Effects of salinity on l ife history traits of amphibians Reporter: Wan-Tso Hsu Advisor: Dr. Yeong-Choy Kam.

Effects of salinity onEffects of salinity on llife history traits of ife history traits of

amphibiansamphibians

Reporter: Wan-Tso Hsu Reporter: Wan-Tso Hsu Advisor: Dr. Yeong-Choy KamAdvisor: Dr. Yeong-Choy Kam

ContentsContents

Amphibian life history traits Amphibian life history traits

Effect of salinityEffect of salinity

The adaptation to salinityThe adaptation to salinity

ContentsContents

Amphibian life history traits Amphibian life history traits



Amphibians have a Amphibians have a complex life historycomplex life history

Postmetamorphic life stage could be affected bPostmetamorphic life stage could be affected by an associated trait from premetamorphic life y an associated trait from premetamorphic life stage experiencing a different habitats.stage experiencing a different habitats.

““The time of larval period and weight at metaThe time of larval period and weight at metamorphosis can be predict adult amphibian’s sumorphosis can be predict adult amphibian’s survival and success of matingrvival and success of mating.”.”

(Deban & Marks, 2002. Relyea & Hoverman, 2003)

Traits at metamorphosis Traits at metamorphosis are very important to future fitnessare very important to future fitness

(Smith & Gill, 1978)

Adults can escape the extreme environment, Adults can escape the extreme environment, but larvae can not.but larvae can not.

http://www.tooter4kids.com/Frogs/life_cycle_of_frogs.htm

Environmental factors influencing Environmental factors influencing life history traitslife history traits

FoodFood TemperatureTemperature pHpH PredatorsPredators DensityDensity

(Newman, 1992)

Environmental factors influencing Environmental factors influencing life history traitslife history traits

SalinitySalinity

(Gomez-Mestre & Tejedo, 2005)

In a high salinity In a high salinity environmentenvironment

Salt : Na, Cl,

K, Ca …

Permeable skin makes ionic balance difficult

ContentsContents

Amphibian life history traitsAmphibian life history traits



ContentsContents


Effect of salinityEffect of salinity SurvivalSurvival Development and growthDevelopment and growth MetamorphosisMetamorphosis


ContentsContents




Survival in different salinities Survival in different salinities Litoria ewingii

(Chinathamby et al 2006)

http://www.frogsaustralia.net.au/frogs/display.cfm?frog_id=151

48-hr survivorship of tadpoles Rana limnocharis

0 3 5 7 9 11 130

20

40

60

80

100

Su

rviv

ors

hip

(%

)

Water Salinity (ppt)

Green Island Orchid Island Guoshin Tongsiao

(Wu, Unpublished)

ContentsContents





Ionic concentration in Ionic concentration in different salinities different salinities

http://www.herpetofauna.at/amphibien/bufo_calamita.php

Bufo calBufo calamitaamita

Increase as salinity rises

0ppt 6ppt 8ppt P

Na(μmol) 3.86 ± 0.18 4.30 ± 0.17 5.07 ± 0.18 <0.001

Cl (μmol) 5.20 ± 0.20 5.89 ± 0.19 6.74 ± 0.20 0.04


Glucose and protein Glucose and protein concentration in different concentration in different

salinitiessalinities

Decrease as salinity rises•Spend a lot of energy in osmoregulation•Lower metabolic rate in saline water

Glucose (μmol) 0.55 ± 0.4 0.43 ± 0.5 0.36 ± 0.4 0.012

Proteins (mg) 0.92 ± 0.5 0.60 ± 0.4 0.6 ± 0.5 <0.01

0ppt 6ppt 8ppt P


Development in different salinitiesDevelopment in different salinities

0 ppt

6 ppt

8 ppt

a

b

b


Larval period in different salinitiesLarval period in different salinities

0 ppt 8 ppt6 ppt

a

bb

Tadpole growth in different salinitiesin different salinities Rana limnocharis

0 1 2 3 4 5 6 7 8 9 10 11 120.00.10.20.30.40.50.60.70.80.91.01.1

0 ppt 3 ppt 5 ppt 7 ppt 9 ppt 11 ppt

(Wu, Unpublished)Time (weeks)

Wei

ght

(g)

Tadpole development in different salinitiesin different salinities Rana limnocharis

0 1 2 3 4 5 6 7 8 9 10 11 122224262830323436384042

0 ppt 3 ppt 5 ppt 7 ppt 9 ppt

Dev

elo

pm

enta

l sta

ge

Time (weeks)(Wu, Unpublished)

ContentsContents




Thyroid hormone is important to Thyroid hormone is important to metamorphosismetamorphosis

Thyroid Thyroid gland gland

Thyroid hormone T3 Thyroid hormone T3 in in different salinitiesdifferent salinities


T3 decrease as salinity rise at Gosner 38 and 42

Thyroid hormone T4 Thyroid hormone T4 in in different salinitiesdifferent salinities


T4 increase as salinity rise at Gosner 38 and 42

Metamorphic time & mass in different salinitiesMetamorphic time & mass in different salinities

(Chinathamby et al 2006)

a

*

aa

aa

bb

b

bc

A B

0 3 5 7 90

10

20

30

40

50

60

70

80

Tim

e (d

ays)

Water salinity (ppt)

BCBC

AC

A

A

0 3 5 7 9

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8


Siz

e (g

)

D

CDAC

B

A

Time Size

(Wu, Unpublish)


When is the best time for metamorphosis ?

MIN

Time

Siz

e

High salinity

Low salinity

MAX

When is the best time for metamorphosis ?

