
Cascade:
Tissue
specific
Aquatic
larval
phase
Monoidonase
TSH
Endocrine
Organ:
PrRH
4.TRH
inhibition
released
LEGEND
Hypothalmus
(PrRH or TRH)
Pituitary
(Prl or TSH)
+ve Endocrine Axis
HP-thyroid
T4
α and β nuclear
receptors (retinoid X) Thyroid
Prolactin
Releasing Hormone
Prolactin
T3 induces
Metamorphosis
Tissue specific effects:
cell death (gills, tail fin)
pigmentation (melanin)
lung development
skull remodeling
hyoid remodeling
Prl
Thyroxine
Releasing Hormone
TRH
Thyroxine
Stimulating Hormone
TSH
Thyroxine
gene transcription:
reorganize larval form
PrRH
T3, T4
Hierarchical Structure of
the Endocrine System:
1. Endocrine
Organ
Terrestrial
adult phase
Adult
2. Endocrine
Cascade
3. Positive-Negative
+ve
Feedback Loops
are made up of 3 -ve
endocrine axes
a) EVOLUTION of LIFE CYCLE STATES
of the SALAMANDER FAMILIES
Yolky Eggs
Aquatic
Larvae
M
M*
Desmognathus
M Metamorphosis
P Paedomorphosis
D Direct Development
Terrestrial
Adult
Aneides
Terrestrial
Adult
Ensatina
D
Plethodon
Eurycea
Plethodontidae (M, P, D)
P
Paedomorph
Pseudotriton
Bolitoglossa
Thorius
D
Terrestrial
Adult
Batrachoseps
Amphiumidae (P)
P
Adult
Ambystoma
M
Axolotl
Adult Ambystoma
Aquatic
Larvae
Paedomorphic
Adult
Axolotl
P
M
Salamandridae (M, P)
Hynobiidae (M)
Anura (Frogs)
Larva
Dicamptodontidae (M, P)
Adult
Larvae
Cryptobranchidae (P)
Sirenidae (P)
P
OUTGROUPS
Eurycea
Ambystomatidae (M, P)
Proteidae (P)
P
M
Rhyacotritonidae (M)
Aneides
Hyrdomantes
Ensatina
Anura (Frogs)
Gymnophiona (Caecelians)
Desmognathus Hemidactylium Bolitoglossa
Bolitoglossa
Option 2
Free Tongue
Adult
Miniaturisation
Larva
Adult
M*
M
M
D
Option 1
Free Tongue
Embryo
D
D
Larva
M
Adult
Larva
M
Adult
Embryo
Atavism
Hypothetical Ancestral State
Thorius
Adult
Option 2
Free Tongue
b) TONGUE and HYOID
EVOLUTION in the
PLETHODONTID
SALAMANDERS
a. Ancestral Complex Metamorphosis
b Collapse of adult trade-offs in paedomorphs
LARVAL GROWTH
Metabolic effect
Growth hormone
WATER DRIVE
PrRH
Prl
Prl
PrRH
Hypothalmus
Pituitary
TRH
-ve
TSH
Metabolic effect
PROLACTIN
Prl
LARVAL GROWTH
WATER DRIVE
Metabolic effect
PROLACTIN
Metabolic effect
PROLACTIN
T3 -ve
MUTATION
Thyroid
Adrenal
Aquatic
larval
phase
Metamorphosis
size
timetludA
larval
survival
Thyroid
LEGEND
Gonad
Reproductive
Effort
Adrenal
Prolactin
PrRH
Releasing Hormone
T3
Prolactin
Prl
Thyroxine
T3, T4
Hierarchical Structure of
the Endocrine System:
Migratory
distance
1. Endocrine
Organ
2. Endocrine
Cascade
T3
disabled
Aquatic
adult
phase
Migration
Life history
trade-offs collapse
d. Complex metamorphosis with an alternative paedomorph strategy
LARVAL GROWTH
Metabolic effect
Growth hormone
Behavioral effect
PROLACTIN
WATER DRIVE
Prl
Prl
-ve
TSH
TSH
PrRH
PrRH
Hypothalmus
Pituitary
TRH
Prl
Metabolic effect
PROLACTIN
T3 -ve
Thyroid
Thyroid
Adrenal
size
Gonad
Reproductive
Effort
Adrenal
Aquatic
larval
phase
Metamorphosis
size
No T3
Terrestrial
adult phase
Adult
survival
Maternal
Care
Trade-offs associated with adult
reproduction such as offspring
quality and care are elaborated
Gonad
Reproductive
Effort
T3
quantity quality
time
Life history trade-offs
associated with
aquatic larvae collapse
quantity quality
Adult
survival
aquatic
adult
survival
MATERNAL CARE
HP
Metamorphosis
tludA
time
Terrestrial
adult phase
Life History
