Anurans in the semi-arid Caatingas: convergence,divergence, and implications for global warming

Carlos A. Navas

Universidade de São Paulo - Brazil

* According to models by J. Marengo et al., CCST/INPE - Brazil

Projections of Climate Change in North Eastern Brazil for 2010-2100*

- Rainfall reduction, more intense by 2071-2100.

- Increase in air temperature by 2-3 C in 2010-2040, and by more than 4 C by 2071-2100.

- Increase in the frequency of hot days and nights, and heat waves.

- Water deficits varying between 2-3 mm/day in 2010-2040 and 6-9 mm/day by 2071-2100.

- Aridization and possible desertification in parts of the semiarid land

I - Why caatingas, why anurans

Brazilian Institute for Geography and Statistics

Two-

mon

th p

erio

d

Year Interval for prediction

More rain

Less rain

Models by J. Marengo et al., CCST/INPE - Brazil

Rhinella granulosa

Corythomantis greeningi

Phyllomedusa nordestina

Dendropsophus minutus

Scinax eurydice

Leptodactylus ocellatus

Proceratophrys cristiceps Physalaemus gracilis

Pseudis bolbodactyla

Adenomera sp.

Dermatonotus muelleri

Rhinella jimi

Despite its semi-arid nature , the Caatinga is home to 40+ anuran species

After aridizationBefore aridizationAfter further aridization?

Likely, anurans have colonized the Caatinga via permanence during a process of aridization lasting 10000 years

So, why Caatingas, why anurans…

• Caatingas are a recent semi-arid biome, present only in Brazil and in great risk due to climate change. Anurans are expected to be at particular risk in the predicted scenarios.

• The anuran community of the Caatingas reflects a diverse and evolutionarily-recent subset of lineages derived from Cerrado, Atlantic Forest and Amazonian Rainforest.

• We do not know if these species and populations differ from related stock from more moderate biomes.

Why Caatinga anurans are vulnerable to climate warming

and eventually…

Why semi-arid anurans are vulnerable to climate warming

What is next? How to start?

• Do Caatinga anuran species share enough aspects of natural history as to propose valid generalizations about how they will be affected by climate change?

• Valid generalizations: common consequences of climate change due to shared aspects of natural history and physiology.

Can we propose valid generalizations for anurans is the Caatinga?

Conservation of habits and physiology? Leptodactylus ocellatus

RH= 40%

Humid cotton fluff

Navas, Jared et al. 2002

Some species displays integrated physiology and behavior that result in keen ability to detect humid microhabitats

Specialization on microhabitat selection and sensorial physiology?Corytomantis greeningi

1 cm.

Prates & Navas, 2009

Habitat generalist specialized on water uptake?Bufo jimmi

Behavioral conservation and physiological specialization?Juvenile R. jimmi and R. granulosa

B. calamita, M. Emmers

B. marinus, R. Shine

B. americanus, Lookoutnow

B. alvarius, J.P. Clare B. Boreas (Wildherps)

B. granulosus, C. Jared

> 45 °C

Navas, Carvalho et al., 2007

CS

resid

ual acti

vit

y(%

of

norm

al at

30

oC

)

Incubation time at 50oC (min)

R. granulosa

R. jimi

R. icterica

R. granulosa (juvenile)

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70

Behavioral conservation and physiological specialization?Juvenile Bufo jimmi and B. granulosus

Is water proofing enough? Phyllomedusa

?

P. bicolorAmazonian forest

P. distinctaAtlantic forest

P. burmeisteriSemi-deciduous forest

hypochondrialis group

burmeisteri group

P. ayeayeCerrado (restricted)

P. nordestinaCaatingasP. azurea

Chaco, Cerrado

Aestivation seems diverse among Caatinga anurans

Proceratophrys, Dermatonotus and others, Typical aestivation?

Pleurodema, Atypical aestivation?Bufo jimmi, no aestivation?

Bufo granulosus, facultative aestivation?

0.0

25.0

50.0

75.0

100.0

125.0

4 6 9Time after last rain (months)

Dep

th (

cm)

Pereira et al., não publicado

0.00

0.10

0.20

0.30

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0.50

Active Aestivating

Sp

ee

d (

m/s

)

0.0

6.0

12.0

18.0

24.0

30.0

Rains DroughtSo

lub

le P

rote

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tra

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(mg

/g o

f h

um

id t

issu

e)

Possible specialization: Aestivation with vertical migration in Pleurodema

90% RH

• Anuran life in the Caatinga involves behavioral, ecological and physiological traits that vary in relative importance among lineages.

• Due to microhabitat choice and behavior, species are likely to differ in the type and magnitude of physiological challenges.

Conclusions

Proposal

• Rainfall reduction Microhabitat specialists

• Increase in air temperature by 2-4 C Spp. with diurnal juveniles

• Water deficits (longer dry seasons) Typical aestivators

• Aridization and possible desertification Refugia specialists

Predicted climatic change Expected highest impact

•Given this diversity, it is difficult to generalize about consequences of climate change for Caatinga anurans. •The most productive generalizations regarding impact of climate change on semi-arid anurans may be based on ecological convergence across lineages.

Cited collaborators

Carlos Jared (Butantan)Marta Antoniazzi (Butantan)Fernando R. Gomes (UNESP)Jose E. Carvalho (UNESP)Hanna Suzuki (Butantan)Titon Braz Jr. (UNESP)Monique Simon (USP)Isabel C. Pereira (USP)Ivan Prates (I. Butantan)

Field assistance

Francisco de Assis Rodriguez

Research Program on Global Climate Change