MIN MAX

Metamorphic size and time are Metamorphic size and time are plastic to amphibian larvaeplastic to amphibian larvae

MIN

MAX

plasticity

Time

Siz

e

Extreme high salinity

Low salinity

high salinity

0 3 5 7 90

10

20

30

40

50

60

70

80

Tim

e (d

ays)


BCBC

AC

A

A

0 3 5 7 9

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8


Siz

e (g

)

D

CDAC

B

A

Time Size

(Wu, Unpublish)


Benefit and cost of plasticityBenefit and cost of plasticity

Plasticity helps to avoid rapid change in enviroPlasticity helps to avoid rapid change in environmental conditions.nmental conditions.

But small adult amphibians may not survive beBut small adult amphibians may not survive better or have lower reproductive succees in the ftter or have lower reproductive succees in the future.uture.

(Semlitsh, R.D. 1987)

When a population is restricted at a When a population is restricted at a brackish habitatbrackish habitat

ContentsContents




How to test plasticity or How to test plasticity or adaptationadaptation

“Distinction between genetic variation and environmentally induced phenotypic variation is best made using reciprocal transplant experiments.”

(Reznick and Travis 1996)

Transplant experimentsTransplant experiments

Fresh Saline

Fresh water population

Saline water population

Three outcomesThree outcomes Population genetic basis

low high

survival

salinity

high

low



Three outcomesThree outcomes Environment phenotypic plasticity

low high

survival

salinity

high

low



Three outcomesThree outcomes

Interaction Local adaptation

(Alonso et al. 2001)low high

survival

salinity

high

low



Local adaptation of an anuran amphibian to osmotically stressful environments

Fresh Saline




Embryonic survival

Fresh 6 ppt 8 ppt

Embryonic survivalEmbryonic survival

Fresh 6 ppt 8 ppt Fresh 6 ppt 8 ppt

Fresh 1

Fresh 3

Fresh 2

Saline

CV=80.9 CV=132.1

CV=90

CV=37.6

Larval survivalLarval survival

Fresh Saline Saline

P = 0.943

P = 0.09 P < 0.001

Larval survivalLarval survivalfresh brackish brackishfresh

Fresh 1

Fresh 3

Fresh 2

Saline

Salinity–population interaction Local adaptation

low high

survival

salinity

high

low



SummarySummary

Water salinity represents an environmental stress for many species of amphibians

High salinity decrease larval survivalHigh salinity decrease larval survival

Metamorphic time and size of amphibian Metamorphic time and size of amphibian larvae are plastic in different salinitieslarvae are plastic in different salinities

SummarySummary

Larvae at a low salinity will metamorphose at Larvae at a low salinity will metamorphose at the maximum size.the maximum size.

Larvae at a extreme high salinity will Larvae at a extreme high salinity will metamorphose at later at a minimum size.metamorphose at later at a minimum size.

Larvae at a high salinity will metamorphose Larvae at a high salinity will metamorphose earliest at a smaller sizeearliest at a smaller size

SummarySummary

When population migration is restricted, selectWhen population migration is restricted, selection under extreme habitats lead to local adaptaion under extreme habitats lead to local adaptation.tion.

Results of transplant experiments showed population–salinity interactions, suggesting local adaptation in R. calamita.

Thanks for your attentionThanks for your attention

DevelopmentDevelopment

Adult amphibians increase in their osmotic conAdult amphibians increase in their osmotic concentrationcentration urine retentionurine retention accumulation of electrolytesaccumulation of electrolytes enhanced urea synthesisenhanced urea synthesis

(Gordon 1962; McBean and Goldstein 1970)

0 3 5 7 90

10

20

30

40

50

60

70

80

ABABABB

A

Tim

e (

day

s)


Orchid Island: As salinity increased, size at metamorphosis decreased

0 3 5 7 90.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

C

BBB

A

Siz

e (

g)


Time Size

(Wu, Unpublish)

PlasticityPlasticity

Environmental heterogeneity tends to increase the phenotypic plasticity of traits, with phenotypes optimized to the particular conditions on each environment.

(Rawson and Hilbish 1991; Sultan and Spencer 2002)

PlasticityPlasticity

When gene is affected by variation of environWhen gene is affected by variation of environments, genotype will lead to multiple phenotypments, genotype will lead to multiple phenotypeses Life historyLife history Metamorphic size and timeMetamorphic size and time behaviorbehavior physiologyphysiology

(Miner et al. 2005)

High salinity tolerant speciesHigh salinity tolerant species

http://www.hlasek.com/bufo_viridis_da1531.html

Bufo viridis

http://www.britannica.com/eb/art/print?id=4886&articleTypeId=0

Xenopus laevis

http://www.froghome.idv.tw/html/class_1/rana_cancrivora.html

Rana cancrivora

AdaptationAdaptation

““Different phenotypes among populations can Different phenotypes among populations can be considered adaptive if they have a genetic be considered adaptive if they have a genetic basis, and they confer fitness advantage in a basis, and they confer fitness advantage in a given environment.”given environment.”

(Endler 1986; Sinervo and Basolo 1996)

Wilbur and Collin’s modelWilbur and Collin’s model

W > b

dW

Wdt

Additional growth

Initiate metamorphosis

W > b+cno

noyes

yes

yes

no

> g

Effects of salinity on l ife history traits of amphibians Reporter: Wan-Tso Hsu Advisor: Dr. Yeong-Choy Kam.

Documents

different habitats

premetamorphic life

best time

salinity rises0ppt

salinity risesspend

effects of salinity

time of larval period

unpublishmetamorphic