Trade-off
c. Adult Trade-offs Associated with Direct Development
Metabolic effect
Growth hormone
Gonad
Reproductive
Effort
T3
larval
survival
3. Positive-Negative
+ve
Feedback Loops
-ve
Life history trade-offs associated
with complex life cycles
LARVAL GROWTH
Aquatic
larval
phase
size
Terrestrial
quantity quality
adult phase
Adult
survival
larval
survival
HP
larval
survival
timetludA
Terrestrial
quantity quality
adult phase
Adult
survival
Aquatic
adult
phase
aquatic
adult
survival
Migratory
distance
Life history trade-offs associated
with complex life cycles
ROAD MAP FOR ENDOCRINE EPISTASIS:
Physiological causes of life history plasticity and trade-offs
and alternative pathways in larval spadefoot toads
2. Biotic Inputs
(e.g., crowding)
1. Metabolic Inputs (e.g.,
growth hormone and prolactin)
PrRH Hypothalamus-
Prl
+ve
3. Abiotic Inputs
(e.g., water level)
TRH
Prl
TSH
Pituitary
CRH
ACTH
TSH
+ve
-ve -ve
T3 B
+ve
T3 -ve
T3
Monoidonase
Tissue
specificity
T4
α and β nuclear
receptors (retinoid X)
Thyroid
B
gene transcription
Eat Fairy Shrimp
Exogenous T 3
I nd
uc
ti
Life history
plasticity
on
e
ivor
Carnivore
LEGEND
keratenized
beak
Hypothalamus-Pituitary Hormones:
jaw muscles
larval
survival
gut length
cannibalism
vs. social
Slow development
Fast
Thyrotropin Releasing Hormone
Corticotropin Releasing Hormone
Prolactin Releasing Hormone
Thyroid Stimulating Hormone
Adrenocorticotropic hormone
Prolactin
Steroid Hormones:
Corticosterone B
kin
altruism
TRH
CRH
PrRH
TSH
ACTH
Prl
Octopeptides:
Thyroxines T3 T4
Hierarchical Structure of
the Endocrine System:
rate
size
Gonadal
rn
Ca
INDUCED
TRAITS:
Adrenal
of
Alternative pathways
for larval development:
Omnivore
B
Stress
1. Endocrine Regulatory
System/Organ(s)
time
2. Endocrine
Cascade
juvenile
survival
larval survival and size and time to
metamorphosis and survival
costs of kin
altruism
LARVAL LIFE HISTORY
TRADE-OFFS
SOCIAL
TRADE-OFFS
3. Positive-Negative
Feedback Loops
Life History Trade-off
-ve
+ve
ROAD MAP FOR ENDOCRINE EPISTASIS:
Life-history trade-offs and plasticity in
reproduction of side-blotched lizards
Biotic Inputs
Social crowding by
female morphs
LEGEND
Hypothalamus-Pituitary Hormones:
Gonadotropin Releasing Hormone GnRH
Thyrotropin Releasing Hormone TRH
Corticotropin Releasing Hormone CRH
Abiotic Inputs
(e.g., photoperiod
triggers reproduction)
Thyroid Stimulating Hormone
Follicle Stimulating Hormone
Luteinising Hormone
Adrenocorticotropic hormone
HypothalamusPituitary
FSH
LH
ACTH
Life history
plasticity
Steroid Hormones:
Corticosterone B
Testosterone T
Estrogen E
GnRH
CRH
+ve
+ve
-ve B
Stress
-ve
E
T
B
Energy
+ve
Adrenal
Hierarchical Structure of
the Endocrine System:
FSH
LH
1. Endocrine Regulatory
System/Organ(s)
Gonadal
Life history
tradeoffs
Liver cells
E
Immune function
Cell-mediated
Humoral
FSH
3. Positive-Negative
Feedback Loops
Vitellogenin
Reproductive
Effort
MHC
2. Endocrine
Cascade
Follicles
FSH
ERE
B
TSH
FSH
LH
ACTH
-ve
+ve
Life History Trade-off
Yolk
Yolk
Clutch
Size
Egg
Size
Progeny
Survival
dispersal
philopatry
altruism
Female
Survival
COSTS OF REPRODUCTION
TRADE-OFF
OFFSPRING QUANTITY
VS. QUALITY TRADE-OFF
SOCIAL
TRADE-OFFS
Density-dependent survival trade-offs
r-strategist
oo genotype
K-strategists
yy genotype
bb genotype